As has been said before; MMC are working on a solution to the M3W front suspension & steering concerns. It is of course true that there is a lot of bump/roll steer for all the obvious reasons already stated, the steering & suspension geometry was designed by MMC and was and still is their responsibility, as is right and proper.
The initial design of springs and dampers were designed and developed and funded by SUPLEX UK Ltd. The first cars that went as demonstrators had SUPLEX springs and dampers and generally had good write-ups for ride and handling. These units had an integral rebound spring to restrict droop of the inner wheel on cornering thus increasing roll stiffness AND a rising spring rate in bump achieved with a spring assister on the damper rod. The damper characteristics were also tuned to this set up.
Due to the unexpected success of the M3W production volumes were significantly increased and SUPLEX were unable to ramp up production quick enough and so mass production was given to SPAX. The current SPAX units have none of the sophistication of the initial SUPLEX units resulting in the bump/roll steer being far more noticeable. Also the SPAX cars ride higher making to bump/roll steer effect even worse. The SUPLEX units did restrict the bump/roll steer as there was no droop on the inner wheel so no steer effect there, and also the bump travel was limited with the rising rate to also minimise the steer effect. SUPLEX have no design input in the steering geometry as that is being worked on by MMC. So although Kevin Rivette has come up with a spring/damper solution is it as sophisticated as the SUPLEX design, I do not know. SUPLEX UK are part of the solution to this concern and are of course working with MMC.
I hope that this helps - PJB
(Contract - Consultant Engineer and Test Driver for SUPLEX UK).
PS Both BMW and Mercedes are introducing rebound springs into their dampers to limit roll and thus reduce antirollbar stiffness to improve single wheel bump responses.
