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View Full Version : What is the front/rear bias on our Quattro?



Neo1130
12-05-2006, 11:17 AM
I thought it was about 50/50 or 40/60 but as I have been doing some dounuts and whatnot in the recent snow we had, I noticed that my rear tires spin about twice the speed of the front ones!! Or is that just because of the weight in the engine up front?

maxspeed
12-05-2006, 11:20 AM
the rear wheels do appear to get more torque, as even in dry weather the rear tires spin more than the front...

sandnessmj
12-05-2006, 11:27 AM
I believe it's 2:1 (back/front) which would be 66%/33%.

The Stasis center diff makes it 4:1.

ridelikeme
12-05-2006, 11:35 AM
hmm i did not know the stasis made that big of a difference.. im interested now

sandnessmj
12-05-2006, 11:37 AM
Originally posted by ridelikeme
hmm i did not know the stasis made that big of a difference.. im interested now

Yeah, if I didn't have a billion other things to spend my money on first, I'd be dropping $550 to have a 80/20 bias towards the rear.

offroader1006
12-05-2006, 11:38 AM
stasis makes a big difference in cornering

ridelikeme
12-05-2006, 11:40 AM
Tuning the center differential provides one of the most significant performance gains available to the Quattro owner. The standard torsen center differential in the S4 and A4 provides a 2:1 torque distribution capability. This enables the end of the car with traction (generally the rear) to deliver twice the torque being delivered by the least tractive end of the vehicle (generally the front).



The STaSIS high bias torsen provides a dramatic improvement in negotiating a turn quickly and efficiently. Now your car can be 3 cars in one( front, all and rear wheel drive):



Hard braking leading into a turn
Car acts like a front wheel drive – torsen acts like an open differential when its not under power. Wheels turn independently and car control is improved.



Mid Corner, Throttle On
Car acts like an all wheel drive– torsen delivers equal amounts of power to front and rear wheels. This maximizes grip, allowing more power to be applied at this stage of a turn.



Corner Exit, Hard Acceleration
Car acts like a rear wheel drive car – front wheel slip is rediced because the torsen delivers up to 88% of the engine torque to the rear wheels where the most traction is.

BeeFiveQuattro
12-05-2006, 08:22 PM
(aside from the fun factor) Just keep in mind having a stronger rear-wheel bias will make it harder to initiate a drift upon corner entry... while also inhibiting traction upon corner exit. (so you are limiting the biggest advantage our quattro's have).
-I would like to see the new 3:1 diff from some of the B7's, on our cars. should take the edge off of the understeer. while also alowing the rear to rotate a little sooner.

sean1.8t
12-05-2006, 08:44 PM
my friends S4 has the STaSIS center diff...


It is amazing!

once i have enough power do spin the wheels on my car i will have one in my car without a doubt

that is all

Euro
12-05-2006, 09:33 PM
Originally posted by sandnessmj
I believe it's 2:1 (back/front) which would be 66%/33%.

The Stasis center diff makes it 4:1.

Can anyone confirm the 66% back/ 33% front.?



+1 for the stasis diff.

sandnessmj
12-05-2006, 09:44 PM
Originally posted by the Stasis Engineering website
The standard torsen center differential in the S4 and A4 provides a 2:1 torque distribution capability.

And I take back what I said about the Stasis differential...it says on their website that it can provide up to a 7:1 ratio - which is in keeping with the 88% figure someone else quoted earlier...

DRA4
12-05-2006, 09:54 PM
Wow, i just noticed they suspended Neo account. Whats is going on here?

sean1.8t
12-05-2006, 09:59 PM
Originally posted by DRA4
Wow, i just noticed they suspended Neo account. Whats is going on here?

read his "Just trying to see what color shift boots people want " post.. it is some pretty amazing stuff

DRA4
12-05-2006, 10:19 PM
Oh damn, i just saw it. That was crazy, the dude was cool here.

beejohn
12-07-2006, 08:36 AM
From http://forums.audiworld.com/a4/msgs/1896967.phtml:

"A4 quattro uses a torsen center diff, which has a 50/50 torque distribution under normal conditions, and up to 33/66 or 66/33 torque split. I don't remember the details on the TT quattro system, but it uses a haldex diff, and it's 100F/0R under normal conditions (essentially FWD), and up to 50F/50R torque split is available."

Daft
12-07-2006, 09:49 AM
The Torsen diff is 50/50. I called Torsen and researched this long ago.

You can add washers to the larger end of the torsen to modify TBR but, you would effectively change the TBR under positive and negative loads.

Here's the bottom line.

There are 2 versions of the Torsen diff in Audi cars.

T-1: This model is used in MT cars only. It has been the same model since quattro was first brought to production in 1986. There was one subtle change in late 1997 where a needle bearing on the rear end was swapped in favor of a teflon inpregnated washer set. Standard ranges of TBR are: 2.5:1 - 3.5:1

T-2: This unit was added in 1995 for Audis with Automatic transmissions. Before 1995, there were no Audi cars that had both an automatic transmission and quattro. Standard TBR ranges are: 1.5:1 - 2.5:1

The hard facts of the Torsen diffs used in Audi cars:

In standard part throttle driving, the Audi A4/A6/A8 drivetrain is a 50/50 split. If you are under load via throttle, your rear wheels can receive as much as 65-70% of the engine's output. When you are in a negative load condition such as downshifting, the torsen can direct as much as 80-85% to the front wheels. This was a requirement from Audi because you don't want your torque bias to high in the rear under deceleration. This can cause the rear wheels to drag the car into a left/right yaw and will send you off the road.

onemoremile
12-07-2006, 11:33 AM
Originally posted by Daft
This was a requirement from Audi because you don't want your torque bias to high in the rear under deceleration. This can cause the rear wheels to drag the car into a left/right yaw and will send you off the road.

That has happened to me and it sucks. I've had three cars that would break the rears loose on a casual downshift. If you didn't rev match it would at least chirp the tires every time. In the rain that feels just like the passenger yanked on your e-brake handle.

[drive] [drive] [drive]

nAUDI
12-07-2006, 09:39 PM
most of the weight is over the front, which is why the back wheels spin in snow. well thats my guess anyways

onemoremile
12-08-2006, 10:51 AM
I don't know what kind of weather you have in Magnum PI land but we've got snow here and all 4 of my tires are spinning. [:D]