- Front Brake Caliper page 2 of 3
The grooved wiper seal being removed from under the retainer ring.
Retainer ring might need a slight knock to pull it out.
New seal kits from http://www.bgdevelopments.co.uk/ they also supplied me with brake pads.
These comprise 2 sizes in each kit to suit the 2 sized pistons, they differ by only a couple of mm in diameter, so be careful to use the right ones. There were 2off each small seals left over in the kits that I got, the metal retainer rings were seperate from the rubber seals. Use a light coating of red rubber grease for fitting of all parts, this will ensure easy assembly of the piston and prevent seal damage.
New custom stainless steel pistons available from Ned Kelly mailto:nedler@ntlworld.com
The grooved wiper seal should be fitted inside the retainer ring before being pressed into the caliper. I used a G clamp with 2 pieces of flat metal to press the retainer ring into position. The retainer rings have serrated edges which grip the inner top edge of the caliper bore. They must be pressed in so that they finish completely flush with the inner caliper faces. Sometimes the ring does not press home squarely to start with, but will straighten up. Be very careful because you don't get spares of the retainer rings !! Fitting of the main seal can be done before or after the wiper seal and retainer ring.
For one of the retainer rings I had to use a tube which fitted over the brake pipe boss to give a flat surface to clamp to.
Next locate the small end of the springs onto the piston spigot and press into the caliper, again be sure to use a light coating of red rubber grease on the pistons. It is very important that the piston sits all the way into the bore, it must not be proud of the inner caliper face, not even 1/2 mm or when fitting the new pads with new discs, the pads will bind. If the piston will not sit flush, it will be because the spring which is designed to coil flat within itself, is not doing so because 1 or more of the coils is overlapping, remove and check the fit on the piston spigot.