CLUTCH SECTION QR Sub-Section Page General Description QR.1 3 Clutch Pedal QR.2 4 Hydraulic Release System QR.3 5 Clutch Assembly QR.4 10 Clutch Potentiometer QR.5 15 Updated 9 th January 2017 Page 1
Clutch System General Layout Friction plate Clutch cover Extension/adaptor Release bearing Retaining spring Release fork NVH Damper Fork pivot Fork gaiter (if fitted) To fluid reservoir Clutch Master cylinder Slave cylinder Hose from chassis to transmission Pipe routing along sill q80 Page 2
QR.1 - GENERAL DESCRIPTION The Lotus Evora uses a cast iron flywheel bolted to the rear end of the engine crankshaft, secured with 8 bolts. Fitted between the flywheel and crankshaft is a steel plate carrying the starter ring gear also secured to the periphery of the flywheel with 6 bolts. 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 fitted between the flywheel and pressure plate. The diaphragm spring between the clutch cover and pressure plate clamps 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 adaptor/distance piece to the ends of the diaphragm spring fingers. This action releases the clamping action of the spring outer rim 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. Updated 9 th January 2017 Page 3
QR.2 - CLUTCH PEDAL M A. Pedal housing B. Pedal pivot shaft C. Shaft retaining screws D. Over centre spring retaining nuts E. Over centre spring re- B taining washers F. Pivot shaft bearings C G. Over-centre spring E D H. Over centre spring re- G taining screws I. Clutch pedal assembly D E J. Clutch/Brake pedal pads K. Clutch potentiometer L. Potentiometer retaining screw K M. Clutch pedal downstop pad N. Clutch master cylinder O. Clutch master cylinder clevis pin P. Clevis pin retention clip Q. Master cylinder spacer R. Master cylinder gasket J A F H I L R O Q P N The clutch pedal is fabricated from steel plate and fitted with a separate alloy foot pad. Synthetic bushes are used for maintenance free articulation on a steel pivot shaft which is bolted to a steel mounting plate, which is bolted to the inside of the pedal box. The clutch pedal is fitted with an overcentre assist coil spring linkage in order to reduce the pedal effort required to maintain full disengagement. Pedal travel is monitored by a potentiometer module, refer to sub-section QR.5 for further information. 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. Page 4
QR.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 brake fluid reservoir. The master cylinder incorporating a 'quick fit' outlet pipe connection. There is no provision for any servicing of the master cylinder and if found to be faulty, the unit should be replaced. Reservoir hose Reservoir hose retaining clip Clutch fluid inlet port Outlet pipe quick fit connector Clutch master cylinder Upper pedal box housing Clevis pin Retaining nuts Spacer (if fitted) Master cylinder replacement Master cylinder gasket Mounting bolts Removal: 1. Remove the front clamshell (see service notes section BD.6). and remove the RH or LH radiator upper outlet duct as required 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. Release the clip securing the reservoir hose to the clutch fluid inlet port. 5. Disconnect and immediately plug and cap the hose connection from the fluid reservoir hose. Retention clip Clutch pedal Radiator upper outlet duct removed to access Clutch master cylinder (LHD shown) Brake/clutch fluid reservoir Clutch master cylinder q65 Page 5
6. 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 'quick-fit' connector, see right hand illustration. Master cylinder outlet port 7. From inside the footwell, remove the clevis pin connecting the pushrod to the clutch pedal. 8. 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. Refitment: Is the reverse of the removal procedure. Outlet pipe Push in 'Quick-fit' connector clip to release outlet pipe q66 -- 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 CHEMI- CALS OR LUBRICANTS TO AID FITMENT AS THIS COULD CAUSE FLUID CONTAMINATION WHICH MAY RESULT IN AN INEFFECTIVE CLUTCH PEDAL. - Push the fluid outlet pipes quick fit connector into clutch master cylinder outlet port. - Bleed the hydraulic system of air, using the bleed nipple provided on the slave cylinder. Reservoir to clutch master cylinder hose The specification and diameter of the individual hoses supplying fluid to both the brake and clutch master cylinders is identical. The individual hoses are cut to the required length at the time of production and similarly are supplied in 1 metre lengths as a service replacement item requiring them to be cut to length prior to fitment. Reservoir hose layout - LHD Vehicles Item Description Length A. Reservoir to clutch 525mm master cylinder hose Clutch master cylinder A Brake fluid reservoir Reservoir hose layout - RHD Vehicles Item Description Length B. Reservoir to clutch master cylinder hose 256mm Brake fluid reservoir B Brake master cylinder hoses (refer to service notes section JP.8) Clutch master cylinder Page 6
Slave Cylinder Slave cylinder retaining bolts 12Nm Clutch slave cylinder Clutch fork Damper bracket fixings to transmission screws (20Nm) Damper bracket Damper to cylinder fluid pipe Clutch hydraulic line Damper to bracket fixings M6 x 12 screws (8Nm) Clutch damper q77 The slave cylinder is secured to the left hand side of the clutch housing by two M8 bolts. 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. Removal: 1. Remove the rear undertray (see service notes section AA.3 for further information). 2. From underneath the vehicle, disconnect the damper to cylinder fluid pipe (at the cylinder union) and immediately seal the open end of the pipe and the cylinder port. 2. 3. Release the two fixing bolts and mounting bracket and withdraw the cylinder from the end of the clutch fork and clutch housing. D. 4. Take all necessary precautions to guard against contamination of painted surfaces with brake fluid. To refit/replace: 3. -- Is the reversal of removal. A. Position the cylinder into place ensuring the cylinder A. push rod spherical end is seated into the concaved section at the end of the clutch fork. B. Refit the two M8 bolts securing the slave cylinder to the bell housing, torque to 12 Nm. C. Re-connect the clutch pipe union to the cylinder, torque to 15 Nm. D. Bleed the system of air, tightening the bleed nipple to 5 Nm, refer to clutch bleeding procedure on following pages for further information. E. Finally, ensure that the heat shield is returned to its original shape in order adequately to protect the slave cylinder and hydraulic line. Page 7
Hydraulic Pipe Circuit Pipe 'E' Pipe 'A' Damper 'D' Hose 'C' Pipe 'B' 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. From the outlet port of the clutch master cylinder, the outlet pipe (A) is routed down to the LH wheelarch area where it is connected to the bodyside pipe (B) which is fitted within the front support foam and routed along the outside of the chassis LH main siderail, behind the composite bodyside panel and supported, together with other pipes and hoses in foam blocks. The rear end of the bodyside pipe is secured and supported by a bracket which is fixed to the outer side of the LH chassis siderail. A flexible hose (C) connects the rear end of the bodyside pipe to an NVH clutch damper (D) mounted onto the transmission casing. A short rigid pipe (E) then connects the damper to the slave cylinder. The clutch damper contains a flexible diaphragm to damp out pressure pulsations in the fluid line caused by frequencies generated by the crankshaft which are normally isolated from rest of chassis via the engine mounts etc, but when the clutch pedal is depressed the frequency can travel through the clutch cover, release bearing, slave cylinder and through the fluid line back 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 at 5000 rpm. The end section of the clutch damper to slave cylinder pipe is fitted with additional protective heat wrapping 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. Heat wrap insulation If renewing the pipe ensure to transfer over the heat wrapping from the original pipe to the replacement pipe, or renew the heat wrapping as required. Page 8
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: 1. Remove the rear undertray (see service notes section AA.3 for further information). 2. 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 JP.3 for further information. 3. If the reservoir requires 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. 4. From underneath the engine bay, fit a suitable bleed tube and container to the slave cylinders bleed nipple then open the nipple. 5. 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. 6. Test the operation of the clutch pedal, if the pedal operation is spongy repeat the process until an acceptable pedal action is obtained. 7. Top up the fluid level in the reservoir (but do not overfill) then replace the filler cap securely. 8. Refit the undertray Page 9
QR.4 - CLUTCH ASSEMBLY The clutch assembly comprises: A. Friction plate (centre plate). B. Clutch cover assembly (pressure plate/ diaphragm spring/cover). C. Bearing adaptor. D. Release bearing. 5 2 A B 1 4 TRANSMISSION SIDE D C 6 3 Clutch cover bolt loosening sequence For access to the clutch assembly, the complete power unit must first be removed from the vehicle and the transmission and engine assembly separated (see service notes sections EP.5 & FR.5. for further information. Clutch Removal: 1. Unless the cover is to be renewed, first match mark the cover in relation to the flywheel prior to removal. 2. Progressively loosen the M8 x 16 bolts (6) in the sequence as shown, to release the clamp load without distorting the clutch cover. 3. Remove the bolts and withdraw the cover from the flywheel dowels and prepare to capture the friction plate which will also be released. Inspection: 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. 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. The 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. 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. 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. The maximum runout is 0.15 mm. If necessary, renew the flywheel. Page 10
Lotus Service Notes Section QR 5 7 1 4 Spacer ring 3 2 Ring gear 8 6 Flywheel bolt loosening & tightening sequence Ring gear to flywheel retaining bolts Flywheel removal: 1.Using a suitable flywheel holding tool, lock the flywheel ring gear against the engine casing. 2.Progressively loosen the eight bolts securing the flywheel to the crankshaft in the sequence as shown 3.Remove the bolts and withdraw the flywheel and prepare to capture the spacer ring fitted between the ring gear plate and the crankshaft flange. Ring gear removal: 1.Progressively loosen and remove the 6 bolts securing the ring gear to the flywheel. 2.Separate the ring gear from the flywheel. Ring gear refitment: -- Ensure scrupulous cleanliness of the ring gear to flywheel contact surfaces before locating the ring gear against the flywheel. Ensure that the ring gear plate swages face towards the flywheel. -- Fit the ring gear to the rear side of the flywheel. -- Use a suitable alignment tool to ensure the ring gear and flywheel are aligned/concentric before tightening the 6 securing bolts to 30 Nm. Flywheel/ring gear refitment: -- Ensure scrupulous cleanliness of the ring gear to crankshaft contact surfaces before locating the flywheel/ ring gear assembly onto the crankshaft flange. Permabond application -- Fit the assembly to the crankshaft, ensuring 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. -- Apply a single bead of Permabond A130 along the length of the threads of each of the 8 the flywheel retaining bolts. Page 11 Upda ted 9 th Januar y 2017
Lotus Service Notes Section QR Important: The drillings for the flywheel retaining bolt threads pass completely through the crankshaft flywheel mounting flange. It is possible that under running conditions, oil within the engine may travel between the flywheel retaining bolt and flywheel mounting flange threads. Therefore Permabond A130 should be utilised as both a thread lock and sealant to prevent the potential of oil leaking from the engine and onto the flywheel and clutch assembly. -- Refit the bolts and progressively tighten the bolts in a diagonal sequence, locking the ring gear before finally torque tightening to 75 Nm. Clutch Refitment: MISS AN S TR ION SIDE Preparation: On re-assembly, using a suitable automotive clutch and brake cleaner, thoroughly degrease the friction surfaces of the flywheel and pressure plate. ION SIDE 1. Friction plate orientation N TRA SMISS 1.Place the friction plate the correct way against the flywheel (identified by the 'TRANSMISSION SIDE' text on the plate). 2.Use a suitable* alignment tool to position the friction plate centrally to the flywheel. *The alignment tool used must not protrude further than the clutch cover spring fingers. This will ensure that the clutch cover compression tool, (see step 6) will fully compress the clutch cover against the flywheel. 2. 3. Using an alignment tool which is too long potentially risks the pressure pad of the compression tool contacting the end of the alignment tool before the clutch cover has made full contact with the flywheel. End of alignment tool not to protrude further than clutch cover spring fingers 3.Fit the clutch cover, positioning it to align the 3 locating dowels on the flywheel with the corresponding holes on the cover. 4.& 5. 4.Apply Permabond A130 thread locking compound to three of the clutch cover retaining bolts. 5.Fit the 3 bolts (by hand only sufficiently to hold the centre plate in position when the alignment tool is removed) to every other retaining hole in the cover to the flywheel, this will retain the cover at 3 equal points. Page 12 Upda ted 9 th Januar y 2017
Lotus Service Notes Section QR 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 such as Lotus tool part number T000T1524F. 6.Fit the compressor tool to the flywheel using the remaining 3 fixing points for the clutch cover. 6. 9. & 10. 7.Wind in the spindle of the compressor tool until the spindle pressure pad contacts the spring fingers. 8.Tighten the spindle further to progressively reduce the gap between the clutch cover and the flywheel. 9. Continue compression until this gap is reduced to zero. 7. 7. 10.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. 8. & 10. 9. 11. Unwind the spindle of the compressor tool and then remove the tool from the flywheel. 12. & 13. 12.Apply Permabond A130 thread locking compound to the remaining three clutch cover bolts. 13.Fit the bolts and progressively tightening to 20 Nm. 14.Remove the clutch alignment tool 14. Page 13
Release bearing and adaptor: 15. Ensure that the release bearing is correctly fitted to the release fork by ensuring that the notch in the rear of the bearing is inset of the release fork. 16. Prior to fitment of the clutch fork and release bearing, apply a small amount of Renolit LX EP 2 grease to the forks support peg recess. 17. Apply a small amount of Renolit LX EP 2 grease to the gearbox input shaft collar. Bearing retaining clip located into notch 15. 16. 18. From inside the gearbox bell housing, engage the release bearing around the input shaft collar whilst feeding the opposite end of the fork through the release fork gaiter. q62 19. Align the clutch fork recess against the support peg, then push the fork firmly to fully engage the fork on the support peg. 20. Apply a small amount of suitable automotive multipurpose high temperature grease (such as Castrol multipurpose high temperature grease formerly named LMX) over the forward most 10 mm of the splined area of the gearbox input shaft. 17. 18. 19. 21. Remove any excess grease that has built up on the chamfer on the input shaft which could contaminate the clutch assembly causing a source of potential clutch judder. 22. Ensure the bearing adaptor is located positively against the clutch release bearing. 22. 20. q61 Transmission refitment: Fit the transmission assembly to the engine, refer to service note section FR.5 for further information. f163 Updated 9 th January 2017 Page 14
QR.5 - CLUTCH POTENTIOMETER 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 bodies relative position on the pedal box is set by an integral locating pin which slots into an aperture on the pedal box mounting bracket and is further retained in position with an M4 bolt tightened to 4Nm. The potentiometer arm is held in its relative position to the potentiometer body by a locating pin on the clutch pedal. Movement of clutch pedal rotates the arm relative to the position of the potentiometer. Clutch pedal pin Locating pin Arm Data on clutch pedal position is used by the engine management system for: - Cruise Control operation. - Gearchange fuel cut off (to assist rapid smooth gearchanges). - Start inhibit function on Federal market vehicles from start of production and introduced as a running change for other markets for vehicles built from June 2016 onwards. Retaining bolt Potentiometer q75 Refer to Service Notes Section EMD 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 inadvertently disable the cruise control. Page 15