Quote Originally Posted by Jibz View Post
So given that the Mugen SS lowers my car by 1.4 inches (35mm), a modification of some sort is needed for my tie rods?
Nope, not the tie rods, the steering arms. You need a set with the tie rod end taper downwards, instead of upwards like the standard steering arms.



The bump steer on our cars is also a function of the very small caster angles too, isn't it?
Nope, caster realy has nothing to do with bump steer. Bump steer is changes in the toe settings as the suspension moves up and down. For example you set the car at zero toe at normal ride height and it toes out 5 mm when the suspension compresses 50 mm. Then it toes in 5 mm when the suspension extends 25 mm. So it drives down the road toeing in and out every time it hits a bump, making the car steer all over the place. Hence the term "bump steer".

It's even worse for a race car where the constantly changing toe angle disrupts the tyre's contact patch and it loses traction. So the car won't hold a line through a corner, it steers and slides all over the place. Very slow and, maybe more importantly, very unsettling for the driver.


Cheers
Gary