I am currently working out the suspension geometry for my kit-car and am wondering if anybody else is using anti-dive geometry? If so, how much are you using? I was thinking of angling the bottom wishbone by approx. 3 degrees towards the centre of gravity.

Have a look here -

http://www.locostbuilders.co.uk/viewthread.php?tid=65564

there are several other anti-dive threads as well.

Weird, when I looked at this thread title, I saw, "Anti-gravity geometry."

Carroll Smith notes that it doesn't work well because it binds up the suspension joints.

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Originally posted by drlloyd
I am currently working out the suspension geometry for my kit-car and am wondering if anybody else is using anti-dive geometry? If so, how much are you using? I was thinking of angling the bottom wishbone by approx. 3 degrees towards the centre of gravity.

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3 degree of anti-dive will probably be way to much. Even heavy America front engine cars normaly do not have that much. I would shot for no more then one and half degrees. A locost has a much lower C. G. then most cars. DaveW

Thanks for the advice, I have a number of books by Staniforth, Herb Adams, etc that cover anti-dive geometry but there is no indication of how much is really required. I think I will probably limit it to inclining the bottom wishbone up by 1.5 degrees.

What you have to watch is that with that arrangement the bottom wishbone ball joint moves forward with suspension movement, which rotates the upright and has all sort of unwanted effects on bump steer, roll steer, caster angle............

I am aware of that but approx. 3" of suspension travel would equate to only 2mm of forward wishbone movement with a wishbone inclination of 1.5 degrees.
I would not expect to regularly get this amount of travel in my kitcar and I expect that the rubber bushes at the chassis end of the wishbone would allow the wishbone to move forwards by at least 1mm anyway.

I've not been able to find any definitive data at all on what effect this has on stopping distance s for one.

The other thing is that there are all sorts of other transient conditions the vehicle goes through such as braking whilst changing direction, where the effects of this type of geometry are going to be hard to predict in advance.

Unless anyone can come up with test data such as stopping distance figures or lap times that prove there's an improvement then I'd steer clear (get it?) of the whole subject.

Its also interesting to note that in the 1980's anti dive was seen as a big issue for motorcycles, after a lot of effort by a lot of companies the idea has basically been abandoned now as a dead end in development. Bikes now just concentrate on having structurally sound properly valved suspension, and I think there's a lesson in that.