CP4509 - 'Seal on Piston' Replacement Seal Kits

Brake calipers are a safety-critical item and AP Racing recommends that calipers be reconditioned and piston seals inspected regularly to maintain optimum performance. Where calipers have been subjected to high temperatures or have been used in adverse conditions e.g. Off Road / Rallying, the calipers should be reconditioned and seals replaced more frequently to ensure that safety and performance levels are maintained. When cleaning calipers use warm soapy water or an alcohol based cleaning fluid e.g. Methylated Spirits.

DO NOT USE PETROL, GASOLINE OR MINERAL OIL CLEANER / LUBRICATE as this will damage the seals. Replacement seal kits are available for all AP Racing brake calipers. Depending on the seal type being replaced the following recommended procedures should be followed.

1. Soak new seals in brake fluid for a minimum of 30 minutes.
   
2. Clean brake caliper with warm soapy water and dry off.
3. With the pads removed insert a brake disc or block into the centre of the caliper. Using either hydraulic pressure or compressed air carefully extend all pistons against the disc or block. Remove block and remove pistons. Keep all body parts away from escaping air and caliper pistons.
   CAUTION: Your caliper is fitted with a Glyd Ring just inside the opening of each caliper bore. This ring should be examined and replaced if caliper has been subjected to high temperatures or used in adverse conditions e.g. Off Road / Rallying or not changed for a year.
4. Carefully remove old seals with a narrow blunt edged tool.
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 replacement seal into groove in caliper body ensuring that it seats correctly in the groove. Check seals are free from damage and correctly seated in groove 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 the piston does not slide smoothly into bore remove & check seal has been fitted correctly.

Part Numbering

• Two letters after Kit indicates 4 seals - e.g. -JJ
• Bore Identification Letters:
• A - 25.40mm (1.00")
• B - 26.00mm
• C - 27.00mm (1.06")
• D - 28.60mm (1.125")
• E - 31.80mm (1.25")
• F - 34.00mm
• G - 34.90mm (1.375")
• H - 36.00mm
• J - 38.10mm (1.50")
• K - 41.30mm (1.625")
• L - 44.5mm (1.75")
• M - 47.60mm (1.875")
• N - 50.80mm (2.00")