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Lotus Eleven/Elise/Exige. Manual - part 25

Page 5

Lotus Service Notes

Section CI

Camber Adjustment

Camber is the angle from vertical of the wheel when viewed from the front, and is said to be negative when

the wheel leans inwards at the top (positive when leaning outwards). The primary purpose of camber is to

achieve the maximum efficiency of the tyre under cornering loads and body roll, with the specification closely

allied to a particular wheel/tyre combination. The camber angle changes with suspension travel, becoming

more negative on bump, and should be measured only at the specified ride height. Incorrect camber can result

in handling deficiencies and excessive tyre wear.

Camber adjustment is effected by adding or deleting shim plates between the steering arm (to which the

upper steering swivel joint is fixed) and the hub carrier.

Shimplates are available in 1mm and 3mm thicknesses.

Reducing the shim pack thickness will increase negative camber. Adding shims will reduce negative

camber.

A 1mm shim plate will alter camber by approximately 0.25°.

In March '04 the caphead bolts securing the ball joint plinth to the hub carrier were upgraded from 8.8 to

10.9 grade, with a corresponding increase in torque from 45 to 68 Nm. Before fitting these bolts, inspect

the cap head for the grade marking, apply Permabond A130 (A912E7033) to the threads, and torque

tighten to the appropriate figure.

Camber angle

c29

Vertical Wheel centreline

Camber adjustment

shimplate

Steering arm

Hub carrier

c30a

Page 6

Lotus Service Notes

Section CI

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.

FRONT

Top &

bottom

steering

swivels

Castor angle

c27

Top Wishbone Inboard Fixing

FRONT Front leg Rear leg

1.5mm shim 1.5mm shim

washers washers Flanged plastic

outer sleeve

No interleaf Inner steel

Bonded Bonded on this bush sleeve

plate Rubber faced inserts

c32

snubber washer

Page 7

Lotus Service Notes

Section CI

Notes

Shim distribution at the front bush of either wishbone must be copied at the rear bush of that wishbone.

Transferring a 1.5mm shim washer from ahead of, to behind the pivot bushes, will

reduce castor by ap-

proximately 0.4°.

Transferring a 1.5mm shim washer from behind, to ahead of the pivot bushes, will

increase castor by

approximately 0.4°.

Ensure that the load spreading washers are correctly located beneath the bolt heads and nuts as shown

in the drawings.

Ensure that the pivot bolts are tightened only with the vehicle at ride height. Torque to 45 Nm.

CI.3 - ANTI-ROLL BAR

Three types of anti-roll bar and chassis mounting have been used:

1. The standard tubular steel anti-roll bar is mounted in pivot bushes onto the front face of the chassis, and

is linked to the outboard ends of each lower front wishbone via short ball jointed links. The bar is mounted

to the chassis using rubber pivot bushes for noise isolation, retained by alloy clamp brackets. Washers

welded to the bar bear against the inner sides of the bushes to provide lateral location of the bar. Castrol

LMX rubber grease, or equivalent, should be used when fitting the rubber bushes onto the anti-roll bar.

2. On Elise and Exige models built with 'Super Sport' suspension prior to August '06, a stiffer adjustable bar

is used with 5 holes in each end to allow some adjustment of roll stiffness to be made. Standard setting is

centre hole. Using a more forward hole increases stiffness. Two hard plastic clamping blocks secure the

bar to the chassis via the front lower wishbone inboard front pivot bolts, with 'top hat' section steel spacers

preventing the clamps from being crushed. An M5 bolt is used to close the bottom of each clamp.

Anti-Roll Bar Mounting - Rubber

Spacer plate

Rubber mounting

Clamp bracket

c40

Anti-Roll Bar Mounting - Hard 1 'Top hat' spacer

Clamping block

M5 bolt

Lower wishbone pivot bolt

Anti-roll bar

c40a

Page 8

Lotus Service Notes

Section CI

These hard type mountings provide optimum steering response but will transmit more noise and require

periodic lubrication with MoS

grease at 3,000 mile (5,000 km) intervals. Noise from excessive clearance

may be ameliorated by judicious shaving of the clamping block faces.

2. Elise and Exige models built with 'Super Sport' suspension from August '06, use a yellow painted, standard

rate, 5-hole adjustable bar, sharing the chassis mounting higher position of the standard bar but using

hard plastic bushes housed in alloy clamps. Each split pivot bush incorporates a raised shoulder around

its centre in order to engage with a groove in the two part clamp, and provide lateral location of the bush.

A pip on this shoulder locates in a hole in the clamp cap to prevent rotation of the bush. No lubrication is

required. These hard bushes benefit dynamic response at some penalty to refinement.

Anti-Roll Bar Drop Link

Lower wishbone

Anti-roll bar

drop link

Anti-roll bar

c31

Anti-Roll Bar Mounting - Hard 2

Smaller washer Bearing clamp rear

Alignment

dowel Anti-rotation

pip

Cap head bolt

Chassis

front face

Anti-roll bar Synthetic Bearing

split bush clamp

c40b

cap Flat washer

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