Lotus Elise Service Notes page 322

Lotus Service Notes Section JH
JH.1 -GENERAL DESCRIPTION
The braking system of the Lotus M111 comprises of ventilated discs all round with AP Racing 2-piston fixed
calipers on the front and Brembo single piston sliding calipers on the rear. A tandem master cylinder, without
servo assistance, operates the calipers via a front/rear split hydraulic circuit. The centrally mounted parking
brake lever, operates the rear caliper pistons by control cables.
The AP Racing front calipers, have lightweight alloy bodies housing two opposed pistons, and are mounted
via two bolts directly to the rear of the extruded aluminium alloy front hub carriers. The Brembo rear brakes use
single piston sliding calipers, with cast iron bodies, mounted via an adaptor plate to the rear of each hub carrier.
The rear calipers are also used on some versions of the Lotus Esprit. A common ventilated brake disc is used on
all four wheels, with cars built prior to June '98 (approx. VIN W 3714) using discs constructed from a silicon
carbide reinforced aluminium metal matrix. Later cars use cast iron discs, with a corresponding change in brake
pad material. The discs are sandwiched between the road wheels and hubs and use no additional fixings.
The tandem master cylinder is made by ITT, and incorporates a front section to supply both front brakes,
and a rear section to supply the rear brakes. A translucent fluid reservoir surmounting the cylinder, services both
front and rear circuits, and also, via a linking hose, the clutch master cylinder. A fluid level sensor is incorporated
into the filler cap, and lights a fascia tell tale lamp if the level becomes dangerously low.
The parking brake ratchet lever is mounted between the seats and uses a balancing linkage to actuate
individual control cables to each rear caliper. Adjustment of the caliper mechanism to compensate for brake pad
wear is automatic. The brake should be applied by pulling upwards firmly and fully to engage the maximum
number of ratchet 'clicks'. When parking the car on a slope, the additional precaution should be taken of leaving
the transmission in first or reverse gear and steering the wheels towards the kerb. If the parking brake is applied
when the brakes are hot (e.g. after prolonged or vigouous braking), special care should be taken to ensure that
the parking brake is securely engaged in order to allow for any potential affect on brake performance due to
temperature change.
The braking system is designed to enhance brake performance during high speed driving, with good fade
and pad wear characteristics, and have a higher friction level when heated to normal working temperature than
when cold. Required pedal effort will reduce as cold brakes become heated to normal working temperature.
After fitting new brake discs or pads, the braking efficiency will increase significantly as the brakes 'bed-in', and for
cars with aluminium discs, as a deposit of the brake pad material builds on the part ceramic discs, characterised
by a dull grey band around the rubbing surface. Maximum braking efficiency will be achieved if, for the first few
hundred miles, needless heavy braking is avoided, and the brake pads are allowed to 'bed in' fully before being
used to their full potential.
JH.2 - BRAKE FLUID CHECK & CHANGE
Before checking the brake fluid level, ensure that the car is parked on a level surface, and remove the front
bonnet. The level of fluid in the reservoir may be inspected without disturbing the filler cap, and should lie
between the 'MIN' and 'MAX' marks moulded on the transluscent reservoir body. The level will fall progressively
as the brake pads wear in service, and should be checked at each service interval. A sensor incorporated into
the filler cap will light a fascia mounted tell tale lamp if the level becomes dangerously low. As a bulb check, the
tell tale should light for about six seconds when the ignition is first turned on, but may also be tested by pressing
the button on the filler cap, which action should light the tell tale with the ignition switched on.
An internal baffle divides the reservoir into two compartments, with the front section supplying the front
brake circuit, and the rear section the rear brakes in addition to, via a short linking hose, the clutch master
cylinder. Service wear of the clutch friction plate will cause fluid to be displaced from the self adjusting clutch
slave cylinder, back to the reservoir, and will counteract to some extent the dropping of the level due to brake pad
wear.
If the reservoir needs topping up, first clean around the cap
to reduce the possibility of contamination before unscrewing the
cap; it is not necessary to disconnect the level sensor cables. Take
suitable precautions to guard against damage to paintwork caused
by brake fluid dripping from the level sensor.
Use only a fresh supply of DOT 3 or DOT 4 non-mineral
type fluid, identified by a yellow and black symbol.
J 1 4 6
1998 / 03
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