Lotus Eleven/Elise/Exige. Manual - part 67

   Lotus Service Notes

                Section JJ

Page 21

JJ.11 - PEDAL BOX

PRIOR TO '06 M.Y.

The extruded and welded aluminium alloy pedal box is bonded and rivetted to an aperture in the chassis

scuttle.  A hollow steel pivot shaft serving all three pedals is bolted to a steel mounting plate, itself bolted to the
inside of the pedal box.  Each  pedal is machined from a common alloy extrusion, with the throttle pedal being
of a narrower section than that used for the brake and clutch.  An extruded footpad is keyed, bonded and
rivetted to the clutch and brake pedals, and is bolted to the throttle pedal.  All the pedals use synthetic bushes
for maintenance free articulation on the steel pivot shaft, and the clutch pedal uses a cylindrical steel trunnion
supported in synthetic bearing rings to actuate the master cylinder pushrod.

In order for the required pedal spacing to be achieved within the packaging constraints of the vehicle, the

brake pedal uses a relay lever to move the output plane inboard of the pedal line.  A steel relay lever pivots on
the common pedal shaft, and is equipped with two legs, one of which is used to connect to the brake pedal via
an integral trunnion, whilst the other leg is connected to the brake servo pushrod by a clevis pin.

The throttle pedal actuates the throttle cable directly, which is routed along the cockpit centre, beneath the

gear lever and parking brake lever trim panels, beneath the fuel tank bay and up to the front of the engine bay
to the throttle body.

Adjustment
Throttle cable:
-

The pedal is pulled against a rubber buffer on a steel upstop bracket by an extension spring.

-

Adjust the cable outer length at the engine end abutment bracket to allow 2 - 3mm of pedal movement
before the throttle is actuated.

-

Set the downstop in the pedal footpad such that vigorous full depression of the pedal achieves full
opening of the throttle butterfly without allowing the cable to be strained.

-

An alternative pedal position which may be preferred for 'heel and toeing' may be achieved by replacing
the rubber upstop buffer with a M5x15 hex. head setscrew, with three flat washers beneath the head for a
total thickness of around 7mm.  The cable must then be re-adjusted at the engine abutment as above.
The footpad downstop bolt should then be replaced by an M8x20 setscrew and reset as above.

Brake pedal:
-

The pedal is pulled 'off' by an extension spring anchored to a bracket rivetted to the scuttle beam.

-

There is normally a gap of approximately 3mm between the brake pedal and the pedal box upstop flange
with the pedal released.  If preferred, the brake pedal can be raised slightly by adjusting the effective
length of the pushrod at its connection to the clevis, but the master cylinder must never be preloaded, i.e.
there must always be a small clearance between the pedal and upstop bracket to ensure that the master
cylinder piston is allowed fully to return and open the reservoir port.

-

After any adjustment, tighten the clevis locknut and check operation of the brake light switch.

Clutch pedal:
-

The pushrod, which is captive in the master cylinder, is screwed fully into the pedal trunnion, and controls
the pedal height.  Rubber buffers are provided to cushion the pedal at full travel.

Pedal Removal

To remove a pedal from the pivot shaft, the pedal shaft mounting plate must be removed from the pedal

box complete with all three pedals:
1.

Remove the intermediate steering column (see Section HG).

2.

Disconnect the brake servo clevis pin from the pedal relay lever, and release the throttle cable from the
pedal.

3.

Remove the two bolts securing the clutch master cylinder assembly to the pedal box and unscrew the
pushrod from the pedal trunnion.

4.

Remove the two bolts securing the brake servo mounting plinth to the pedal box and provide alternative
support for the servo/brake master cylinder assembly.

 

   Lotus Service Notes                                  Section JJ

Page 22

5.

Release the pedal return springs and remove the stop lamp switch.

6.

From above, release the six M6 screws securing the pedal shaft mounting bracket to the top of the pedal
box, and the single screw in the front face of the pedal box.  Withdraw the pedal shaft assembly from
inside the pedal box.

7.

Remove the three M5 screws securing the pedal shaft to its mounting bracket, and disassemble the
pedals from the shaft taking careful note of spacers and washers.

8.

On re-assembly, note that the pivot bushes of the brake pedal and relay lever should be lubricated with
Syntheso GLK1, or equivalent.  Check pedal pushrod and stop switch operation as detailed above.

Pedal shaft mounting

Pedal box

plate fixing

Throttle

Throttle cable

cable

abutment on
scuttle

Pedal
shaft
mounting

Pedal

plate

footpad

Pedal pivot
bush

Clutch
pedal

Downstop

trunnion

 pl1401mt

Pedal shaft

Alloy clutch

Brake pedal

pedal

steel relay lever

Throttle cable
abutment on
engine plenum

   Lotus Service Notes

                Section JJ

Page 23

FROM '06 M.Y.

Introduced for the 2006 model year, was electronic throttle control (ETC), which dispensed with the me-

chanical throttle cable linking the accelerator pedal to the throttle body.  The ‘drive by wire’ throttle actuation
uses a throttle pedal fabricated from steel rod which is pivotted in a plastic housing bolted to the pedal box.
The plastic housing incorporates two pedal position potentiometers operated by rotation of the pedal pivot, and
provide signals to the engine ECU, which then interprets driver commands allied to emission and engine
management requirements, and drives the throttle butterfly stepper motor to the appropriate position, or rate of
change of position.

Other changes to the pedal box include fabricated steel, silver painted brake and clutch pedals fitted

with alloy pedal pads.  Some markets, principally Canada, are fitted with a pedal actuated 'clutch down' switch
to inhibit engine cranking unless the clutch pedal is fully depressed.

The throttle pedal assembly may be removed by disconnecting the harness plug from the module and

releasing the three M8 bolts and nuts securing the unit to the pedal box.
-

The throttle pedal upstop is set internally within the electronic housing, with a downstop moulded into the

housing itself.

-

The brake pedal is pulled 'off' by an extension spring anchored to a bracket rivetted to the scuttle beam.

-

There is normally a gap of approximately 3mm between the brake pedal and the pedal box upstop flange

with the pedal released.  If preferred, the brake pedal can be raised slightly by adjusting the effective
length of the pushrod at its connection to the clevis, but the master cylinder must never be preloaded, i.e.
there must always be a small clearance between the pedal and upstop bracket to ensure that the master
cylinder piston is allowed fully to return and open the reservoir port.

-

After any adjustment, tighten the clevis locknut and check operation of the brake light switch.

-

The clutch pushrod uses an integral plastic clevis to connect to the pedal and control the pedal up position

as the master cylinder tops out.  A downstop buffer is provided on the pedal box flange.

Pedal box

Module to pedal

Pedal shaft mounting

box fixing

plate fixing

Throttle
pedal
electronic
module

Pedal shaft
mounting
plate

Module
connector
socket

Pedal pivot bush

Steel pedal

Pedal shaft

Alloy footpad

                pl1401mt6

 

   Lotus Service Notes                                  Section JJ

Page 24

JJ.12 - ABS THEORY OF OPERATION

The Kelsey-Hayes antilock brake system is an 'add on' type used to supplement the dual circuit, tandem

master cylinder, vacuum servo assisted brakes fitted to the Elise.  A single electro-hydraulic unit comprising a
hydraulic modulator, hydrauliic pump, microprocessor and solenoid valve bank, is mounted in the front serv-
ices compartment and plumbed into the front and rear brake circuit lines from the tandem master cylinder.

The microprocessor (ECM) receives signals from magnetic wheel speed sensors integrated into each of

the four road wheel hubs, and interprets the individual wheel acceleration, deceleration, and comparative
wheel speeds.  From this data, the ECM is able to determine if any wheel is tending to lock up, and if imminent
lock up is sensed, the microprocessor commands the relevant solenoid valves firstly to reduce pressure in that
particular brake circuit in order to restore wheel speed, and then to modulate pressure to that providing the
maximum braking force consistent with continued wheel rotation.  The system is able to monitor and independ-
ently control each of the four wheel brakes, and is referred to a 4-channel system.

In order to achieve the required pressure modulation, three basic modes are used:

-

Pressure hold;

-

Pressure reduction;

-

Pressure increase;

In order to maintain the safety provision of two entirely independent hydraulic circuits, one for the front

brakes, and one for the rear, the hydraulic elements of the control unit are doubled up, with no part of the
system shared between the two circuits.  For the pressure hold function, four isolation solenoid valves are
used, one in the hydraulic circuit for each wheel brake.  The pressure reduction function is achieved by a
separate dump solenoid valve in each of the four wheel brake circuits, and the pressure increase provided for
by a single electric motor operating two hydraulic pumps, one serving the front, and on the rear brake circuit.
Separate low pressure accumulators are used for the front and rear circuits.

Electro-Hydraulic Control Unit

The electro-hydaulic control unit comprises an alloy valve block containing the four isolation valves, four

dump valves, two hydraulic pumps and two accumulators, with the single pump motor screwed to the housing,
and with a solenoid block and ECM unit attached to the topside.  The complete assembly is flexibly mounted
via three rubber isolator bushes to a steel cradle, which is itself mounted on three rubber bobbins to the
passenger side front chassis.  The eight solenoid valves are grouped in two rows, with the valve plungers
protruding in sealed canisters from the topside of the unit where each one is surrounded by a solenoid coil.  The
isolation and dump valves share a similar construction, but the spring loaded isolation valves are normally
open, and the dump valves normally closed.

Anti-lock ECM

Valve block

Control unit
mounting cradle

ECM isolator grommet

Cradle mounting bobbin

Passenger side damper bracket

         j190