live axle rear suspension

[ant0276]

Hi all.

New to this forum, like the posts so I joined.
I was wondering whether anyone knows more than me about four link rear, I'm rebuilding a car with four link live axle suspension, and have little experience with it. My problem is with controlling the anti squat as the suspension bumps, as it seems that there is no way to controll the downward motion of the I.C. All my modelling sugests that the nature of the beast is for a system that positively feedbacks onto it's antisquat characteristics, compounding the antisquat as the suspension droops, or having to pass the 100% line and go into squat as the suspension bumps. I'm looking to control the rear of a very light front engined V8 with geometory, as I want as much bump compliance as I can get, to counter the effects of a light back end (without balast). IRS is not an option, as it's too much of a depart from the original design of the car, and I want to keep it (sort of) original in concept as I rebuild from ground up with a new space frame chassis. unfortunately there is not much room for long swingarms, so I have an I.C. that moves substantially during suspension travel (100mm bump/50mm droop). If all else fails I'll go for a parallel fourbar, but I really want to try to avoid this, as I've had a lot of success using goemetric centres in suspension design on open wheelers.

look forward to replies.


>> Edited by ant0276 on Wednesday 4th January 01:50

[GreenV8S]

Trying to get anti-squat from the axle thrust is a dodgy proposition because the anti-squat effects are highly dependant on ride height. Have you considered exploiting the axle torque instead? It means the diff 'nods' in pitch/bump, but you have the potential to achieve more consistent anti-squat.

[ant0276]

Thanks.

I'm not qute sure how the torque reaction can do anything but make the body squat, as it always tends to make the axle want to twist bakward with a four bar system, but I'm guessing you are talking about a similar geometory to a ladder bar in a strip car. I'll have to hit the library.

Thanks

P.S. I don't have a TVR or lotus, but I have an aussie (arguably) hybrid of the two. Bolwell Nagari. You guys should check them out. Small, but way fast. www.bolwellcarclub.com.au

[GreenV8S]

Yes, I'm thinking of a simple ladder bar. If you only aim for partial anti-squat you can use quite a long bar, which should mean the diff doesn't need to nod very much.