Question: 80Q "limited slip" center diff doesn't limit slip...

["Avram Dorfman" <dorfman@est.org>]

Ok, if anyone can help me understand this, I'd appreciate it.

 

My brother has a 1988 80 quattro, which according to the manula, has a torsen center diff. This would seem to be confirmed by the fact that only the rear diff can be locked.

 

If a single rear wheel looses traction, and all three other wheels have traction, the one wheel spins free, and no power goes to any other wheel. We confirmed this with the following test:

 

He went into a 2 level parking lot with a steep ramp, and drove up on the edge of the ramp so that the right rear wheel came off the ground, but all others were firmly planted. The wheel in the air spun free as the care came to a stop and started rolling *backwards* until the fourth wheel hit the gound again (and then made a lot of noise and smoke 8-)

 

This doesn't match my understanding of "limited slip" which is this: It allows only a certain percantage difference in rotational speed between it's two sides. Namely, for the rear shaft to spin at 100 rpms, the front "shaft" must be spinning at some percentage of that, e.g. 60 rpms. Well, if the rear axle is spinning forwards and the car's not moving, that's pretty much full slip, right? And if the car can go backwards, then it's really full slip, right?

 

Is it possible for the mechanism that limits slip to wear out? This car has 150k miles, and it's has 3 worn out synchros, so it's quite possible that it's been driven very hard.

 

Any explainations or theories would be appreciated! Please cc email me...

 

-Avram