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Lotus Elise / Lotus Exige. Instruction - part 46

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Lotus Service Notes

Section FJ

The clutch housing bolts to the back of the engine block and provides a dry chamber for the clutch mecha-

nism, and roller bearings for the gearbox input and output shafts. The taper roller bearing for the differential

RH output shaft is also accommodated. The gearbox main case provides ball bearings for the two shafts, and

houses gears 1 to 4 including the reverse gear pinion on its idler shaft. The end cover or casing houses 5th

and 6th gears. On the 5-speed transmission, the 5th speed gears are overhung on the ends of the input and

output shafts, but on the 6-speed, the alloy end cover contains ball bearings to support the ends of the two

extended shafts, both of which are thus supported by a total of three bearings. The housing for the ﬁnal drive

and differential is shared between the clutch housing and main case, with taper roller bearings supporting the

differential case.

6-Speed Gear Clusters

The input shaft includes integral drive pinions for 1st, 2nd and reverse gears, and carries the clutch driven

plate, the 3rd/4th synchroniser and the 5th/6th synchroniser, with the latter housed in the end cover. The output

shaft features an integral ﬁnal drive gear, spline ﬁxed 3rd/4th/5th/6th driven pinions, and carries the 1st/2nd

gear synchroniser. All forward gears are constant mesh with inertia lock type synchromesh, with reverse gear

attained by sliding a spur idler pinion into engagement with both a gear on the periphery of the 1st/2nd syn-

chroniser and a drive gear integral with the input shaft. All gears, with the exception of reverse, use a helical

tooth form for quiet running.

Sychromesh: For each gear ratio, one of the shafts has a ﬁxed gear, and meshes with a freely revolving gear

on the other shaft. To engage a particular gear, the freely revolving gear must be connected to its shaft via

the sychro hub. As an example, third gear operates as follows: Under normal road driving, when the clutch is

depressed as a precurser to a gear change, the input shaft with the third gear synchroniser are de-coupled from

the engine, but will be turning under decaying inertia, clutch windage and oil drag, from the drive pinions (which

in this condition are being driven by the output shaft). Third gear pinion on the input shaft is driven by the ﬁxed

gear on the output shaft, which itself is driven by the roadwheels. Before the outer sleeve of the synchroniser

may be slid on its axial splines to engage with the spline ring integral with third speed input shaft gear, the speeds

of the two parts must be commonised. To aid this process, a sychroniser/baulk ring is ﬁtted between the two

parts, being rotationally driven by the synchroniser, and equipped with a female conical surface to mate with a

6th gear 5th gear 4th gear 3rd gear

2nd gear 1st gear

Reverse Input shaft

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Output shaft Double cone 2nd Final drive gear

gear synchromesh

Lotus Service Notes

Section FJ

Page 4

male cone integral with the gear. Teeth on the outside of the synchro ring, over which the synchro sleeve must

slide before engaging the third gear splines, perform a baulking function described below:

When the gear lever is operated, the outer sleeve of the synchroniser is pushed towards third gear, and

pushes three spring detent plates which press the synchro ring onto the gear cone. As the input shaft train

is turning faster than third gear, the synchro ring is dragged to one end of its rotational constraint slots in the

synchroniser, in which position the internal spline teeth of the synchroniser sleeve are mis-aligned with the teeth

on the outside of the synchro ring. When further pressure is applied via the gearlever, the detent plates are

overidden, and the synchroniser sleeve splines are pressed against the ends of the sychro ring teeth, increasing

the pressure on the conical surfaces. The bevelled ends of the sleeve splines and synchro ring teeth tend to

turn the ring into alignment, but whilst a speed differential between the ring and the gear remains, the cone drag

force (caused by gear inertia) is dominant and maintains spline mis-alignment. This is the 'baulk' function.

When the speed of the input train is synchronised to that of third gear, there ceases to be a force dragging

the synchro ring to the end of its slots, such that the force at the bevelled ends of the splines is now dominant,

allowing the synchro ring to move back in its slot to align the splines and for the synchroniser sleeve to be slid

over the ring teeth towards the spline teeth on third gear. These teeth, whose position in relation to those on

the synchro ring was entirely at random when speed synchronisation occurred, are unlikely to align, but are

now freed to turn under the action of the spline end bevels, since once the synchroniser sleeve is slid over the

sychro ring teeth, there is no longer any pressure applied to the cones. The sleeve completes engagement by

sliding over the gear spline teeth to connect the synchroniser with the gear.

On 6-speed transmissions, in order to cater for the heavy demands made on the second gear synchroniser,

and provide high durability, this gear is ﬁtted with a double cone mechanism to increase the conical surface

area within a small space.

The selector mechanism cross shaft uses Teﬂon bushes to minimise friction, and a mass damper to improve

gearchange feel. A slotted interlock cage allows the selector ﬁnger to operate only one selector shaft at a time.

In order to inhibit the unintended selection of reverse gear, a spring detent mechanism is arranged to act on the

cross-shaft, in conjunction with, on 6-speed versions, a lift collar at the gearchange lever, and on 5-speeders,

a mechanism allowing selection of reverse gear only on approach from the central neutral position.

Differential

Standard cars use a conventional 'open' two bevel gear differential contained in a housing bolted to the

ﬁnal drive output gear, and supported in two taper roller bearings. Optional on some models, in conjunction

with electronic Lotus Traction Control (LTC), is a Torsen type limited slip differential (LSD) in an otherwise un-

changed transmission housing (Character 3 of 7 digit code on bar code label: 'O' = open; 'L' = LSD). The LSD

uses worm wheels to interconnect the two output shafts and uses the poor torque reversal efﬁciency of this

type of gearing to ensure that both wheels are always supplied with driving torque.

Driveshafts

An output extension shaft supported in a ball bearing mounted on the cylinder block, is used on the right

hand side to allow equal length drive shafts to be used. The driveshafts use Rzeppa type joints on their out-

board ends and plunging joints at the inboard ends to accommodate the driveshaft length variation concomitant

with suspension travel.

FJ.2 - GEARCHANGE MECHANISM

6-Speed

The gear lever is spring biased towards

the 3rd/4th gear plane, and must be moved

against light spring pressure to the left before

selecting ﬁrst or second gear, or against similar

pressure to the right before selecting 5th or

6th speed.

Engaging Reverse Gear:

With the vehicle at a

complete standstill, pause for a moment with the clutch pedal fully depressed be-

fore moving the lever to the left, raising the lift collar beneath the knob, and then further to the left over a spring

detent before ﬁnally pushing forwards to engage the gear.

LIFT

COLLAR

6-SPEED CHANGE PATTERN

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Lotus Service Notes

Section FJ

Crossgate Gearchange Cable Schematic (prior May '07)

Shift

Reverse gate lift collar

Reverse

gate Crossgate Crossgate cable

release bellcrank lever

cable Shift cable

Gear lever

ball pivot Reverse gate Abutment

stop arm block

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5-Speed

The gear lever is spring biased towards

the 3rd/4th gear plane, and must be moved

against light spring pressure to the left before

selecting ﬁrst or second gear, or against similar

pressure to the right before selecting 5th.

Engaging Reverse Gear:

With the vehicle at a

complete stand-

still, pause for a moment with the clutch

pedal fully depressed before moving the lever

against spring pressure fully to the right, and

then rearwards to engage the gear. Note that

an inhibit mechanism requires that the lever

approaches reverse gear only from the central

neutral position. Direct access from 5th gear

is blocked.

A two cable mechanism is used to connect the gearchange lever with the transmission, one cable ('shift')

to transmit the fore/aft movement of the lever, and a second ('crossgate') cable for the sideways movement.

The gearchange lever is pivotted at its base and operates the shift cable directly via a ball joint half way up the

lever. The base of the lever has an extended ball pin on the right hand side which engages with a crossgate

bellcrank lever, the other leg of which operates the crossgate cable. An inhibit mechanism prevents the gear

lever being moved into the reverse gear plane unless a collar beneath the gear knob is lifted. Prior to May '07,

the collar is connected by control cable to a pivotted stop arm sprung to an 'up' position. In this position, a stop

pin on the crossgate bellcrank lever abuts against the end of the stop arm and prevents gearlever movement

into the reverse gear plane. When the collar is lifted, the stop arm is pulled down against its spring, to clear

the stop pin and allow reverse gate selection. From May '07, lifting the collar raises a boss at the base of the

lever above a curved inhibitor block, allowing the lever full leftward movement.

5-SPEED CHANGE PATTERN

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Lotus Service Notes

Section FJ

Page 6

The front end of both inner cables are equipped with socket joints which may be clipped on and off the ball

pins provided on the gearchange mechanism. The outer cables are retained by a forked plastic block bolted

into the gearlever/handbrake mounting frame.

The gear cables are routed along the centre of the cabin ﬂoor, beneath the fuel tank bay, and loop under

the engine to an abutment bracket on the top of the transmission housing. Both cables are retained in the

abutment bracket by spring 'C' clips. The shift cable is ﬁtted on the left, and uses a bellcrank lever and ball

jointed link to connect with the transmission cross-shaft lever, in order to rotate the shaft. The cross-shaft lever

incorporates an inertia weight to smooth the gearchange action and improve feel. The crossgate cable is ﬁtted

on the right and uses a centre pivotted lever arm to impart an axial motion to the transmission cross-shaft. The

ends of both inner cables threaded into alloy eyes which are retained on the lever pins by 'R' clips.

Gearchange Cable Adjustment

Under normal circumstances, no adjustment to the gear cables should be required. If a cable is replaced

in service, it may be necessary to make minor adjustments via the threaded ball joint at the front of the cable

in order to accommodate lever movement within the shroud aperture.

Gearchange Cable Replacement

For access to the gear cables, the gear lever shroud and parking brake lever trim must be removed: Un-

screw the gear lever knob, remove the single screw each side of the shroud, and withdraw the shroud over the

gear and parking brake levers. Remove the engine bay undertray.

At the front end of the cables, unclip the inner cable ball joint sockets from the ball pins on the mechanism

levers. Release the outer cable plastic abutment block from the mounting frame. At the rear end of the cables,

remove the 'R' clips retaining the inner cable eyes to the levers, and the 'C' clips securing the outer cables to

the abutment bracket. Release the 'P' clips and cable ties as necessary to allow the cables to be withdrawn

from the car, noting the routing of the cables past the parking brake lever and wiring harness.

Reﬁt in reverse order to removal, paying particular attention to the routing through or alongside the park-

ing brake lever mounting frame.

Transmission 'R' clip 'C' clip

External Levers

Shift bellcrank lever

Crossgate cable

Crossgate

Inertia lever Shift cable

weight

Transmission

cross-shaft

housing

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