A big thank you to whoever created this video. The visualization makes all the difference. I've read so many forums and articles that just repeat the same words over and over without adding to any actual understanding.
Locking differential at 3:28...Do both axles actually receive equal power (P)? Since they are locking the angular velocities (w) are equal, and the torque (T) on the side with more traction should be greater? P=T*w so T=P/w. If P is equal on both axles and so is w then T would be as well which is not the case correct?
Great video - I am 52 and never understood the differential fully. It's hard for most people to understand how things were BEFORE the differential came along - try one of those off-road vehicles or go-karts without this device - it judders on a bend and of course, has better grip on the straight for acceleration. It's fair to say, it was probably made to improve the comfort of some posh bloke in a big limousine - should look it up I guess! This is the perfect animation, I sat and 'paused' the action, and thought through how it works - so now I know that in normal operation, driving straight ahead on a good road with no tyre slip, the 'twiddly bits' in the core of the action sort of act as 'locked up'. Then come a bend or tyre slip on one wheel say, that situation changes. Such a straightforward vid to view and think about how it works. Good work. Also, for further thought people out there could figure how to limit the slip for extra traction on snow etc? Obvs, lots have tried it and there are umpteen variations both involving the differential itself, freewheel-type devices on each axle (like bicycle, one way it's turned it provides drive, not the other, think about it!), aand the old standby now, using ABS system to jam the wheel that's spinning free, to 'force' the wheel with grip to turn a bit. Yes, food for thought, great vid.
My cousin has an FJ Cruiser. I pressed the "lock differential" button and went offroading with it...upon coming back to the road, the car felt very very weird on turns, i thought i have ruined something in the suspension...after several hours, my brother pointed out that i still had my "Lock Differential" button activated.../facepalm
MrSakninsh Only if it is an incredibly weak and poorly built one, but I'm assuming he actually meant rear diff lock and not transfer case lock because I don't think FJ's are full time all wheel drive, in which case it's a completely different part he is talking about.
MrSakninsh Well, depending on what you want to mean, pretty much every differential has to be "interaxial" by design. While the only "Toyota" I've owned had almost no Toyota parts on it, Toyota's reputation would indicate that neither a transfer case mounted or rear axle mounted locker should break ever in that circumstance. Also, a rear diff lock should disengage automatically above about 15 MPH for safety reasons. All OEM ones that I'm aware of do that.
sleekitwan I don't believe it was made for limousines, from what I've gathered early cars used to be only 1 wheel drive, but that was terrible since most roads were very rough and definitely not paved, which made cars really tedious to drive. Making cars two wheel drive was a necessity at the time, therefore the differential was created to allow both rear wheels to have power.
Spot on with your description. So many people misunderstand ABS Traction Control. I have a Volvo XC90 with this kind of traction control, and I'm amazed at how many Volvo owners are confused about this. (They also confuse Spin Control with Traction Control--two different things completely. Volvo recommends turning off Spin Control when in low traction situations.) I don't have a button for Traction Control though--it's all automatic.
@89Silhouette Again, the brakes are pulsed via an ABS type system to not stop the wheel from turning but to create some drag to transfer power to the opposite axle. That type of system is a low-speed only system. There seems to be a misunderstanding that the brake "holds" the wheel from turning but it's rapidly pulsed only to the extent needed to transfer power. It has to be manually engaged via a button also.
1:35 A false claim is made; the power will remain the same! It is the torque and speed that will very. Of course assuming all frictional losses are comparable between the different gear ratios.
There are a number of different but related software packages that control wheel slip via use of the brakes but they are actually technically independent. VSC (skid control), TRAC (traction control) ALSD (auto LSD), ABS (anti-lock-brakes), and Brake Assist (BA) all utilize wheel slip/brake control to accomplish a task but they are independent and were not always included as a full set of installed software. Some of the systems reduce engine power, some change brake pressure etc.
To be fair, its very difficult to explain this to someone without pictures or a video. Either way you cant describe it correctly or even if you do, the person you are talking has not the required abilities of imagination. :)
@Jesus45U I wrote the script and it was for training sales consultants not for marketing. The primary disadvantage is that it's designed for low speed situations where the vehicle is likely to get stuck. It's not designed for all driving situations like, say, a mechanical LSD.
I did a little research, a humming noise is often caused by an incorrectly installed ring and gear pinion, which needs to be adjusted, the incorrect installation of ring and pinion gear prevents proper tooth contact and can cause rapid tooth wear and can cause gear failure. This humming noise converts into growling noise when the wear increases. Humming noise can also be caused due to worn out bearings, which needs to be replaced.
I finally understand basic differentials now. I grew up thinking that a basic differential sent power to one dominant wheel (right side) 100% of the time and the other wheel part of the time. Turns out both wheels are treated exactly the same in relation to one another.
You did happen to skip a very well-known differential, the 2-speed differential. I'm not sure if Toyota ever put one in any of their commercial trucks, but most all other manufacturers have, from 1-ton trucks up, at some point. To see how they work is truly ingenious and resolves the age-old question: gear for torque, or gear for speed. With a 2-speed, you can have both. In a truck, this is very helpful.
I don't see why not though the key to this is not just holding that brake but pulsing it so that wheel does still have some ability to turn. To do it "elegantly", the ABS sensor and electronic system works it but what you are describing would be like modulating the brake on that wheel as a driver would have done aggressively braking in the pre ABS times.
Awsome ! After many failed attempts consisting of sites , forums and hours of googling, I finally find in a 5 min package and understand everybit of it :D :D !!!
@allegroracing please demonstrate how it's possible for a differential to be placed on either left or right of an Axle instead of the center, like on the Toyota land cruiser 70 series. Thank you.
Might not be supposed to be a high budget movie.. never the less, it looks very professionally done. And is well done and pretty illustrated. Ty for clearing my thoughts on how a LSD works.
+faisal3398 very true locking kits are cheap and not hard to fit though not everyone heeds the disclaimer from the manufacturer. Recently in Australia a bloke (who possibly entered the gene-pool when the life guard wasn't looking) fitted one to his Commodore (Pontiac by GMH in the USA and I think Opal in UK). While fun in a straight line the LS2 engine trying to lift the front and push both rear wheels ahead equally under full power meant steering was reduced to "pointing" and he wrecked not far from his driveway. Sadly he took his toddler on this test drive and you can guess the result.
i have a question . when you want to rotate two front or rear wheels, with gears or differential, have you checked the precise rotations of both the wheels with digital meter. I guess, there can be difference.
@thebluecommet The video states that ALSD(aka brake based traction control) does a better job of trasfering torque then other differentials. And it does. Mechanical LSDs can't really change the torque distrabution, they just limit how much of the torque can go to the wheel with the least amout of traction. Brake based traction control can make the wheel with the least amount of resistance the wheel with the most amout of resistance. This why many modern cars use it.
@allegroracing Great Video! We're trying to produce something similar for our products. Who did you use to create the 3d animation? Thanks for your help!
The guy has long since retired...he wasn't the greatest animator and built the rudimentary models himself. I'm sure there are commercially available 3D models of far superior quality nowadays. A guy I worked with on some of the other videos did legal reconstruction animations. He was good because he understood physics and motion.
That's a tough question to answer. Remember it's the tires adhesion that ultimately determines if the car moves or the tires just sit there spinning (or skidding if the car is moving). The ability to control wheel slip and distribute power to any of the 4 wheels is very helpful in situations where one or more wheels are slipping but one or more have traction. However, if all 4 tires are on ice and there's no adhesion for any tire, no drive system will get the car moving.
Because it uses an already existing ABS sensor and is just software. There's no additional hardware or wear components added to a simple open differential. In some cases, mechanical systems require frequent maintenance due to the normal wear caused by their operation.
@PayDroification DRE (driveshaft rotation effect) also means that if you attempt to back up quickly, you may spin the left rear wheel more than the right. It's not that only "one wheel drives", it's that your "go traction" is limited by the wheel with the least traction. One of the advantages of independent rear suspensions on rear driven wheels is the elimination of DRE.
Complicated question. There's the creative director (in this case me) who wrote and storyboarded it then a 3D animator, then a VO artist, then a video editor and this was part of a project that had a producer and other people so it's a big number even though in the scale of this type of project it was "low budget."
Hi, i have a 1987 ford scorpio which has a limited slip differential but the differential has backlash and i need to change it. I have found an open differential that fits perfectly. But i want to know if an open differential would affect the car's handling in a negative way or not. For example, in a rainy day, driving on a curved road, would the car get out of control easier? The car is mostly being used in highway. Thanks.
"Posi" is a term for a limited-slip differential. There are a variety of technologies used in limited-slip differentials but Posi refers to "Posi-traction" which was a brand name for an Eaton LSD unit.
@mastersduhgree It doesn't "drag" the brake, auto LSD can pulse the brake a fraction of a second or several times per second and stops as soon as the other size gets traction. Trying to do this with the parking brake has a similar effect but is nothing like as sophisticated as the high-speed brake pulsing. It's also the basis of the CRAWL system which allows vehicles like the Lexus 460 to decline incredibly steep hills with both feet on the floor.
@PayDroification I'm not a Mustang expert but I know there was a friction-disc LSD on some Mustang rear ends and open diffs on others. If you find out you had an LSD on your particular model of Mustang, it's possible that the friction discs are worn out and it's not providing a limited-slip effect. If you have an open diff, the power tends to always go to the same axle so you would find "1-wheel drive" on the same wheel would be normal.
That's a good question. Normally in racing situations, of course, you'd want a limited slip diff. I would think with drifting that you'd still want some differential action but you'd want to really limit it so the amount of "slip" is low so that you can ensure lighting up both rear tires. If the car isn't actually drifted but is driven on curves, a locked differential would not only produce really bad handling but would also potentially damage the diff when turning so my guess is adjustable LSD.
I have used all 3 type of Diff's and like the clutch pack lsd the best because Locking diff's come on suddenly and blow the entire truck sideways and can be downright scary when side hilling above rivers ect, the electronic ones dont work when rallying at speed and wait to kick in when you have already lost all speed. The clutch system is a constent manageble mesh that works great in the situations I drive.
does the differential add a reduction ratio? i mean internally, I know a reduction will be made having in mind the difference in the ring gear and in the pinion gear, but i do not now if its internal mecanism also add a reduction ratio
I'd think that the answer depends on how tight the tracks (or areas) you're going to run on would be. If you need to turn tightly and the vehicle is pretty wide, it will handle better with a differential than a solid axle. If traction isn't huge on the vehicle (like if it was an off-road RC truck) then it wouldn't matter much. Keep in mind, Karts run with solid axles and they handle great, their track and wheelbase are small.
You answered your own question. Because ALSD only operates at low speeds, the brake friction is low and the brake wear is negligible. Some truck LSDs require frequent oil changes (as frequently as 12 or 20,000 miles) and there are more mechanical components that wear. Changing brake pads is cheaper and easier than differential parts.
oh sorry one more question. if a car is already in motion then LSD might not be needed right? if one (or even both) rear wheels lose traction the car already has momentum, so the front wheels would keep moving the car forward losing speed, but hopefully before you reach 0 your rear wheels have regained traction and can move the car forward again right? but if you are already stopped and your rear wheels don't have traction then that's when you are screwed right?
With a clutch type lsd, you say the power to provide the wheel with traction is limited. So does that mean it is limited by the amount of torque needed to lock the clutch packs? Or do they automatically lock when it senses one wheel spinning faster than the other? -Thanks
Yes it would but the acceleration would suffer (check out Bonneville speed cars that have to be push started because they have such tall gears) because there would be no mechanical advantage from the differential. But you're correct, the axle ratio is a large component in both acceleration and top speed. However, in order to really make the car that much faster, it would need an exponential increase in horsepower because aerodynamic drag is the biggest issue at high speeds.
So then when turning to the right, the left wheels will be moving faster than the right wheels. Does this mean that since the more of the engine's power is going to the left wheels to keep them turning faster that the left wheels have less resistance in this scenario?
It depends what sort of diff the vehicle has. If it's an open diff, it depends which wheel is providing the most resistance. Usually the outside one (due to weight transfer) so it's common that the inside tire has the power and the outside one is just coasting. Not really what you want though because the outside tire has more potential traction so could handle more power. A LSD would try to put a lot of power to the loaded outside tire while still keeping some power to the inside as well.
Look up the difference between part-time and full-time 4wd. Your center differential is there to allow you to use 4wd on pavement, and it works between your front and rear driveshafts the same way an axle differential works between the wheels. Locking the center differential makes your truck behave like any other part-time 4wd rig, unlocking it makes your truck behave more like a Subaru or other all wheel drive vehicle. Lock it when you're offroad if you're worried about traction.
Hey, could you please tell me what simulator you used ? I'm doing a project for one of my exams and I can't accomplish the physical part so I want to simulate it. Thanks.
@Jesus45U Actually it's not a requirement that all passenger cars in the US have skid control...that means they also have ABS as standard so given that all new vehicles have ABS sensors, it's really just software to accomplish this and utilizes existing components. If the diff was being used for high-performance driving (ALSD disengages at low speed) then you would, in fact, tend to cook the brakes as often happens at track days with skid control.
I wish I could do some more extensive videos like this. I had put this on the web for a single conversation on a forum with 6 people viewing it and next thing I knew it had all these hits. If I ever get the opportunity though, I'd make a more wide-ranging video. For instance, I was focused on low-speed differential characteristics because this was trucks. It would be good to do high-speed where LSDs and other mechanical diffs are superior to brake-diffs (which don't work at speed).
Welding a differential takes another design of diff (like an open diff) and creates a "LOCKED" differential. So the explanation of a locking differential basically applies to welded diffs. The goal of welding a diff is to cheaply convert it into a full-time locked differential. This is nearly always for off-road use.
Hope you don't mind me asking you a question...I have A ford Explorer(93)..and my rear dif is staying locked...is there any why I can disengage it? Thanks...
hey you guys seem to know your lsds well. could you help me out with a question maybe? I'm am considering purchasing a subaru wrx because I feel it is an excellent choice of car for a daily driver, especially for winter months of snow. I understand the wrx is awd and has a rear lsd. this means when power is transferred to rear is can be further divided between the left and right rear wheel. the wrx does not have a front lsd. so my question is when traction is lot on both rear wheels
Quick question. I have a 2000 Mustang, & I hate doing burnouts, but I peeled out in the rain & noticed I only get one tire spinning. The rear passenger side. Is my Mustang using one wheel under all driving circumstances for power? Or is ita basic open differential where I get power to both tired until I begin to skid? Am I getting the 2 rear wheels working? Or just one?
help with my issue lol. I am unsure what kind of rear axel I have. But today I drove my car and noticed that if I'm driving straight. My rear end slides to the right-at 20-25mph. The roads were a little damp after snow and rain cleared. Is this normal?
I don't claim to be a mechanic but when it was stated the LSD system via brakes provided fewer parts and less maintenance, are they assuming the *maintenance* was only concerning the immediate LSD system and excluding the brakes? I'm having a hard time assuming the brakes wouldn't wear down sooner....increasing the maintenance frequency? Or am i getting caught up on the word *less as apose to more and they are not refering to time but volume?
Hi guys, I have got Land Cruiser 120, but only have central diff lock. Does it mean it is less capable offroading comparing with 4x4s,which have front and rear diff locks ? And how usefl is central diff lock in offroad ?
A welded diff is basically a jerryrigged locking differential. It forces the rear axles to turn at the same speeds at all times by welding the differential together, giving the benefits of extra traction of a locked differential, without the benefits of an open, limited slip, or electronic (streetability) differential at a very low cost. Welded diffs cause axle hop during cornering and are almost unusable on a daily driver.
@thebluecommet Nowhere in that video does it claim that ALSD (which is far from a unique application of that technology in the auto industry) is superior to anything other than an open diff. ALSD has two benefits over other LSDs, it's lighter and it's cheaper to maintain. That is the only statement in the video. The reason so many differential designs exist is that each is suited to a specific need and have advantages and disadvantages depending on how the vehicle is going to be used.
faster, the ring gear will generally have a gear ratio of between 3-4:1 but it can be higher or lower depending on the car. This means that the axles will spin at 1/3 to 1/4 of the speed of the driveshaft
i have a locking differential on my 1987 chrysler fifth avenue. its annoying. it locks between 35-40 mph. You can floor it from a stop, and no matter what, the differential limits my acceleration. Not to mention the differntial, is 20+ yrs old, but amazingly still works. Im going to a junkyard to replace the diffrential, because its going out. Once i get a new differntial in, is there anyway to "unlock" it for better acceleration? or am im just going to have to replace it with a diffrent type?
Drift cars typically use very limited slip differentials to fully locked differentials. Since the rear is sliding, the differential effect of the turn is irrelevant. It's more important to get power to both rear wheels to keep them spinning. "Normal" handling is degraded due to a reduction in differential wheel speeds.
@PayDroification You LIKELY have an open diff. There's probably some tag on the diff that would tell your Ford parts guy whether it's open or LSD. Ford used to call their LSD "Traction-Loc", GM called theirs "Positraction" and Chrysler called theirs "Sure Grip". Part of what you're noticing is "driveshaft rotation effect" (my term). DRE with a live axle setup like the shown Tundra or your Mustang tries to pick up the right rear wheel when going forward. This reduces it's traction and it spins.
ALSD's work great for the average driver who seldom goes off road, but for serious off road you need locking front & rear diffs. If you have full time 4WD you also need a locking center diff. Brake activated ALSD systems overheat with continuous usage & waste engine power.
I have a Subaru Impreza 2006 automatic, subarus AWD system can be hard to get to slide and have fun in snow in tight ereas, is it OK for me too pull the E-brake for 1 sec? Please answer, but dont if you know litterly nothing about cars as me :) ?
What would happen if i put a 265/75 R16 in one side and the other side a 31x10.50 R15 stock tire size my is limited split differential by the way. What would it damaged the diffrential??
Can you think of a way of doing this using simple mechanics? Sophisticated mechanical parts can wear even faster than electronics and can be much more destructive to itself. Power going to the path of least resistance is universal. Even in electronic circuits.
A big thank you to whoever created this video. The visualization makes all the difference. I've read so many forums and articles that just repeat the same words over and over without adding to any actual understanding.
i think i have learnt more in 4:44 than i have in my life :) thanks , really good vid
This video really grinds my gears
Locking differential at 3:28...Do both axles actually receive equal power (P)? Since they are locking the angular velocities (w) are equal, and the torque (T) on the side with more traction should be greater? P=T*w so T=P/w. If P is equal on both axles and so is w then T would be as well which is not the case correct?
You did this on a budget. Proof that expense doesn't necessarily equal quality. Great video!
Great video - I am 52 and never understood the differential fully. It's hard for most people to understand how things were BEFORE the differential came along - try one of those off-road vehicles or go-karts without this device - it judders on a bend and of course, has better grip on the straight for acceleration. It's fair to say, it was probably made to improve the comfort of some posh bloke in a big limousine - should look it up I guess! This is the perfect animation, I sat and 'paused' the action, and thought through how it works - so now I know that in normal operation, driving straight ahead on a good road with no tyre slip, the 'twiddly bits' in the core of the action sort of act as 'locked up'. Then come a bend or tyre slip on one wheel say, that situation changes. Such a straightforward vid to view and think about how it works. Good work. Also, for further thought people out there could figure how to limit the slip for extra traction on snow etc? Obvs, lots have tried it and there are umpteen variations both involving the differential itself, freewheel-type devices on each axle (like bicycle, one way it's turned it provides drive, not the other, think about it!), aand the old standby now, using ABS system to jam the wheel that's spinning free, to 'force' the wheel with grip to turn a bit. Yes, food for thought, great vid.
My cousin has an FJ Cruiser. I pressed the "lock differential" button and went offroading with it...upon coming back to the road, the car felt very very weird on turns, i thought i have ruined something in the suspension...after several hours, my brother pointed out that i still had my "Lock Differential" button activated.../facepalm
MrSakninsh My cousin uses the car pretty much everyday, there aren't any problems
MrSakninsh
Only if it is an incredibly weak and poorly built one, but I'm assuming he actually meant rear diff lock and not transfer case lock because I don't think FJ's are full time all wheel drive, in which case it's a completely different part he is talking about.
MrSakninsh
Well, depending on what you want to mean, pretty much every differential has to be "interaxial" by design.
While the only "Toyota" I've owned had almost no Toyota parts on it, Toyota's reputation would indicate that neither a transfer case mounted or rear axle mounted locker should break ever in that circumstance.
Also, a rear diff lock should disengage automatically above about 15 MPH for safety reasons. All OEM ones that I'm aware of do that.
sleekitwan I don't believe it was made for limousines, from what I've gathered early cars used to be only 1 wheel drive, but that was terrible since most roads were very rough and definitely not paved, which made cars really tedious to drive. Making cars two wheel drive was a necessity at the time, therefore the differential was created to allow both rear wheels to have power.
Spot on with your description. So many people misunderstand ABS Traction Control. I have a Volvo XC90 with this kind of traction control, and I'm amazed at how many Volvo owners are confused about this. (They also confuse Spin Control with Traction Control--two different things completely. Volvo recommends turning off Spin Control when in low traction situations.) I don't have a button for Traction Control though--it's all automatic.
Incredible, I turned 345 last Wednesday and even at my age I understood this video easily.
@89Silhouette Again, the brakes are pulsed via an ABS type system to not stop the wheel from turning but to create some drag to transfer power to the opposite axle. That type of system is a low-speed only system. There seems to be a misunderstanding that the brake "holds" the wheel from turning but it's rapidly pulsed only to the extent needed to transfer power. It has to be manually engaged via a button also.
1:35 A false claim is made; the power will remain the same! It is the torque and speed that will very. Of course assuming all frictional losses are comparable between the different gear ratios.
تفاعلات تكوانسا حركة ممتازة بدون عطل حركة
Voice Over artist. Someone who professionally does voice recording work.
Never heard of the Auto LSD till this video. But I just thought about in my head it right before I saw it. Nice job Toyota. Practical simplicity.
There are a number of different but related software packages that control wheel slip via use of the brakes but they are actually technically independent. VSC (skid control), TRAC (traction control) ALSD (auto LSD), ABS (anti-lock-brakes), and Brake Assist (BA) all utilize wheel slip/brake control to accomplish a task but they are independent and were not always included as a full set of installed software. Some of the systems reduce engine power, some change brake pressure etc.
i just discovered differentials today, and this stuff is very, very interesting. is there anywhere i can learn more about stuff like this?
Very informative! Sales people at off-road stores can’t even explain it like this. Using Laymen’s term is the secret!
To be fair, its very difficult to explain this to someone without pictures or a video.
Either way you cant describe it correctly or even if you do, the person you are talking has not the required abilities of imagination. :)
@Jesus45U I wrote the script and it was for training sales consultants not for marketing. The primary disadvantage is that it's designed for low speed situations where the vehicle is likely to get stuck. It's not designed for all driving situations like, say, a mechanical LSD.
I did a little research, a humming noise is often caused by an incorrectly installed ring and gear pinion, which needs to be adjusted, the incorrect installation of ring and pinion gear prevents proper tooth contact and can cause rapid tooth wear and can cause gear failure. This humming noise converts into growling noise when the wear increases. Humming noise can also be caused due to worn out bearings, which needs to be replaced.
so LSD and driving go hand in hand?
Depends on what kind of trip you want.
Yeah, it's when you go on a trip and never leave the farm.
I hope you ain't talking about lysergic acid diethylamide!
Go out of Town and never leave the driveway! Lol
I finally understand basic differentials now. I grew up thinking that a basic differential sent power to one dominant wheel (right side) 100% of the time and the other wheel part of the time. Turns out both wheels are treated exactly the same in relation to one another.
You did happen to skip a very well-known differential, the 2-speed differential. I'm not sure if Toyota ever put one in any of their commercial trucks, but most all other manufacturers have, from 1-ton trucks up, at some point. To see how they work is truly ingenious and resolves the age-old question: gear for torque, or gear for speed. With a 2-speed, you can have both. In a truck, this is very helpful.
I don't see why not though the key to this is not just holding that brake but pulsing it so that wheel does still have some ability to turn. To do it "elegantly", the ABS sensor and electronic system works it but what you are describing would be like modulating the brake on that wheel as a driver would have done aggressively braking in the pre ABS times.
Awsome ! After many failed attempts consisting of sites , forums and hours of googling, I finally find in a 5 min package and understand everybit of it :D :D !!!
Do you allow me to use your video in making my videos on channel auto oprema?
You have really done some hard work, thank you, its informative.
Really cool video. Easy to understand and follow. Well done!
I was workin on a Lego model truck with deferential,this vedio helped me to figure out few tricks to modifie it!thanks for such a great video
@allegroracing please demonstrate how it's possible for a differential to be placed on either left or right of an Axle instead of the center, like on the Toyota land cruiser 70 series. Thank you.
thanks for the vid. basically summed up half of my course and simplified the components.
Might not be supposed to be a high budget movie.. never the less, it looks very professionally done. And is well done and pretty illustrated. Ty for clearing my thoughts on how a LSD works.
so for burnouts, limited slip is the way to go so that you don't have one wheel squeals?
Bearbait01 If you really want a solid burnout go with a locked rear differential :)
Ian LaRiviere Or weld your own diff (warning: as you would guess it'll be extremely unsafe so do at your own risk)
+faisal3398 very true locking kits are cheap and not hard to fit though not everyone heeds the disclaimer from the manufacturer. Recently in Australia a bloke (who possibly entered the gene-pool when the life guard wasn't looking) fitted one to his Commodore (Pontiac by GMH in the USA and I think Opal in UK). While fun in a straight line the LS2 engine trying to lift the front and push both rear wheels ahead equally under full power meant steering was reduced to "pointing" and he wrecked not far from his driveway. Sadly he took his toddler on this test drive and you can guess the result.
Bearbait01 a Spool would work better
Ok Bearbait01 🚙
i have a question . when you want to rotate two front or rear wheels, with gears or differential, have you checked the precise rotations of both the wheels with digital meter. I guess, there can be difference.
@thebluecommet The video states that ALSD(aka brake based traction control) does a better job of trasfering torque then other differentials. And it does. Mechanical LSDs can't really change the torque distrabution, they just limit how much of the torque can go to the wheel with the least amout of traction. Brake based traction control can make the wheel with the least amount of resistance the wheel with the most amout of resistance. This why many modern cars use it.
@allegroracing Great Video! We're trying to produce something similar for our products. Who did you use to create the 3d animation? Thanks for your help!
The guy has long since retired...he wasn't the greatest animator and built the rudimentary models himself. I'm sure there are commercially available 3D models of far superior quality nowadays. A guy I worked with on some of the other videos did legal reconstruction animations. He was good because he understood physics and motion.
That's a tough question to answer. Remember it's the tires adhesion that ultimately determines if the car moves or the tires just sit there spinning (or skidding if the car is moving). The ability to control wheel slip and distribute power to any of the 4 wheels is very helpful in situations where one or more wheels are slipping but one or more have traction. However, if all 4 tires are on ice and there's no adhesion for any tire, no drive system will get the car moving.
Are the diameters of the differential gears also need to compensate for the width of the car?
Because it uses an already existing ABS sensor and is just software. There's no additional hardware or wear components added to a simple open differential. In some cases, mechanical systems require frequent maintenance due to the normal wear caused by their operation.
Can you teach us about different types of four wheel steering.
@PayDroification DRE (driveshaft rotation effect) also means that if you attempt to back up quickly, you may spin the left rear wheel more than the right. It's not that only "one wheel drives", it's that your "go traction" is limited by the wheel with the least traction. One of the advantages of independent rear suspensions on rear driven wheels is the elimination of DRE.
God bless you man. 5 stars for the video.
LOCKING DIFF. are widely used in Tractors.
Complicated question. There's the creative director (in this case me) who wrote and storyboarded it then a 3D animator, then a VO artist, then a video editor and this was part of a project that had a producer and other people so it's a big number even though in the scale of this type of project it was "low budget."
Have had my tundra for 10 years, had no idea what Auto LSD does. Ty!!!
Hi, i have a 1987 ford scorpio which has a limited slip differential but the differential has backlash and i need to change it. I have found an open differential that fits perfectly. But i want to know if an open differential would affect the car's handling in a negative way or not. For example, in a rainy day, driving on a curved road, would the car get out of control easier? The car is mostly being used in highway. Thanks.
"Posi" is a term for a limited-slip differential. There are a variety of technologies used in limited-slip differentials but Posi refers to "Posi-traction" which was a brand name for an Eaton LSD unit.
@mastersduhgree It doesn't "drag" the brake, auto LSD can pulse the brake a fraction of a second or several times per second and stops as soon as the other size gets traction. Trying to do this with the parking brake has a similar effect but is nothing like as sophisticated as the high-speed brake pulsing. It's also the basis of the CRAWL system which allows vehicles like the Lexus 460 to decline incredibly steep hills with both feet on the floor.
Nice! also helped to answer my question about the difference between a truck and a sports car
Very informative video! I knew about slip differential because of my truck but I never knew whats really going on in the rear end.
@PayDroification I'm not a Mustang expert but I know there was a friction-disc LSD on some Mustang rear ends and open diffs on others. If you find out you had an LSD on your particular model of Mustang, it's possible that the friction discs are worn out and it's not providing a limited-slip effect. If you have an open diff, the power tends to always go to the same axle so you would find "1-wheel drive" on the same wheel would be normal.
That's a good question. Normally in racing situations, of course, you'd want a limited slip diff. I would think with drifting that you'd still want some differential action but you'd want to really limit it so the amount of "slip" is low so that you can ensure lighting up both rear tires. If the car isn't actually drifted but is driven on curves, a locked differential would not only produce really bad handling but would also potentially damage the diff when turning so my guess is adjustable LSD.
Great video! However with the Toyota Brake LSD, doesn't that causes uneven brake wear?
Brakes wear so slow, especially on the rear, if any uneven wear was occurring it wouldn't be a problem.until well past 100k miles
I have used all 3 type of Diff's and like the clutch pack lsd the best because Locking diff's come on suddenly and blow the entire truck sideways and can be downright scary when side hilling above rivers ect, the electronic ones dont work when rallying at speed and wait to kick in when you have already lost all speed. The clutch system is a constent manageble mesh that works great in the situations I drive.
Excelent vid. Animtation is pretty clear, don't need enough.
does the differential add a reduction ratio? i mean internally, I know a reduction will be made having in mind the difference in the ring gear and in the pinion gear, but i do not now if its internal mecanism also add a reduction ratio
I'd think that the answer depends on how tight the tracks (or areas) you're going to run on would be. If you need to turn tightly and the vehicle is pretty wide, it will handle better with a differential than a solid axle. If traction isn't huge on the vehicle (like if it was an off-road RC truck) then it wouldn't matter much. Keep in mind, Karts run with solid axles and they handle great, their track and wheelbase are small.
You answered your own question. Because ALSD only operates at low speeds, the brake friction is low and the brake wear is negligible. Some truck LSDs require frequent oil changes (as frequently as 12 or 20,000 miles) and there are more mechanical components that wear. Changing brake pads is cheaper and easier than differential parts.
oh sorry one more question. if a car is already in motion then LSD might not be needed right? if one (or even both) rear wheels lose traction the car already has momentum, so the front wheels would keep moving the car forward losing speed, but hopefully before you reach 0 your rear wheels have regained traction and can move the car forward again right? but if you are already stopped and your rear wheels don't have traction then that's when you are screwed right?
With a clutch type lsd, you say the power to provide the wheel with traction is limited. So does that mean it is limited by the amount of torque needed to lock the clutch packs? Or do they automatically lock when it senses one wheel spinning faster than the other? -Thanks
Yes it would but the acceleration would suffer (check out Bonneville speed cars that have to be push started because they have such tall gears) because there would be no mechanical advantage from the differential. But you're correct, the axle ratio is a large component in both acceleration and top speed. However, in order to really make the car that much faster, it would need an exponential increase in horsepower because aerodynamic drag is the biggest issue at high speeds.
So then when turning to the right, the left wheels will be moving faster than the right wheels. Does this mean that since the more of the engine's power is going to the left wheels to keep them turning faster that the left wheels have less resistance in this scenario?
It depends what sort of diff the vehicle has. If it's an open diff, it depends which wheel is providing the most resistance. Usually the outside one (due to weight transfer) so it's common that the inside tire has the power and the outside one is just coasting. Not really what you want though because the outside tire has more potential traction so could handle more power. A LSD would try to put a lot of power to the loaded outside tire while still keeping some power to the inside as well.
gfcb
awesome job guys! great video even though i knew how a diff works this video makes it easier for me to explain what i know to others
Look up the difference between part-time and full-time 4wd. Your center differential is there to allow you to use 4wd on pavement, and it works between your front and rear driveshafts the same way an axle differential works between the wheels. Locking the center differential makes your truck behave like any other part-time 4wd rig, unlocking it makes your truck behave more like a Subaru or other all wheel drive vehicle. Lock it when you're offroad if you're worried about traction.
This might sound like a silly question, but does differential calculus have anything to do with these calculations?
+Vinay Seth im in differential equations....I'm sure there's some type of like ODE associated with studying these but I have no idea haha
+kalef1234 Oh ok. Thanks.
Hey, could you please tell me what simulator you used ? I'm doing a project for one of my exams and I can't accomplish the physical part so I want to simulate it. Thanks.
@Jesus45U Actually it's not a requirement that all passenger cars in the US have skid control...that means they also have ABS as standard so given that all new vehicles have ABS sensors, it's really just software to accomplish this and utilizes existing components. If the diff was being used for high-performance driving (ALSD disengages at low speed) then you would, in fact, tend to cook the brakes as often happens at track days with skid control.
the powertrax no-slip is the best auto locker ever made and best set up for on or off-road.
I wish I could do some more extensive videos like this. I had put this on the web for a single conversation on a forum with 6 people viewing it and next thing I knew it had all these hits. If I ever get the opportunity though, I'd make a more wide-ranging video. For instance, I was focused on low-speed differential characteristics because this was trucks. It would be good to do high-speed where LSDs and other mechanical diffs are superior to brake-diffs (which don't work at speed).
University of toyota ??
Internal training department for dealers. No longer in existence.
allegroracing - thanks ;)
Let's go Yotes!
Welding a differential takes another design of diff (like an open diff) and creates a "LOCKED" differential. So the explanation of a locking differential basically applies to welded diffs. The goal of welding a diff is to cheaply convert it into a full-time locked differential. This is nearly always for off-road use.
Hope you don't mind me asking you a question...I have A ford Explorer(93)..and my rear dif is staying locked...is there any why I can disengage it? Thanks...
hey you guys seem to know your lsds well. could you help me out with a question maybe? I'm am considering purchasing a subaru wrx because I feel it is an excellent choice of car for a daily driver, especially for winter months of snow. I understand the wrx is awd and has a rear lsd. this means when power is transferred to rear is can be further divided between the left and right rear wheel. the wrx does not have a front lsd. so my question is when traction is lot on both rear wheels
Quick question.
I have a 2000 Mustang, & I hate doing burnouts, but I peeled out in the rain & noticed I only get one tire spinning. The rear passenger side. Is my Mustang using one wheel under all driving circumstances for power? Or is ita basic open differential where I get power to both tired until I begin to skid? Am I getting the 2 rear wheels working? Or just one?
What software did you use to animate the workings of the differential?
help with my issue lol. I am unsure what kind of rear axel I have. But today I drove my car and noticed that if I'm driving straight. My rear end slides to the right-at 20-25mph. The roads were a little damp after snow and rain cleared. Is this normal?
Just watched all your vids and I must say pretty interesting. Nicely done
I don't claim to be a mechanic but when it was stated the LSD system via brakes provided fewer parts and less maintenance, are they assuming the *maintenance* was only concerning the immediate LSD system and excluding the brakes? I'm having a hard time assuming the brakes wouldn't wear down sooner....increasing the maintenance frequency? Or am i getting caught up on the word *less as apose to more and they are not refering to time but volume?
Minimal wear on pads. Non issue.
Hi guys, I have got Land Cruiser 120, but only have central diff lock. Does it mean it is less capable offroading comparing with 4x4s,which have front and rear diff locks ?
And how usefl is central diff lock in offroad ?
A welded diff is basically a jerryrigged locking differential. It forces the rear axles to turn at the same speeds at all times by welding the differential together, giving the benefits of extra traction of a locked differential, without the benefits of an open, limited slip, or electronic (streetability) differential at a very low cost. Welded diffs cause axle hop during cornering and are almost unusable on a daily driver.
@thebluecommet Nowhere in that video does it claim that ALSD (which is far from a unique application of that technology in the auto industry) is superior to anything other than an open diff. ALSD has two benefits over other LSDs, it's lighter and it's cheaper to maintain. That is the only statement in the video. The reason so many differential designs exist is that each is suited to a specific need and have advantages and disadvantages depending on how the vehicle is going to be used.
It just clicked! Hell yeah. I've been curious forever about this topic.
Is this viscous coupling animation video?
could you change the horizontal input (drive shaft) to a vertical in put? if so how?
1:35 that's wrong, the power is the same, what varies is the torque applied to each wheel...
Correct but it was clearly mentioned "applied power" to the wheel - not the same as engine power. There was no error.
Does the driveshaft spin faster or slower than diff axles?
faster, the ring gear will generally have a gear ratio of between 3-4:1 but it can be higher or lower depending on the car. This means that the axles will spin at 1/3 to 1/4 of the speed of the driveshaft
i get it , so drifter have to weld it together , so the 2 wheels spin at the same speed ?
"Low traction situations" drifting?
Louis Smith not necessarily, it could also mean going on sand or dirt.
i have a locking differential on my 1987 chrysler fifth avenue. its annoying. it locks between 35-40 mph. You can floor it from a stop, and no matter what, the differential limits my acceleration. Not to mention the differntial, is 20+ yrs old, but amazingly still works. Im going to a junkyard to replace the diffrential, because its going out. Once i get a new differntial in, is there anyway to "unlock" it for better acceleration? or am im just going to have to replace it with a diffrent type?
Drift cars typically use very limited slip differentials to fully locked differentials. Since the rear is sliding, the differential effect of the turn is irrelevant. It's more important to get power to both rear wheels to keep them spinning. "Normal" handling is degraded due to a reduction in differential wheel speeds.
What is the mechanical difference between lsd and locker?
What software did you use to make that
@PayDroification You LIKELY have an open diff. There's probably some tag on the diff that would tell your Ford parts guy whether it's open or LSD. Ford used to call their LSD "Traction-Loc", GM called theirs "Positraction" and Chrysler called theirs "Sure Grip". Part of what you're noticing is "driveshaft rotation effect" (my term). DRE with a live axle setup like the shown Tundra or your Mustang tries to pick up the right rear wheel when going forward. This reduces it's traction and it spins.
Great work. Thanks for sharing info.
ALSD's work great for the average driver who seldom goes off road, but for serious off road you need locking front & rear diffs. If you have full time 4WD you also need a locking center diff. Brake activated ALSD systems overheat with continuous usage & waste engine power.
I have a Subaru Impreza 2006 automatic, subarus AWD system can be hard to get to slide and have fun in snow in tight ereas, is it OK for me too pull the E-brake for 1 sec? Please answer, but dont if you know litterly nothing about cars as me :) ?
so would a posi rear be the first one shown that isnt and open diff
.. i may be wrong but i counted 5:1 rotation 1:20
+Skylin Megas i guess u r wrong ;/
+Andrzej Skrzyński I counted 5 turns on the pinion gear to 1 turn from the axle gear .. please explain where I fudged my count :)
+Skylin Megas you can count the spikes of each gear and that basically gives you the ratio in size.
XhunterDragon96 I see ... My bad , I assumed it was it's rotation
***** I'm pretty sure it should be exactly the same quantity though, I didn't count them so you may be right.
This video gave me a great help to update my knowledge thank you.
This was amazing. I learned about differentials
What differential does range Rover Evoque 2015 have?
What would happen if i put a 265/75 R16 in one side and the other side a 31x10.50 R15 stock tire size my is limited split differential by the way. What would it damaged the diffrential??
Can you think of a way of doing this using simple mechanics? Sophisticated mechanical parts can wear even faster than electronics and can be much more destructive to itself. Power going to the path of least resistance is universal. Even in electronic circuits.