Has anyone played with unequal length trailing arms for the rear suspension of a DeDion car??

What'll hapen is that under cornering, one side of the car will drop more than the other, and the unequal length arms will cause one hub to rotate (about the driveshaft axis) by more than the other, putting the (DeDion) beam into torsion.

I realise the dangers if it is done badly (torsional rupture, crash), but if analysed and designed well, this would give a wicked anti-roll system for the rear suspension, for naff all extra weight and no more parts.

Anyone played with this??

Ed.

[Edited on 11/3/06 by ed_crouch]

Designing in geometry that deliberately causes binding dosen't sound good to me, the forces imposed on the bushes and brackets will be horrendous.

sounds like a bad idea to me. the bar has to be proper stiff to keep the steering geometry, I think other things like your arms and brackets are going to give way first.

I had thought a bit about dedion with a hub (or hubs) that were allowed to rotate around the bar, so that geometry could be changed in bump/droop. tricky though.

in theory , even with equal length arms , youll get some form of rear steer .

you would need more twist/rotation for it to work as an anti roll bar for the full range of suspension movement .

Lotus did it with the live axle on the Seven S4 --- took the form of a watts linkage --- places very high loads on chassis and axle just not required anyway.

Which 7 used an A frame to the bottom of the diff and two trailing arms to the top of each end of the axle? That design puts a lot of torque through the axle itself, and I belive there were several failures...

quote:

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Originally posted by MikeRJ
Which 7 used an A frame to the bottom of the diff and two trailing arms to the top of each end of the axle? That design puts a lot of torque through the axle itself, and I belive there were several failures...

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That sounds like quite a neat solution, the A frame providing lateral location and doubling up as one of the trailing links. Are there any major disadvantages? Any reason why it wouldn't work with two trailing arms rather than leadinf/trailing?

If not then it sounds like it could be doable on a locost to remove the panhard rod and give a bit more boot space perhaps.

Chapman tried that as well it took a bit of finding

Rear de Dion suspension fitted on some Lotus Elevens


source http://lotuseleven.org/motor_racing_march_1956.htm

[Edited on 12/3/06 by britishtrident]

[Edited on 12/3/06 by britishtrident]
Rescued attachment MotorRacing3.JPG

I know these things were back in the day an all, but damn that looks just a tiny bit flimsy!

Hmm, I didn't think too hard about it, but clearly the pivots of the A frame should be running at 90 degrees to the long axis of the car to avoid any lateral movement of the axle in bump. That might make locating the the inner bracket problematic as it would have to be somewhere on the transmission tunnel level with the standard outer bracket. Certainly an interesting variation on the standard Panhard/Watts linkage though.