[Edward]

Hi,

First posting here. I will be a Q3 owner very soon, in fact just a few more days. In the mean time I have some questions regarding how the Q3 quattro system works. I hope someone can chimp in

- From what I understand (from the Audi websites and wiki...etc), the Q3 has its majority of torque at the front axle under normal driving conditions. But I can't seem to find exactly the percentage though, like 80%/20%, 90/10, or 95/5...etc. Since the MPG is so close between the FWD and Quattro, I would guess it's at least 90% on the front axle. Anyone has more concrete numbers?

- And how about torque distribution between the left and right wheels? Some said only the front axle can freely distribute torque among the front wheels, but not the rear axle... I find that a bit strange... is that true?

Thanks in advance!
Edward

 

[Q3User]

Hi,

First posting here. I will be a Q3 owner very soon, in fact just a few more days. In the mean time I have some questions regarding how the Q3 quattro system works. I hope someone can chimp in

- From what I understand (from the Audi websites and wiki...etc), the Q3 has its majority of torque at the front axle under normal driving conditions. But I can't seem to find exactly the percentage though, like 80%/20%, 90/10, or 95/5...etc. Since the MPG is so close between the FWD and Quattro, I would guess it's at least 90% on the front axle. Anyone has more concrete numbers?

- And how about torque distribution between the left and right wheels? Some said only the front axle can freely distribute torque among the front wheels, but not the rear axle... I find that a bit strange... is that true?

Thanks in advance!
Edward

It uses a at least the 3rd gen Haldex sytem - prevalent on FWD/Traverse (sideways) engine mounted cars - & activated most of the time @ 95/5 Front wheel bias.
If the front wheels slip, the percentage going to the rear is increased upwards to 100% or any other % to the other non slipping driving wheels.


See #11 here

Listed under Vehicles equipped with Haldex AWD

 

[john]

Ahh good to know. So we basically have a front driver and all wheel driver only when needed!

 

[rnlabas]

Other than trucks and off-road vehicles, THIS is a pretty normal setup for cars - and a quite desirable one. If you had say 60:40 all the time, first it would NOT be needed, and second would consume way too much fuel for sensibilities. Haldex cars are great in that they do exactly what you need just exactly when you need them to. There is nothing wrong with knowing that.

For strictly performance cars, like the RS cars or the R8, a rear-drive bias is also optimal, and having some front drive capability just improves that when pulling out of corners ... perhaps not as exciting looking as drifting, but when you look at the numbers, sideways is ALWAYS slower on asphalt than rolling at the edge. Just think about it - tires are designed to roll, not slide. MAXIMUM grip is attained when rolling, sliding has none - and this goes almost 3x for braking ...

 

[Edward]

Thanks for the information. One more thing that I would like the understand more:

How about torque between the left and right wheels? According to those pages, seems like the front axle has an open diff with EDL (Electronic Differential Lock), but I am not sure about the rear axle. Let's say if both front wheels and 1 of the rear wheels lose traction, will the system able to send more torque to the remaining wheel (on the rear axle) that has more traction?

Thanks!

 

[rnlabas]

In these cars (w/Haldex) the rear diffs are a limited slip type, usually affording about 75% lockup to the other side, when needed. The Sports-Diff is a bit more complex, but also a clutch-type that will be a bit more aggressive - say 90% side-to-side...

 

[Edward]

Thanks a lot Roger! It's nice to understand how the system works.

 

[john]

So my Q3 is a front driver - why don't I detect any torque steer?

 

[rnlabas]

So my Q3 is a front driver - why don't I detect any torque steer?

Mostly cuz Audi has designed the front suspension pretty well to mostly eliminate it. That coupled with a comparatively mild throttle tip-in for a car with substantial heft in the front, keeps it in check also (as well as nice tight control arm bushings, dampened intermediate shaft, etc.)

btw, with my SprintBooster turned up (red) and in Sport, yup - there's definitely a dose when you tromp on it ...

 

[john]

Thanks Roger. I always appreciate your explanations!!