Wondering...

I drove a 740 wagon -- base model, manual tranny, no frills -- for 11 uneventful, reliable (though slow) years before moving up (way, way up) to a Saab 9-5 Aero wagon. While I love the Aero on dry pavements, it's a challenge to handle on wet, snowy or slick roads, it has a very busy, often noisy suspension, and the FWD on this high-hp car creates some major torque steer... making this car a challenge to handle on anything other than pretty straight roads.

My other car is a '98 Audi A4 Quattro 4-door. I really love the AWD, and wish the Saab had it.. The Audi's suspension is light years better than the Saab's, and the A4 is far nimbler (though far less brutish under a heavy right foot).

So, among other possibilities, I'm considering a move back to Volvo when the Saab lease expires... anyone have any thoughts on the V70 Wagons, esp. the "R" model? I've only read about it thus far, but it sure sounds as though it has everything the Aero has, plus the Volvo AWD system. Comments?

Reply to
Andrew Mosner
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I believe one of the differences between Volvo AWD and Audi AWD is that Volvo is a front wheel drive until AWD is required. Audi splits the power

50/50 under normal driving. This was true of my 1990 Quattro. Someone please correct me if I am incorrect in this assumption as it applies to the latest Volvo and Audi models.

Jack

Reply to
Jack G

The big difference with the Haldex system (Current Volvo, VW, et al) is this matter of division of power. Haldex is a computer controlled clutch pack appended to the rear differential of a basically FWD vehicle. If the computer (via AWD sensors) detects slippage, front vs rear, the clutch is engaged instantly (as in 1/6 of a wheel revolution!).

In the older systems with silicon "clutch" there was at least some power to the rear wheels at all time. Any slippage at the coupling caused it to begin lock-up with increasing slippage that raises of the temp of the fluid, which causes the coupling to progressively lock - this applies to the initial ('98 until ??) Volvo system and to the VW "Synchro" system.

Audi's Quattro system has always appealed to me, though I've never owned one - for a variety of reasons. The Audi's "heart" is the Torsen torque-dividing differential at the point of power input. While totally mechanical, it allows variable division of power front/rear. This seems a very elegant solution to me.

I've never had occasion to inquire into the systems used by BMW, MB, etc. The Haldex seems to be the coming thing - inexpensive, yet effective. It is being evaluated by most of the U.S. manufacturers at this time. Visit the Haldex website to get the full story.

bob noble Reno, NV, USA

Reply to
Bob Noble

I believe that the transverse engined Audis use the same Haldex system as Volvo - the car is front drive until wheels slip, then power is added to the rear. The longitudinal engined ones have the Torsen center diff (earlier versions had an electrically lockable open diff), which sends some power to front and rear all the time.

Reply to
Mike F

I am getting kind of tired correcting this... A car with Haldex is not FWD, even if you are just crusing at constant speed. In such a situation, it is more biased towards front (most of the torque goes to the front), but that is not necessarily negative. Think of the fuel that you save... Immediatly when you press the gas pedal, a larger percentage of the torque is transfered to the rear. What I mean is that the Haldex doesn't wait until it detects slip before increasing its torque transfer, and the torque transfer is there when you need it.

The torsen is good as well, while the visco is an inferior system. An advantage of the Haldex is that it is no disaster if you have differently worn tires front/rear, and it is also possible to change only 2 tires (no need to change all at once as you have to with most AWD systems).

Yes, cars from the VW group (including Audi) that have transverse engines do have Haldex AWD system.

/Staffan

Reply to
Staffan Nilsson

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