jdT Posted September 4, 2007 Report Share Posted September 4, 2007 Out of curiosity, me and a friend were talking and were wondering about the quattro system on the S3. Does anybody know the power distribution between the front and the back wheels? Thanks, jT Link to comment Share on other sites More sharing options...
CarMad Posted September 4, 2007 Report Share Posted September 4, 2007 Which S3 new one or the old. I think the new one is 40/60 the old one was 60/40. Link to comment Share on other sites More sharing options...
Cupramax Posted September 4, 2007 Report Share Posted September 4, 2007 No, haldex puts nothing or very little power to the rear until slip is detected. The old S3 was 100-0, think the new one is 95-5 then once slip is detected its infinitely variable bepending on grip to each axle. Link to comment Share on other sites More sharing options...
Dandle Posted September 4, 2007 Report Share Posted September 4, 2007 Both systems will be transfering power aft if the car is being driven. The Second generation haldex transfers power slightly faster than the old system but both have a big bias to the front wheels unless the car is being driven hard or the front wheels are loosing grip. A common misconception is that slip is wheelspin, it isnt its mearly a difference in torque between the front axle and the rear. As this increases on acceleration or hard conering for example more power will be transferred to the rear. Link to comment Share on other sites More sharing options...
DukeDesmo Posted September 4, 2007 Report Share Posted September 4, 2007 [ QUOTE ] Out of curiosity, me and a friend were talking and were wondering about the quattro system on the S3. Does anybody know the power distribution between the front and the back wheels? Thanks, jT [/ QUOTE ] I asked this question of Haldex when I bought my A3, this was the answer I got back; "The Haldex Coupling do not have a fixed split between front and rear. On regular driving/steady state the coupling gives around 5-10 Nm to the rear. On a 1/7 of a wheelturn we can transfer all available torque to the rear. In a theoretical situation with the front wheels in the air we would transfer 100% torque tro the rear within 250ms. However it is hard giving exact times and split since it is all depending on driving situation, temperature etc etc since we do not use a straight curve for the torque split, we just take what you need and transfer it to the rear Best Regards, Mats Johansson Haldex Traction" Not sure if the S3 system is any different though. Link to comment Share on other sites More sharing options...
PetrolDave Posted September 7, 2007 Report Share Posted September 7, 2007 [ QUOTE ] Not sure if the S3 system is any different though. [/ QUOTE ] It's the same. Link to comment Share on other sites More sharing options...
PetrolDave Posted September 7, 2007 Report Share Posted September 7, 2007 [ QUOTE ] I think the new one is 40/60 the old one was 60/40. [/ QUOTE ] 40:60 is only with "proper" quattro (i.e. Torsen), and on the B7 RS4 (and newer B7 S4s IIRC). Link to comment Share on other sites More sharing options...
DigimeisTTer Posted September 7, 2007 Report Share Posted September 7, 2007 Is the RS4 torsen? Link to comment Share on other sites More sharing options...
S3Rob Posted September 7, 2007 Report Share Posted September 7, 2007 [ QUOTE ] The new S3 has the same haldex system as the RS4, which is rear biased contrary to popular belief [/ QUOTE ] Digi, RS4 is Torsen, S3 is haldex! It's impossible for Haldex to be rear biased Link to comment Share on other sites More sharing options...
DigimeisTTer Posted September 7, 2007 Report Share Posted September 7, 2007 Bugger! you caught my knee jerk response before i did a tad of research Link to comment Share on other sites More sharing options...
S3Rob Posted September 7, 2007 Report Share Posted September 7, 2007 Busted! Link to comment Share on other sites More sharing options...
Paul Posted September 8, 2007 Report Share Posted September 8, 2007 Remap an 8L S3 and your be suprised just how often it is in 4x4. Quattro is engaged alot more than people give it credit for. Link to comment Share on other sites More sharing options...
Dandle Posted September 8, 2007 Report Share Posted September 8, 2007 [ QUOTE ] Remap an 8L S3 and your be suprised just how often it is in 4x4. Quattro is engaged alot more than people give it credit for. [/ QUOTE ] Its engaged all the time the car is moving fwd and not braking. The more power a car is putting down though the more that will sent to the back wheels. Link to comment Share on other sites More sharing options...
Hopsta Posted September 8, 2007 Report Share Posted September 8, 2007 You sure... i thought it was always FWD unless it needs to put power at the rear Link to comment Share on other sites More sharing options...
Paul Posted September 8, 2007 Report Share Posted September 8, 2007 Its Quattro when it needs it. Usually through detected slip from the front wheels. you are correct on the braking. It is disengaged when given a braking signal, including one notch on the handbrake crude test method which forces 2wd. Link to comment Share on other sites More sharing options...
Mook Posted September 9, 2007 Report Share Posted September 9, 2007 The first thing you need to remember here is that Quattro is used for the S3 (and other A3s) as a marketing name only. All A3s and S3s use the same Haldex 4WD system as the Golf (original A3/S3 was the same system as the Mk4 Golf - current A3/S3 uses the same system as the Mk5 Golf). The Haldex based 4WD system is electronically controlled, and uses input from the ESP electronics to enable more torque to get to the rear wheels when it senses slip at the front. It's forever variable and it's "technically" possible to get all torque being sent to the rear wheels, if, for example, your front wheels are on snow, but this is only temporary. That's why you can front wheelspin an S3 until the electronics work out what's going on and chuck some torque to the rear. You can upgrade the Haldex control unit to engage its clutch more quickly, but it won't throw any more torque to the rear wheels. The Torsen-based 4WD system used on all the other Audis (A4, S4, A6, S6 etc.) has a 60 front 40 rear split. It's entirely mechanical. The RS4 has a rear biased Torsen centre diff and it's set up to send 60 to the rear and 40 to the front, which is why it's very predictable, as are all other Torsen-based Audis, although in a different way (understeer being the main one!). HTH Link to comment Share on other sites More sharing options...
Dandle Posted September 9, 2007 Report Share Posted September 9, 2007 [ QUOTE ] Its Quattro when it needs it. Usually through detected slip from the front wheels. you are correct on the braking. It is disengaged when given a braking signal, including one notch on the handbrake crude test method which forces 2wd. [/ QUOTE ] Slip is not wheels spin. Its a difference in torque detected between the front and rear driveshafts. Which is why when driving the car will constantly be sending some power aft to balance up the torque difference between front and rear. The reason you get a slight chirp when launching really hard is because the clutch pack although controlled electrically requires the input shaft into it to be turning. Which in turn powers a pump inside the haldex unit which will close the clutch pack the required amount. The chirp is because the system is inactive when still and takes a little time to initially engage the clutch pack. Link to comment Share on other sites More sharing options...
Mook Posted September 9, 2007 Report Share Posted September 9, 2007 And this still applies when you have the uprated Haldex, but, when you're pushing the car hard into a corner, rear drive will engage quicker than with the stock Haldex controller Link to comment Share on other sites More sharing options...
Dandle Posted September 10, 2007 Report Share Posted September 10, 2007 [ QUOTE ] And this still applies when you have the uprated Haldex, but, when you're pushing the car hard into a corner, rear drive will engage quicker than with the stock Haldex controller [/ QUOTE ] The rears will already be engaged if the car isn't on the brakes. The uprated controller just moves more power aft at a said torque difference compared to what the stock controller would. Link to comment Share on other sites More sharing options...
Merlot Posted September 10, 2007 Report Share Posted September 10, 2007 [ QUOTE ] The first thing you need to remember here is that Quattro is used for the S3 (and other A3s) as a marketing name only. All A3s and S3s use the same Haldex 4WD system as the Golf (original A3/S3 was the same system as the Mk4 Golf - current A3/S3 uses the same system as the Mk5 Golf). The Haldex based 4WD system is electronically controlled, and uses input from the ESP electronics to enable more torque to get to the rear wheels when it senses slip at the front. It's forever variable and it's "technically" possible to get all torque being sent to the rear wheels, if, for example, your front wheels are on snow, but this is only temporary. That's why you can front wheelspin an S3 until the electronics work out what's going on and chuck some torque to the rear. You can upgrade the Haldex control unit to engage its clutch more quickly, but it won't throw any more torque to the rear wheels. The Torsen-based 4WD system used on all the other Audis (A4, S4, A6, S6 etc.) has a 60 front 40 rear split. It's entirely mechanical. The RS4 has a rear biased Torsen centre diff and it's set up to send 60 to the rear and 40 to the front, which is why it's very predictable, as are all other Torsen-based Audis, although in a different way (understeer being the main one!). HTH [/ QUOTE ] A good explanation of haldex With torsen you are not quite right as most Audis' are still 50:50. If I am correct the only ones which are 40:60 are the RS4, S6, S8, R8 and Q7. Of course these ratios are in the steady state. All can vary the torque split. I can't recall the limits of variability but it is something like 75:25 in either direction. I own both torsen and haldex quattros'. The former is much more rewarding to drive from a traction perspective. Link to comment Share on other sites More sharing options...
J_C Posted September 10, 2007 Report Share Posted September 10, 2007 The A5 quattros (and S5 of course) are 40:60 too. Link to comment Share on other sites More sharing options...
Merlot Posted September 10, 2007 Report Share Posted September 10, 2007 Knew I would forget one - thanks. So will the new RS6. Link to comment Share on other sites More sharing options...
cdco2 Posted September 25, 2007 Report Share Posted September 25, 2007 Shame the muppets in Audi's integration department didn't read the Haldex specs when they integrated it with the traction control.... Im fed up of turning ESP off to get out of junction quickly without the damn car kangarooing between the ESP cutting in then the haldex shifting power rear wards !! Link to comment Share on other sites More sharing options...
Sparky Posted September 25, 2007 Report Share Posted September 25, 2007 Never once had that problem with the haldex on my S3, and I leave junctions pretty sharpish! Link to comment Share on other sites More sharing options...
stevie_d Posted September 26, 2007 Report Share Posted September 26, 2007 [ QUOTE ] Never once had that problem with the haldex on my S3, and I leave junctions pretty sharpish! [/ QUOTE ] Likewise... Link to comment Share on other sites More sharing options...
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