re: U/S Torsen

[Dave Eaton <dave.eaton@minedu.govt.nz>]

wrt: previous query about a torsen which wasn't working.

having experienced both the manual locker and the torsen, in my mind there is no question that the torsen is a better option for normal use.  if you want to emulate a tractor in the mud, then a manual locking diff would be a better bet.

the torsen really excells when you are driving fast and encounter a low traction situation.  the torsen senses (no pun intended) this and compensates *extremely* quickly.  in extremis you have an instaneous 75% of torque switched to the axle with the most traction.  in the same situation with the manual locker, if you're not locked, you're in trouble - if you are then you're running with only 50% of the torque.

in my ur-quattro, i found that to avoid this situation when driving fast, i'd always lock the diff.  as a result the car lost some feel for the road, and understeered more etc. etc.

i've found the ur-quattro with the torsen understeered a lot less than the ur-quattro with the open centre diff.

as i understand it, the big advantage of the torsen centre diff as opposed to the viscous variety is:

1) the spped of the reaction to low-traction situations
2) the ease of implementation of abs.

-dave.