Torsen Limited Slip Differential - Explained

[@BernieLee]

Have you thought about revisiting this video? I love how your videos have evolved over time and I think you could really knock this out of the park with an actual differential opened up to show how it works and go through the pros and cons.

[@johnbailey7038]

Bernie Lee i was feeling the same way, but thats not to say the original is bad though. This is a really difficult thing to try explaining to people who may not be mechanically inclined

[@autoSRI]

It’s easy to understand if you already understand it but if your trying to learn it’s really confusing

[@gonzccs]

Love to see this guy making a living out of this channel from this humble beginnings. Who would have thought that being a KZbinr could become something 8 years ago?

[@benmudn]

I totally agree. Having recently bought a TrueTrac and for the life of me can not grasp how it completely works. I have watched every video on yt and still no luck. I consider myself fairly mechanically inclined, heck I installed the gears in the axle with the TrueTrac. Yukon/Spartan just release their version of the Torsen LSD.

[@WraithlingRavenchild]

I would like you to revisit this series. Your skills as a presenter were good. You have become much better.

[@Nada-Mal]

I'm sitting procrastinating in front of my pc, coffee in hand. Having just bought a Audi with a Torsen Quattro I've been watching video's all morning. After watching this I was thrown back to my University days and I'm sitting reminiscing! Thanks for the video, you can't beat a nice simple white board explanation: and well done on the isometric projection of the worm wheel. If I'd drawn that it'd have been much more wobbly looking!

[@EngineeringExplained]

Malcolm King Glad you enjoy the videos! The drawings are certainly challenging at times.

[@EngineeringExplained]

That said, it is nice to have someone realize how much effort it takes, rather than just saying "make more videos!"

[@jogrobler]

That eureka moment when you explained the reasoning behind the spur gears (them not being able to turn the same direction when both wheels have equal traction). I've got massive respect for you attempting to explain this man and think you've succeeded pretty well. Quite a daunting thing to explain.

[@jogrobler]

JO Grobler Also, this video helped me visualise how it all works. Even though it's in French, it's really well done visually and even includes a cut-away of a working Torsen >> /watch?v=vS6FXZSx8aA

[@ahobimo732]

This is some CLASSIC KZbin right here.

[@vanepico]

So put basically, the only time the wheels are allowed to spin at different radial velocities is when each one has friction with the ground, creating an equal and opposite radial velocity in relation to the diff housing, when one is slipping, the reverse worm drive effect blocks any lost torque. If one wheel is not imparting any force back through the differential then the diff locks automatically. I'd hate to be the engineer who designed this trying to explain his idea!

[@georgipartsalev6193]

Your comment was genuinely very helpful!

[@benbrinkhurst8722]

Fantastically helpful

[@konstantin.v]

Indubitably! Only now I get it: *the torque from the wheel lessens the friction at the worm gear,* thus allowing it to slip. If that torque gets too low, the friction prevails and the worm gear locks. Umm... Right? 🙂

[@EngineeringExplained]

They're both directly driven from the ring gear, as the shafts running through the worm wheels are connected to the worm gears of each drive axle, thus both axles are rotated by rotating the differential housing. Thanks for watching!

[@infidel900rr]

Trying to understand this in a hard driving scenario: Q. When power oversteering out of a corner, if the inside wheel starts spinning out (one-wheel-peel scenario of an open diff), will the outside wheel engage and turn but turn at a slower rate? OR Will the outside wheel which is already rotating faster (entering the apex, but not yet breaking traction), remain the faster rotating wheel as power oversteer is introduced after the apex of the corner? Thanks and sorry for the comment on an old video - trying to figure out which LSD I want to buy.

[@boblee6847]

I have to share a quick story on how I first learned how a differential worked...47 years ago as a young teenager. My friends dad built a working differential using parts from a mechano set. He was a mechanical engineer and a very clever man. He is 93 today and still works at his home based machine shop. Nothing like holding something in your hand to see how it works. Some things are so difficult to explain but some how you seem to manage. Great video!

[@NabilChouchany]

It's remarquable how you were able to explain this using a white board only! I teach auto mechanics and was never able to explain this efficiently using only a board. However, it seems that you only explained the operation during the normal phases (when acting as an open differential), and you forgot to explain the easier phase, when it locks (as one wheel has no traction and the system locks: only one wheel wants to turn, its worm gear as well, trying to turn the worm wheel, the worm wheel is meshing with the opposite worm wheel which in turn tries to turn its worm gear, it cannot. So the worm wheels are unable to spin on their axis, the worm gears are both driven as it locks) Cheers!

[@EngineeringExplained]

+Nabil Chouchany Thanks for the kind words! I created a second video explaining how the torque transfer occurs: kzbin.info/www/bejne/onXWgnSpZbGXm9U Cheers!

[@nblax41]

Difs are probably the hardest thing to explain to people in terms of how they work without using a physical model, you do a great job explaining them using just the trusty whiteboard.

[@sweinnc]

It is difficult to explain, but it makes perfect sense. It is so simple, but yet very hard to grasp. There should be a good 3D video out there showing exactly what happens in the different scenarios, but I’ve not found it.

[@briankolley3550]

Very Impressive set of videos. A way to look at it that might make it easier to explain how a Torsen allows the output shafts to rotate at different rates is to treat the faster rotating output shaft like it's the only rotational input to the system. If you held one output shaft and applied a rotation to the other output shaft, then the worm gear of the driven output shaft will rotate it's corresponding worm wheel. The spur gears on the worm wheels synchronize the worm wheels together and force them to rotate at the same rate. The rate at which the worm wheels rotate is exactly the rate required for the worm wheel of the held output shaft to move around the circumference of it's associated stationary worm gear at a rate equal to the that which the driven output shaft is rotated. So, when both shafts are rotating at different rates, as in a turn, relatively speaking, it's exactly the same scenario as I described above. It's as if the ground is rotating the faster tire at a rate equal to the difference while holding the slower tire. That rotational "input" from the ground to the faster tire allows the worm gears to turn the worm wheels, allowing the worm wheel of the slower output shaft to traverse the circumference of its associated worm gear, thus allowing the tires to rotate at different rates. On the other hand, In the slippery wheel scenario, there is no rotational "input" from the ground. The only rotational input is from the ring gear. Since a worm wheel cannot rotate a worm gear, it must lock against it and transmit the case rotation to the output shafts, thus transmitting torque to the wheel with the most resistance and locking the rotation rate of both output shafts to that wheel. I don't know if that makes it any clearer, but it's how I think about it.

[@ap0llo.0ne51]

This is honestly one of THE most clearest explanations of a torsen LSD that I have ever seen! Thank you so so much Jason :)

[@knoblis]

Jason, I think it might be very usefull for you to revisit this, not only because of your hairstyle.

[@justlife2129]

When it comes to technical things, you are simply THE BEST.

[@EngineeringExplained]

Haha, it took a few tries. I didn't even want to think about drawing diffs when I first started this channel. But since it's grown, I'll put a tad more effort in. Glad to hear it's appreciated!

[@EmirAsari]

world is a better place with your videos ! Thx.

[@EngineeringExplained]

Haha great to hear, thanks for watching!

[@jorikarjalainen]

Agreed

[@theadel8591]

I'm astonished of how cleverly the mechanism was designed to work, hats off to the great engineers.

[@DoctaMarcos]

Have you ever thought about doing a live video? To answer questions about what your explaining depending on the topic? Another thing is, have you ever thought about doing this stuff on the computer to add moving pictures etc. Your drawings are amazing and must take a long time to do. Thank you!

[@paulholden7698]

I can tell how much easier you now find explaining rather basic (once you know) mechanical engineering principles for the general layman. I went through a process of trying to design my own method as there's quite a few variations but figured why re Invent the wheel. 🤔

[@alexchapman6981]

First, I really appreciate this video. Second, I have a correction. He says toward the end that one wheel moving faster than the other will cause the worm wheels to rotate and one will slide over the slower-rotating wheel's worm gear. However, this is not what happens. If one wheel moves faster than the Diff housing by a certain amount, the other wheel must slow by that exact amount *on its own* for the worm wheels to turn. This is what happens when making a turn. If that is not the case, then the Diff housing and output shafts effectively lock up and torque is transferred from the faster-rotating side to the slower side. This is why the Diff is called "limited slip."

[@PauloAugustoTolentino]

It makes absolute sense at the end. You should just have said "the whole torsen group will rotate around the 'stationary' gear". Thanks for the amazing vids.

[@EngineeringExplained]

No, they both are connected to the diff housing via the shafts in the worm wheels, thus, both receive the same rotational force.

[@Reckec]

I got it, I watched a video with a 3-D model and didn't catch on but with your help I see how one wheel can spin at a different speed. Thanks, great video.

[@Inimbrium]

7:48 I get it! Man it was hard to understand initially, but as soon as you said that, it suddenly made sense. Congrats on a successful explanation of a VERY difficult topic.

[@charles1379]

in effect it is not that the slower axle moves backward but rather the worm on that axle is in a locked position on the axle and revolves with it. as a result the faster axle (less loaded) is forced to spin faster - as the axle can spin the worm but not the other way around. thanks for a good video.

[@thefirstviolinist]

So great going back and looking at the old videos. Been following for almost nearly as long. Always a treat!

[@dunx125]

I knew you were excellent at explaining things, but this one is particularly impressive considering the complexity of the mechanism. Well done :)

[@yerffejmurffy]

I had to scratch my head a couple times but it made sense for the most part. Whoever invented the Torsen Differential was an engineering god!

[@Bobby8451]

One thing I love is gears. I've always been fascinated with then. Gear ratios and all that. Haven't took any classes on it but I've always as a little kid took things apart that involved gearing to see how it all worked. Lol

[@joandar1]

Interesting. I understand that Torsen came up with the idea of this form of drive for a diff. Unless I am mistaken it was Gleason in America, a gear making company that got it with their gear cutting tech. I only here in Australia know it as a Torsen/Gleason Diff well used and highly respected by many that need the benefits of the traction and ability to go round curves. Cheers from John Australia.

[@rtsoccerplayer]

its fascinating to see how someone actually could design this complicated system of gears.

[@dbeckMSP]

A guy on Jalopnik was wrote an article about 4WD vs AWD the other day and linked this video into to explain it! Great job on the explanation, however that is a very confusing differential...

[@EngineeringExplained]

I'm a little uncertain myself on that point. I agree; it's basically metal on metal and you would assume wear would occur. That said, if the speed difference between the two is fairly minimal, makes sense that it could last quite a while.

[@505197]

Thorson is wonderful. I used it in a stock car rather then a spool and loved it.

[@EngineeringExplained]

Each have situations where one may be preferred. I'm assuming by normal you mean a clutch type. Clutch types are a little more tunable, you can get it to the characteristics you prefer. Torsen is definitely more useful than a typical open differential in order to maximize power delivery to the ground.

[@RY3ER_]

Took me 5 days. 5 days!! But I've finally got it. Amazing teaching mr. Jason, thanks for sharing your knowledge, absolutely appreciated!!

[@EngineeringExplained]

What are we comparing it to? Open differentials, or other LSDs? Better than open for the obvious reasons. Better than viscous because the torque transfer is instant. Doesn't wear like a clutch type. But, it doesn't transfer torque if one tire is in the air, unlike a clutch type.

[@vkotis]

These are the types of videos that are invaluable on youtube. Well explained!

[@EngineeringExplained]

Well, I would say it depends on the application. But for racing probably a clutch type. Though honestly I think Torsen is a great solution to the problem of an open diff as well.

[@EngineeringExplained]

Well, it doesn't have as much wear as a clutch type, and doesn't require specific fluid conditions of the viscous. It certainly has some advantages, though overall I think a clutch based system would likely be all around the best option, once you've nailed down the specific application. It's standard on the new FRS/BRZ, I believe the Miata may use it as well, as well as some Audi vehicles.

[@lanaya6261]

This video made me understand some critical missing points from many 3D animation videos! Great job!

[@KyleBarrf]

I don't know how much money you're making, but if you get an offer to become an engineering professor, do it, you're awesome. . I was confused at how "turning the car" worked with the wheels at different speeds. It makes a lot of sense now. The faster wheel creates excess force on the spur gear which then rotates the other spur gear the opposite direction thus relieving the force on the other wheel allowing it to slow down. . Then the differential works like a locked diff when accelerating because the most force is turning both spur gears from the force of the housing (from the pinion gear) causing the wheels to accelerate equally because both wheels don't have enough force to overcome the force of the engine. . I guess Vernon Gleasman got tired of learning hard physics so he made something from the simple physics that he knows: equal forces. God, I love physics, so glad I decided to take it instead of AP Chemistry. Thanks again Jason, you're awesome!

[@EngineeringExplained]

You are welcome, thank you for watching!

[@EngineeringExplained]

Yes, thinking of how complex it is to explain, versus how complex it is to just "think" of; it's rather remarkable.

[@EngineeringExplained]

I get plenty of sleep! Haha. It's a lot of work for sure, comes down to managing my time well. I'm not searching for a new job either. But yes, 40 hours a week, plus making videos (5-10 hours) plus comments (5 hours) plus website (1-2 hours) plus facebook (~3 hours); it's a lot of work. I enjoy it though! Still get to go skiing on the weekends!

[@EngineeringExplained]

They're the link for the two drive axles. They are what connects the two sides.

[@gehtdianschasau8372]

My daily driver is in the shop for the yearly inspection, so i'm driving an FF with open differential right now. I live near the alps and yesterday we had about 25cm snow. My rx8 really shines in that conditions, the crappy kangoo sucks. I expected the ESP to make up for the open diff at least a littl bit, i hoped it would send some of the power to the wheel with more grip. I was not completely right. It kinda does that, but that also slows the car down. When there is not enough grip to accelerate and you need momentum to get up the hill, that really sucks. Instead of having a big smile, i was worried about getting stuck. Torsen is awesome, if you buy a new car, an it's an option, get it! It's worth every cent.

[@177936]

Had roughly know how this works for a while after watching a 3d animation but this video cleared up any confusing bits. Excellent video.

[@rroge5]

you explained it clearly enough... the housing is spinning around and the funny gears inside of it are spinning 1 output in a opposite direction than the other... both of those things happening at the same time means you go around a corner without dieing.

[@nishantkhalde5698]

man........ u r d best seriously u always help me in passing my xams.... well thats the secondary thing. most important is u just make engineering easy !! keep uploading more videos

[@croooots]

If you look up " DIFFERENTIAL TORSEN diferencial Sport Peugeot" on youtube, there is a great animation. I know it's in french, but its the best animation I've found so far and shows each component.

[@SuperBombbud]

Word just am figuring out my firebird with lsd so I'm pretty pumped to learn more and take it apart but deffently useful info thanks dude

[@willdriverc]

Really good explanation and the animation was a must. I now understand the diff in my car. One suggestion I would make is if you had an ipad or something to play the animation on continuous loop stuck on the wall next to your white board that might help with a little too? Food for thought Keep up the awesome work please

[@daviddrueding3887]

Brave man doing Torsen on a whiteboard ;) Much appreciated.

[@Archibalt3000]

Actually it made a lot of sense. Clear and comprehensive explanation, great stuff once again! These videos are really refreshing and interesting after a day of studying medicine. ;)

[@nfschido]

If you did´t understand at 8:20 just go watch the 3D video of the differential again and check how the spur gears go on different direction while one wheel is going faster than the other

[@P.J16]

Congratulations! is the first video I have seen of Torsen that really help me to understand it. GREAT!

[@EngineeringExplained]

The two spurs cannot move in the same direction. They can move at the same speed, it will just be in opposite directions. When both wheels are rotating at the same speed, the spur gears will not be rotating.

[@pnwgentleman]

Boy have you improved over time! Also, I see how they torsion LSD allows for slip, but I didn't see how it limits the slip to provide traction to both wheels.

[@agma]

Your figures are so nice that a 3d animation is not really necessary

[@N54God666]

Got it the first time. Very nicely explained. Didn't watch your other "advised" videos.

[@zacharylagler242]

+Ellis Preston I watch all his video's. He is very respected for explaining anything car related

[@AMARUCHI]

Great Job on successfully concluding the challenging task! Especially on how you explained the action of the differential, that being the difference in speed between the two axles in terms of relative motion. Wonderful work!

[@gokullakshmanan]

This is something which is very difficult to explain..and you tried your best..welldone... And thank you...:)

[@aw11onfire]

I would say it's a quite good video clip explaining Torsen LSD

[@EngineeringExplained]

I know I need to make an ELSD video; don't know when I will though.

[@agerwick]

Good explanation of how the torsen diff works!

[@juancarlossaavedra4505]

WELL EXPLAINED MATE ! ! Cheers from Australia

[@JayMaverick]

I wanted to know how this works, and here you are with a clear and extensive explanation. Thank you! The thing that bugs me though, is how on earth do the friction plates NOT require maintenance? I would think they wear out like any clutch-surface?

[@trucktechie]

Great explanation, you surely have made it easier to understand. The person behind this marvel of engineering must have had quite the imagination. :)

[@calvingould7908]

As far as my understanding goes: It was the worm wheels inability to drive the worm gear that resulted in the rotation of the tire of the car. Instead of the worm wheel shooting the worm gear in the direction that the worm wheel rotates, it pulls it down in an infinite circular motion driving the tire. In the opposite case where the tire spins faster then the worm gear spins faster which drives the worm wheels. That's about where my understanding cuts off, because after the worm wheels are driven (by the worm gear which is driven by the tire slipping), then the spur gears attached to the worm wheels would need to spin at a fixed rate that is relative to the worm gear driving it. (That's just how gears work, they run at fixed ratios). If the spur gears need to spin one to one, and the worm wheels attached to the spur gears, then ultimately the worm gears that drive the tire would need to spin at that same speed. Resulting in the same situation where both tires spin at the same speed. The above works all well in getting the car out of a situation where one wheel spins too quickly and the opposite becomes the dead wheel, but i still don't see how that same set up can allow for the tires to spin independently around turn. Is there some ratio set between the worm gear and the worm wheels that decides exactly how much variance is allowed between the two speeds of the tires? That is the only solution i can come up with, which seems dangerous because once that decided variance is exceeded then the entire mechanism would lock up and cause both tires to turn at the same speed in THE MIDDLE OF A TURN. I don't know if you've watched any gymkhana videos but i imagine it would result in something similar to that

[@calvingould7908]

(This is under the assumption that the spur gear and worm wheel have to spin at the same speed, which i assumed because the video never clarified for me)

[@Ikoflex1B]

The application for this type of LSD that I remember form an old Popular Mechanics from the 50's, is for use in Airport Mule vehicles. The actual Mule was used to pull the massive B-36, and it was said in the article that one tire could be on ice, and the other, on dry pavement, and it would not spin the ice tire, and pull the B-36 just fine. This has not worked it's way into the auto industry, I would guess, due to the complexity. Just a side note: The B-36C loaded weight of 227,700 lbs.

[@drewguitar2051]

Lol like 2 seconds before you said that probably didn't make any sense at all, I thought, wow that didn't make any sense at all. haha but you did a great job at describing something this complex.

[@ridingtothehorizon]

Thanks for putting so much work into these. They are great and I can't stop watching them!

[@EngineeringExplained]

Thank you! It was certainly a challenge.

[@shahbaazali1195]

still a great video , i understood very well better than my teacher does on other topic

[@EngineeringExplained]

Hopefully haha. For now, the quick answer is it cuts fuel once a certain RPM is hit.

[@xxspalatoxx]

Epic face expression @ 8:17 followed by "and that probably didn't make any sense at all"....made me lol

[@silviuvirgil12]

I am not 100% sure yet, but I think that at 2:40 he makes a fundamental error in saying that the worm gear can't spin the wheel. That is usually the case but in the torsen the angle in the worm gears is not shallow enough to produce this "one way" transmission effect.

[@alexandreplewinski]

It would be great if we could have an answer from Engineering Explained :p

[@misters2837]

I have never seen a "Worm Drive" of any size that you could rotate the Gear by driving the Worm Wheel, regardless of the size or angle of the gears/wheels, in fact doing so usually ends up with stripped teeth on the wheel. (It's possible they exist, but in practical usage of gearboxes, that I have hands on daily usage, I have never seen one.)

[@AndrewOgden]

Could you do a follow up video explaining the differences and potential benefits of Type T-1, T-2, T-2R, and T-3. I'm particularly interested in what applications they are best suited for...front diff, rear diff, center diff.

[@EngineeringExplained]

The other can still rotate assuming it overcomes the internal friction forces.

[@alexp4454]

This seems to make sense. It's basically fighting itself. Right? If so, how doesn't it tear itself apart? Awesome videos, by the way! Thank you!

[@EngineeringExplained]

Check out my video "Torsen LSD Torque Transfer" which goes into the friction a bit more. The worm wheels are part of it, yes, but there are other spots as well. And yes, these friction areas are essentially the "clutch" of a clutch type lsd.

[@Gadgit83]

Well done for explaining something very complex! Mr. Torsen must have had a strange brain.

[@ekner]

I greatly appreciate your work, the differential playlist is pure gold!

[@lukaskozisek9340]

Worm wheel can rotate worm gear! Otherwise it would not work.

[@RobinRhyne]

Complicated AF, thank you for making it understandable!

[@marcMH]

SOME EXTRA HELP TO some people who still have problem to see this moving: here is the link to a French explained movie. Even in muted the video speak and clearing show/explain by itself. video title: DIFFERENTIAL TORSEN diferencial Sport Peugeot 405 Mi16x4

[@EngineeringExplained]

Though it can also be achieved by cutting the spark; this is a bit more harsh of a stop.

[@EngineeringExplained]

It would indeed and I hope to get a bit more into videos with the actual item along side. Ideally I could get companies to send parts (see my nitrous video) but that's not quite as easy as it sounds. Just looking at a few images of a quaife it seems to operate under similar principles as a torsen.

[@EngineeringExplained]

Indeed.

[@Ch1Frequency]

BEST TEACHER EVER!

[@EngineeringExplained]

It transfers torque to the wheel with more grip - which is essentially what defines an LSD.

[@timinsandiego6979]

My dad bought that technology from the inventor for Gleason Works in the 70's.

[@ltcjr71]

thanks Paul

[@EngineeringExplained]

Haha well if you give a mouse a cookie... it'll want videos on every type of differential.

[@alphawav3]

Video 2 was gold

[@EngineeringExplained]

Check out my website FAQs. Link in the video description or on my channel page.

[@fauxpastea4169]

I tried visualising this in my mind by just thinking about where the gears had surface contact ... it seemed to help a little.