[Biturbos4] Wheel spin.

Keman keman at interwolf.net
Wed Apr 13 10:23:17 EDT 2005

> So here I am, audi quattro s4, "stuck" because one wheel doesn't have
> traction?  It seems that all the diffs are open?

The front and rear differentials are open, all you had working in your
favor was the torsen center differential, since there was more torque
required to spin the front wheels than the rear, and the torsen will
multiply torque to that the side with the most resistance.

The problem is, anything times zero, is still zero.

If it takes zero (or near zero, relatively speaking) torque to spin the
rear wheels, the torsen can't do anything to get the front wheels to spin.

The solution for this is to apply a small amount of brake pressure. This
will put resistance into the works, give the torsen something to multiply,
and it'll grab. The ABS will also kick in, preventing any one tire from
locking up, giving you a poormans electronic differential lock (EDL).

My mustang roadrace car has a torsen differential out back, but it's a
hybrid setup, using a clutchpack/spring to preload the torsen with a
certain amount of force. This means even if one wheel is in the air, there
is still plenty of torque transferred to the other wheel. Neat stuff.

- Keman

> wilson '00s4

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