What's a Torsen limited slip differential? 

Which in a car is generally a bad thing

@@gizelle-s How is that a bad thing?

"Mechanical diode" is a very good analogy, I'll be stealing that, thank you.

@@erikkovacs3097 when the engine is off and the car is moving, rotation from the wheels is transferred to the defferential then to the disengaged transmission, if I'm correct then the differential has to break or the car stop moving

where is the worm gear in this differential?

That's right!

Exactly what I was about to say. Strange how they didn't mention this in the video

I like LSD

I took a torsen differential in a party

I'll have to ask my dealer about it next time i see them

In many ways, a torsen is often referred to as a fancy open diff. A clutch based limited slip, which is the most common LSD, is capable of locking the left and right axles together. The Torsen LSD is often referred to as a "torque multiplier" because it uses the spur gears to multiply the amount of torque one wheel gets, when the other wheel starts slipping. You can see the torque multiplication effect in the video when one wheel spins faster because the other wheel is stopped. In certain conditions, the Torsen diff won't work when the spinning wheel has zero traction, because it can't multiply zero torque. Because of that, and other reasons such as driver preference, more traditional LSD setups are preferred in racing or off-road applications.

If you want to get technical, it is a limited slip. While it can't solve the zero traction problem, it does try to ensure that 100% of the power is being used between both wheels (barring things like friction in its own operation) while an open diff is always just 50/50 split regardless.

@@markbickford9092 very good video. Once he said “the worm gear can turn the spur gear but not the other way around” it twigged in my head. Very clever. In practice I think the slope of the teeth means that one gear isn’t 100% spur and the other 100% worm, but changing that slope influences the torque threshold.

@@YoRHaAttackerNo2 except that the Torsen diff is not just a torque splitter, it's a torque multiplier. Going back to the open diff, it's commonly said that it always have a 50/50 split. What that means is that if the spinning wheel only can handle 25 ft-lbs of torque before spinning, then the stationary wheel would receive 25 ft-lbs of torque. Now take the Torsen with the same example. If the diff is rated for 3x torque bias ratio, then the stationary wheel would receive 75 ft-lb of torque if the spinning wheel can only handle 25 ft-lbs. This would be a variable 25/75 torque split, depending on the situation. This variability is a major reason why Torsens aren't always used in racing or off-road applications. In comparison, a clutch LSD would be sending up to 100% of the input torque to a single wheel if needed, or a max of a 0/100 torque split.

@@patx35 That and the clutch LSD can force a 50/50 split in a zero traction situation.

Thanks! :)

Torsen was the only limited slip offered in the miata from 94 to 2003, and it is a limited slip in every sense of the word. Seems you lack experience. You don't just get to redefine things as you see fit, amber turd.

That is in part due to a patent on this design if I recall correctly. Not sure if that's expired yet.

This type of diff is generally used in WRC and other rally categories

I mean, clutch LSDs may be more common overall, but I don't know if any modern car has one of those- helical (like Torsen) and viscous LSDs seem to be the only ones in production vehicles. Yeah there's some things the author could mention, but it's also a heck of a rabbit hole, haha.

I replaced my worn out clutch style with Torsen, drives much better and will never need a rebuild. As far as traction, it performs smoother than my clutch style LSD. Defenetly a bit more expensive and you lose a little efficiency hence the factory not putting them in many vehicles.

It works extremely well with traction control because even if you get a wheel in the air will transfer more torque than an open differential would have

Me too. I still don't understand why this one is so special compared to a normal diff

Yep, the video fails to explain the behaviour of the differential, but we can see the construction and behaviour, of which the last seems identical to regular differential as a wheel can be completely halted, making the other wheel spin faster... I'm not convinced that the displayed model works at all as intended. I've seen a video of a Lego-model Torsen differential, that used worm gears, which can't be turned by the main axles, but now I'm thinking that the Lego-model had flawed operation too... :D

Torsion diff take advantage of worm gear effect. You can turn the screw to rotate a gear but turning the gear doesn't want to turn the worm. A small amount of load on the spinning wheel effectively locks up the worm gear which powers both wheels. Normal limited slip is just a clutch between both axles. There is also viscous couplers and automatically locking diffs

Engineering explained has a decent breakdown of torsion diffs

He did mention the principal of operation, though breifly. It relies on the helical angle of the "worms" being steep enough that they can only pass motion in one direction i.e. the pinion can not drive the worm gear, but the worm gear can drive the pinion.

I think the helical gear arrangement is inherently having greater friction than pinion and spur type. It is this friction that provide some braking force on the side that start spinning freely so you don't need to step on the brake.

With a small enough helical angle on the worm gear, the worm can drive the pinion but the pinion cannot drive the worm.

@@Tymeshifter no its not friction its gear bias. Friction is a plate LSD which basically is a ramped clutch with multiple disks. For off road trucks you don't want an LSD, but a simple locker, as on dirt the low friction surface gives you the differential action you need while keeping the axles locked. With a LSD off-road and a wheel in the air, you are now stuck as a LSD must have some traction on both wheels or nothing happens. On-road, LSD. Off-road, locker.

Found a RU-vid video explain how it works: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-JEiSTzK-A2A.html

@@spinnetti wait really? i always thought the clutch diffs always locked spinning wheel (or as close as the plates can get to “locking”) regardless if the particular wheel’s in the air or on gravel or whatever.

You can download it on my website www.3DPrinterAcademy.com search for 'Torsen'

@@3DPrinterAcademy thanks! If I make this, I’ll be sure to share my success (or failure perhaps) with you.

Yes imagine if the blue gears were made with tiny rollers like a steering rack then it would just be a very complicated diff. But similar to worm gears they lock against each other when the torque is unequal Like having rubbish gear box that keeps locking up. But if they were more aggressively pitched like worm gears then they would be locked all the time and have no differential action under normal loads. but in the mud the vehicle is still loaded a little on the wheel that wants to slip. If you had a hanging wheel (rock crawling) then it would also fail as there would be no resistance to activate locking. The solution there is to touch the brakes a little and then you would get moving again.

It works extremely well with traction control because even if you get a wheel in the air will transfer more torque than an open differential would have. So basically the torque bias effect will multiply the torque coming from Spinning Wheel win the brake grabs then it would have from the spinning wheel of an open diff. So let's say open diff with 1:1 ratio bias spins and the brake grabs and it sends 50 lb over to the gripping wheel well with this 3:1 ratio it will grab with 50 lb and send 150 over. When you press the brake pedal it's not as effective because you're also adding brake Force to the wheel with grip. That's why ABS traction control works super well with these do you know what the wheel in the air. Especially if you put it on something that has a really strong traction control even with open diffs like Land Rover Disco or Range Rover from the 90s and 2000s

@@markbickford9092 Much better! Thank you!

@@markbickford9092 perfectly explained! The fact that the opposite wheel spun faster when he held one still means the worm gear isn't steep enough to actually act as a worm gear. This original vid is just an open diff. without any sort of limited slip at all.

@@didiwin78 Technically it's a type of LSD called a torsion differential. Most LADS are clutch based. This one effectively varies the gear ratio between the two wheels so that if one wheel spins faster the other one gets a higher effective ratio and therefore more torque at the wheel. The only problem is that it still relies on both wheels getting traction like an open diff, so if one wheel gets zero traction, the other gets zero torque. It's an improvement on the open differential, but a true LSD can completely lock the differential if needed. I believe modern ones can also be electronically controlled, like on the Subaru WRX STi I had, which had quite a few settings for different torque splits

@@didiwin78 Technically it's a type of LSD called a torsion differential. Most LSDs are clutch based. This one effectively varies the gear ratio between the two wheels so that if one wheel spins faster the other one gets a higher effective ratio and therefore more torque at the wheel. The only problem is that it still relies on both wheels getting traction like an open diff, so if one wheel gets zero traction, the other gets zero torque. It's an improvement on the open differential, but a true LSD can completely lock the differential if needed. I believe modern ones can also be electronically controlled, like on the Subaru WRX STi I had, which had quite a few settings for different torque splits and could go full diff lock as well.

@@didiwin78 Incorrect. Irrespective of the torque split (helical angle) a torque biasing differential does not provide any limited slip action if one wheel is completely open which is what he demonstrated. This is the weakness of this type of differential, but it offers advantages over plate type diffs that do handle one open wheel (e.g. less tyre wear, no plate wear, no impact on vehicle dynamics when cornering where strong plate diffs can cause understeer).

Yeah, the video lacked any kind of explanation

As he said, even on ice you have some traction/resistance that would be enough to trigger the locking mechanism. The problem is when one tyre is not touching the ground, then it acts as an open diff.

You should pay more attention. It biases torque to the wheel that needs it the most, but it requires that some torque still go through the wheel with the least traction. If one wheel is completely open then it works like an open diff, which is the only real disadvantage of this type of diff. However there is a workaround for low speed low grip situations e.g. trying to pull away with one tyre on mud or ice, by lightly applying the vehicles brakes you provide some torque resistance on the open wheel allowing the diff to apply torque to the wheel with more traction.

@@ferrumignis Fair enough. Your explanation makes more sense. I just feel like it wasn't clearly explained in the video or requires prior knowledge of the operation of the diff to get it. I had to look up Torsen diff to fully understand it.

nope, this will not do anything good in FWD, it was made for AWD, specifically for AUDI Quattro

@@krisg822 it does do good for FWD. My dad and I do lanes rallies in a Vauxhall Nova. We have a torque bias in it and it's an amazing job. Most LSDs that go in FWD cars give it a lot of understeer in tight corners but the torque bias doesn't do that and it pulls so well

@@jackstewart7664 not sure how it's called, but there is a thing like 'Xdif' , it uses ABS to brake one wheel in order for the diff to do the rest of the job. Some cars that claim AWD use it too, altho, AWD is only real with with either torsen or locked differentials. Anyway, for FWD the xdif does not a bad job, it lags somewhat behind, and won't get the car out of mud or snow, but once tha car is moving , it does it's magic.

@@krisg822 I think the gold gti uses that system. Or atleast something similar. Our Vauxhall Nova is far too old for something like that however

​@@krisg822😂 just because Audi puts one of those in the transfer case you get excited and think that that's the only place it works

The helical angle on the worm gears is such that the worm can drive the spur gear, but if the spur gear tries to drive the worm then it binds up.

@@ferrumignis Thanks, that kind of what I was thinking.

it actually can't send torque to the wheel with no grip..it will just spin like an open diff in that case.

@@spinnetti Well I'm no expert and I'm not tryna discredit you, but isn't the whole thing with torsen diffs is that they lock up mechanically in situations where one wheel has less traction?

Yes so touch the brakes a little and you get moving again.

I hope you sort out the demon thing dude, just don't fall through the floors, or the walls, if they look like they are melting, then either they are, or the microwave demon is doing it, I would suggest taking a seat and prepare for the unknown

@@AtomBomb420 mmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmm

He cant explain more than what he knows!

I understand there's a clutch inside it and have to use special lubricant not the normal EP