Lotus 2004 ELISE Service Notes page 182

Lotus Service Notes
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.
Page 4
LIFT
COLLAR
6-SPEED CHANGE PATTERN
Section FJ
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