Understanding Differences in Automotive Differentials
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- Опубликовано: 19 июн 2024
- See 11 different types of automotive differentials and learn how they work. This video is intended for students in the AUSV 1220 Manual Drivetrain class at Weber State University with Professor John D. Kelly.
CORRECTIONS:
1. The differential I called a "Detroit Locker" is not a Detroit Locker. It is just an Eaton Posi Limited Slip differential. A Detroit Locker uses dog teeth and is a truly locking differential. Thank you goes out to Keith MacDonald for catching my error.
2. I did not adequately explain how the clutch packs of a limited-slip differential are applied. The simple rotation of the side gears versus the differential pinion gears does not cause clutch packs to apply, otherwise, the clutches would apply when turning corners at low load (low torque). Torque from the engine (or another propulsion source) is necessary. The more torque you supply to the differential side gears the higher the force on the angled (ramped) teeth, the higher the force on the clutch packs. Thank you to several viewers for pointing out my omission.
3. There is more than one style of Torsen differential. See the JTEKT Corporation's website for more information www.jtekt.co.jp/e/products/ls...
4. I incorrectly described the operation of the original 1956 Dana limited-slip differential. The pinion pins on the original Dana differential have tapered ends. The pins sit in four V-shaped ramps in the differential case. Under a load, the differential case applies rotational torque to the pinion pins causing them to slide up the V-shaped ramps. This action applies outward force to the side gears and the clutch packs. Thank you to several viewers for pointing out my error.
TIMELINE
0:00 Start
0:08 Introduction
0:32 Open Differential
3:55 Power flow through a differential
6:51 Side gear backlash control
9:09 Differential Demonstration
10:21 MUST SEE Differential Equations
13:12 Automotive differential history
14:44 Dana Corporation's 1955 invention of the automatic locking differential
15:33 Various names for Dana's locking differential
17:23 See a 1963 Chevrolet positraction differential with clutch packs
24:00 How rotating gears apply a clutch pack
26:35 Why limited-slip additive may be required for a clutch-type differential
28:46 See a 1970s era GM positraction differential with clutch packs
29:40 See a 1984 Chevrolet Corvette Limited-Slip differential with clutch packs
30:02 See a 2012 Eaton Posi Limited-Slip differential with clutch packs
34:00 MUST SEE See a worn out 2010 Chevrolet Camaro SS Limited-Slip differential with clutch packs
38:00 See a broken 2005 Jeep Wrangler Rubicon Torsen Type B style limited-slip differential with an air locker
43:51 MUST SEE See the pieces of a Torsen Type B style differential and see how it works
48:03 See a 2002 Toyota Tacoma Electric Locking Differential
51:00 See the Eaton Detroit Trutrac (Similar to the Torsen Type B differential design)
49:55 See a spool with no differential action
53:40 See a Mini-Spool and how to install it
56:35 See the Eaton Locker and learn how it works
1:00:45 Final wrapup
ABOUT US:
Weber State University (WSU) Davis Campus - Automotive Technology Department - Transmission Lab. A technical description and demonstration of 11 different types of differentials. We teach current vehicle technologies to our automotive students at Weber State University and online. For more information visit: www.weber.edu/automotive
This video was created and edited by Professor John D. Kelly at WSU. For a full biography, see www.weber.edu/automotive/J_Kel...
Visit my other youtube channel / vibratesoftware to see the amazing NVH app for vibration diagnosis!
DONATE TO OUR DEPARTMENT
Please consider a donation to the Department of Automotive Technology at Weber State University here: advancement.weber.edu/Automotive
My Dad retired from Dana as an engineer and I never thought that was cool until now. This video was fascinating. Thanks for teaching.
The eaton locker used to be called a Gov Loc, they kind of got a bad reputation for grenading when they would slam engage under power. Kind of suprized you didn't mention one of the toughest and oldest of them all the Detroit Locker or it's cheaper brother the Spartan or Lunchbox Locker. These work great as does the ARB Air Locker. For Cable type there is the OX Locker I have a friend in Alaska that has a full size Chevy Blazer with a Dana 60 up front and a custom Dana 60 in the rear both with OX Lockers as well as a NP 203 gear reduction case in front of a NP 205 to double down on low end torque. His truck is a cost is no object beast 😊.
Can we all pause to appreciate how lucky we are to have this content available, any time, for free? 🙌
I wish I’d known about this channel long ago. It would have allowed me to better educate friends and customers in the car world.
Thank you to the crew and Professor Kelly for putting these videos together. 🍻
That was an EXCELLENT tutorial! No stupid music, perfect camera, lights, mic sound! And very sympathicly presented. Many thanks from Germany! I learned a lot from it.
Thank you very much
I heard the music. @43:40 listen to him dump the gears out . . . "Shave and a haircut, Two Bits". But your right, no stupid music.
scootskute thank you very much for pointing that out!
My thoughts exactly.
Yep, as soon as you hear stupid music, it's usually because there's not much to the content. This video channel is excellent. Well done in every way.
No matter how much I think I've learned, The Professor always teaches much more, and in-depth. A natural teacher with great pace for complete absorption.
Thank you very much
@@WeberAuto 2
@@WeberAuto 😊😊😊
Man, this channel can't ever be boring with this much knowledge shared to you.
Some of my friends find it funny how I talk about differentials a lot but they don't know how much goes into it 😂
Thank you very much
Didn’t know they had so many
Differential Gear Ratios are a _big deal_ for freight weights on a semi. The quicker way to mitigate or escalate your RPMs is to experiment with tire sizes. But, has anyone invented a differential gearing system with multiple ratios that could be changed electronically? Do they last as long as a fixated DGR? A trucker reportedly has to consider component longevity to stay financially solvent.
@@wanderingfido Mitsubishi had that kind of system in Pajero and Colt atleast in the 80's. It was called gear multiplier. I remember it having only two gears in the differential, low and high.
@@wanderingfido Eaton made & still makes 2 & 3 speed rear drive axles.
In low range, both axles are in low range. Your inner axle differential lock can be locked.
In medium range, the front axle is in low range, the rear axle is in high range. Your inter axle differential lock can not be used in medium range.
In high range, both differentials are in high range. Your inner axle differential lock can be used.
Hello from north east Montana.
10 miles from the Canadian border.
60 years this has been a mystery to me. This was the most comprehensive explanation I've ever seen. I still don't own a thorough understanding but it makes more sense. Thanks for taking a great deal of your time to share this.
Glad you enjoyed it! Thanks for watching
,,,,,,,,,,,,Amen.................
It's a pleasure to watch a video by someone who knows WTF they're talking about. Even though it's over an hour long, it seems much shorter because he makes it interesting and informative; no stupid music or attempts to be a comedian. Classy and well done +++
A truly excellent instructor. His students are privileged to have the opportunity to learn from him.
I love these videos. I've spent years (~35) trying different differentials in street cars, road racing cars, LD trucks, HD trucks, snow plows, off-road vehicles, etc. and it is nice to see someone who understands how they work.
I don't know if you noticed though, the different ways that the clutch packs are applied in the limited slip differentials (LSDs) shown. In some LSDs, like the 1st one shown from the 1960's, it is the torque applied to the ring gear and the pinion cam profile that proportionally clamps the clutch packs together. For racing this is preferred over the spring preload LSD style. On the other hand for street use in icy and snowy conditions a spring preload LSD tends to perform better. Both the driving experience and how they function is unique to each LSD style. I'll explain below why.
If you look carefully at the 1960's LSD you have and pay special attention to way the spider or pinion cross shaft sits in the differential housing you'll notice it rides on an angled cam machined into the housing. As torque is applied to the ring gear (and hence the differential housing), the pinion cross shaft rides up the cam and this creates the separation force that clamps the clutch pack together. There is still a separation reaction force generated by the spider and side gears, but the majority of the clamping force is due to the cam.
These cam or ramp based LSDs can typically be purchased with different cam angles (not sure about the one from the 1960's). Some have replaceable cams, while others you have to machine (or purchase) the housing with the angle you want. The purpose of this is to adjust the amount of differential "lockup" you get per amount of torque applied. You can also create a different amount of lockup for the forward torque (acceleration) vs reverse torque (deceleration) by using different cam angles for each direction.
The Torsen style differential bahaves functionally similarly to a cam applied LSD, but the downside to a Torsen is the forward and reverse torque induced differential coupling cannot be individually tuned as easily. Most people claim Torsen's can't wear out, but I can confirm they definitely can.
Many modern limited slip differentials used in street cars (like most of the LSDs in the video) do NOT use a cam profile to apply the side clutch packs. Instead they use a less expensive spring's preload to create the majority of side clutch clamping force, combined with the spider/side gear separation reaction force. If the driver simply wants to be able to perform 2 wheel burnouts or drive in the snow, this style can work well.
Detroit Lockers are another story (note in the video the LSD labeled Detroit Locker was not a Detroit Locker). They are not really differentials in the classical sense, nor are they LSDs. If you imagine taking a pair of ratchets from your toolbox, cut off the handle, and weld them to each side where the side gears normally go in a differential, you have created the function of a Detroit Locker. For straight line driving, both wheels turn at the same speed so the ratchets work fine. When you want to corner in good traction, the outside wheel wants to turn faster so that side's ratchet will allow this to happen while going "click, click...". The coolest part of the Detroit Locker is when you switch from drive to reverse and vice versa there is a bit of a clunk (and the driveshaft will turn 1/4 to 1/2 a turn). What this is doing is switching directions for the "ratchets". The direction of torque applied to the ring gear is what selects forwards or reverse for the ratchets.These work great off-road, in snow plowing trucks, and in heavy, long wheelbase vehicles.
Eaton Gov-Loc's are a bit controversial and are poorly understood in general (the video did a great job explaining them). Most people I know hate Gov-loc's because if you rock the vehicle from forward to reverse to forward to reverse to..., spinning the wheels each time, you'll destroy a gov-loc in no time at all. Where I've seen them work very well is when used in a heavily loaded truck and one tire is on ice and the other is on pavement. No common LSD will lock up enough to get anywhere close to spinning the wheel on pavement. With a gov-loc, if you are gentle on the throttle, the governor will engage, the clutch packs will tighten more and more until the differential is effectively locked up, and the truck will simply drive ahead (or will start spinning the tire on pavement, even burning rubber with a heavily loaded truck, if it is stuck badly enough).
With modern vehicles there is another option that most vehicle manufacturers are starting to implement with varying degrees of success (sometimes combined with viscous coupling differentials). This option is to use the ABS system to create a virtual locker. The software monitors steering angle and relative wheel speed (all 4 wheels). If programmed well, the instant a wheel starts to spin, that wheel's ABS engages and slows the spinning wheel down to the speed it should be turning. What I like about this option is every single vehicle sold today has the ability to include virtual lockers, essentially for free. All it takes is a bit of software to use the already present ABS system as a locker and by including drive by wire it becomes a seamless addition.
Fantastic information, thank you for sharing.
This was the best, most helpful comment I've seen on UTUBE
Great info!
And for anyone whose emergency brake works on the drive axle, it's truly a poor-man's solution. Years ago I helped a guy with 2WD Dodge p/u stuck on ice with one wheel and was down to gravel on the other. I asked him if he used his emergency brake on a regular basis. He said ya, but why? I got in and used it to force torque to the wheel on the gravel. It just gently walked right out. He thought I was God Himself, haha. Pretty sure he used that strategy for the rest of his life.
Excellent lesson here also, John. Much appreciated.👍 Looks like the school has a fantastic shop set-up. Great lighting and you and the kids keep it spotless.
The info about Detroit Lockers and Eaton Gov-Loc made me look for some professional video about it. Grat job Slider. 34:40 info about Torsen is misleading. LSD diff with clutch pack allows one wheel to spin (on ice) so the difference in speed (of wheels) creates enough friction to start transferring some power to stationary wheel. So certain % of motor torque may be transferred to stationary wheel. Torsen in such situation spins wheel on ice :(
In LSD if left wheel can handle 10Nm on gravel and right one 100Nm on tarmac, as long as you apply less than 20Nm on axle you will not spin any wheel. You put more than ~30Nm and you will start spinning (internal clutch will eat some Nm) . Torsen works in different way. Assuming that it have TBR 3:1 in the same situation left wheel can get 10Nm and right wheel can get 30Nm (TBR x less grip on axle). Torsen is great for acceleration and cornering when wheels have biggest difference in grip. No other diff allow to put so much torque on wheels without them to spin. But it lack on locking wheels to diff when one wheel have no traction. In other words Torsen does not do the same as LSD. It does quite different. I missed that info in film.
@@user-3tf67bk46u Actually i have heard of using parking brake to help when stuck in snow or ice. I didnt know that it would actually work to some extant in some situations. I will try it this winter when i have snow in my driveway. Now i wish that my truck would have double hand brakes, one for each rear wheel, like my tractor and backhoe have two brake pedals one for each side.
You know John, that in 1947 I learned differentials in auto shop. And of course, the teacher told us they were "spider" gears. And it always happens that when you learn something when you are young, it tends to cast into cement. If'n you git me drift! LOL
Thus, for 70+ yrs now, I always had a problem when someone says other than "spider" gears when talking about differentials..
But I will tell you this kind Sir; since I believe truly that you are one of THE greatest teachers I have ever had; so I will stop having" that problem"; and say something I would never have said, if I had not met you. GRRRRR! LOL
Thank you John. You are truly a cut-above. As an 89 old man, I love your RUclips video's. Among THE best IMHO. Keep up the great work.
Thank you for your kind words. Best wishes!
I am in my 60s and was taught they are called spider gears because they “travel around” the side gears when the vehicle is turning.
@@ronwong7030 Yes indeed. And they kinda mimic how spiders move around. Don't they? Oh well. Thank you. But remember if John Kelley says it, we ain gunna argu wid im. LOL
That was the best explanation I have seen on YT. I now have a much better understanding of all the differences. Thanks John
Cheers 😊
Thank you
Probably the best and most educational video out there for automotive differentials
I probably shouldn’t have started watching this when I had work to do! Such a clear explanation and I now properly understand how locking differentials work. Lucky students - you have a great teacher!
Nice refresher course for us old school guys! Oh the tales of the stuff we did in our youth!!! 🤣
All of the animations on the internet put together would not substitute for a great teacher like this. Professor Kelly predicted every possible question of how differentials work and left no ambiguity.
You’re obviously teaching a trade school how lucky are your students to have somebody who can explain this so succinctly bravo sir.
Mr Kelly.... My son is not easily caught to attention... He has Mastered his Automotive Excellence classes with ONE thing... YOU... I hope you live to a Thousand years as you are 1 in a Million
That is awesome! Thank you very much and best wishes to your son
Finally making it to 65 years has me relearning anew. Professor Kelly, you remind me of one very special mentor, Scott Towsly, who helped me as I struggled during my early learning years. Thank you for being so thorough. I did know some of this lesson was not exactly the correct terminology but knew viewers would be helpful pointing to that. Just the amount of info you brought was plenty tough enough. I'm impressed.
Thank you very much
I'm 75 years old and I've heard of all these different types of positraction rear ends But it is really nice to have the differences Explained in such detail.. Thank you.
Thanks for watching
Instructors like him make things simple and interesting… I bet his students go out to be excellent mechanics…. Thank you Professor Kelly!!!
It has taken me years of study to figure all this out and I still learned something! Now I have a video I can send somebody else to! Thanks!
Thanks for watching
Thanks. In my o-pinion, 55 years of general lore cleared up in one enjoyable hour.
Glad you enjoyed it!
We live in a fascinating era with amazing new technologies but looking at automotive inventions of the past is equally amazing.
The most thorough and easy to understand primer on differentials ever.
Excellent classroom presentation. Couldn’t ask for more information with only an just over an hour of time to cover years of the evolution of the vehicle differential. Those of us that have been around differentials for decades still can learn from this as I was a “posi” guy and never really advanced any further. 2 thumbs up.
Glad you enjoyed it!
BEEN WORKING ON THEM FOR YEARS HE'S TELLING YOU THE WHOLE TRUTH AND HE IS VERY SMART TO SHOW YOU HOW THEY WORK THANKS I REALLY LIKE IT WHEN I KNOW YOUR RIGHT ill be learning on the work converter video
Thanks you very much!
Next you can do some work on your keyboard, and fix that broken CapsLock key !!
This was outstanding! When I was a kid back in the early 70's, I "knew" what positraction was but NEVER understood, or had it explained how the hell it worked. I had a Boss 302 that had the 9inch and just knew that it was 1 - pretty durable 2 - allowed me to get both tires working. I never knew why.....till now! Thanks very much for this. Rick
Thank you so much for this video. I knew conceptually about open differentials versus limited-slip differentials, but it was all a bunch of blackbox magic to me up to now. Your video goes into the exact right amount of detail to get an intuitive understanding of the different ways that the limited-slip can be achieved. I'm so happy to understand this technology now.
Glad it was helpful!
This subject has always frightened me, you made it super understandable, Thank you very much!
Thank you
These channels should get discovery channel money, that crap on drama is nonsense and I discover nothing in one day I gain knowledge here and I’m not being harassed with commercials about self indulgent drama queens. Thank you for your content your time to produce interesting videos , your expertise . These should be in our schools .... thank you sire have prosperous new year and healthy one
Thank you very much
And now you understand why sex n death n destruction is always the guaranteed money maker on general TV.
I'm a journeyman mechanic with 40 years experience, it was great to get a refresher on the principles of diffs. And see all the various types. Very well presented. Well done.
What a BRILLIANT video! I had a 65 GTO (with "Posi" - in fact I put a 4.56 diff in the car for drag racing and boy was that fun) as a teenager but a couple of my friends had Hemi Roadrunners with Dana rear ends. Thanks very much - now I know what those are some 40-50 years later!
Thank you very much
Perfect lecture delivery and so well presented with simple words and hands-on the 11 differentials.
A bucketful of knowledge ready for transfer!
Thank you Sir.
I really like your "Nothing is using regular gear oil"! So truth!
Great explanations!
Thanks for watching!
Sir, you’re a true master of your craft. You helped clear some misconceptions I had, especially at the beginning of the video. Thank you and God bless the work of your labor always.
What is there not to like about this video,? Why would you even click on it if you were not interested in this sort of thing? This bloke explains the chosen subject so well that an imbecile could understand it. No bullshit, no waffle.... without a doubt the best video on any mechanical subject I have ever seen on RUclips and I am an old man.
Thank you very much
There's also the Jeep "Quadra-Trac 2" system.
This uses an oil pump to force the clutch packs together hydraulically when one wheel begins to slip, I had a Grand Cherokee with this setup and it actually worked quite well!
I forgot about that system, thank you.
Mine needed a new solenoid, but yes, they are astounding for putting power to the wheel with traction. Electronic limited slip differential.
Really well explained and it's so cool that you have all the actual parts to show how they work.
Makes it way easier to understand.
Thanks a lot!
Glad you like them!
Finally got to see an open differential working before my eyes!
It's like solving a puzzle whomever came up with it.
The various methods of limiting the slippage and locking up was a fascinating tour. I feel very learned after watching.
Thanks for watching
I heard, watched, read a lot of documents. I found that differential mechanism is magnificent. But, now, the way you teach through video is fabulous. Thank you for your teaching.
THE most interesting and educational video I believe I have ever had the pleasure watching on youtube! Thank you Dr. Kelly! Have always wondered about differential basics. I sent this to several of my colleagues. So much appreciated.
Glad it was helpful!
I've rebuilt engines, but this video highlighted to myself just how little I know about the
variations Differentials come in. The video exceeded my initial expectations, thank you.
Most definitely subscribing.
An excess of theory and practice lead to a successful career in TV, VCR, CD repair,and DVD player repair.
Fixed shit nobody else could.
Thanks for watching!
I'm like in a class room getting serious about learning, I thank you very much, Many people are amazed at me after I started looking in U-tube mechanic teaching, I also started to fix mine and my Son's vehicles , What a great time to spend and get a real true benefit , God bless you , 🎓🔧👍
Thank you for the educational video. I used to work on cars years ago. I did engine repair/replacement, just about everything except transmissions and differentials. I knew of the different kinds of rears, spool, posi, limited slip, open, lockers…etc. but never knew exactly how they worked. Best of luck 🍀with your channel. Thanks again
Thank you for fulfilling my request from some time back. You did cover the majority of the varying differential styles. I was looking forward to the actual Detroit Locker with dog-clutches and also the cone-type limited slip (Auburn). I’ve even seen planetary gear sets used as differentials to vary torque split front to rear in transfer-cases. My compliments on the broad coverage and the history of the better differentials. Your videos make my job easier. Thanks.
Thank you very much
Still love this man for his excellent presentation and thorough knowledge. A real teacher I would like to have during my studies.
Wow, thanks!
Not what I typically watch on RUclips, but the fact that I watched it all the way through, could follow it completely AND found it interesting to the point of becoming engrossed is a testament to how effective this wonderful man is at teaching people new concepts...!! Unfortunately, trying to accomplish this feat is typically about as difficult as trying to herd cats (as my Dad would say lol), but this guy is the teaching equivalent of a professional Wild West cat-wrangler, and I just wish we had more like him to teach the generations to come...
Thank you very much for this investment of your time; it definitely was well-placed, in my book.
BRAVO...! -
Thank you very much
Thank you for breaking down the different types of differentials. Great job giving knowledge in a simple to understand way. Wish you were my teacher. You totally explained the mechanics and made me understand how & why they work. Thanks for the knowledge so I can get the right diff for a particular application. Time to rebuild and rework my crawlers.
This is phenomenal and precisely what I was looking for. I'm having an LSD installed in my Ford Focus ST and wanted to educate myself further on them. Truly awesome. Thank you!
Glad it helped! Thanks for watching
No no, thank you for making!
Another insightful, informative and thoroughly enjoyable video.
Glad you enjoyed it!
Professor Kelly, thank you! What a amazing and in depth explanation. I now understand how these work so that I feel much more confident in working on them.
Outstanding my man!!!!!! Started my apprenticeship in 2001 and still currently a heavy equipment mechanic and took volumes from this. Thank you for this!!!!
That is awesome! Thanks for watching
This was a great tutorial and cleared up a lot of the mystery surrounding diffs for me. Thank you!
Glad it was helpful!
Great video, thanks for taking the time. On the Gleason-Torsen helical diffs, I recall the selling point being that they are torque sensing, thus sending torque to each wheel based on the amount of traction available at that wheel.
Thanks for watching
Thank You Sir. You are a good man. You are admired by the many students you have taught and continue to teach. You share your time, your knowledge, to teach those with a willingness to learn. Thanks again for these tutorials.
This is great, thank you for posting this! I have a 1995 GMC truck 2WD with the 5 speed manual gearbox (NV4500) and the 4:10 (14 bolts) differential. I'm thinking about to get either a limited slip or a locking one. This video really helped me understand the differences!
I have never clicked so fast! Thank you professor!
Thank you
Professor, thanks for posting another excellent video! Two things are constant when enjoying your well made clips. I never have a single regret for the time I spend watching them. I always learn something. Two huge wins by my accounting! Only an elite pantheon of content providers like yourself are worthy of this distinction. Please keep raising the bar.
Dear Sir: I've been a shade tree mechanic and hi-perf guy for 59 years since I was 18 and believe this is one of the finest differential discussions I've ever seen. Back in the day at GM Tech we learned about application and maintenance on diff's but not the variety of types as you have here. As an owner of GM autos (chevy) over the years I've been into these applications for maximum use situations. Of course all this is moot on newer cars as the ABS can power or brake slipping wheels as needed under normal conditions of use. Thank you for this video.
Thank you and Thanks for sharing
If you’ve watched 20 different videos on the function of diffs and still aren’t clear, THIS is the video for you! Excellent explanations.
Thank you very much
This is an excellent video showing the the different differential types. There is a great old Jam Handy/Chevrolet video from the ‘30s entitled “Around the Corner” on You Tube that explains piece by piece how a differential works that is one of my favorites!
Yes, it is one of my favorites too. Thanks for watching
It's great to have a source of information that specializes in educating.
I've watched other videos about this kind of stuff in which the host is either pimping their product or doesn't understand what they're talking about.
Thank you very much!
I've always loved differentials because they really are an ingenious design and I just love learning about all the different types of LSD, lockers, etc. One of my favorites and the one I installed in my Ram is the Torsen type or helical LSD. The only downside being if you get one wheel in the air, you may have to set the parking brake or apply the brakes to sort of fool the differential into thinking there is load on the axles. Very informative video as always! Weber Auto is always one of my goto channels for accurate, easy to understand information.
Thank you very much!
Wow, what an amazing lecture. Thank you so much Professor Kelly. You are definitely in the right profession as you are very easy to understand and your lecture flows so well. This is easily the best coverage of this topic I have ever seen.
Ah, sure wish you were my shop prof back in high school, would have been a much different experience I think- thanks for putting these videos up!
Thank you very much
Great video!!
What makes the side gears pushing on the clutch packs is NOT the rotation, but the force applied: in other words the higher is the input torque and the higher will be the force on the clutches. This force basically acts as a preload: in case of a wheel on ice, the wheel with traction will still transmit the torque that is generated by the clutches (the bias torque) which is needed to "unlock" the differential
The same occurs in "torsen" diffs, but that is achieved by the high friction involved in worm gears. More input torque and more "unlock torque". By changing the pressure angle of the gears it is possible to obtain different ratios between input and unlock torque
F
Thank you, you are correct about the torque being needed. I did not explain that adequately. I posted a correction at the top of the comments.
@@WeberAuto You give examples of True Trac and calling them Torsen, not the same. Torsen uses the non-reversable principle of worm gears. No Torsens in this video.
Great video. There are many diff videos on youtube, this was the first one that covered several types, with all the theory, and physical disassembly on the bench. Just brilliant.
This presentation is excellent!!!
The Professor's ability to convey the information is right on target. Thank you!
Articulate, Informative. Well Done Professor!
Thank you
Something that often goes unmentioned is that an open differential in it's elegant simplicity always delivers equal torque to both axles. The amount of torque may be limited by the axle with the least traction but it is always equal. :)
Thanks for watching
Thank you for this excellent content and for sharing it publicly. I've just swapped out a Torsen diff for a locking differential for offroading. I understood the Torsen diff was a fantastic piece of kit, but now I understand how it and the others work. Great presentation of information also
I went with Eaton heli gear
I've been trying to understand differentials for a few days now but couldnt find a good explanation anywhere but this video really made it click. Thanks so much!
Glad to help. Thanks for watching
a lot of interesting and relevant info , answered many questions I had
Thanks for watching
Great stuff. The only thing missing was a diff with side gears that have cone clutches. Same principle, very different clutch theory. Thanks!
Thank you. I am looking for one now.
and/or the Lock Rite stye lockers or aussie locker!
What a fantastic video, giving me information I have more clarity. In the British Army trucks we had a Diff locl that locked both the front and rear Diffs when the truck got bogged down etc. I think it was air activated but it worked wonders....now i know how it worked. Thank you Professor Kelly.
This is an exemplary & detailed, must-see explanation for many vehicle differential types. I have a 1992 Toyota Celica with all-wheel drive and a viscous coupling.
*_TRUST !!_*
CORRECTIONS:
1. The differential I called a "Detroit Locker" is not a Detroit Locker. It is just an Eaton Posi Limited Slip differential. A Detroit Locker uses dog teeth and is a truly locking differential. Thank you goes out to Keith MacDonald for catching my error.
2. I did not adequately explain how the clutch packs of a limited-slip differential are applied. The simple rotation of the side gears versus the differential pinion gears does not cause clutch packs to apply, otherwise, the clutches would apply when turning corners at low load (low torque). Torque from the engine (or another propulsion source) is necessary. The more torque you supply to the differential side gears the higher the force on the angled (ramped) teeth, the higher the force on the clutch packs. Thank you to several viewers for pointing out my omission.
3. There is more than one style of Torsen differential. See the JTEKT Corporation's website for more information www.jtekt.co.jp/e/products/lsd.html
4. I incorrectly described the operation of the original 1956 Dana limited-slip differential. The pinion pins on the original Dana differential have tapered ends. The pins sit in four V-shaped ramps in the differential case. Under a load, the differential case applies rotational torque to the pinion pins causing them to slide up the V-shaped ramps. This action applies outward force to the side gears and the clutch packs. Thank you to several viewers for pointing out my error.
Prof Kelly regularly goes where angels fear to tread: The variations / updates of thousands of engineers are not readily coverable in ANY single YT video!
Kudos to Prof Kelly for admitting that even a superbly researched article is rarely COMPLETELY accurate!
Thanks
"torsion" is the physical act of applying torque, not a company. The differential uses torsion to achieve it's design goals, hence the name. Also, it is pronounced "tor-shun", not "tor-zion", or "tor-sion".
@@connermcnicholas547 Torsen stands for Torque-Sensing. You should let the current company that makes Torsen differentials know their error. See www.jtekt.co.jp/e/products/lsd.html
@@WeberAuto Oh whoops, I thought you were literally saying torsion. My bad!
Now I know why 'positrac'/LSD's wear out a lot... them clutch packs. Thank you again!
You are welcome
The Eaton Truetrac does not have that issue because there are no clutches to wear out and no friction modifiers in the lube.
Your years of experience and wisdom at which appreciated and I am glad you have shared this.
When we raced fox body mustangs in the 4 cylinder class, there wasn't a mini spool or anything for the Ford 7.5" rear end that came in the mustangs, Fairmont, Grenada, etc...
So, we either welded the spider gears together solid as you mentioned. Or we would out a small beads on all the spider gears to make an X pattern when lined up right. And then put them back in where the beads would line up to prevent the open spider gears from rotating, jammed against the beads making it act like a mini spool.
They worked well on the dirt tracks and usually never broke, them again we weren't running the torquey V8s. It was funny trying to turn the car around on a paved parking lot. The outside tires would be chirping, grabbing and the turning radius sucked. It made it easier to rev it up, dump the clutch and whip it around
I believe that the original LSD operation mode (in my opinion) is different from the explanation given. The clutch packs are squeezed by action of the ramps in the casings and not the bevel of the gears (although it might be part of action).
Specifically, the pinion pins are floating on the ramps/cams (heat treated angled areas in the case) and when there is a speed difference and torque applied the pins will ride up the ramp thus squeezing the clutch packs. This particular case would be identified as 2-way LSD (having effect in both directions).
Note: I might have misunderstood due to possibility that the original LSD was not the same LSD used for demonstration.
I believe you are correct. I got that wrong on that early differential. I tried to find the original patent with the original drawings and description, but could not. Thanks for the feedback!
@@WeberAuto One more item: It is the torque applied to the ring gear that determines the force applied to the clutch packs. It is not the differential action that creates the force. When coasting, the differential has minimal clutch force and spins freely. When torque is applied, the clutch force increases and the differential is harder to slip.
This knowledge can be used to get more traction out of a LSD. If one wheel is freewheeling, little torque is applied to the other wheel. If you apply the brake, apply power and ease off the brake, the clutch packs are loaded with more force and the clutches will transmit more torque to the other side.
16:30 I believe Ford's incarnation was known as Traction-Lok™ in 1958-59, but even earlier Edsel and Mercury models had a version called Equa-Lok™ in 1958.
Great information, thank you
@@WeberAuto WW2 seen many vehicles with all sorts of lockers.
Thank you John that was great info. Definitely a great beginner vid for me. Ive done some week end mechanics through the years. I even rebuilt a 2 speed power glide wen i was 16. I never ventured into the mysterious world of differentials.
Thanks for making it so explicit!
Glad it was helpful!
Thanks
aaaaaah yeah! Thanks John.
Thanks for watching
I can't believe I sat through an hour long video !
Lol. Thanks for watching
This vid took me back to my first year of Voc school in ''77! LOL I would like to add, when pulling the preload springs on a Eaton style LSD you can use a "head on block" valve spring compressor. These cost only few bucks and the jaws are adjustable to spring diameter. Works pretty good.
I really enjoy the specificity of your speech. All words reliably well chosen so it allows my imagination to just be a bit more free to follow along than if I were listening to someone less precise, requiring me to do a bit more processing. Thank you very much for your efforts in teaching!!
Really enjoy the thorough nature of your presentation. I wish you had explained the concept of the ball plate. I assume this is similar to the brake apply mechanism of my massey-Ferguson industrial tractor, and is a self-energizing expansion device that can apply crushing amounts of pressure to the clutch mechanism. Far in excess of what is possible in the Posi setup. I also expect that it may be necessary, in certain instances, to reverse slightly to release tthe pressure, but I may be wrong. Also, in the case of welding the spiders into a spool, the gears are definitely not cast iron. They are high-carbon alloy steel. This detail aside, the dynamics of welding such material is indeed similar to cast iron as electric arc welding introduces such a localized high heat, that the portion of the gear not directly exposed to the arc remains cool enough that it removes the heat from the weldment fast enough to produce a quenching effect that manifests itself in the formation of a brittle boundary layer at the weldment root, similar to cast iron. This boundary layer causes fractures under stress, sometimes during cooling, that many refer to as "tearing out". The solution to the tearing out problem is an understanding of what is actually taking place, as well as special alloy electrodes and a willingness to sacrifice any heat treatment present in the gears. In short, as you say, welding spiders is an extremely bad idea, if for no other reason that the assembly cannot be undone, and will likely be destroyed in the process. However, like the old Aamco ad used to say "let me try boss, I always wanted to work on a transmission." I'm sure Goober is alive and well.
Good info there, Bill👍 I'd like to know a tenth of what you do in welding and metallurgy.
Thanks for making this video! Can you comment on which category Honda’s SH-AWD rear differential falls into?
It is in a category of its own. Maybe someday I will get my hands on one. Thanks for watching
SH-AWD would be classified as an electronically controlled locking differential.
It uses two clutches in the rear differential to achieve torque transfer. One for each axle. This is somewhat like the Haldex clutch system in VW and Audi vehicles. Except they use only one electronic clutch bathed in a separate fluid, which can only disengage and engage the rear drive shaft at a variable slip rate.
For some model years the SH-AWD system instead used a single viscose coupling and dropped the electronic clutches for weight savings and fuel economy reasons. Much like like the Honda CRV's AWD system.
@@WeberAuto, I'd LOVE to see you make a video explaining the differences between Honda's various AWD systems including: 1) Real Time All-Wheel Drive (older CR-V), 2) Real Time All-Wheel Drive with Intelligent Control System (newer CR-V and HR-V), VTM-4 (older Pilot and Ridgeline), iVTM-4 (newer Pilot, Ridgeline, and Passport), and the FOUR generations of Acura's SH-AWD. I'd be happy to contribute what I can based on my understanding of these various systems such as which ones use a single clutch vs. dual clutches, mechanically-controlled vs. electrically-controlled vs. hydraulically-controlled, overdriven vs. non-overdriven, etc. As a long-time Honda enthusiast and mod/admin of several Honda forums, I see a LOT of misinformation and misunderstanding about these and other AWD systems on the market.
The overdriven versions are the coolest in my opinion. Don't forget the RLX Sport hybrid's twin electric motor variation. I would love to do that, but obtaining the components is always an issue. I like to show the parts in action rather than drawing on a whiteboard or just talking about them. I am actively trying to find the RLX sport hybrid version at this time. Thanks for watching.
John Kelly is an engineering genius and humble to boot. He got there by many years of hard work and dedication. If you ever want to match him in his genius then there's no time like the present. I'll see you in a few years!!!
I finally understood why they call differential a differential. this is great information. I love the way you explain things. God bless you!
I remember asking my dad when I was about 6, for a month how does a clutch work?, Then I hounded him asking him how spider gears worked this is special
Thanks for watching
Thanks a lot!
You're welcome! Thanks for watching
@@WeberAuto ,, I have a 97 Honda Inspire 5 cylinder . I am not sure what differential it uses. I am having a thumping sound when moving from park . Mechanic said it is a backlash in the differential. Car changes out beautifully. I have to hold the brake firmly to limit the sound. Any suggestions appreciated.
@@michaell3711 in
@@archiemrara5048 ,,,,. In ??? What are you asking ?
Thank you, Professor. This was educational, fun and a real history lesson as well. My nephew and I both have the Chevy Colorado 2.8L diesel with locking Z71 package. Jamie's had chatter in front differential & was told it will sort itself out over time. It has but it took 25k miles.
That's like a surgeon telling you that the cancer will sort itself out over time. Find a transmission company who knows what they are doing.
As someone who as to drive on ice in Quebec a limited or locking differential is bad they are to easy shift the vehicle side to side and not allowing the vehicle to turn in tight curves, I mention that for people’s who thinking all vehicles should have the limited slip differential since it gives a better traction and ABS brake system with traction control helps and very good for ice driving !
I just did a complete rebuilt a Toyota front differential with the electric lock was nice to see new stuff !
Thanks for video 😊
Very interesting video!
I was wondering, which is more economical for manufacturers these days; installing a LSD or use a regular open diff and use the ABS system to individually brake the wheel that has lost traction in order to transfer power to the wheel that grabs?
Also, what is a "torque vectoring" system on an AWD vehicle? Does it use the ABS system to do what I've described, but for all four wheels?
Thank you for sharing, professor. Always very clear and easy to understand explanations and demonstrations.
Thank you very much. That is a good question. I am looking at several differentials from Tesla models S and 3 and they are all open differentials. Some performance cars come with Torsen style differentials. I suspect it is less expensive use the brake system for traction control. More to come on torque vectoring. Thanks for watching!
You can't use ABS to brake one wheel. ABS only reduces brake pressure. You need a traction control system (with a pump and computer controlled servo valves) to add pressure at a wheel. Using traction control you need to see a wheel slip and then respond to it. It's inherently slower and harder to control than a dedicated locking diff system (but cheaper). For example, a wet or dry brake rotor will change the characteristics of the traction control system dramatically. Typically off-road or high performance vehicles use locking/LSD diffs and traction control together. Torque vectoring uses this type of system with some fancy control algorithms.
P. S. The stability control (and torque vectoring) systems are the same concept as traction control except it is controlling the wheels during a turn, whereas traction control is only when the steering wheel is straight.
@@tomgnyc
Thanks. You're absolutely right, my mistake. I should have said TCS and not ABS. Lucky that I'm not a mechanics professor! 😆
McLaren p1 has that design lol
The only one you didn't have was a Lunchbox Locker, it's basically a mini spool but with dog teeth and springs. It "can" have slip from one wheel to the other but it sounds like a ratchet when it does, as the dog teeth slide over each other
Thank you, yes, I need to find one
He also didn't cover the Vicious LSD
@@inorite4553 I'm guessing that's because it's a vile abomination.
Wow really great video. Explains a subject which has been as clear as mud for years. Thank you for clearing up a lot of misunderstandings.
Mr. John D. Kelly you are an amazing man and a master teacher, I am passionate about engines and all things mechanical but I never ended up working in a car service,
I have worked since leaving school at least 8 different jobs and I hope that in the future I will practice auto mechanics.
The way you explained about the differentials is formidable if we also take into account the year of appearance of those parts.
The pinion pin on the Dana Differential, instead of going in a round hole in the case, it goes on V, creating a ramp , as the case applies the torque to the pin it rides on the V forcing it to the side and against the side gear applying the clutch, thats ingenious, because in a daily low torque to the wheels maneuver, the clothes don't engage as much has in a high torque situation, making the differential work as an open diff when limited slip in no necessary.
Thank you. I was wrong about that original Dana differential operation. Thank you for the clarification.
@@WeberAuto the score of clarifications is way way on your side! Thank you professor