Torsion bars on Le Mans race car?

SpeedracerIndy · 09-18-2003, 03:29 PM

This article about a Bentley Le Mans car talks about "a unique torsion-bar rear suspension". If race cars are using torsion bars still, why did Porsche ever stop using them?

Car and Driver article - page 2 about half way down.

Mr9146 · 09-18-2003, 03:36 PM

There was a good thread ont his a while back. F1 cars still use tortion bars, too. I believe Porsche switched because of the revised geometry and how it improved overall ride quality without sacrificing too much on the performance side of things.

silverc4s · silverc4s's Garage

I read somewhere that the original 911 TB suspension design could not accomodate ABS braking, for some reason - had to do with castor, camber, toe, or the like....?

Wil Ferch · 09-19-2003, 09:36 AM

Coil springs vs straight torsion bars is usually a packaging thing. Both are torsion bars...one is simply a "coiled-up" straight TB.

Coils are much easier to adjust ride height and to change settings, also easier to provide variable rate geometry if you design the spacing between the coils in a changing-space manner.

---Wil Ferch

jluetjen · jluetjen's Garage

I agree with Wil. There is no change in the ride "quality". In that regard a spring is a spring, wether you coil it or not.

Mr9146 · 09-19-2003, 10:42 AM

Quote:

I agree with Wil. There is no change in the ride "quality". In that regard a spring is a spring, wether you coil it or not.

I disagree. With the advancements in spring technology - i.e. progressive rates, various alloys - I believe that coil-over provides far superior quality in that it is far more versatile.

For example, a progressive rate spring can be very soft under minimal load, but increase tension under heavier loads. Tortion bars, to my knowledge, are constant rate ... however, I have been known to be mistaken.

jluetjen · jluetjen's Garage

Oh yeah -- rising rate springs -- the ultimate in suspension. Or are they??? I feel a sense of deja vu all over again.

CHILI · CHILI's Garage

Quote:

Originally posted by CDiercks
If race cars are using torsion bars still, why did Porsche ever stop using them?

Car and Driver article - page 2 about half way down. [/B]

I read somewhere that it was because the stiffness Porsche needed exceeded T-bar capabilities. I.e. they couldn't make T-bars as stiff as they needed. Can't remember what book it was in, though. I have too many!