camber changes from body roll

[KnifeEdge_2K1]

2 things im wondering about

first is that if it is possible to design a suspension which gives negative camber to the outside wheel under body roll ... ive been messing with some double wishbone setups changing the initial angle and the control arm lengths yet have not been able to achieve such a setup, the only method i could achieve is making the upper arm parralell with the line where the joints of the 2 arms meet at the body essentially making a triangle with the top segment having a joint in the middle, as you can imagine this would be pretty hard to pull off

secondly how would you determine the amount of negative camber to give your car ??

the way im thinking is figure out the max body roll you could achieve using the theoretical maximum grip of the tyres and stiffness of your shocks/springs then figure out the minimum roll you would have (this would be much harder to do as it would depend on the track you drive on and what not), then figure out the average roll you would have in a corner and set it so that under the average amount of body roll your suspension gives you no camber at all on the outside heavily loaded tyre

[RacingManiac]

kinematically it is possible to have your car to have no camber change in roll. In the double wishbone setup you just need to have your instaneous center of your wishbones in a front view system to be at half track(ie, center of your car). The downside is you are going to have A LOT of camber change under bump/droop, which is not good for the car under inline acceleration. Therefore it is always a compromise. Another way is by playing with your rates, and physically limits your roll, so you don't roll the tires over to positive. In a mechanical based system(no active damper, anti-roll...etc), this would also become a compromise as by either increasing your spring rate or anti-roll bar rate will reduce your ride compliance and reduces your grip over single wheel bump. Most racecars will fall into this category as their environment will usually let them get away with this(smoother surface on the track). Many new suspension systems are trying to address these issues, by using hydralic linking each damper to allow roll-rate and ride rate to be tuned differently and most importantly, independent of each other. Most of these are proprietary technology and you need to read their patent to see how they work specifically. There are also attempt at providing a kinematic solution to this, with cars like Mercedes's F400 Carving concept with active camber control, or Michelin's Optimum Contact patch system. Both involving manipulating the a-arm mounting either via a control system and hydralic(F400) or a passive mechanical setup. I don't know too much of the details in those...

Of course the optimum camber angle will depend on your choice of tire....

[KnifeEdge_2K1]

one thing about the instantaneous center of rotation, doesnt it change with your suspension movement, afterall it is an instantaneous center of rotation, just because it gives perfect camber control at the start doesnt mean it will keep giving that same quality ...

[RacingManiac]

but provided that your rate and travel is designed as such, you can minimize its migration.....its going to be an iterative process to find the solution, but its definitely there....

[culver]

You could use a solid axle!

[RacingManiac]

^^ by far the easiest way......though you'll be dealing with 0 camber all the time...