Joe Lucchio

I found the review of the new A6 V8 in CAR magazine to be quite interesting. Of particular note was the little sentence at the end which stated that the Audi would have won the comparison hands down IF it had the new Haldex AWD system rather than the older Torsen system. Although I have yet to drive the new Haldex equipped cars, everything I have read about the system looks like it should be superior to the older torsen system (of which I am a big fan). Just found that to be interesting, that's all. Any comments?

Robbie

I'm also a fan of the HALDEX design. <p>I saw a rumor not too long a go that the new AWD HALDEX system was shredded by the 220hp TT in testing. Anyone know if this is true?<p>If so, have these problems been worked out yet?<p>

Todd W

The Haldex system saps too much power and is a wear item, also it seems to disengage on deceleration. Torsens rarely go bad after hundreds of thousands of miles. The quattro system is always engaged and gives great stability under braking. That said, I don't think having one Torsen and EDL is worth it over open diffs. I would prefer 2-3 Torsens and no EDL. Those of you with A4's can get the Quaiffe which is the same thing. If you want speed around the track put one in the front, if you want throttle steer put one in the back :-) <p>The one exception for me is the '90 V8 which had something closer to the Haldex, but a much better use of the technology. It also had a rear Torsen <p>Todd W

Drew S.

<i>"The quattro system is always engaged and gives great stability under braking."</i><p>Are you referring to engine-braking? The quattro system is only engaged while power is being applied. If you take your foot off the gas to coast, then quattro is not helping you in any way.<p>Please explain the great stability to which you are referring.<br>

wmv

I'll second Todd's comments about the v8 quattro setup. I've owned an 86 4000csq, an 88 90q, a 90 v8q, and a 91 200tq. The v8 with hydraulic central control and a torson rear axle has been by far the best awd setup both in dry and in nasty conditions the car just feels totaly planted, and easily controlled

Todd W

Quattro more or less disengages when you stick in the clutch - NO OTHER TIME. That does not mean that it is very effective the rest of the time, just that it is "laying in wait" - engaged. You are right to say that it provides no real benefit when coasting, but it is a passive system. Just as quattro balances the power across the chassis under acceleration, it will do the same under hard deceleration if you do not stick in the clutch. If you depress the clutch the you allow the 5th point, the input shaft, to spin freely which unloads the quattro system. There is still a noticeable amount of effectiveness due to internal friction of the diffs, etc. but it is not the same.<p>The stability under braking is a race-proven characteristic that is only blatantly obvious during very aggressive driving (emergency situations don't allow the time to realize the benefit, just an OMG how did I get out of that!). Ride around the track with an instructor in a quattro and you will quickly see what I mean.<p>Todd W<p>p.s. Real engine braking is at or near redline

randall

nt<br>

E

The Torsen works when power is applied and when engine braking. The<br>bias ratio are different though. I believe that EDL is not operational when engine<br>braking (but I may be wrong on this point).<p>E<br>

Todd W

I do not consider EDL a core part of quattro, as I have 2 quattros and neither has EDL (or Torsen for that matter). Torsen doesn't vanish into thin air when no power, it just doesn't play as noticeable a role. It does "work" when using the brakes.<p>Todd W

E

> I do not consider EDL a core part of quattro, as I have 2 quattros and<br>> neither has EDL (or Torsen for that matter).<p>EDL is integral to quattro IV. Without EDL, one torsen and 2 open diffs would<br>not be AS effective (below 25 mph), e.g. ice under the right front and right<br>rear tire would render the car useless. EDL would get you out of that situation.<br>During high speed driving, EDL is not activated.<p>Older quattros have either locked diffs or a rear torsen instead of the open<br>diffs and EDL. Arguments can be made on which system is more effective -<br>better control, feel etc.<p>> Torsen doesn't vanish into thin air when no power, it just doesn't play as<br>> noticeable a role. It does "work" when using the brakes.<p>Yes. As I said, Torsen works all the time, from when power is applied to when<br>when it is not (engine braking). Though, the characteristic Torsen bias ratio is<br>different when applying power vs. engine braking.<p>E<p>