B7 RS4 sport diff?

[ducatiman]

Just curious if our b7 RS4's have the same technology as the new 'sports diff'? See link below.


http://microsites.audi.com/quattro-onli ... popup.html?

[Andyuk911]

In a word 'no'

[caldy]

Try this

http://iamaudi.com/2009-audi-s4-sport-d ... explained/

[Nib]

I'm not sure I'd really want a 'sports diff' on an RS4. In my (humble) opinion, the car's about right with it's current set-up, (although I doubt Audi's claim that it's 60/40 rear biased). On top of ESP etc etc the sports diff would seem to be just another 'safety blanket' - one that would further inhibit any adjustment of cornering line with the throttle........ Perhaps I'm missing the point (again).

Just my 2 cents worth!

[JonLittlechild]

Judging by the balance of wheel spinning that occurred in the snow over the last week, I'd say 60/40 rear/front split is probably about right. A rear wheel always started to spin first, even when the front had already driven over the slippery-ness. Then given some beans, a front wheel would join in.

I think RS4 would definately benefit from a limited slip diff at the back, you could make more use of the power and it'd theoretically make the car very slightly more tail biased too, which wouldn't be a bad thing. I assume that the centre diff is a Torsen based unit which will already control the distrubution of the power front to back very effectively, but once the power arrives at the designated axle(s) it's only passed to one wheel through the axle's open diff. In slippery conditions, an RS4 becomes two wheel drive; one front and one rear (in the same way that a two wheel drive car becomes one wheel drive).

I don't know how the 'Audi sports diff' would compare to a limited slip diff, but I would hope it can do similar things to an LSD when required.

Jon

[PetrolDave]

In slippery conditions, an RS4 becomes two wheel drive; one front and one rear (in the same way that a two wheel drive car becomes one wheel drive).

Unless you leave the ESP/TC turned on when the spinning wheel will be braked until it stops spinning.

[JonLittlechild]

True, but unfortunately it's just a cheap way of preventing wheel spin, not such an effective way of improving forward progression. In the snowy conditions of last week, on one occasion I got to the stage where it was having to apply the brakes to the spinning wheels so much that the car virtually stalled and the brakes started to smell quite bad! Rather than cut the power and or brake a wheel, an LSD allows you to distribute the power to where it can be used.

[PetrolDave]

With an open diff a two wheel drive car actually becomes zero wheel drive - since all the torque is diverted to the spinning wheel, so the wheel that might have grip does zilch, zip, nada, nothing.

So an RS4 with ESP/TC off and no grip on both a front wheel and a rear wheel is also zero wheel drive (since while the centre diff is a Torsen the front and rear diffs are both open.

Some kind of LSD or lockable diff both front and rear would be a better solution than ESP/TC but given how rare losing grip on a front wheel and a rear wheel is would the cost (financial and weight) of limited slip or lockable diffs be justified?