Hi,<br>The ad for the new Jeep drives me up the wall with the claim that the QUADRA-DRIVE is the ONLY one that delivers maximum power all the time. It is able to get the Jeep out of situations even if only ONE wheel has traction..... Geez the power of marketing ...! It appears to me that before the QUADRA there was the QUATTRO...what gives..???<p>Kandiah<br>97 A4 2.8QM<p>

<br>Quattro does not control torque to all wheels like on the Jeep, that's the traction control. The Jeep has torque controlling diffs in both axles, the A4 only has it between the axles. This is more than sufficient for 99% of public road driving with the traction control activated.<p>Todd W

According to the 99 A4 brochure...The Quattro system has 3 differentials, Front, Centre, and Rear and can allocate as much as 66% of the engine power to any one wheel on an as needed basis.<p>The Jeep literature that I have read indicates that the Quadra Drive can allocate as much as 100% of the power to any one wheel on an as needed basis. I am assuming that it must also have a front, centre, and rear differential setup.<p>Kirk

Quattro system has 3 diffs - front, center and rear. <br>If you read Jeep's ad carefully, you will notice that they mention the *speed* sensing, torque transfer! IMO, that's no better than Subie's AWD system - again, speed sensing. In Quattro, it's a *torque* sensing system. Advantage: Quattro.<br>And it's no surprise that they need upto 100% power to 1 wheel to get a jeep moving... they are so d*mn FAT! :)<p>

Jeep has something like 4 systems currently on the market. So, I assume you are talking about their new promo. The new jeep system uses a new clutch pack system that is a little more advanced than the old one. <p>It is a rotationally sensitive system that supposedly has less wear than traditional clutch packs. This does not truly lock the diff since it works on the friction of the clutch disks. Like a dumb Haldex (they use a microprocessor). Haldex uses this system for the newest synchro, because the microprocessor can bias the traction depending on other factors.<p>Sube's viscus system (like the old synchro) is also rotationaly sensitive. This means that the wheel has to spin a bit before it hooks up. They also work less effectively in very warm temperatures. They have a very unprogressive lockup, essentially all on or all off. This can lead to handling problems.<p>These systems are also problematic because they stay linked when coasting or when the brakes are applied, which is very ungood (that's why the Haldex microprocessor is an improvement because it unlinks).<p>We have a Torsen (torque-sensing) system that essentially is only linked when there is torque applied. It is very progressive: Give it less torque and it has less lockup. Ours does not give a fully-locked condition, I think it is 80/20. The EDL/xxx brake-based system is a simple and efficient way to mimic limited slip differentials at the front and rear axles. This is the same system that Mercedes uses on its suv's and 4matics.<p>Either the Audi or Jeep system will allow the vehicle to move with just one wheel on traction, and both offer less than 100% to that wheel. This is good engineering, but bad advertising copy. Imagine if you had 180 lbs, of torque on the one wheel: it would eventually damage something, and it would be dangerous to drive that way. <p>I think that the language here was a little confusing since the sytems accomplish the same end result just in very different ways.

MB had a AWD system before that did that I think. The problem was that if you started turning and went into a flat spin, and let's say the outer rear wheel was the only one with traction, then it would get 100% of the traction and keep you in a donut spin. That was problematic. Also, 100% torque will tend to tweak the axel in ways you didn't want it tweaked. <p>Subie's got the best speed sensative system period. Agreed. Audi's got the best torque sensative system. Torque = big smile on face. Audi = better.

Take a close look at the "gerotor" graphics. A gerotor is a common system (like Ford oil pumps) used to pump fluids (like the fluids in hospitals and labs). It is a good reliable system. <p>What is hidden under all the words though is just a simple clutch pack. It is better than the old style clutch packs in that they don't wear nearly as badly and there is a rising rate pressure adjustment (the gerotor). In fact, the center pack is attached to a planetary gear and the F/R differential packs are mounted conventionally.<p>Jeep is absolutely right about the EDL/Mercedes system not being the best system for off road purposes. If you are mudbogging and crawling on wetlogs or slickrock, I would want their system or arb lockers. Of course, you are not going to find a 45,000 mercedes or my A4 doing too much of that.

... in their minivan Renault Espace Quadra. It designated the AWD version (surprise). I believe Audi won, and their argument was that in some languages of common markets the pronounciations of "Quattro" and "Quadra" are too close for comfort.<p>Gus

think about it. If you only have RWD or FWD sans traction control or limited slip...100% of your available power is going to only one wheel and that describes probably 90% of the cars in the world.<p>Kirk<br>(NOT saying that the Jeep is better, or I would have bought one!)