Steering Geometry

[mike]

I have recently checked the steering geometry of my 1969 S4SE Elan for the first time.
The toe in was correct at about a 1/16 inch, :blink: [SIZE=1] the camber was just under 1 deg positive, and the caster was 3.5 degrees positive; All these are to spec. But the Swivel pin or King Pin Inclination (kpi) was 16 degrees positive. It was the same both sides and shows no signs of damage. The camber would be wrong if there was. Does any one know if any uprights were made with higher kpi and why. The car handles very well.

[david miller]

Michael, as you are perhaps already aware the workshop manual advises checking the wishbone to vertical link mountings (ie, top ball joints/trunnions) for any wear in this instance. However, given you have the same reading on both sides of the car it seems wear/damage is not very probable. My manual (albeit +2) quotes 9.5 degrees kpi, so you are some way out. Looking at the front suspension diagram in the manual kpi seems inextricably linked to camber, excepting any change to chassis points and wishone lengths. I would be tempted to check my gauge/figures again, making sure the vehicle loadings/specified ride height were correct.

Interestingly, looking at the front suspension set-up in the manual really gives an idea of Chapman's genius. The fact that the top and bottom wishbones are set at quite different angles, as well as being unequal length, means that in roll the outside wheel increases negative camber and the inside wheel increases positive camber - exactly what is needed to keep the wheels vertical, despite the angle of the body.