BPW TSB Disc Brake Service Tips
Below are a few helpful tips when working on the TSB disc brake:
1. When turning back the brake pad tappets to insert new pads do not turn the T25 adjustment screw back to far as the internal thread may jam and prevent the calliper from re-adjusting properly.
2. When removing the old worn brake pads the dowel on the front of the tappet may become wedged inside the hole in the backing plate thereby pulling the tappet out of its mount. Should this occur inspect the tappet boot for damage and if undamaged reinsert the tappet into its housing.
3. When installing the brake pads make sure to always install the inner pad first and ensure that the dowels on the tappets are correctly lined up with the holes in the rear of the pad. Then install the outer pad.
4. When installing new tappet boots and the bayonet clip fitting is locked in place, tap the clips on the face of the calliper inwards slightly to tighten the grip of the bayonet clip.
5. Always ensure that new wear plates are installed in the calliper seating before the new pads are installed.
6. Check the brake pad retention bridge for any signs of wear, replace if signs of wear are present.
7. If the calliper is removed, the cap screws that attach the calliper to the axle beam must be replaced. Never re-use the old cap screws. The correct tightening torques for the new cap screws are:
M=260Nm (250Nm – 270Nm)
8. To adjust the TSB system, park the vehicle on level ground, chock the wheels and release the brakes. Tighten up the T25 adjustment screw until the brake pads touch the disk (never over-tighten the adjustor), and then turn back until one hears three “clicks”.
9. Ensure that the sealing cap is replaced over the adjustment screw to prevent water ingress.
10. Always inspect for wear on the dowel pin and brake pad hole when inspecting/replacing brake pads. The allowable wear on the dowel pin is 2mm, measured in any direction.
The pin diameter of the dowel measures 10mm when new, hence a worn dowel pin diameter is 8mm. The allowable wear of the brake pad hole is 3mm, measured in any direction. The hole diameter of the brake pad measures 11mm when new, hence a worn hole diameter is 14mm.