What effect does lengthening or shortening wishbones have on the suspension geometry of a locost i.e. without adjusting the mount points?

I'm looking at a mid engine setup with very short wishbones at the back and I'm wondering what its going to be like handling wise.

[Edited on 13/12/05 by Kowalski]

In short it increases the moment on the wishbones reducing the design margin and screws up the roll centre. You need to work out the roll centre hieght for the new set up and increase the wall thikness of the tube to cope with the additional bending moment

I think it's the opposite. It's the same force, over a *shorter* distance, so the applied torque to the wishbones is less. Half as long = half as much torque = half as much force on the tubes. But yes, it'll definitely change the camber gain curve, making camber change much faster. Depending what you want that's either good or bad.

Sorry By in short i meant in summary and then discussed the problem with extending them (does anybody ever shorten them?)

Only people who have an engine in the way i.e. mid-engine rear wishbones.

I initially made my front bones much longer as the front of my car was designed to 18 inches wide - it had a long wheelbase. I had the geometry worked out but after a couple of eng. friends of mine at work here looked at the measurements and did a rough calcs on them the force on the tubes - (mine were about 6 inches longer on the lower) was cubed or more. I was still sure they would hold but would not risk taking my kids for rides if there was any possiblilty of failour. This caused me to redesign the whole front end .
Dale