AP Racing Catalogue Issue 4

visit www.apracing.com for installation drawings & up to date product range details 25 BRAKE CALIPERS - Replacement Caliper Seals CP4525&CP4527 (BOOT TYPEWITHDIRT SEAL) Removal: Before removal procedure begins the brake caliper should be thoroughly cleaned using warm soapy water only. Ensure that all hydraulic ports are sealed before cleaning and dry caliper thoroughly before work begins. Do not use chemical cleaners of any kind or petrol/gasoline or miner- al oil based, as these will cause permanent damage to the new seals. 1) Use a reaction block selected to fill the full width of the caliper pathway as shown in fig.1. This block must span the length of the caliper opening and be well supported between the brake pad abutments at either end of the caliper. 2) Loosely insert a hydraulic fitting (M10x1.0) into the caliper feed port as shown in fig.2 (a spare Bleed Screw loosely fitted will suffice). Do not tighten to form a seal. 3) Press a hand held air gun against the fitting as shown in fig.3 and allow a short, high pressure burst of air to enter the caliper (a perfect seal between the air gun and fitting is neither necessary or advisable). Keep all body parts away from escaping air and caliper pistons. 4) A single burst of air should be sufficient to extend all pistons at once as shown in fig.4. If one or more pistons remain jammed in the caliper body after repeating this step then the caliper may need to be returned to AP Racing for assessment. Please contact AP Racing Technical for assistance. 5) Remove reaction block. It is possible that the dirt seals may become de- tached from the caliper body at this point. If so the pistons can be carefully pulled from the caliper body with dirt seals attached. It is also possible that the dirt seal may become detached from the piston in which case the piston should be pulled through the dirt seal to remove. Where dirt seal remains attached to both piston and caliper body a small blunt instrument (such as a rounded off screwdriver, see fig.10) should be used to carefully release the dirt seal from the piston, as shown in fig.5. 6) Fig.6 shows pistons removed with dirt seals remaining attached to caliper body. 7) The dirt seal can now be removed by carefully inserting a narrow, blunt blade (such as a medium sized screwdriver) through the seal opening and between the outer ring of the seal and the back wall of the dirt seal recess as shown in fig.7. By gently turning the screwdriver the seal should work free. Only very light force is required to perform this operation. Never use excessive force as damage to caliper body may result. 8) Once dirt seal is removed the pressure seal will be exposed, located in the groove in the caliper body as shown in fig.8. 9) Using the small blunt instrument from step 5 (see fig.10), carefully remove the pressure seal from the caliper body as shown in fig.9. 10) All dirt and pressure seals should be removed from the caliper by fol- lowing the above procedure. Before new seals are fitted all pistons and the caliper body should be inspected for damage. If damage of any kind is present on either the caliper bores or piston outer diameters the caliper should be considered unfit for use and either replaced of returned to AP Racing for assessment. If in doubt regarding any aspect of caliper safety please contact AP Racing Technical for assistance. Refitting: 11) Before re-assembly ensure that all parts are perfectly clean and free from debris or moisture. Replacement pressure seals should be soaked in APRacing brake fluid for 30minutes prior to fitment. Do not remove excess brake fluid as the excess will aid fitment of pistons. Do not soak dirt seals. 12) Carefully fit pressure seal into groove in caliper body ensuring that it seats correctly in the groove. Seal should be free from damage and not be twisted or kinked. Pre-assemble dirt seal on piston (seal locates in groove on piston end). Carefully slide piston into caliper bore (pressure seal must already have been installed as shown in fig.11. Only light pressure applied by hand is required. If piston does not slide easily into place, remove and inspect parts. If difficulty is experienced when installing pistons please contact AP Racing Technical for assistance. 13) The dirt seals can now be pressed into caliper body. Carefully locate seal in caliper body using finger pressure only. Then select a suitable rigid, flat bar or similar as shown in fig.12. and position to cover dirt seal. fig 1. fig 2. fig 3. fig 4. ORDERING To determine the correct seal kit proceed as follows:- 1) If you know the part number of your caliper then determine the correct part number of the kit required by referring to the individual caliper listings. 2) If you do not know the part number of your caliper then proceed as follows:- a) measure the nominal piston diameters. b) determine the type by comparison with the drawings on pages 24/25. c) Look at the column (caliper bore in mm) identify your sizes. The relevant kit number can be found on the right. d) When ordering please quote the seal kit part no, given from the relevant table, then contact your nearest AP Racing stockist for availability. 3) Each kit contains seals to repair one caliper:- a) One letter after Kit Nos = 2 seals, e.g. -J b) Two letters after Kit Nos= 4 seals, e.g. -JJ c) Three letters after Kit Nos = 6 seals, e.g. -CEJ d) Four letters after kit Nos = 8 seals, e.g. -AEAE NB. Kits are priced more competitively compared to purchasing individual seals. NB . With CP4519, CP4525 and CP4527 seal kits, the appropriate number of dirt seals and or boot seals are also included. NB . Kits contain one caliper set of seals e.g. 2, 4, 6, or 8. 14) Apply slow and even pressure to dirt seal using bar as shown in fig.13. Care must be taken to ensure that dirt seal is inserted square to the caliper body. 15) On correct installation the dirt seal should sit flush with the caliper body as shown in fig.14. Repeat steps 12 to 15 to fit all remaining pistons and seals. Once calipers are refitted to vehicle a pressure test should be carried out to check for leaks. With the engine running press the brake pedal and hold at a constant load for 60 seconds. No ‘sinking’ of the brake pedal should occur. If the pedal does ‘sink’ (travel further when under con- stant/steady load) it should be considered that a leak in the brake system is present. If a leak is suspected check all hydraulic joints and inspect re-conditioned calipers. If cause of leak cannot be identified contact AP Racing Technical for assistance before vehicle is used. The repair kit may also contain 2 off small ‘O’Rings for replacement of Bleed Screw seals where fitted. There may also be replacement Bleed Screw dust caps included. Where included these parts should be fitted to the brake caliper. Replacement seal kit details for all piston configurations used in AP Racing brake calipers “seal in bore”, “seal on piston” and “seal in bore with dirt seals” are given in the table on page 26. fig 5. fig 6. fig 7. fig 8. fig 9. fig 10. fig 11. fig 12. fig 13. fig 14. CP4519 (SEAL INBOREWITHDIRT SEAL) CON’T. 5) Ensure that caliper bores, seal grooves and pistons are clean and free from debris and moisture. Use only Alcohol based cleaning fluid, not Mineral oil. 6) Carefully fit both replacement seals into groove in caliper body ensuring that they seat correctly in the grooves. Check seals are free from damage and correctly seated in grooves not twisted or kinked. 7) Carefully engage piston into caliper bore and using a suitable rigid flat bar to apply even pressure, push pistons fully into body. N.B. Excessive force should not be necessary. If piston does not slide smoothly into bore remove & check seals has been fitted correctly.