Rear Suspension

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Apr 28, 2000 | 07:42 AM

Apurva

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Rear Suspension

According to Audi's literature - the TT's rear suspension is a "Torsion-beam axle with trailing arms". Does that mean that it is not an independent rear suspension system? Does that matter for a AWD sports car?

Apr 28, 2000 | 07:53 AM

Geza

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FWD uses Torsion beam - AWD uses an independant rear suspension

Apr 28, 2000 | 07:58 AM

cxcheng

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Torsion beam for all FWD, Quattro has multi-link setup

That's one of the primary reasons Quattro is preferred. Porsche made do with this setup on the 911 till the 993, but it is definitely crude. I tried autocrossing my '89 Audi 80 with the same rear suspension setup in heavy rain. It was exciting but in the wrong way. At times I felt like only my front tires were on the ground, and I had a few near spinout situations. Granted 10 years have gone by and the 80 was never meant to be autocrossed, it speaks to a good extent on how they are. My 95 Saab 9000 has the same setup. Works fine when the road is even and dry and IMO makes the car more neutral, but gets problematic when traction is uneven, say on bumpy roads.

Apr 28, 2000 | 08:29 AM

Geza

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I think you are talking about...

"torsion bar" springs at the rear of pre-993 911s (which had a trailing arm independant suspension).

Apr 28, 2000 | 08:36 AM

cxcheng

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Torsion bar and beam are the same, aren't they?

The Audis also have the trailing link as well. Just like my Saab. My Audi 80 looks the same as my Saab underneath. Haven't looked underneath a classic 911 but the diagrams I've seen look similar.

Apr 28, 2000 | 08:56 AM

Geza

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Actually, they are quite different...

the torsion bars (ala 911) are rods attached to the pivot point of the trailing arm on one side, and fixed to the chassis on the other. Suspension movement in the trailing arm causes the torsion bar to twist - this action provides the suspension spring force. There are no coil springs in a torsion bar suspension - the torsion bar itself is the spring (thru this twisting action).

The torsion beam suspension used in Audis employs coil springs as the suspension spring. The torsion beam part refers to the fact that (although a single beam axle is used to connect the left and right wheel) when one wheel moves (when hitting a bump) the axle is design to twist, limiting the amount of effect one wheel has on the other. It sorta helps them (the wheels) remain independant, even though they are connected. Hope this helps.