What most people don't appreciate is that "grinding gears" isn't damaging the actual gears that transmit power, but the dog teeth on the synchro system.
Makes me appreciate that big truck transmissions generally do not have synchronized gearsets. I had to rebuild an entire transmission when someone had broken the main output shaft in one. No books, no drawings, nothing but brute competence. I will say, the way that they are made with dual or triple countershafts, the design is ingenious. The input and output shaft are only connected by a pilot bearing. The fact that the main output was snapped into two pieces, and the transmission didn’t fly apart is testament to the designer! The countershafts held the gears in their proper location, even though the shaft was toast! No synchronization there, just a good gear matching hand was required!
I have a Kawasaki motorcycle and the factory service manual chapter on repairing the transmission has one line about " paying attention to the mating dogs ". Made me chuckle.
@Franky997 grinding gears on old stuff like '47 chevy, farmall tractors, or cub cadet lawn mowers does damage the actual gear teeth. The whole gear slides to engage
I have overhauled countless gearboxes, measuring gaps and replacing parts, but this is the best explanation of how a gearbox works that I have ever seen.
The cleanest explanation of synchro that I have ever seen. No other video that I have referred has explained the functioning of the key, which in my opinion, brings the whole thing together. Kudos!👏
Thank you. Most comments are similar to yours. I do occasionally get one from someone who is real picky or they just like to knock me down. I appreciate the positive comment.
I wish teachers at school would teach the same way. Amazing video with lots of different presentations, I don't think this could be explained any better than this!!!
This is terrific. Details like the back cut on the engagement teeth on both the synchronizer sleeve and the speed gear, are new to me. This is shown under magnification at 2:15, and is easily missed when you have the parts in your hand. This back cut is what holds the two parts together under load, and prevents the car from popping out of gear. When an older transmission pops out of gear people will tell you with authority and confidence: 'oh, the synchronizer rings are bad'. But the synchro rings have little to do with this function. However when this tiny back cut, on on the engagement teeth of the speed gear or the synchronizer sleeve is worn away, there is nothing left to hold speed gear and sleeve together. In this case a new set of synchro rings will do nothing to fix the problem. And that is very much worth knowing.
Thank you for your comments. Please note that the back cut is not present on all synchronizer sleeves and gears. I see it missing mostly on older transmission designs. There are several reasons why a transmission will jump out of gear and worn out back cut is one of them. Normally what happens is the oil is not changed when it should be and or the driver is rough on the transmission and the blocker rings start to wear causing grinding (gear clash) which in turn chews up the clutching teeth on the gear and on the sleeve which wears away the back cut. It's often a domino effect.
Would be good to explain that the synchro ring is made of brass hence it's gold color. Brass is softer and is sacrificial meaning it will eventually wear out and need replacement. Brass is the perfect companion metal to press against the hard steel gear and do no damage to it as it tries to either speed it up or slow it down so the the synchro hub can slide over and complete the lockup. It's important to remember that the synchronizer assembly must adjust the speed of the entire cluster gear and input shaft including clutch disc in order to perform the lockup into the selected gear. Quite a task and shows why you must have clean clutch release so that the disc is completely free to rotate. This is a very good video, especially with the gear train illuminated with the strobe light to show what happens.
Thank you for your good comments. You are correct. One note. although these blocker rings are brass there are other blocker rings made of other materials and sometimes either lined with a friction material similar to brake lining and others that use a bi-metal design with a sintered metal inner cone that is soft with a high coefficient friction. I will consider a followup video with this additional information.
@@Franky997Can confirm that because some years ago I worked for a company that made synchromesh rings for many of the major European car manufacturers. Selector forks were also made from phosphor bronze, but of a different grade.
Yes. He really has all the fine details down. Gear boxes for Spec Miata racing are rebuilt all the time. However the re-builds tend to have problems. If a rebuilder replaces the bearings, the brass synchro rings, and the seals then the gearbox will shift into gears easily and the box will hold oil, but will it stay in gear? Apparently if the back-cut (2:15 in the video) on the engagement teeth between speed gear and synchro sleeve are worn, these parts need to be replaced too. Someone who is simply installing a 'rebuild kit' will miss this.
You always think there must be an easier way. Loads of engineering and sleepless nights have gone into all these details to run smooth operations. Amazing and well explained. Great work.
As the sleeve moves towards the speed gear, the keys weakly push the blocking ring ahead until the conical friction surfaces make contact. The resulting frictional torque rotates the blocking ring so that it's teeth are 1/4 tooth pitch misaligned with the sleeve teeth which causes contact of the teethes' angled surfaces. This is called "energizing". As well as causing the blocking teeth to block the sleeve, the sleeve can now apply a strong force to the blocking ring via the tooth contact, increasing friction and synchronizing torque.
The best video for ASE, I watched this video 2 times before the test and still didn't pay enough attention. This video need to be watch 3 times for ASE manual transmission test
Thank you! The demonstration of the synchro in action at 7:00 helps it all make sense. (The first part of the video is the nitty gritty of what makes it work. The demo shows it in action.)
Drivemaster, you're the best Master. My language is Portuguese, but I didn't understand the Brazilian videos and I understood your video. I didn't understand how the synchronized ring works but thank for you, I understand now.
This is a very valid question and not an easy concept to understand so let me give this explanation a try. When the sleeve is forced in the direction of the gear to engage then next gear the keys will push on the blocker ring which pushes on the gear. Friction and heat is generated between the blocker ring and the gear. With the heat expansion forces occurs. This expansion from the heat creates a force that pushes the blocker ring and keys back against the sleeve. This force makes it difficult for the sleeve to continue in the direction of the gear until everything is in sync or very close to being in sync. When everything is in sync the friction, heat and resistive force is reduced to a point where the sleeve can now easily slide over and engage with the gear. I hope this makes sense.
@@DrivelineMaster thanks. I did more research today i found that the mass/inertia of the constant mesh gears trying to be slowed by the blocker ring will force the splines to be out of alignment (and unable to engage) until the gear speeds are in sync. Only then can the tapered splines be aligned by the driver pulling the shifter because there is no longer any force "binding" the splines
That is the reason the blocker ring can't immediately synchronize the rotational speed of the gear with the sleeve however it is the friction and the expansion forces that prevent the sleeve from moving over to attempt to lock onto the gear while they are rotating at different speeds.
Kids used to say they could drag race powershift as in brute force abuse without using the clutch, but the way the synchronizer is designed, this is impossible, because the harder you try to force a shift, the harder the synchro will ride up onto the cone and fight to prevent it
After several videos trying to figure this out, I finally get it. Excellent video. Now I wonder if there would be other ways to slow shaft/gear speed. Synchro's are spendy parts "labor wise" to replace. I also wonder what fluid would cause the least amount of wear & still give satisfactory shifting.
I don't want to give the wrong information. Most manual transmissions can not and should not use ATF. ATF can only safely be used in a manual transmission if and only if the service information or owners manual says so. Never use ATF in a manual transmission unless it has been specified by the manufacture as an acceptable winter oil option.
I'll point out that everyone praising how clear this video is then goes on to describe all the transmissions they've rebuilt. So as the only person who's here to learn instead of to see what they already know, I'll say that I completely disagree about the clarity. This is supposed to be about SYNCHRONIZERS / synchromesh. Instead, it's about the entire transmission. Yes, I see that it happens. But I still don't understand what mechanism is locking it. Is it the conical taper? Is it a friction surface? Don't know -- we moved on to naming over half the various components of a transmission without explaining what they are ... which means only people who already know the information will brag about it's clarity. While you're at it, why not define a word using the word you're defining? Do syncros require a particular alignment? Or can they synchronize in any orientation? As in ... they aren't uniform. So does it require at least 1 full rotation to align features? Also ... why can't syncros grind? Because of the taper at the front of the teeth ..? What's the purpose of the conical taper? Is that what synchronizes the mechanism? (Why not spend a little extra time explaining how/when it occurs with each of the mechanisms to drive home the principle that the video was TITLED?) If it's the teeth meshing ... then why don't synchros need synchros? The taper / conical interaction with a friction coating makes sense as to why it wouldn't need synchros. But why would those teeth as animated synchronize without grinding any better than the gears we're synchronizing? When the only people praising your edu are those who are all practical application valedictorians, you should be concerned that you didn't make the content as _introductory_ as your title suggests. There are many fields in which I have expertise, and when I try to explain them to others, the main thing I focus on is the avoidance of jargon, of relying on predicate knowledge that the only people who need the information wouldn't have, and on remembering what it was once like to not know those things; because it's that _empathy for ignorance_ that is lost with the very expertise required to explain the content. Mind you, this was by far better than all the other videos I've yet watched on syncros. So please don't take it as a blanket critique across the board. And clearly, great effort went into this production (and corresponding animation) ... which couldn't have been cheap in either time, money or expertise. All of which I'm grateful for, as this is free content. Please don't mistake my critique as ingratitude. I'm just unwilling to lie and pretend I've gone from being ignorant to being knowledgeable (even rudimentary) from watching it 5-6 times.
I'm sorry this missed the mark for you and all those who are learning but are not familiar with the terminology. A goal of mine is to try and keep the videos high quality and as short as possible and if I have a long winded subject to make it into multiple parts. As someone watching who has not had some formal transmission training or rebuild experience I need to let you know that this is by far not how the entire transmission works and it truly is just about synchronizer operation. A fair amount of viewers have never rebuilt a transmission (Like your) but they may have had some formal training or they are attending a class on manual transmissions and the video helps to clarify what they didn't understand from their instructor. With that said I will try to address your operational questions. The conical tapered surfaces between the gear and the blocker ring when pressed together create friction which will attempt to make them rotate at the same speed which if successful will synchronizing the speed between them. What is not shown is the shift fork, rod, gate, detent, interlock and shifter. Yes, I know these are technical terms that are not defined. Basically these components are responsible for moving the sleeve which pushes on the keys which push on the blocker ring in an effort to synchronize the gear to the blocker ring and synchronizer assembly so a gear ratio change can be made. These videos are about detent and interlock mechanisms and they may help. ruclips.net/video/z7Qht3yOfDg/видео.htmlsi=6cY5W393OPiiq1xL and ruclips.net/video/U7MBaIPoPZ4/видео.htmlsi=CFUVtq0YD9ehFlXk. What holds the gear into engagement (Sleeve locked onto the gear) is a combination of the shifter position (which moves the shift rod, fork and sleeve), the detent mechanism, and the cutback design on the clutching teeth on the gear and sleeve. (Timestamp 4:10.) Synchronizers can be mounted vertically and function but most manual transmission with synchronizers tend to be horizontal in operation. They do not require one full revolution to synchronize and they will work if the vehicle is stopped or going very slow such as in a parking lot (going from reverse to 1st) or during stop and go heavy traffic. The goal of the synchronizer is prevent grinding and it does this by using the friction between the blocker ring (rotating at shaft and synchronizer assembly speed) and the gear rotating at a different speed. Once the two are in sync the clutching teeth between the sleeve and the gear are close enough in alignment to allow the sleeve to move over (from force of the driver pushing on the shifter) locking the two together. The transmission is now locked into the new gear ratio and held there by the design of the clutching teeth and the shifter and detent mechanism and position. If, or when the blocker ring surface wears to a point where it's incapable of providing efficient synchronization grinding between the clutching teeth on the sleeve, blocker ring and gear will take place and can be heard when the driver shifts gears. This is called "Gear Clash". If these teeth become heavily worn down the transmission will pop out of gear (The shifter will move all by itself into neutral) under heavy acceleration. The shifter and detent alone are unable to maintain gear engagement when the clutching teeth are heavily worn from driving a vehicle that has excessive gear clash during shifting. In summary: the conical surface does the synchronization when the shifter is moved but it's not strong enough to handle the torque of the gear ratio. This is why the clutching teeth on the sleeve need to engage and lock onto the clutching teeth on the gear. The synchronizer sleeve is moved through a mechanical shift mechanism when the driver moves the shifter to change gears. The shifter mechanism, detent (see video links) and clutching teeth keep the gear engaged until the driver moves the shifter again for the next gear selection. This was my attempt to clarify your operational questions. The video is what it is and your critique is noted. If you have additional technical operational questions I'm happy to answer them. You might also find these videos helpful. Into to manual transmission power flow and gear ID: ruclips.net/video/aAG8kdw1WEk/видео.htmlsi=MU8s5wGrDLMKGcZ6 Front wheel drive manual transaxle shifter mechanism: ruclips.net/video/odzSu699njs/видео.htmlsi=G2QMd06MzFJxzvpd These videos may also have similar critiques from you since my videos are all designed to support my lectures and assume a minimal amount of automotive transmission nomenclature knowledge. I will keep this in mind when creating new technical content and make an effort to clarify a technical term into everyday language when I feel that it is needed and it won't make the video too long unlike this response.
so, synchronization only works when the car is moving since we need the gears to be spinning correct? engaging first gear from a standstill therefore does not need to be synchronized just like reverse?
Pretty much correct, the synchronization only takes place when the gears are spinning. Even though the car is not moving if your engine is running and the trans is in neutral but vehicle is not moving some of the gears inside the transmission are spinning. If you push the clutch pedal to the floor and move the shifter quickly some synchronization might take place. If on the other hand after you push the clutch pedal to the floor you wait about 30 seconds before moving the shift lever then all the gears will most likely be stopped.
Question: Since the small clutching teeth is what mechanically locks the free spinning speed gear to the shaft and actually transfers the power why dont we see more of those stripped vs the actually gear teeth on high powered cars? It looks like it has much less material engagement would seem to be the weak link. I would also think the narrow sleeve that couples the two together would be prone to strip out before the actual speed gear teeth would strip under high power.
1) the small clutching teeth are already 95% in alignment with the teeth on the gear before the sleeve is allowed to slide onto the gear so there is no grinding. This is accomplished by the proper operation of the blocker ring. When the blocker ring becomes worn out and can no longer perform properly that is when the clutching teeth start the grind during the shift. This is the grinding noise that can be heard by the driver between shifts and is called gear clash. The reason these tiny teeth can handle the torque comes from the total surface area contact between the gear and the sleeve. The number of teeth and the length of the teeth determine the total contact surface area. I'm not an engineer but this is something that has to be engineered into the design. They must determine the maximum torque that the synchronizer and gear would have to be able to handle and how much contact is needed.
Between two gears, only one tooth on each gear is engaged with the other gear at any time. Between the parts of the synchronizer assembly, all of those small teeth are engaged at the same time, spreading the load out between them. Many small teeth are as strong as one large tooth.
That is so cool to see it working like it should. My KW T800 has an 8LL and its synchroniser has been very noisy since the heat exchanger went bad and got water into the transmission.
@@DrivelineMaster I just have changed the incorrect 90 wt for 50 wt motor oil. That by its self worked wonders. It made it possible to where the gear shift would actually move the gears in and out. Before that I could take it out of gear and it would stay in gear. It did that one morning until the oil got warm. I ran it all day, came in and drained that 90 wt while hot and its been better ever since. Everything but the synchroniser. So mine is not slowing the gear down when all that noise is going on? I wonder if the air shifter could be sticky somehow?
Unless the manufacture says you can use motor oil instead of GL4 or GL5 gear oil I wouldn't leave the 50st motor oil in your transmission. 90wt gear oil is not the same as it would be if it was 90wt motor oil. The way they measure thickness for gear oil is different than motor oil. Once again I would recommend the Redline MFT. I know it cost more but it is worth it. Unless your transmission was designed to work with motor oil (like some honda's) you will end up damaging your transmission and costing you more $$$ in the long run.
@@DrivelineMaster It calls for 50 wt engine oil. Granted Synthetic would be better but we just had a cracked head replaced at 6,389.00 on the truck and now the compressor has blown apart on the other truck leaving us stuck with a core fee. Cat wants 1,500.00 just for the core fee alone. Fleet Pride got us a refurbished for little over a grand and no core charge.
As long as the factory specification is 50wt engine oil then that is what you should use and have confidence that you won't cause any damage. This is the first trans that I know about that uses 50 wt straight motor oil.
Not many explanations go into the importance of the key springs and tapers that let the pressure build against the friction ring and bring the gears to the same speed. Then suddenly snap and engage the teeth.... to me that is the most important function of the syncro.
Here you go. The sleeve pushes on the keys which push on the blocker ring. The job of the blocker ring through friction between the ring and the gear is to grab the gear and make it go the same speed (synchronize) so the sleeve can slide over and lock the two together. If the blocker ring is unable to synchronize the gear to its speed a lot of friction is taking place. With more friction more heat is generated. With more heat there is expansion of components. The heat and expansion is a counter force pushing back on the blocker ring. That force on the blocker ring is transferred to the keys and then onto the sleeve. The counter force prevents the sleeve from moving close enough to the gear for the clutching teeth to touch. If the clutching teeth are allowed to touch before synchronization a grinding noise (gear clash) will be heard. Hope this helps.
The best video to explain synchronizer. But I am a little confused, why did the sychronier blocker ring slow down the speed to snchronize with speed gear? It should be reversed, I mean, speed gear speeds up to sych with blocker ring.
When the transmissions is in 1st gear and you shift into 2nd gear (upshift) the speed of 2nd gear is rotating faster because the gear ratio for 2nd gear is a small ratio number such as 1st being 4:1 and 2nd being 3:1. Because the speed of 2nd gear is rotating faster than the output shaft and the synchro in 1st gear the 2nd gear must slow down to match the speed of the synchro and output shaft before it can engage and lock 2nd to the shaft. This happens with every gear change during upshifting. During downshifting this is reversed. The output shaft is going faster than the gear being downshifted into. Such as going from 4th at 1:1 down to 3rd at 2:1. Now when the blocker ring grabs the next lowest gear that gear will need to rotate faster or speed up to match the output shaft speed in order to synchronize. I hope this made sense. Also, those gear ratios are not actual but instead just used as examples to make a point.
Very nicely explained. I have a car Vauxhall Victor FB 1964, has a 3 speed manual transmission, there have always been a problem with 2nd gear, the shifting is not smooth, it makes a noise upon shifting, I have a technique of shifting to 2nd speed smoothly is by jerking the throttle/accelerator pedal twice, and like that the shifting is smooth without noise. Why is that?
You are doing what we call rev matching or revolution matching. By playing with the throttle speed you speed up or slow down the input shaft and counter shaft along with the 2nd speed gear. If you can get that speed close to the speed of the output shaft and synchronizer then engagement will be smooth. You essentially are doing the job of the synchronizer for it because it's worn out.
@@DrivelineMaster thanks a lot for replying. Another question is is the synchronizing rings inner groove worn out or the taper surface of 2nd speed gear worn out? Is the EP Lubricant cause of making bad the yellow synchronizing rings?
Typically it's the brass ring that wears out since it's softer than the hard steel cone on the gear. Wear on the blocker ring can be from multiple reasons and old, contaminated or wrong fluid can play a part in premature wear. Additionally hard driving or poor quality of the original parts. If there is a history of your vehicle having second gear synchronize problems this can point to manufacturing. The fact that this is a 1964 I might contribute this to age as much as anything else. I don't know if you can get the Redline brand of manual transmission fluid (MTF) or not but this is a fantastic synthetic MTF and would be worth a try to change your oil and install this. If not, try to locate another high quality synthetic MTF. i could help.
@@DrivelineMaster, thank you once again for responding. The manufacturer has strictly warned of not using EP (Extreme Pressure) lubricant as EP Lubricant is harmful for synchro mesh mechanism as it contains sulphur which badly harms the brass synchronizing rings, the manufacturer has specified SAE 90 straight transmission oil whereas the mechanics use to put SAE 140 EP poor quality lubricant. It also became bad due to shifting of gears at a very speed by my late father then.
I don't know for sure if the synthetic Manual Transmission Fluid (MTF) from Redline is extreme EP or not but I don't think so. It is rated as a multigrade 75 or 80W -90 grade. What I do know for sure is that I have had several older manual transmissions with gear clash while shifting and replacing the mineral based 90 grade gear oil with this fluid vastly improved shift quality and reduced gear clash grinding. At this point I don't think it would hurt your transmission. Also know I don't work for or have any interest in the Redline product, company or brand. I just know it works and have no problems recommending it.
@@DrivelineMaster ok thanks is the key connected rigidly to the blocker ring? and how are they connecting? and how does the blocking ring return its original position?
Could be several things. As the video shows the teeth with the cut back. if those are worn from years of grinding during gear shifting that can do it. Excessive free play in the shifter linkage or worn detent springs. Depending on how old the vehicle is old 1960 and 1970's vehicles could have misaligned bell housings. I even had a VW once that had the shifter boot installed backward that cause this. You could have worn shift forks or synchronizer sleeves. Anything that would prevent full engagement can cause it to slip out of gear. Holding the shifter ensured the synchronizer stays engaged with the gear.
I have a few quesions, regaring an actual example in the topic. What can cause that I can barely get out of first gear in colder weather? The story a bit more explained: The MX-5 ND's manual recommends 75W90 GL-4 oil if the original oil is not available (which is often te case btw). One might thing that the original oil is also 75w90, but that seems not to be the truth, it's waaaay less viscous than a 75w90. I also put 75w90 in the trans and now even when I start at 15 deg C, it's hard to get out of first gear, I have to shift very eary into second. Also it's nearly impossible to shift into first while the car is moving. Putting the trans into reverse at 0 degress C is barely working. I don't experience any grinding btw. The syncro spec is as follows: 1: Triple Cone with Carbon coating 2: Triple Cone with Carbon coating 3: Triple cone 4: Triple cone 5: Double cone 6: Single cone with Carbon coating R: Single cone The original oil was very "dirty" looked like dark grey paint. Turned out it looked like this for everybody. Honestly it looked like someboday added molybdenium additive to the oil, but that's 100% not the case. So, can these symtoms caused by the more viscous oil? I mean, problems when putting it into gear is is one thing but I can barely get it out from first when above 10 km/h. After driving 4-5 minutes and the trans oil heats up everything feels way smoother again. What does one actually risk when a thicker or thinner oil is used thena what prescribed? Can a molybdenium additibe (LiquyMoly) cause any issues by times? (Synchro issues, and so on) Thanks and any info/explanation or suggestion would be appreciated. Absolutely great video btw.!
First of all 75W90 and 75w90 are supposed to be the same viscosity. the large or small W has nothing to do with it. These oils are tested in a lab at a specific temperature even if you feel they flow differently and one seems thicker than the other. What is critical is that you make sure your oil is GL4 grade. If you put in GL5 or GL4/GL5 this can cause issues. It's also possible that the old gunky lube was holding your trans together and the gunk between the blocker rings and the cones got flushed out with the new lube and the gunk was adding the necessary friction that is needed to shift. Normally the symptoms you describe have more to do with the clutch not disengaging. So let me ask. Can you shift OK with the engine off? If so your clutch might not be fully disengaging or your pilot bearing might be binding on the input shaft. I'm a big fan of Redline Manual Transmission Fluid (MTF). It's synthetic with superior friction qualities. if you can get this you might want to give it a try. Also check the owners manual. When I worked for Mazda some of those transmission would take Dexron Automatic Transmission fluid when the vehicle was being used in cold weather and 75w90 when it was used in hotter climates.
@@DrivelineMaster oh ok. Thanks. The w/W was just a typo. But if the clutch not disengaging then why does it work ok after a few minutes and why did the problem start immediately after the oil change? I think with engine off i chan shift but doesn’t it also depend on the wheel speeds (trans output shaft speed)? What i also can try maybe is to lift the rear put it in 1st and check if the wheels start spinning when i press the clutch pedal. Im not sure but if the clutch is completely disengaged then it should not move the wheels at all, right? Im planning to try something similar you mentioned if I can’t get the original oils. About the gunk. Yes, Im a but afraid that this is one of the issues. What do you think about the molybdenum additives? Is that a bad idea? Btw: the oil i put in was gl4/5. I didn’t think this could be a problem. Motul gre 300 75w90 btw.
Your right that if you had a clutch disengagement problem then the shifting problem should not have started right after the oil change. the W or w was the only difference I saw in your oil specs in your original message. Yes, if you raise both drive wheels, engine running and clutch pedal fully depressed that the drive wheels should not rotate. I once installed Redline 75w90 gear oil in a manual trans and it would not shift worth a darn and it would grind a lot. I took it out and put in Redline 75w90 Manual Trans fluid MTF and it shifted great. It was obvious that these were two different products both labeled 75w90. With the engine off and the vehicle not moving there is nothing to synchronize so shifting should be easy. Also clutch discs can stick to the flywheel or bind on the input shaft when the pedal is depressed. this can cause difficult shifting. Again this does not explain why the problem started just after an oil change. I would not put any additive in the trans unless it says right on the package that it's for manual transmissions. You don't want to make the oil slipperier there needs to be more friction between the oil and the blocker ring cones. If the oil was as bad as you say it's possible you flushed out what was holding the blocker rings to the gear and the clean oil is slipperier.
@@DrivelineMasterJust FYI: the original Mazda oil finally arrived and I put it in the car yesterday. It's WAY less viscous than the 75w90-s I tried before. Shifing is good now even in cold temps, no issuse at the moment.
Im trying better to understand the basics of 90s Honda manual transaxles. Why is the imput shaft gears pressed on and not built into the shaft like rear wheel drive, drive gears? And when changing gears to a custom ratio sometimes only the driven gear gets changed. If your changing the ratio wouldn't both gears need to be changed? Thank you
Normally when a gear is pressed onto a shaft as compared to being part of the shaft it's because the gear needs to come off in order to remove or install something else. It's for assemble and disassemble purposes. Normally when there is a ratio change both gears are replaced. I don't see how it is possible to only change one gear. Let's say you want more low end torque and you want to change from a 3.5:1 1st gear to a 4:1 first gear. The input shaft gear must get smaller but in order for it to mesh properly with the output shaft that gear must be bigger. I have never done a ratio change on a Honda but it doesn't make logical let alone mechanical sense.
Who on Earth came up with this? I rebuilt two entirely different manual transmissions years ago. One on my '64 GTO and one on a '68 Ford Cortina. The inventors need a Nobel Prize in transmission design.
Hay I have a 2008 dodge ram 1500 with a manuel 238 Getrag 6speed transmission in it. I'm have the same problem with second gear. Where can I find the parts for a 238 getrag and can I replace it with another manuel.
Unfortunately I don't have a source for that transmission. I once had a Getrag from a Toyota Supra and not even Toyota sold replacement parts short of an entire transmission. You can try West Coast Standard or midwest trans (www.midwesttrans.com/product-information/getrag-238-6-speed-rebuilt-manual-transmissions). try searching the internet using "getrag 238 rebuild kit" as your key words.
One perhaps ignorant question on the final demonstration. What is the gear on the far left of the video? I assume it looks like the speed gear, and maybe I'm not adequately understanding the relationship between the speed gear and the speed gear clutching teeth.
I believe that was 1st gear speed gear. The speed gear and the speed gear clutching teeth are all part of one gear assemble. The speed gears area also the free spinning gears check out from time stamp 2:44 to view the speed gear AKA free spinning gear.
I'm trying to wrap my head around why the synch is free to rotate +/- 10º with respect to the sleeve, and why the synch has external teeth at all. I understand these two features are related. However, it seems that if the synch could NOT rotate that 10º, and if it did NOT have the external teeth - it would still work. The keys would still push the synch up against the speed gear cone, slowing/speeding it appropriately, allowing the sleeve to pass over the synch and onto the dogs of the speed gear...?? It seems to me that once the synch has brought the speed gear to an rpm that matches the output shaft rpm, it's only random chance if the dogs of the sleeve, synch and speed gear will actually be in alignment. I'm assuming this is on purpose and is why the synch is often referred to as a "blocker". Part of it's function is to specifically misalign with the sleeve so the sleeve may NOT be pushed further toward the speed gear. But I don't see how this can be controlled by anything other than chance (and I know it's not...).
The slight rotation of the synchronizer blocker ring and the teeth improve synchronization and engagement when the sleeve moves over for the mechanical connection. When the sleeve starts to move the first set of teeth it engages are on the blocker ring. If those teeth are not in perfect alignment with the sleeve teeth the ring will rotate slightly to make a perfect alignment. When the ring moves slightly it will also attempt to move the gear as well in an effort to provide a perfect alignment between the sleeve and the dog teeth on the gear. The blocker ring teeth and slight movement are required for this to happen. Additionally the extra teeth on the blocker ring adds additional holding or load caring capabilities. Yes, it could work if it was fixed and didn't have teeth. This is the best I can offer. I'm sure there is an engineering explanation that is beyond my capabilities. I hope this helps.
@@DrivelineMaster I appreciate your thoughtful reply; thank you. I do have some questions/comments though: While the speedgear is NOT at a matched speed, when the synch is pressed against the speedgear cone, isn't the synch going to be at one of the extreme ends of its shift key notch? For it to impart any rotational friction onto the speedgear, the synch needs to be supported by something ; the shift keys. So during friction/synchronization, the synch will be misaligned with the dogs in the sleeve. Right? Meanwhile, as force continues to be applied on the gear stick, force continues pressing the synch up against the speedgear cone... So what would then cause the synch to unlock from the cone and allow it to rotate so that it can be centered on its shift key notches, and come into alignment with the dogs in the sleeve? Where would this "reversing torque" on the synch come from, that would re-center it?
GREAT Questions which causes me to search the depth of my understanding of the working application. Let me give this a shot since I will be applying functional operation with mechanical logic which doesn't always come out to be true but more often than not it has served me well. What you said.... All true except I don't believe the blocker ring would break adhesion from the speed gear as the sleeve moves to engage. Once the speed gear is in sync as the sleeve moves over if the dogs are not in perfect alignment and a shift is required for perfect alignment the blocker and speed gear will rotate together for alignment. At this point the blocker dog teeth can be aligned with the sleeve. If the dogs on the speed gear are still misaligned the sleeve will be engaged with the blocker ring but not the speed gear. Pressure that the keys are applying is reduced to reduce the friction force between the speed gear and the blocker ring. The reduction in force on the blocker is caused by the keys being moved down (inwards towards the center of the shaft) against the key springs as the keys are no longer centered in the key raised portion that is fitted into the recess in the sleeve. When the keys are moved inward against the spring the force from the sleeve pushing the blocker against the speed gear is reduced enough for the points on the dog teeth to shift the speed gear separately from the blocker ring a slight amount to create perfect alignment. You make a good point about the blocker being seated against one edge of the slot on the blocker. This makes me want to look at several synchronizes to see if the blocker ring dog teeth are in perfect alignment with the sleeve when the blocker is rotated fully in either direction. If they are in perfect alignment when rotated to the extreme in either direction this would make a lot of sense. This recent discussion about the more in depth details of synchronization makes me what to create a followup video to address these more in depth questions that my viewers have asked me.
@@DrivelineMaster I love that you take viewer input to try and understand the mechanical logic better, to try and explain better. I saw your videos and you haven't made that follow up video on advanced manual synchro function, are you still planning on making it?
I was hoping someone wouldn't call me on that. I'm under Shelter in place orders right now but Yes, I do plan on a followup video for more advanced synchronizer explanation.
![BRASIL vs. URUGUAY [1-1] | RESUMEN | ELIMINATORIAS SUDAMERICANAS | FECHA 12](http://i.ytimg.com/vi/-hWBAuxF1eY/mqdefault.jpg)
What most people don't appreciate is that "grinding gears" isn't damaging the actual gears that transmit power, but the dog teeth on the synchro system.
You are absolutely correct.
Makes me appreciate that big truck transmissions generally do not have synchronized gearsets.
I had to rebuild an entire transmission when someone had broken the main output shaft in one.
No books, no drawings, nothing but brute competence.
I will say, the way that they are made with dual or triple countershafts, the design is ingenious.
The input and output shaft are only connected by a pilot bearing.
The fact that the main output was snapped into two pieces, and the transmission didn’t fly apart is testament to the designer!
The countershafts held the gears in their proper location, even though the shaft was toast!
No synchronization there, just a good gear matching hand was required!
I have a Kawasaki motorcycle and the factory service manual chapter on repairing the transmission has one line about " paying attention to the mating dogs ". Made me chuckle.
Not if you have old stuff with slider gears
@Franky997 grinding gears on old stuff like '47 chevy, farmall tractors, or cub cadet lawn mowers does damage the actual gear teeth. The whole gear slides to engage
I have overhauled countless gearboxes, measuring gaps and replacing parts, but this is the best explanation of how a gearbox works that I have ever seen.
Thanks for the compliment.
Using a strobe light to see gears at speed mesh, Brilliant!
Works just like a timing light
This was really well explained. The video at the end really capped it off and pulled it all together for me. Thanks.
Best and only video of a synchronizer in live operation that I've seen.
The cleanest explanation of synchro that I have ever seen. No other video that I have referred has explained the functioning of the key, which in my opinion, brings the whole thing together. Kudos!👏
Thank you. Most comments are similar to yours. I do occasionally get one from someone who is real picky or they just like to knock me down. I appreciate the positive comment.
I wish teachers at school would teach the same way. Amazing video with lots of different presentations, I don't think this could be explained any better than this!!!
Really sir you said true thing
Given the hard job, its a reasonably good explanation.
This is terrific. Details like the back cut on the engagement teeth on both the synchronizer sleeve and the speed gear, are new to me. This is shown under magnification at 2:15, and is easily missed when you have the parts in your hand. This back cut is what holds the two parts together under load, and prevents the car from popping out of gear. When an older transmission pops out of gear people will tell you with authority and confidence: 'oh, the synchronizer rings are bad'. But the synchro rings have little to do with this function. However when this tiny back cut, on on the engagement teeth of the speed gear or the synchronizer sleeve is worn away, there is nothing left to hold speed gear and sleeve together. In this case a new set of synchro rings will do nothing to fix the problem. And that is very much worth knowing.
Thank you for your comments. Please note that the back cut is not present on all synchronizer sleeves and gears. I see it missing mostly on older transmission designs. There are several reasons why a transmission will jump out of gear and worn out back cut is one of them. Normally what happens is the oil is not changed when it should be and or the driver is rough on the transmission and the blocker rings start to wear causing grinding (gear clash) which in turn chews up the clutching teeth on the gear and on the sleeve which wears away the back cut. It's often a domino effect.
Would be good to explain that the synchro ring is made of brass hence it's gold color. Brass is softer and is sacrificial meaning it will eventually wear out and need replacement. Brass is the perfect companion metal to press against the hard steel gear and do no damage to it as it tries to either speed it up or slow it down so the the synchro hub can slide over and complete the lockup. It's important to remember that the synchronizer assembly must adjust the speed of the entire cluster gear and input shaft including clutch disc in order to perform the lockup into the selected gear. Quite a task and shows why you must have clean clutch release so that the disc is completely free to rotate. This is a very good video, especially with the gear train illuminated with the strobe light to show what happens.
Thank you for your good comments. You are correct. One note. although these blocker rings are brass there are other blocker rings made of other materials and sometimes either lined with a friction material similar to brake lining and others that use a bi-metal design with a sintered metal inner cone that is soft with a high coefficient friction. I will consider a followup video with this additional information.
We had some Mustangs rings made of paper! Replaced many.
@@Franky997Can confirm that because some years ago I worked for a company that made synchromesh rings for many of the major European car manufacturers.
Selector forks were also made from phosphor bronze, but of a different grade.
@@shaggydogg630 of ... paper? No joke?
No, has to be a joke. Sounds impossible.
@@trumanhw compressed paper , no joke.
One of the best videos i have ever watched about synchro mechanism. Incredible presentation.
Thank you
Yes. He really has all the fine details down. Gear boxes for Spec Miata racing are rebuilt all the time. However the re-builds tend to have problems. If a rebuilder replaces the bearings, the brass synchro rings, and the seals then the gearbox will shift into gears easily and the box will hold oil, but will it stay in gear? Apparently if the back-cut (2:15 in the video) on the engagement teeth between speed gear and synchro sleeve are worn, these parts need to be replaced too. Someone who is simply installing a 'rebuild kit' will miss this.
Great video! Wonderful explanation. I especially appreciated the summary in the beginning of the three functions of the synchronizer.
Never understood how they worked until I watched this. Very well done.
You always think there must be an easier way. Loads of engineering and sleepless nights have gone into all these details to run smooth operations. Amazing and well explained. Great work.
Wow, using the strobe light to show synchronizer at work is brilliant! Thank you!
Excellent video, thank you. You just filled up another small gap in my mechanical knowledge.
As the sleeve moves towards the speed gear, the keys weakly push the blocking ring ahead until the conical friction surfaces make contact. The resulting frictional torque rotates the blocking ring so that it's teeth are 1/4 tooth pitch misaligned with the sleeve teeth which causes contact of the teethes' angled surfaces. This is called "energizing". As well as causing the blocking teeth to block the sleeve, the sleeve can now apply a strong force to the blocking ring via the tooth contact, increasing friction and synchronizing torque.
The ability or willing to show what you explaining just earned you a subscriber.
The best video for ASE, I watched this video 2 times before the test and still didn't pay enough attention. This video need to be watch 3 times for ASE manual transmission test
Why the test, if you don't mind me asking???
Thank you!
The demonstration of the synchro in action at 7:00 helps it all make sense. (The first part of the video is the nitty gritty of what makes it work. The demo shows it in action.)
A great video , actually had doubts about the internal shafts used and the sleeve and gear engagement but this video had it all covered
Fantastic presentation!....Great technical detail & functional explanation! Strobe light visual on the Rotating System really brought-it-all- together! Thank you!
Great video and the strobe light showing the operation was brilliant thanks from Canada
Drivemaster, you're the best Master. My language is Portuguese, but I didn't understand the Brazilian videos and I understood your video. I didn't understand how the synchronized ring works but thank for you, I understand now.
Your Welcome
Really good, well explained and easy to understand demonstration. Thanks for making and sharing this video
Excellent job on the video, structured and explained perfectly and pleasure watching
Still the best video on RUclips on this subject
Thank you. This is one of my top videos.
the strobe light detail was above and beyond and really helped explain it thank you so much
Thanks. I too thought that was a great technique to display moving parts.
@@DrivelineMaster I still dont understand how the sleeve will not engage the gear until the gear speeds are in sync??
This is a very valid question and not an easy concept to understand so let me give this explanation a try. When the sleeve is forced in the direction of the gear to engage then next gear the keys will push on the blocker ring which pushes on the gear. Friction and heat is generated between the blocker ring and the gear. With the heat expansion forces occurs. This expansion from the heat creates a force that pushes the blocker ring and keys back against the sleeve. This force makes it difficult for the sleeve to continue in the direction of the gear until everything is in sync or very close to being in sync. When everything is in sync the friction, heat and resistive force is reduced to a point where the sleeve can now easily slide over and engage with the gear. I hope this makes sense.
@@DrivelineMaster thanks. I did more research today i found that the mass/inertia of the constant mesh gears trying to be slowed by the blocker ring will force the splines to be out of alignment (and unable to engage) until the gear speeds are in sync. Only then can the tapered splines be aligned by the driver pulling the shifter because there is no longer any force "binding" the splines
That is the reason the blocker ring can't immediately synchronize the rotational speed of the gear with the sleeve however it is the friction and the expansion forces that prevent the sleeve from moving over to attempt to lock onto the gear while they are rotating at different speeds.
Kids used to say they could drag race powershift as in brute force abuse without using the clutch, but the way the synchronizer is designed, this is impossible, because the harder you try to force a shift, the harder the synchro will ride up onto the cone and fight to prevent it
Thank you for explaining & animating, this technology is becoming clearer, thank you
very good explanation. The only video I found that explains the synchronizing gear in great detail
I'm glad this worked out for you.
Very good explanation of this mechanism. Thank you a bunch for your time and experience! 👍👍
This was absolutely awesome these videos should be in schools to teach students
They are used in all my classes.
excellent description of the synchronizer but I wish you talked a bit more about the locking keys and springs and the purpose they serve
They are not locking keys. They are synchronizer keys. They transfer the force between the sleeve to the blocker ring.
Any time I think I am smart, I need to watch this and realize how much I don’t know.
Great fucken video don't give up you'll be up to 1 million subscribers soon. Best of luck and thanks for making things clear and simple to understand
really nothing beats a good explanation and some actual footage or hands on with my actual hands. ty for this.
Great with strobe, I had a 1958 Mack truck when I was young no syncro’s man you had to shift just right, you get used to it. Great video
¡EXCELLENT MASTER CLASS AND GREAT TEACHER GREETINGS FROM LIMA PERU!
Awesome Presentation, now I understand how this really works!
Thanks for sharing what you know with us brilliant video tutorial amazing
From Nick Ayivor from London England UK 🇬🇧
Excellent video and explanation of how this works... Thank you...
Liked the way you tried everything to make us get the idea, thanks
Its Amazing teach Video I Ever Seen. Good Jobs
Thanks for the video! An excellent explaination,best on YT for gears.
Woo, this time Manual Transmissions. If i literally had an instructor that taught like this I think it'd go into my head alot easier :P
Great Vid. Well explained... Thanks for sharing...
i want to use this to make a fixed gear / free wheel bicycle hub! never understood this before thank you!
Amazing video thanks alot hope u r having a beautiful life ❤
Thank you for the very clear explanation!
Wow!!!! That was awesome 👌 thanks you so much for posting.
After several videos trying to figure this out, I finally get it. Excellent video. Now I wonder if there would be other ways to slow shaft/gear speed. Synchro's are spendy parts "labor wise" to replace. I also wonder what fluid would cause the least amount of wear & still give satisfactory shifting.
Unless a specialized fluid is specified and the spec is 75w-90 or 80w-90 GL4 I really like Redline Manual Transmission Fluid (MTF)
Good ole stinky 80-90 gear lube is the highest temp rated fluid
Up here in MN maybe a 75-85 would be a good choice. I think up in the cold states an ATF is hard to beat. @@DrivelineMaster
I don't want to give the wrong information. Most manual transmissions can not and should not use ATF. ATF can only safely be used in a manual transmission if and only if the service information or owners manual says so. Never use ATF in a manual transmission unless it has been specified by the manufacture as an acceptable winter oil option.
Great job explaining!
Applause! Real gentlemen applaud this good video!
I'll point out that everyone praising how clear this video is then goes on to describe all the transmissions they've rebuilt. So as the only person who's here to learn instead of to see what they already know, I'll say that I completely disagree about the clarity. This is supposed to be about SYNCHRONIZERS / synchromesh. Instead, it's about the entire transmission. Yes, I see that it happens. But I still don't understand what mechanism is locking it. Is it the conical taper? Is it a friction surface? Don't know -- we moved on to naming over half the various components of a transmission without explaining what they are ... which means only people who already know the information will brag about it's clarity. While you're at it, why not define a word using the word you're defining?
Do syncros require a particular alignment? Or can they synchronize in any orientation?
As in ... they aren't uniform. So does it require at least 1 full rotation to align features?
Also ... why can't syncros grind? Because of the taper at the front of the teeth ..?
What's the purpose of the conical taper? Is that what synchronizes the mechanism? (Why not spend a little extra time explaining how/when it occurs with each of the mechanisms to drive home the principle that the video was TITLED?)
If it's the teeth meshing ... then why don't synchros need synchros? The taper / conical interaction with a friction coating makes sense as to why it wouldn't need synchros. But why would those teeth as animated synchronize without grinding any better than the gears we're synchronizing?
When the only people praising your edu are those who are all practical application valedictorians, you should be concerned that you didn't make the content as _introductory_ as your title suggests. There are many fields in which I have expertise, and when I try to explain them to others, the main thing I focus on is the avoidance of jargon, of relying on predicate knowledge that the only people who need the information wouldn't have, and on remembering what it was once like to not know those things; because it's that _empathy for ignorance_ that is lost with the very expertise required to explain the content.
Mind you, this was by far better than all the other videos I've yet watched on syncros. So please don't take it as a blanket critique across the board. And clearly, great effort went into this production (and corresponding animation) ... which couldn't have been cheap in either time, money or expertise. All of which I'm grateful for, as this is free content. Please don't mistake my critique as ingratitude. I'm just unwilling to lie and pretend I've gone from being ignorant to being knowledgeable (even rudimentary) from watching it 5-6 times.
I'm sorry this missed the mark for you and all those who are learning but are not familiar with the terminology. A goal of mine is to try and keep the videos high quality and as short as possible and if I have a long winded subject to make it into multiple parts. As someone watching who has not had some formal transmission training or rebuild experience I need to let you know that this is by far not how the entire transmission works and it truly is just about synchronizer operation. A fair amount of viewers have never rebuilt a transmission (Like your) but they may have had some formal training or they are attending a class on manual transmissions and the video helps to clarify what they didn't understand from their instructor. With that said I will try to address your operational questions.
The conical tapered surfaces between the gear and the blocker ring when pressed together create friction which will attempt to make them rotate at the same speed which if successful will synchronizing the speed between them. What is not shown is the shift fork, rod, gate, detent, interlock and shifter. Yes, I know these are technical terms that are not defined. Basically these components are responsible for moving the sleeve which pushes on the keys which push on the blocker ring in an effort to synchronize the gear to the blocker ring and synchronizer assembly so a gear ratio change can be made. These videos are about detent and interlock mechanisms and they may help. ruclips.net/video/z7Qht3yOfDg/видео.htmlsi=6cY5W393OPiiq1xL and ruclips.net/video/U7MBaIPoPZ4/видео.htmlsi=CFUVtq0YD9ehFlXk.
What holds the gear into engagement (Sleeve locked onto the gear) is a combination of the shifter position (which moves the shift rod, fork and sleeve), the detent mechanism, and the cutback design on the clutching teeth on the gear and sleeve. (Timestamp 4:10.)
Synchronizers can be mounted vertically and function but most manual transmission with synchronizers tend to be horizontal in operation. They do not require one full revolution to synchronize and they will work if the vehicle is stopped or going very slow such as in a parking lot (going from reverse to 1st) or during stop and go heavy traffic. The goal of the synchronizer is prevent grinding and it does this by using the friction between the blocker ring (rotating at shaft and synchronizer assembly speed) and the gear rotating at a different speed. Once the two are in sync the clutching teeth between the sleeve and the gear are close enough in alignment to allow the sleeve to move over (from force of the driver pushing on the shifter) locking the two together. The transmission is now locked into the new gear ratio and held there by the design of the clutching teeth and the shifter and detent mechanism and position. If, or when the blocker ring surface wears to a point where it's incapable of providing efficient synchronization grinding between the clutching teeth on the sleeve, blocker ring and gear will take place and can be heard when the driver shifts gears. This is called "Gear Clash". If these teeth become heavily worn down the transmission will pop out of gear (The shifter will move all by itself into neutral) under heavy acceleration. The shifter and detent alone are unable to maintain gear engagement when the clutching teeth are heavily worn from driving a vehicle that has excessive gear clash during shifting.
In summary: the conical surface does the synchronization when the shifter is moved but it's not strong enough to handle the torque of the gear ratio. This is why the clutching teeth on the sleeve need to engage and lock onto the clutching teeth on the gear. The synchronizer sleeve is moved through a mechanical shift mechanism when the driver moves the shifter to change gears. The shifter mechanism, detent (see video links) and clutching teeth keep the gear engaged until the driver moves the shifter again for the next gear selection.
This was my attempt to clarify your operational questions. The video is what it is and your critique is noted. If you have additional technical operational questions I'm happy to answer them.
You might also find these videos helpful.
Into to manual transmission power flow and gear ID: ruclips.net/video/aAG8kdw1WEk/видео.htmlsi=MU8s5wGrDLMKGcZ6
Front wheel drive manual transaxle shifter mechanism: ruclips.net/video/odzSu699njs/видео.htmlsi=G2QMd06MzFJxzvpd
These videos may also have similar critiques from you since my videos are all designed to support my lectures and assume a minimal amount of automotive transmission nomenclature knowledge. I will keep this in mind when creating new technical content and make an effort to clarify a technical term into everyday language when I feel that it is needed and it won't make the video too long unlike this response.
so, synchronization only works when the car is moving since we need the gears to be spinning correct?
engaging first gear from a standstill therefore does not need to be synchronized just like reverse?
Pretty much correct, the synchronization only takes place when the gears are spinning. Even though the car is not moving if your engine is running and the trans is in neutral but vehicle is not moving some of the gears inside the transmission are spinning. If you push the clutch pedal to the floor and move the shifter quickly some synchronization might take place. If on the other hand after you push the clutch pedal to the floor you wait about 30 seconds before moving the shift lever then all the gears will most likely be stopped.
I'm getting ready to rebuild my gearbox, so I'm learning as much as I can.
Wow, did I just learn something today!!!! Thanks!!!
Brilliant idea with the strobe light. Thanks!
Question: Since the small clutching teeth is what mechanically locks the free spinning speed gear to the shaft and actually transfers the power why dont we see more of those stripped vs the actually gear teeth on high powered cars? It looks like it has much less material engagement would seem to be the weak link. I would also think the narrow sleeve that couples the two together would be prone to strip out before the actual speed gear teeth would strip under high power.
1) the small clutching teeth are already 95% in alignment with the teeth on the gear before the sleeve is allowed to slide onto the gear so there is no grinding. This is accomplished by the proper operation of the blocker ring. When the blocker ring becomes worn out and can no longer perform properly that is when the clutching teeth start the grind during the shift. This is the grinding noise that can be heard by the driver between shifts and is called gear clash. The reason these tiny teeth can handle the torque comes from the total surface area contact between the gear and the sleeve. The number of teeth and the length of the teeth determine the total contact surface area. I'm not an engineer but this is something that has to be engineered into the design. They must determine the maximum torque that the synchronizer and gear would have to be able to handle and how much contact is needed.
Between two gears, only one tooth on each gear is engaged with the other gear at any time.
Between the parts of the synchronizer assembly, all of those small teeth are engaged at the same time, spreading the load out between them.
Many small teeth are as strong as one large tooth.
Thank You for this video. Very informative.
very informative; thank you.
You did phenomenal work putting this together and your explanations. Learned a few things.
Glad you enjoyed it and found it of value.
awesome video, very well explained! many thanks
That strobe demo was great
That is so cool to see it working like it should. My KW T800 has an 8LL and its synchroniser has been very noisy since the heat exchanger went bad and got water into the transmission.
Try Changing the oil and put Redline Manual Transmission Fluid (MTF) in it. This stuff does wonders sometimes.
@@DrivelineMaster I just have changed the incorrect 90 wt for 50 wt motor oil.
That by its self worked wonders. It made it possible to where the gear shift would actually move the gears in and out. Before that I could take it out of gear and it would stay in gear. It did that one morning until the oil got warm. I ran it all day, came in and drained that 90 wt while hot and its been better ever since. Everything but the synchroniser.
So mine is not slowing the gear down when all that noise is going on?
I wonder if the air shifter could be sticky somehow?
Unless the manufacture says you can use motor oil instead of GL4 or GL5 gear oil I wouldn't leave the 50st motor oil in your transmission. 90wt gear oil is not the same as it would be if it was 90wt motor oil. The way they measure thickness for gear oil is different than motor oil. Once again I would recommend the Redline MFT. I know it cost more but it is worth it. Unless your transmission was designed to work with motor oil (like some honda's) you will end up damaging your transmission and costing you more $$$ in the long run.
@@DrivelineMaster It calls for 50 wt engine oil. Granted Synthetic would be better but we just had a cracked head replaced at 6,389.00 on the truck and now the compressor has blown apart on the other truck leaving us stuck with a core fee. Cat wants 1,500.00 just for the core fee alone. Fleet Pride got us a refurbished for little over a grand and no core charge.
As long as the factory specification is 50wt engine oil then that is what you should use and have confidence that you won't cause any damage. This is the first trans that I know about that uses 50 wt straight motor oil.
Somebody needed to show this video to my old '67 VW bug.
Not many explanations go into the importance of the key springs and tapers that let the pressure build against the friction ring and bring the gears to the same speed. Then suddenly snap and engage the teeth.... to me that is the most important function of the syncro.
Very nicely explained!
Best video on the topic!
Thank you.
gotta love the reverb on the voice
Exceptional video. Thank You!
John Smith from Plymouth, MI?
Great video! The one part that I don't understand - how does the blocker ring prevent engagement if the gears cannot be synchronized?
Here you go. The sleeve pushes on the keys which push on the blocker ring. The job of the blocker ring through friction between the ring and the gear is to grab the gear and make it go the same speed (synchronize) so the sleeve can slide over and lock the two together. If the blocker ring is unable to synchronize the gear to its speed a lot of friction is taking place. With more friction more heat is generated. With more heat there is expansion of components. The heat and expansion is a counter force pushing back on the blocker ring. That force on the blocker ring is transferred to the keys and then onto the sleeve. The counter force prevents the sleeve from moving close enough to the gear for the clutching teeth to touch. If the clutching teeth are allowed to touch before synchronization a grinding noise (gear clash) will be heard. Hope this helps.
The best video to explain synchronizer. But I am a little confused, why did the sychronier blocker ring slow down the speed to snchronize with speed gear? It should be reversed, I mean, speed gear speeds up to sych with blocker ring.
When the transmissions is in 1st gear and you shift into 2nd gear (upshift) the speed of 2nd gear is rotating faster because the gear ratio for 2nd gear is a small ratio number such as 1st being 4:1 and 2nd being 3:1. Because the speed of 2nd gear is rotating faster than the output shaft and the synchro in 1st gear the 2nd gear must slow down to match the speed of the synchro and output shaft before it can engage and lock 2nd to the shaft. This happens with every gear change during upshifting. During downshifting this is reversed. The output shaft is going faster than the gear being downshifted into. Such as going from 4th at 1:1 down to 3rd at 2:1. Now when the blocker ring grabs the next lowest gear that gear will need to rotate faster or speed up to match the output shaft speed in order to synchronize. I hope this made sense. Also, those gear ratios are not actual but instead just used as examples to make a point.
Damn fine job on the strobe use!
Very nicely explained. I have a car Vauxhall Victor FB 1964, has a 3 speed manual transmission, there have always been a problem with 2nd gear, the shifting is not smooth, it makes a noise upon shifting, I have a technique of shifting to 2nd speed smoothly is by jerking the throttle/accelerator pedal twice, and like that the shifting is smooth without noise. Why is that?
You are doing what we call rev matching or revolution matching. By playing with the throttle speed you speed up or slow down the input shaft and counter shaft along with the 2nd speed gear. If you can get that speed close to the speed of the output shaft and synchronizer then engagement will be smooth. You essentially are doing the job of the synchronizer for it because it's worn out.
@@DrivelineMaster thanks a lot for replying. Another question is is the synchronizing rings inner groove worn out or the taper surface of 2nd speed gear worn out? Is the EP Lubricant cause of making bad the yellow synchronizing rings?
Typically it's the brass ring that wears out since it's softer than the hard steel cone on the gear. Wear on the blocker ring can be from multiple reasons and old, contaminated or wrong fluid can play a part in premature wear. Additionally hard driving or poor quality of the original parts. If there is a history of your vehicle having second gear synchronize problems this can point to manufacturing. The fact that this is a 1964 I might contribute this to age as much as anything else. I don't know if you can get the Redline brand of manual transmission fluid (MTF) or not but this is a fantastic synthetic MTF and would be worth a try to change your oil and install this. If not, try to locate another high quality synthetic MTF. i could help.
@@DrivelineMaster, thank you once again for responding. The manufacturer has strictly warned of not using EP (Extreme Pressure) lubricant as EP Lubricant is harmful for synchro mesh mechanism as it contains sulphur which badly harms the brass synchronizing rings, the manufacturer has specified SAE 90 straight transmission oil whereas the mechanics use to put SAE 140 EP poor quality lubricant. It also became bad due to shifting of gears at a very speed by my late father then.
I don't know for sure if the synthetic Manual Transmission Fluid (MTF) from Redline is extreme EP or not but I don't think so. It is rated as a multigrade 75 or 80W -90 grade. What I do know for sure is that I have had several older manual transmissions with gear clash while shifting and replacing the mineral based 90 grade gear oil with this fluid vastly improved shift quality and reduced gear clash grinding. At this point I don't think it would hurt your transmission. Also know I don't work for or have any interest in the Redline product, company or brand. I just know it works and have no problems recommending it.
Thanks for the such a nice explanatary video...
amazing work
but what is the speed of the blocking ring ?
is it equal to shaft or gear speed before synchronizing?
The synchronizer hub which is splined to a shaft, the sleeve and the blocker ring all rotate at shaft speed.
@@DrivelineMaster ok thanks
is the key connected rigidly to the blocker ring?
and how are they connecting?
and how does the blocking ring return its original position?
This video was great!!! Thank you for it.
Now THAT is some high tech mechanical engineering!
That was pretty interesting. I never knew how any of that worked.
Beautiful video sir.
Simply beautiful 👌
Great clear video thank you
Thanks,,,great informative vedio of the operations
WONDERFUL MY MAN. I DID NOT UNDERSTAND THIS BEFORE BUT NOW I HAVE THE GUTS TIO GO OPEN GEARBOX. LOL
MOSHITOA ( S AFRICA)
What makes a gear to jump out in gear when driving but when you hold a lev
er for a while it works well
Could be several things. As the video shows the teeth with the cut back. if those are worn from years of grinding during gear shifting that can do it. Excessive free play in the shifter linkage or worn detent springs. Depending on how old the vehicle is old 1960 and 1970's vehicles could have misaligned bell housings. I even had a VW once that had the shifter boot installed backward that cause this. You could have worn shift forks or synchronizer sleeves. Anything that would prevent full engagement can cause it to slip out of gear. Holding the shifter ensured the synchronizer stays engaged with the gear.
I have a few quesions, regaring an actual example in the topic.
What can cause that I can barely get out of first gear in colder weather?
The story a bit more explained: The MX-5 ND's manual recommends 75W90 GL-4 oil if the original oil is not available (which is often te case btw). One might thing that the original oil is also 75w90, but that seems not to be the truth, it's waaaay less viscous than a 75w90. I also put 75w90 in the trans and now even when I start at 15 deg C, it's hard to get out of first gear, I have to shift very eary into second. Also it's nearly impossible to shift into first while the car is moving. Putting the trans into reverse at 0 degress C is barely working. I don't experience any grinding btw. The syncro spec is as follows:
1: Triple Cone with Carbon coating
2: Triple Cone with Carbon coating
3: Triple cone
4: Triple cone
5: Double cone
6: Single cone with Carbon coating
R: Single cone
The original oil was very "dirty" looked like dark grey paint. Turned out it looked like this for everybody. Honestly it looked like someboday added molybdenium additive to the oil, but that's 100% not the case.
So, can these symtoms caused by the more viscous oil? I mean, problems when putting it into gear is is one thing but I can barely get it out from first when above 10 km/h. After driving 4-5 minutes and the trans oil heats up everything feels way smoother again.
What does one actually risk when a thicker or thinner oil is used thena what prescribed?
Can a molybdenium additibe (LiquyMoly) cause any issues by times? (Synchro issues, and so on)
Thanks and any info/explanation or suggestion would be appreciated.
Absolutely great video btw.!
First of all 75W90 and 75w90 are supposed to be the same viscosity. the large or small W has nothing to do with it. These oils are tested in a lab at a specific temperature even if you feel they flow differently and one seems thicker than the other. What is critical is that you make sure your oil is GL4 grade. If you put in GL5 or GL4/GL5 this can cause issues. It's also possible that the old gunky lube was holding your trans together and the gunk between the blocker rings and the cones got flushed out with the new lube and the gunk was adding the necessary friction that is needed to shift. Normally the symptoms you describe have more to do with the clutch not disengaging. So let me ask. Can you shift OK with the engine off? If so your clutch might not be fully disengaging or your pilot bearing might be binding on the input shaft. I'm a big fan of Redline Manual Transmission Fluid (MTF). It's synthetic with superior friction qualities. if you can get this you might want to give it a try. Also check the owners manual. When I worked for Mazda some of those transmission would take Dexron Automatic Transmission fluid when the vehicle was being used in cold weather and 75w90 when it was used in hotter climates.
@@DrivelineMaster oh ok. Thanks. The w/W was just a typo.
But if the clutch not disengaging then why does it work ok after a few minutes and why did the problem start immediately after the oil change? I think with engine off i chan shift but doesn’t it also depend on the wheel speeds (trans output shaft speed)? What i also can try maybe is to lift the rear put it in 1st and check if the wheels start spinning when i press the clutch pedal. Im not sure but if the clutch is completely disengaged then it should not move the wheels at all, right?
Im planning to try something similar you mentioned if I can’t get the original oils.
About the gunk. Yes, Im a but afraid that this is one of the issues.
What do you think about the molybdenum additives? Is that a bad idea?
Btw: the oil i put in was gl4/5. I didn’t think this could be a problem. Motul gre 300 75w90 btw.
Your right that if you had a clutch disengagement problem then the shifting problem should not have started right after the oil change. the W or w was the only difference I saw in your oil specs in your original message. Yes, if you raise both drive wheels, engine running and clutch pedal fully depressed that the drive wheels should not rotate. I once installed Redline 75w90 gear oil in a manual trans and it would not shift worth a darn and it would grind a lot. I took it out and put in Redline 75w90 Manual Trans fluid MTF and it shifted great. It was obvious that these were two different products both labeled 75w90. With the engine off and the vehicle not moving there is nothing to synchronize so shifting should be easy. Also clutch discs can stick to the flywheel or bind on the input shaft when the pedal is depressed. this can cause difficult shifting. Again this does not explain why the problem started just after an oil change. I would not put any additive in the trans unless it says right on the package that it's for manual transmissions. You don't want to make the oil slipperier there needs to be more friction between the oil and the blocker ring cones. If the oil was as bad as you say it's possible you flushed out what was holding the blocker rings to the gear and the clean oil is slipperier.
@@DrivelineMaster understand. Thanks a lot!
@@DrivelineMasterJust FYI: the original Mazda oil finally arrived and I put it in the car yesterday. It's WAY less viscous than the 75w90-s I tried before. Shifing is good now even in cold temps, no issuse at the moment.
Thank you great explanation
thank you for its very explained and
helpful
Marvelous! Thank you so much!
Im trying better to understand the basics of 90s Honda manual transaxles. Why is the imput shaft gears pressed on and not built into the shaft like rear wheel drive, drive gears? And when changing gears to a custom ratio sometimes only the driven gear gets changed. If your changing the ratio wouldn't both gears need to be changed? Thank you
Normally when a gear is pressed onto a shaft as compared to being part of the shaft it's because the gear needs to come off in order to remove or install something else. It's for assemble and disassemble purposes. Normally when there is a ratio change both gears are replaced. I don't see how it is possible to only change one gear. Let's say you want more low end torque and you want to change from a 3.5:1 1st gear to a 4:1 first gear. The input shaft gear must get smaller but in order for it to mesh properly with the output shaft that gear must be bigger. I have never done a ratio change on a Honda but it doesn't make logical let alone mechanical sense.
Who on Earth came up with this? I rebuilt two entirely different manual transmissions years ago. One on my '64 GTO and one on a '68 Ford Cortina. The inventors need a Nobel Prize in transmission design.
Them and whoever came up with the differential. Brains all around.
Good work
Fantastic video. Thanks!
There’s more to it than that, the key slots and ramps of a blocking ring are timed to each other, and if that relationship is off, it won’t work.
Thanks for your input.
Hay I have a 2008 dodge ram 1500 with a manuel 238 Getrag 6speed transmission in it. I'm have the same problem with second gear. Where can I find the parts for a 238 getrag and can I replace it with another manuel.
Unfortunately I don't have a source for that transmission. I once had a Getrag from a Toyota Supra and not even Toyota sold replacement parts short of an entire transmission. You can try West Coast Standard or midwest trans (www.midwesttrans.com/product-information/getrag-238-6-speed-rebuilt-manual-transmissions). try searching the internet using "getrag 238 rebuild kit" as your key words.
Thanks very well explained 🙏🙏🙏
One perhaps ignorant question on the final demonstration. What is the gear on the far left of the video? I assume it looks like the speed gear, and maybe I'm not adequately understanding the relationship between the speed gear and the speed gear clutching teeth.
I believe that was 1st gear speed gear. The speed gear and the speed gear clutching teeth are all part of one gear assemble. The speed gears area also the free spinning gears check out from time stamp 2:44 to view the speed gear AKA free spinning gear.
Thanks for the video! Helped me study.
I'm trying to wrap my head around why the synch is free to rotate +/- 10º with respect to the sleeve, and why the synch has external teeth at all. I understand these two features are related. However, it seems that if the synch could NOT rotate that 10º, and if it did NOT have the external teeth - it would still work. The keys would still push the synch up against the speed gear cone, slowing/speeding it appropriately, allowing the sleeve to pass over the synch and onto the dogs of the speed gear...??
It seems to me that once the synch has brought the speed gear to an rpm that matches the output shaft rpm, it's only random chance if the dogs of the sleeve, synch and speed gear will actually be in alignment. I'm assuming this is on purpose and is why the synch is often referred to as a "blocker". Part of it's function is to specifically misalign with the sleeve so the sleeve may NOT be pushed further toward the speed gear. But I don't see how this can be controlled by anything other than chance (and I know it's not...).
The slight rotation of the synchronizer blocker ring and the teeth improve synchronization and engagement when the sleeve moves over for the mechanical connection. When the sleeve starts to move the first set of teeth it engages are on the blocker ring. If those teeth are not in perfect alignment with the sleeve teeth the ring will rotate slightly to make a perfect alignment. When the ring moves slightly it will also attempt to move the gear as well in an effort to provide a perfect alignment between the sleeve and the dog teeth on the gear. The blocker ring teeth and slight movement are required for this to happen. Additionally the extra teeth on the blocker ring adds additional holding or load caring capabilities. Yes, it could work if it was fixed and didn't have teeth. This is the best I can offer. I'm sure there is an engineering explanation that is beyond my capabilities. I hope this helps.
@@DrivelineMaster I appreciate your thoughtful reply; thank you. I do have some questions/comments though:
While the speedgear is NOT at a matched speed, when the synch is pressed against the speedgear cone, isn't the synch going to be at one of the extreme ends of its shift key notch? For it to impart any rotational friction onto the speedgear, the synch needs to be supported by something ; the shift keys. So during friction/synchronization, the synch will be misaligned with the dogs in the sleeve. Right?
Meanwhile, as force continues to be applied on the gear stick, force continues pressing the synch up against the speedgear cone... So what would then cause the synch to unlock from the cone and allow it to rotate so that it can be centered on its shift key notches, and come into alignment with the dogs in the sleeve? Where would this "reversing torque" on the synch come from, that would re-center it?
GREAT Questions which causes me to search the depth of my understanding of the working application. Let me give this a shot since I will be applying functional operation with mechanical logic which doesn't always come out to be true but more often than not it has served me well. What you said.... All true except I don't believe the blocker ring would break adhesion from the speed gear as the sleeve moves to engage. Once the speed gear is in sync as the sleeve moves over if the dogs are not in perfect alignment and a shift is required for perfect alignment the blocker and speed gear will rotate together for alignment. At this point the blocker dog teeth can be aligned with the sleeve. If the dogs on the speed gear are still misaligned the sleeve will be engaged with the blocker ring but not the speed gear. Pressure that the keys are applying is reduced to reduce the friction force between the speed gear and the blocker ring. The reduction in force on the blocker is caused by the keys being moved down (inwards towards the center of the shaft) against the key springs as the keys are no longer centered in the key raised portion that is fitted into the recess in the sleeve. When the keys are moved inward against the spring the force from the sleeve pushing the blocker against the speed gear is reduced enough for the points on the dog teeth to shift the speed gear separately from the blocker ring a slight amount to create perfect alignment. You make a good point about the blocker being seated against one edge of the slot on the blocker. This makes me want to look at several synchronizes to see if the blocker ring dog teeth are in perfect alignment with the sleeve when the blocker is rotated fully in either direction. If they are in perfect alignment when rotated to the extreme in either direction this would make a lot of sense. This recent discussion about the more in depth details of synchronization makes me what to create a followup video to address these more in depth questions that my viewers have asked me.
@@DrivelineMaster I love that you take viewer input to try and understand the mechanical logic better, to try and explain better. I saw your videos and you haven't made that follow up video on advanced manual synchro function, are you still planning on making it?
I was hoping someone wouldn't call me on that. I'm under Shelter in place orders right now but Yes, I do plan on a followup video for more advanced synchronizer explanation.