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Lotus Service Notes
Section QJ QJ.4 - CLUTCH ASSEMBLY The clutch assembly comprises the friction plate, clutch cover assembly (pressure plate/diaphragm spring/ cover) and release bearing. For access to the clutch assembly, the complete power unit must first be removed from the chassis (see sub-section EJ.5). To separate the transmission from the engine, see sub-section FL.5. The clutch cover is secured to the flywheel by 6 x M8 bolts and located by 3 dowels. Unless the cover is to be renewed, first match mark the cover to the flywheel before gradually loosening the 6 bolts in an even pattern, to release the clamp load without distorting the clutch cover. Finally, remove the bolts and withdraw the cover from the flywheel dowels making provision to capture the friction plate which will also be released. Inspection & Replacement 1. Clutch cover: Check the surface of the pressure plate for excessive scoring or discolouration through overheating. Check the fingers of the diaphragm spring for excessive wear at the release bearing contact surface and for even height. If the cover is accidentally dropped, the setting or balance of the assembly could be disturbed; replacement of the cover is recommended.
On re-assembly, use a universal type of centralising mandrel to position the centre plate (ensuring it is the correct way round - refer to markings) whilst the clutch cover is fitted. Apply a suitable thread locking compound to the cover fixing bolts before locating the cover on the flywheel dowels and progressively tightening the bolts in a diagonal sequence to avoid distorting the cover. Torque to 20 Nm.
2. Friction plate: Check the cush drive springs for breakage or cracking of the hub. Examine the condition of the friction material for signs of oil contamination, scorching, or any other damage. Measure the depth of material on both sides of the plate from the friction surface to the head of the rivets;
Minimum service depth = 0.3 mm.
If any of the above inspections are failed, or if addressing symptoms of clutch judder, renew the friction plate. 3. Release bearing & fork: Unclip the release bearing from the fork, and check the bearing for discernible play, noise or rough feeling, and renew if there is any doubt. Check the arm for undue wear on any of the contact surfaces and for cracks. Check the release fork pivot ball. 4. Flywheel: Check the friction surface of the flywheel for excessive scoring or discolouration through over- heating. Using a dial test indicator, measure the axial run-out at the centre of the flywheel friction surface. Maximum runout: 0.15 mm.
If necessary, renew the flywheel:
- Lock the flywheel ring gear and progressively release the eight bolts securing the flywheel to the crank- shaft and withdraw, noting the loose spacer ring between the ring gear plate and the crankshaft flange.
- If necessary, release the six bolts securing the ring gear to the front of the flywheel. When re-fitting, ensure that the ring gear plate swages face towards the flywheel. Use an appropriate alignment mandrel to ensure concentricity of the ring gear to the flywheel before tightening the 6 securing bolts to 30 Nm.
- When re-mounting the assembly to the crankshaft, ensure the spacer ring is fitted between the ring gear and crankshaft, with the dimple on the spacer locating in the crankshaft flange dowel hole.
- Ensure scrupulous cleanliness of all mating surfaces before locating the flywheel onto the crankshaft and fitting the 8 bolts to which Permabond A130 (A912E7033) has been applied to the threads.
- Progressively tighten the bolts in a diagonal sequence, locking the ring gear before finally torque tighten- ing to 65 Nm. Re-assembly Apply sparing quantities of Molybdenum Disulphide (MoS2) grease to the contact points of the release fork fingers, pivot socket, and pushrod socket. Also apply sparingly to the input shaft splines, or use the special grease provided with a new friction plate. Fit the fork through the housing aperture and grommet, locate on the pivot ball, slide the release bearing over the input shaft and clip to the release fork arms. Fit the transmission assembly to the engine (see sub-section FL.5), and refit the power unit (sub-section EJ.5). |