Hi,
I've always wanted to test the LSD on my 08 MCS. Today, with some snow, I put the passenger tire on the snow pile by the side of the road, and the driver's tire with very nice traction on the asphalt.
I tried a quick start, with DSC on the car started really slow.
I disabled the DSC.. the car went to 6000 rpm and was not moving... tried again, and the same. I'm totally disappointed with my "LSD"

Is this the way it works? or there's something wrong with my car?

Thanks.

 

Do you know anything about what a LSD does? Why did you order it??

 

Not exactly. Did you order the mechanical LSD? The DSC button has no effect on the mechanical LSD. Turning the DSC button off disables the electronic ASC which cuts engine power when the drive wheels start to spin.

LSD only transfers a % of power to the other drive wheel when one starts to slip. In your test I would expect LSD to move you forward slowly, but I've never tried it. I could be wrong.

If you have LSD and you accelerate hard on normal asphault, the torque steer should pull one way then the other.

 

Disclaimer - My MINI does NOT have the LSD. My old GSX did (well, actually it had more than one ). If put in the same situation as you described, the tire in snow would spin, but the tires on dry pavement would pull.

 

This is what LSD does. It's not for gaining traction in snow. It's for allowing one wheel to "slip" so it doesn't override the other. A perfect example is accelerating while turning on a curve. The lead in tire needs to turn fewer RPM's to match the outer tire. The LSD allows this "slip" so you get maximum and equal traction. Without you can get wheel hop and less acceleration.

EDIT: I found a better and simpler explanation here.

 

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Got it. Thanks Julien, very helpfull article.

Robin it's whatever comes with the car when you include the LSD option ($ 500 I think?). I bet you can jack up one tire and let the clutch go, and the tire in the air will spin just like a car with a regular differential.

Kevin, I just realized that I don't know enough about LSD. Why did I order it? Because I thought that the power would go to the wheel with traction (ie the wheel in the asphalt in this case) or at least 50/50 even with one tyre in the air. To be a little safer in snow.
I thought that this was the system used by Audi 10 or 20 year ago and the system the Subaru uses, and that you can only have traction on one wheel and it will be the one getting the power.
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The LSD option from my understanding when ordering from MINI is a brake applied "limited slip" that temporarily applies brake pressure to a wheel. Its by no means like a clutch type LSD offered by Quaife and Peloquin for cars. I had a Quaife in my VW with front wheel drive. It allows equal distribution of power to both front wheels, at all times. The only problem with this in FWD is if one wheel spins, the other HAS to be spinning as well if theyre always locked.

This could be very dangerous, especially in a turn if you lose traction, both of my wheels would begin to spin....not very fun

 

That description includes the function of the differential into the definition of LSD. While correct, it is a little confusing when discussing the difference between a standard differential and a limited slip differential.

A standard differential will allow one drive wheel to turn at a different speed than the other. Without such a system, both drive wheels would be forced to go at the same rpm--causing problems when turning. If you jack up one side and run it in gear, the raised wheel will spin while the wheel on the floor will stay stationary. Almost no torque goes to the wheel on the ground.

An LSD is supposed to limit the amount spinning the raised wheel does, and transfer torque from it to the stationary wheel. I would not want to jack up one wheel and run it in gear with LSD. I would be afraid that it would pull itself off the jack and lurch forward.

If you put one wheel on an icy surface with no traction, and the other on a surface with good traction, I would expect the LSD to transfer some torque to the wheel with good traction, and move the car forward. However, only a limited % of torque gets transferred, so it wouldn't be a fast start.

If your car (with one wheel in the snow and one on asphault) did not move forward, would suspect that the snow was deep enough to provide significant resistance to moving forward.

My understanding of this may not be exactly accurate. If so, I'd like to hear an explanation of why an LSD equipped car would not move forward with one wheel on a slick surface.

 

If you bought a LSD, it should work as I described. It is a mechanical differential and has nothing to do with the brakes. DSC works by braking a spinning wheel. DTC and EDLC are yet more electronic marvels, but are not LSDs.

 

Robin,
I had the same idea as you have about the LSD. I thought that the tire with traction will pull the car (of course not at 100% but.. a 10-12 sec 0-60 if you accererate hard).

Maybe it's because I tried to do a fast start (2500 -3000 rpm, let the clutch kind of fast). I did it intentionally because I wanted the wheel with no traction to spin (and of course make the LSD work - or "lock the differential"). But when I did this, the car was not moving at all and one tire was spining and there was a sound like a buzz coming from the differential I guess.

The snow whas not deep at all, maybe 1" or 2" of hard pack/ice. I did a regular start or a smooth start, the car would move forward (wheel in the snow spins while the wheel on the alsphal slowly pulls the car). But my SUV with RWD would accelerate at the same rate in this situation.

My conclusion is that if you end up with one of the tires in a ditch, the tire with traction will not pull you out (with LSD).

I'll try to put a video next time it snows.

 

If you drop the clutch at 3k in any lightweight vehicle with the kind of torque the Mini has it won't matter if its fwd, rwd, or awd the tires are going to spin.

 

I wouldn't expect a 10-12 sec 0-60 with only one wheel having traction, with any kind of differential.

Hope you didn't damage anything.

This is what I would expect.

Are you sure it doesn't have a limited slip differential?

My conclusion would be that it is best to make a more sensible start when one wheel has no traction.

I don't think that is a very good idea.