Lotus 2004 Eleven Service Notes page 99

Lotus Service Notes
Castor Adjustment
Castor is the angle from vertical of the steering axis of the wheel when viewed from the side. Its primary
purpose is to provide a natural straight running tendency of the steered wheels with forward vehicle motion.
Castor angles have a complex interaction with other steering geometries and if unbalanced or outside of speci-
fication, can result in various stability and handling deficiencies.
The wishbone pivot bushes are bonded rubber type with a plastic flanged outer sleeve, a plain steel in-
ner sleeve, and a plastic interleaf sleeve within the rubber bush to control the flexing characteristic. The top
wishbone rear bush, identified by a blue paint mark, has no interleaf sleeve.
The top wishbone pivots are sandwiched between the walls of transverse chassis box sections, the pick
up points in which are reinforced either with machined inserts, or in the case of the foremost position, a thick
alloy plate, each being bonded to the chassis with epoxy adhesive. Spacer washers are fitted ahead of and
behind each of the top wishbone pivot bushes to allow the wishbone to be displaced forwards or backwards,
with an associated change of castor angle. A rubber faced snubber washer fitted against the rear face of the top
wishbone front bush prevents metal to metal contact under extreme braking forces. The spacer washers may
be re-distributed between the front and rear of each pivot bush but the snubber washer position, and the total
shim pack thickness of 4 x 1.5mm at each pivot (inc. the 1.5mm snubber washer) must remain unchanged.
Top Wishbone Inboard Fixing
FRONT Front leg
1.5mm shim
washers
Bonded
plate Rubber faced
snubber washer
Page 6
Top &
bottom
steering
swivels
Bonded
inserts
Section CI
FRONT
Castor angle
c27
Rear leg
1.5mm shim
washers Flanged plastic
outer sleeve
No interleaf Inner steel
on this bush sleeve
c32