Is200 Castor Adjustment

[MacRS200]

Well a few dealers have used my settings...... What's ironic is the target camber positions are still within there checking range so i don't violate anything.... I think there a two main reasons why dealers/ tyre centres struggle with my settings...

1: The procedure looks horrific

2: Understanding the need to correct the nonadjustable castor

And this is why?

1: The small change in camber aggressively moves the toe (it looks worrying) then the toe correction moves the castor.

2: The camber and castor have a relationship on the corner... As the wheels are turned the castor plays a big part in moving the cars weight from one place on the tyres contact patch to another.

Eureka, only taken 3 years but I think I finally got it at last, I'm sure Tony will correct me if I'm wrong though.

BECAUSE of the castor angle "winding in" some negative camber causes toe in like when you bank a motorbike over. If you then correct the toe in, the castor will reduce because the wheel is pushed back by the track rod.

Is that it?

[Tony-Bones]

Welcome to the realm of chassis dynamics :)

It's not easy to explain and a nose bleed to read but here we go........

On the turn there are interactions between the X, Y, Z axis, our concern is Y&Z. As the turn is initiated the inner wheel, will sweep the castor forward and in doing so the position of the steering arm (now moving to the wheels centre) activates the TOOT (toe-out-on-turns). This activation lifts the inner wheel toward a positive position (top away from car) if the castor is to low then the lift effect is belayed.....

Still with me.... The position of the cars weight at the tyre footprint is called the Scrub radius, as the wheel is turned the SR needs to migrate to the inside of the tyre... Now since the lazy TOOT is effected by the castor the SR is to far out board meaning the inner part of the tyre has to much weight on it, accentuating the tyre wear.

The problem with the IS200/300 has never been the camber but the castor which is a fixed angle.... As you know wim found a way to increase this angle geometrically without the need to replace the tie rod.

By the way the Tezza mentioned in the news area on the main board is your car "suspension research results".