How does a Torsen Limited Slip Differential work?

[ezridermn]

I just bought a 2017 Mustang GT with the Performance Package. It has the Torsen limited slip differential with 3.73 gears. When I put high power to the rear wheels and they start to break loose the rear end vibrates a bit and feels like it is slipping. It is a feeling I haven't felt in any other car I've driven. I know that it is likely the way Torsen LSD is supposed to work when it feeds power to the other wheel when slippage occurs. However, I'm just a bit concerned that it actually might be a real mechanical problem that needs to be fixed.

I would appreciate it if you can describe how the car should feel when the Torsen LSD engages during wheel slippage. Should it be like what I am feeling or should it be smooth to the point that I might not even know it is working?

Thanks in advance for your help!

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[68Vert/18GT PP1]

https://auto.howstuffworks.com/differential6.htm

I haven't felt anything different from my Torsen equipped car than any other car I've driven.

 

[aleccolin]

 

[tom_sprecher]

What you are experiencing is probably wheel hop. The gears in a Torsen are always engaged, so there is nothing to slip and is inherently smooth.

 

[BmacIL]

What you're experiencing is wheel hop. It's primarily caused by 3 things: 1) tires, 2) uncontrolled subframe movement and 3) uncontrolled suspension geometry. Wheel hop can be very damaging to the halfshafts, the rest of the driveline and even to the engine in certain circumstances. The factory Pzero summer tires on 2015-2017 GT PP cars are notorious for bad wheel hop. At normal street tire pressures they hop like crazy. A few things can be done to limit it, though, the most effective and high value of which is the BMR CB005 cradle lockout kit. That will get rid of about 80-90% of it.

During cornering, the torsen mechanically biases torque between the inside and outside rear wheels seamlessly and it is not what you're experiencing. Sometimes you will feel/hear some inside wheel chatter during slow/tight cornering under power, some of which is the diff doing its thing, some is other sources of deflection in the suspension.

 

[ezridermn]

Good morning everyone--

Thanks for the feedback. It's now clear to me that the Torsen differential is not the source of my problem. I have experienced wheel hop when I jump on it hard in a rolling burnout sort of way. It is quite noticeable and identifiable. The feeling in the rear end that I described in my first post occurs when the car is in the 2500 to 3000 rpm range and I let the clutch out quickly and maintain the rpm range. At that point and the tires break loose just a bit and I sense something going on in the rear end. But it is much more subtle than the high rpm clutch dump hop I recognize for what it is. I'm now wondering if the traction control system might be activating causing an abnormal feedback. However, I don't recall the traction control light coming on so that would suggest it is not the traction control system. Still a wheel hop issue that just feels a bit different due to the lower rpms? What do you think? Any additional thoughts?

Thanks!

 

[BmacIL]

Good morning everyone--

Thanks for the feedback. It's now clear to me that the Torsen differential is not the source of my problem. I have experienced wheel hop when I jump on it hard in a rolling burnout sort of way. It is quite noticeable and identifiable. The feeling in the rear end that I described in my first post occurs when the car is in the 2500 to 3000 rpm range and I let the clutch out quickly and maintain the rpm range. At that point and the tires break loose just a bit and I sense something going on in the rear end. But it is much more subtle than the high rpm clutch dump hop I recognize for what it is. I'm now wondering if the traction control system might be activating causing an abnormal feedback. However, I don't recall the traction control light coming on so that would suggest it is not the traction control system. Still a wheel hop issue that just feels a bit different due to the lower rpms? What do you think? Any additional thoughts?

Thanks!

It is still wheel hop at the lower rpm.

 

[texasboy21]

TIRES TIRES TIRES

TIRES TIRES TIRES

A handful of inexpensive Steeda or BMR goodies will eliminate it completely (well 95% of it).

 

[Schumi7time]

Sigh. I just came across this if anyone reads this and is experiencing this problem. The first thing you should do is turn off your traction control.

 

[Cobra Jet]

TIP:
- If the rear diff has Trac-loc guts, you won't be able to see through it with axles removed. There will be a "bar" in the hole which is for the spider gears.

- If the rear diff has Torsen guts, you'll be able to see through it with axles removed.


Everything you wanted to know about how a Torsen works is here:
https://www.mustang6g.com/forums/threads/inside-the-super-8-8-rear-end.150514/

And here:
https://torsen.com/how-it-works/

And here:
https://www.kmpdrivetrain.com/differentials/torsen-vs-plated-limited-slip-differential/

Also more than anyone could need about the function of the Torsen is in the attached PDFs.

 

[Dfeeds]

Good morning everyone--

Thanks for the feedback. It's now clear to me that the Torsen differential is not the source of my problem. I have experienced wheel hop when I jump on it hard in a rolling burnout sort of way. It is quite noticeable and identifiable. The feeling in the rear end that I described in my first post occurs when the car is in the 2500 to 3000 rpm range and I let the clutch out quickly and maintain the rpm range. At that point and the tires break loose just a bit and I sense something going on in the rear end. But it is much more subtle than the high rpm clutch dump hop I recognize for what it is. I'm now wondering if the traction control system might be activating causing an abnormal feedback. However, I don't recall the traction control light coming on so that would suggest it is not the traction control system. Still a wheel hop issue that just feels a bit different due to the lower rpms? What do you think? Any additional thoughts?

Thanks!

Just because the light isn't on doesn't mean traction control isn't doing anything.

 

[Schumi7time]

It's either off or on. It's not an advanced launch control system.

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