Lotus Service Notes Section QJ

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Lotus Service Notes

Section QJ

CLUTCH

SECTION QJ





Sub-Section

Page



General Description

QJ.1

3



Clutch Pedal

QJ.2

4



Hydraulic Release System

QJ.3

5



Clutch Assembly

QJ.4

9

Page 1

Upda ted 21st Februar y 2013

Friction plate

Release bearing

Fork gaiter

Fork pivot

Hose from chassis to transmission

NVH attenuator

q54

Lotus Service Notes

Page 2

Upda ted 25th Jul y 2011

Pipe run along sill

Slave cylinder

Master cylinder



To fluid reservoir



Retaining spring Release fork



Clutch cover Extension/adaptor



Clutch System General Layout



Section QJ



Lotus Service Notes

Section QJ

QJ.1 - GENERAL DESCRIPTION The Lotus Evora uses a CMS C500 cast iron flywheel bolted to the rear end of the engine crankshaft, secured with 8 bolts and located by a dowel pin. Sandwiched between the flywheel and crankshaft is a steel plate carrying the starter ring gear, and also secured to the periphery of the flywheel with 6 screws. The driving surfaces of the clutch assembly comprise the rear face of the flywheel, and a corresponding surface on a pressure plate carried by the spring diaphragm clutch cover which is bolted to the periphery of the flywheel. The driven element, constitutes a single, dry, double sided friction plate, splined to the gearbox input shaft, and sandwiched between the flywheel and pressure plate. The diaphragm spring between the clutch cover and pressure plate serves to clamp the friction plate between the pressure plate and flywheel and provide the drive connection between engine and gearbox. The gearbox input shaft, on which the friction plate is free to slide axially, is 'overhung' from the gearbox, with no spigot bearing in the rear end of the crankshaft. The hydraulic clutch release mechanism uses a master cylinder fixed to the pedal box and operated by the clutch pedal, and a slave cylinder bolted to the left hand side of the clutch housing operating a release fork pivoted on a ball pin inside the housing to apply an axial thrust to the release bearing. The release bearing surrounds the gearbox input shaft and transmits the thrust via a ball bearing race and separate distance piece to the ends of the diaphragm spring fingers. This action releases the clamping action of the spring outer rim, serving to disengage the drive. No routine adjustment of the clutch or release mechanism is required. The clutch slave cylinder is self adjusting, with the 'rest' position of the piston dependent on the thickness, or degree of wear, of the friction plate. As wear of the friction plate takes place, and its thickness is reduced, the slave cylinder piston is pushed progressively further back on the return stroke with a corresponding rise in the reservoir fluid level.

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Upda ted 25th Jul y 2011



Lotus Service Notes

Section QJ

QJ.2 - CLUTCH PEDAL The clutch pedal is fabricated from steel plate, and features synthetic 'top hat' bushes for maintenance free articulation on the steel pivot shaft, and a serrated alloy footpad. A hollow steel pivot shaft serving the brake and clutch pedals is bolted to a steel mounting plate, itself bolted to the inside of the pedal box. The clutch pedal is equipped with an overcentre assist coil spring linkage, in order to reduce the pedal effort required to maintain full disengagement. Clutch pedal travel is monitored by a potentiometer module. The potentiometer comprises of a pronged arm which rotates around the main body of the potentiometer assembly which is fixed in place to the pedal box. The potentiometer position on the pedal box is set by an integral locating pin and is retained in position with an M4 bolt tightened to 4Nm. The potentiometer arm is held in its relative position to the potentiometer by by a locating pin on the clutch pedal. Movement of clutch pedal rotates the arm relative to the position of the potentiometer. Data on clutch pedal position is used by the engine management system for:

Arm

Potentiometer Retaining bolt

- Cruise Control operation - Gearchange fuel cut off (To assist rapid smooth gearchanges - Start inhibit function on Canadian market vehicles. Please see Service Notes Section EMR for Diagnostic Trouble Codes (DTC) associated with the clutch potentiometer. Please Note: If Cruise Control is disabled without driver intervention but the service light has not been illuminated check that the potentiometer is secure to the pedal box bracket. If the assembly is secure, then as the next course of diagnostic evaluation, renew the potentiometer as a condition exists where excessive flexing of the potentiometer arm may inadvertantly disable the cruise control.

Clutch pedal pin

Locating pin q55

The master cylinder pushrod is captive in the end of the master cylinder, and uses an integral 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.

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Upda ted 25th Jul y 2011

Lotus Service Notes



Section QJ

QJ.3 - HYDRAULIC RELEASE SYSTEM Master Cylinder The clutch master cylinder is mounted on the pedal box, and is accessible with the front clamshell removed. The cylinder is not equipped with its own fluid reservoir, but instead is linked via hose to the adjacent brake fluid reservoir. From the start of production naturally aspirated vehicles were fitted with metal cylinders with a threaded outlet port. The clutch fluid outlet pipe is then screwed into cylinder using a pipe union nut. From the start of production all manual Evora S variants have been fitted with a plastic master cylinder incorporating a 'quick fit' outlet pipe connection. Fitment of the plastic master cylinder also involved modifications to the pedal box to configure the plastic cylinders mounting points. The plastic master cylinder was then fitted to naturally aspirated manual vehicles as a running change from ‘11MY VIN BHD11343 (LHD), '11MY VIN BHC11524 (RHD) and '11MY VIN BHA11528 (FEDERAL). Note: due to factors such as the pedal box mounting configuration and outlet pipe connections, metal and plastic cylinders are not interchangeable. There is no provision for any servicing of the master cylinder, and if found to be faulty, the unit should be replaced. CLUTCH MASTER CYLINDER (Plastic type shown - early metal version similar)

Upper pedal box housing

Clutch fluid inlet port Reservoir hose Outlet pipe quick fit connector

Clutch master cylinder

Push rod yoke of plastic master cylinder is made also made of a plastic material Clevis pin

Clutch pedal

Retaining nuts Spacer (if fitted)

Master cylinder gasket

Mounting bolts q64

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Upda ted 21st Februar y 2013



Lotus Service Notes

Section QJ

To replace the master cylinder To remove: 1.

Remove the front clamshell (see sub-section BV.6). and remove the RH or LH radiator upper outlet duct as requuired to gain access to the clutch master cylinder.

2.

Clean the master cylinder and surrounding area with methylated spirit. Do not use petrol or paraffin.

3.

Take all necessary precautions to guard against contamination of painted surfaces with brake fluid.

4.

Disconnect and immediately plug and cap the hose connection to the fluid reservoir, refer to illustration on previous page.

5.

Release the output pipe connection. Note: Metal master cylinders: Release the pipe union nut.

Radiator upper outlet duct removed to access Clutch master cylinder (LHD shown)

Clutch master cylinder

Brake/clutch fluid reservoir

Plastic master cylinders fitted with 'quick-fit' connectors: Gently push the output pipe into the master cylinder and push in the sprung loaded retaining clip on the end of the hose connection to release the pipe from the cylinder, see right hand illustration.

q65

Plastic clutch master cylinder outlet port

6. From inside the footwell, remove the clevis pin connecting the pushrod to the clutch pedal, refer to illustration on previous page. 7. Remove the M8 bolts (2) and M8 flanged nuts (2) securing the cylinder to the pedal box and withdraw the cylinder from the pedal box and ensure to collect any spacers if fitted as well as the cylinder to pedal box gasket, refer to illustration on previous page.

Outlet pipe

Push in 'Quick-fit' connector clip to release outlet pipe q66

To refit: Is the reverse of the removal procedure. --

Refit the pedal box fixings and torque to 28 Nm.

-

Renew the Oetiker clip securing the reservoir hose to master cylinder then refit the hose onto the master cylinder inlet port THE HOSE SHOULD BE PUSHED ONTO THE PORT DRY - DO NOT USE ANY CHEMICALS OR LUBRICANTS TO AID FITMENT AS THIS COULD CAUSE FLUID CONTAMINATION WHICH MAY RESULT IN AN INAFFECTIVE CLUTCH PEDAL.

-

Refit the clutch outlet pipe. Note: For metal master cylinders tighten the outlet pipe connection to 20 - 24 Nm. For plastic cylinders push the pipes quick fit connector back into outlet port.

-

Bleed the hydraulic system of air, using the bleed nipple provided on the slave cylinder. Page 6

Upda ted 30 th October 2012

Lotus Service Notes



Section QJ

Slave Cylinder Clutch slave cylinder

Additional heat wrap

Slave cylinder retaining bolts 12Nm

Damper bracket

Clutch hydraulic line

Damper bracket fixings to transmission M8 x20 screws (20Nm) Damper to bracket fixings M6 x 12 screws (8Nm)

Clutch actuation damper q58b

The slave cylinder is secured to the left hand side of the clutch housing by two M8 fixings into tapped holes. The cylinder is protected from radiated heat from the front catalytic converter by an aluminium heat shield, part of which may be bent back to allow improved access to the slave cylinder bleed nipple. WARNING Do not attempt to bleed the clutch hydraulic system when the catalytic converter is hot - spilled hydraulic fluid could initiate a fire. Wait until the engine and converter is cool to the touch. To replace the slave cylinder To remove: -- Remove the rear undertray (see sub-section a - introduction for details). -- From underneath the vehicle, disconnect the clutch pipe union and immediately seal the open end of the pipe and the cylinder port. -- Release the two fixing bolts and withdraw the cylinder. -- Take all necessary precautions to guard against contamination of painted surfaces with brake fluid. To refit/replace: -- Is the reversal of removal. -- Refit the the two M8 bolts securing the slave cylinder to the bell housing, torque to 12 Nm. -- Re-connect the clutch pipe union to the cylinder, torque to 15 Nm. -- Bleed the system of air, tightening the bleed nipple to 5 Nm. -- Finally, ensure that the heat shield is returned to its original shape in order adequately to protect the slave cylinder and hydraulic line. Hydraulic Pipe A 2-part rigid steel pipe is used to convey the hydraulic fluid from the master cylinder to the left hand front corner of the engine bay. The pipe is routed down the LH 'A' post to run along the outside of the chassis LH Page 7

Upda ted 30 th October 2012



Lotus Service Notes

Section QJ

main siderail, within the composite sill member, and is supported, together with other pipes and hoses in foam blocks. Another pipe is used to connect the rear end of the chassis pipe to an NVH clutch damper mounted on the transmission. A short rigid pipe then connects the damper to the slave cylinder. The clutch damper was introduced as a running change and contains a flexible diaphragm to damp out pressure pulsations in the line caused by frequencies generated by crankshaft that are isolated from rest of chassis via engine mounts etc, but when the clutch pedal depressed the frequency travels through the clutch cover, release bearing, slave cylinder and through the fluid line up to the clutch pedal. These pulsations give the symptoms of a ‘roaring’ noise and vibration which can be felt through the clutch pedal when it is depressed at high revs, typically 5000 rpm. ‘12 MY vehicles from VIN CH_10179 have been fitted with additional protective heat wrapping positioned around the clutch slave cylinder pipe to provide insulation from potential excessive engine bay temperatures. The brake fluid contained within the clutch pipe may exceed its maximum working temperature especially if the vehicle is subjected to either extreme ambient temperatures and/or regular continuous high speed driving. Vehicles subjected to these conditions have experienced difficultly in engaging or changing gear combined with other symptoms such as very little or no resistance required to depress the clutch pedal or the clutch pedal has failing to return to its original position when released, Also see Technical Service Bulletin TSB 2011/29 for further details. Clutch Bleeding Procedure WARNING Do not attempt to bleed the clutch hydraulic system when the catalytic converter is hot - spilled hydraulic fluid could initiate a fire. Wait until the engine and converter is cool to the touch. • If the clutch fluid is to be renewed, or an hydraulic component replaced, the system should be bled of air using the following procedure: • Remove the rear undertray - see service notes section an - introduction for details. • Using only a fresh supply of DOT 4 non-mineral type brake fluid, top up the brake/clutch reservoir as necessary - also see service notes section JL.3 for further information. • 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. • From underneath the engine bay, fit a suitable bleed tube and container to the slave cylinders bleed nipple then open the nipple. • Using conventional manual techniques, or low air pressure applied to the reservoir, bleed the system from slave cylinder bleed nipple in turn until no air bubbles can be seen. • Test the operation of the clutch pedal, if the pedal operation is spongy repeat the process until an acceptable pedal action is obtained. • Top up the fluid level in the reservoir (but do not overfill) then replace the filler cap securely. • Refit the undertray

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Upda ted 30 th October 2012



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. Apply a suitable thread locking compound to three of the clutch cover retaining screws, and retain the clutch cover with these three screws, tightening only by hand sufficiently to hold the centre plate in position when the mandrel is removed. On re-assembly, thoroughly degrease the friction surfaces of the flywheel and pressure plate before using a centralising mandrel to position the centre plate (ensuring it is the correct way round - refer to markings on the plate) whilst the clutch cover is located.

To ensure that the most uniform spring pressure is applied to the plate, with minimum distortion of the diaphragm fingers, it is essential that a proprietary clutch cover compressor tool is used.





Remove the centre plate mandrel, and fit the compressor tool to the flywheel using the remaining 3 fixing points for the clutch cover.



Wind in the compressor to contact the spring fingers. From this point, further tightening of the compressor will progressively reduce the gap between the clutch cover and the flywheel.



Continue compression until this gap is reduced to zero. Apply a further 2 complete turns (equivalent to 3mm axial travel) to preload the diaphragm spring before evenly tightening the three clutch cover retaining screws to a final torque of 20 Nm.

Release the compressor, and remove from the flywheel. Apply thread lock to the remaining three clutch cover screws before fitting and progressively tightening to 20 Nm. Page 9

Upda ted 25th Jul y 2011

2.

Lotus Service Notes

Section QJ

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 these inspections are failed, or if there was an issue with clutch judder, the friction plate should be renewed.

3.

Release bearing & fork: Be aware of the extension/adaptor which may or may not be retained in the release bearing. 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 condition of the release fork pivot ball.



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. Insert the spigot on the extension/adaptor into the release bearing.

4.

Flywheel: Check the friction surface of the flywheel for excessive scoring or discolouration through overheating. 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 crankshaft 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 plate 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 tightening to 65 Nm.

Re-assembly Fit the transmission assembly to the engine (see sub-section FL.5), ensuring that the extension/adaptor is correctly located in the release bearing and refit the power unit (sub-section EJ.5).

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Upda ted 25th Jul y 2011