AP Racing Catalogue Issue 4

94 visit www.apracing.com for installation drawings & up to date product range details WEAR COMPENSATION & MAINTENANCE - WEAR COMPENSATION AP Racing Carbon-Carbon clutch covers are machined to suit the new carbon stack height and spring characteristics of that particular clutch. The clutch is then given its own unique serial number. NB The Carbon plates must not be switched between clutches and the mating carbon faces must be kept in their original relationship to each other. Never switch complete carbon stacks from cover to cover. The serial number, and the original combined thickness of all the carbon plates when new, called the “Stack Height”, are etched onto the cover. (See Fig 6), Each carbon plate is identified with notches to identify the intermediate plate number (Fig 2), and dots or notches to identify the drive plate number (Fig 2). - CARBON MEASUREMENTS For accuracy when measuring the carbon plates, each individual plate is measured in the centre of the worn surface in 3 positions (approx. every 120° (see Fig 7 & 8.) and the mean thickness is then calculated (The measurements can be recorded on the carbon clutch measurement sheet provided). The mean thickness from all plates is added together to obtain the “Present Stack Height” and this is subtracted from the “New Stack Height” etched on the cover (Fig 6.). The correct pressure plate should then be selected from the “Pressure plate fitment sheet” which will restore the “Wear In” to approximately its original value. Measurement of the carbon should only be made with a proper micrometer with flat anvils, not a sliding vernier or micrometer with a sharp point. NB The maximum total wear allowed on the carbon stack is indicated on the pressure plate fitment sheet. Under no circumstances should this figure be exceeded. Wear over the total allowed could cause carbon plate failure and no hub axial float. - PLATE MEASUREMENTS (Fig 6) DRIVEN PLATES (FIG 7.) INTERMEDIATE PLATES (FIG 8.) RELEASE LOADS / DIAPHRAGM SPRING All clutches have a set maximum release travel, (see clamp/release graph on page 95). Exceeding this travel will damage the diaphragm spring, and result in a decrease in clamp load and change the spring character- istics. Wear on the diaphragm spring fingers can indicate release bearing problems, misalignment, or just normal wear over an extended period. If excessive wear is present, or it is known the spring has been over stroked it is advisable to return the unit to AP Racing for fitment of new springs. Carbon clutches are very durable, but not indestructible. Although the carbon material will not be significantly harmed by extreme heat gener- ated by excessive slipping of the clutch, aluminium alloy can soften and distort. The diaphragm springs will also lose clamp load if subjected to prolonged or excessive heat. Excessive slipping is therefore best avoided. Any clutches that have been subjected to excessive heat should be returned to AP Racing for inspection. MAINTENANCE & SERVICING All clutch components should be examined frequently for signs of damage or abnormal wear. Remove dust with a brush or vacuum cleaner, and any light deposits of oil or grease with a non-oil based solvent. Heavier deposits of oil on the carbon plates are best cleaned in an ultra- sonic wash. After cleaning the carbon plates with any fluid, it is recom- mended that any remaining traces of oil or solvent be removed by baking them for an hour at 300°C minimum in a suitable oven. WARNING: NEVER USE BRAKE CLEANER TO CLEAN CARBON. A FILM OF CLEANERWILL REMAINON THE CARBONCAUSING THE CLUTCH TO SLIP ON INITIAL USE, EVEN IF THE CARBON IS BAKED. User servicing is limited to replacing the main pressure plate and hubs when required. Other replacements require the use of specialised test equipment to set up the clutch and the unit should be returned to AP Racing for reconditioning. CUSHIONING SYSTEMS (CFS & CPS) The cushioning systems available in AP Racing’s carbon clutch range, either “Cushion Flywheel” CFS or “Cushion Pressure Plate” CPS, are designed to give more clutch controllability during engagement, and is achieved by a secondary lower spring rate from precise belleville springs inserted into the flywheel or main pressure plate faces. Although the bellvilles fitted have a high temperature capability, excessive clutch temperature can result in loss of cushion, when the bellevilles collapse. If belleville height above flywheel or pressure plate falls below 75% of its original figure, it is recommended that the clutch be returned toAP Racing for reconditioning and replacement of bellevilles. The split rings in intermediate p/plate #1, or main pressure plates, are designed as bearings for the belleville springs and transfer the load into the c/c plates, if these overheat they can loose their retention and fall out when the clutch is disassembled. These can also be replaced during reconditioning. (Fig 9.) Intermediate. CARBON DRIVE FACES The wear on drive faces (backlash) between the Intermediate Plates and Clutch Cover / Basket, and between Driven Plates and Hub, should also be monitored. This is done by placing the intermediate plate into the cover/basket and using feeler (slip) gauges to measure the gap between the drive faces of the carbon plates and cover lug as shown in, (Fig 9). The drive plate can also be measured in a similar manner by placing the drive plate on to the hub and using feeler (slip) gauges to measure the gap between carbon drive slot and hub tooth, (see Fig. 10). Maximum tolerances as follows: - Clutches up to Ø115mm = 0.75mm - Clutches Above Ø115mm = 1.00mm (Fig 10.) Driven Plate. CARBON / CARBON CLUTCH - Wear Compensation & Maintenance