AP Racing Catalogue Issue 4

92 visit www.apracing.com for installation drawings & up to date product range details CLUTCH FUNCTIONALITY / TERMINOLOGY - PUSH:- The most popular type of diaphragm spring clutch, where the release bearing is pushed against the diaphragm spring fingers (i.e. towards the flywheel), to release the clutch. - PULL:- This type of clutch has the release bearing fulcrum inside the clutch, and requires the diaphragm spring fingers to be pulled (i.e. away from the flywheel), in order to release the clutch. Although generally more complex, in terms of release mechanism, pull types are more efficient in terms of clamp and release loads. OVERHEATING AND ABUSE Carbon / Carbon clutches are very durable, but not indestructible. The Carbon / Carbon material itself will not be harmed by the heat, which can be generated by excessive slipping of the clutch, but aluminium alloy components, which are completely satisfactory under normal conditions, can soften and fail if overheated. For particularly arduous applications, special versions can be supplied using alternative materials for covers, baskets, hubs and main pressure plates, but this will result in an increase in the weight and the cost of the unit. Please contact AP Racing for more details. RELEASE MECHANISM As the spring rate and clamp load of the clutch increases, so does the release bearing load required to release the clutch. The release bearing used should be a high quality, steel caged, radius contact, ball bearing, either 50mm (for Ø140mm and lower) or 54mm (for Ø184mm & Ø200mm). The release mechanism should be arranged so that the bearing is free of the spring fingers when the clutch is fully engaged. The release travel should be limited by means of an external stop to avoid damage to the diaphragm spring. Suitable release bearings are available from AP Racing, See page 119. CLUTCH MOUNTING The recommended method of mounting the clutch to the flywheel is with a mounting stud and K-Lock nut. Recommended tightening torque are 10Nm (7.5lb/ft) for M6 and 22Nm (16lbft) for M8 & 5/16” UNF. AP Racing offer a range of studs for mounting clutches to flywheels, See page 120. RECONDITIONING AND REPAIR User servicing is limited to replacing the main pressure plates when required. Other replacements require the use of specialised computerised test equipment to set up the clutch and the units should be returned to AP Racing to be reconditioned. service sheet), with the raised fulcrum against the diaphragm spring and the identification mark adjacent to the similar mark on one of the clutch housing lugs. NEXT, INSTALL THE CARBON PLATES IN THEIR ORIGINAL POSITIONS AS FOLLOWS: The carbon Intermediate plates are identified with notches on the outside edge (Fig. 2). The plates are not all identical, and must be installed in the correct sequence, and the correct way up. Install number 1 Intermediate plate (1 notch), next to the Main Pressure Plate with the marking facing away from the Main Pressure Plate and the highest numbered plate (this depends whether it is a 2, 3, or 4 plate), last, against the flywheel. The intermediate plates also have a paint line marked on the external edge, and this should be adjacent to the corresponding line marked on one of the lugs on the Clutch Cover. The Driven Plates are similarly numbered with dots or notches on the drive lug surfaces (Fig. 2). These must be fitted in sequence, in the same way as the Intermediates, with the number 1 Driven Plate next to the number 1 Intermediate Plate, with the marking towards the flywheel. Continue fitting the remaining Carbon Inter- mediate and Driven Plates in sequence. The Hub must be fitted prior to fitting the last Driven plate and Intermediate, with the flywheel bolt relief and the flange / web towards the flywheel (see Fig 2a). Ensure the marked Hub drive tooth is engaged with the outlined drive slots in the Carbon plates. Complete the assembly by fitting the last Intermediate and Driven Plates N.B. Carbon Clutches always have a Carbon Intermediate plate next to the flywheel. Some clutches are supplied with an installation clip fitted between the spring and clutch cover (Fig 3). This clip maintains the clutch in a par- tially released condition to assist the installation and removal of the clutch from the flywheel. It should be used whenever the clutch is installed or removed, failure to use the clip can result in the carbon plate nearest to the flywheel being trapped under the clutch cover lugs, resulting in damage to the carbon plate and other clutch components. Ensure that the bottom carbon intermediate plate is located correctly and install the clutch onto the flywheel, tighten the retaining nuts down progressively, in a diagonally opposite pattern, to the recommended torque. When the clutch is tightened down the installation clip will become loose, remove the clip before use. NB The installation clip should be retained for future clutch removal. CARBON / CARBON CLUTCH OPERATING INSTRUCTIONS - GENERAL NOTES All carbon clutches are capable of achieving a very long life. AP Racing carbon clutches are bedded during manufacture, this process continues for approximately the first 0.5 mm of wear, after which the wear rate should settle to a consistent and low level. The “Total Allowable Wear” figure quoted on the pressure plate fitment sheet gives total clutch life, provided that the clutch remains in good condition and that the axial float of the hub is maintained. This is normally the case, provided the wear is evenly distributed across all the carbon rubbing surfaces. To achieve the clutches full life potential, several interventions to compensate for wear are required. The “Wear In” of a clutch denotes the amount of incremental wear on the carbon faces that can occur before the clamp load, and hence torque capacity of the clutch, drops below its minimum specified value. Wear compensation then becomes necessary to restore the original characteristics. ASSEMBLING AND INSTALLING A PUSH TYPE CARBON / CARBON CLUTCH This is the traditional type of diaphragm spring clutch where the release bearing is pushed against the diaphragm spring fingers (towards the flywheel) to release the clutch (Fig 1.). Before installing the clutch onto the flywheel, ensure that the plates are correctly assembled into the clutch in their original positions. First install the main pressure plate into the clutch housing, (see pressure plate (Fig 2) Coloured line on plates to be adjacent to corresponding line on cover. Carbon drive plate notches to be aligned with corresponding line on hub Notched carbon intermediate plates to be fitted in correct sequence, 1 nearest to cover. Fig 1. (Fig 2a) CARBON / CARBON CLUTCH - Operating Instructions (Fig 3)