Rick
The Front and Rear Calipers are often very much neglected when carrying out a full service. These are the one component that deserves special attention especially on an older bike. This is a 20 year old bike next year.
The calipers are not of the modern radial type and therefore less efficient so even more so all the reason to perform a full service on them.
Calipers Split
Make sure you drain all the brake fluid before doings this. TOP TIP loosen all fastners whilst the caliper is still on the bike. Here you can see the build up of debris. These may never have been taken apart before.
Removing the Pistons
This may prove tricky. However once you've done them a few times it comes fairly easy. Before you start to remove any excess fluid by wrapping them in a rag and shaking and turning upside down. You won't remove all the fluid as some will still reside under the pistons. Wrap a rag over one of the calipers covering the pistons. Apply some air compression through the banjo bolt hole. You will find the larger of two move out. Place a rag over and wrapped around the remaing smaller piston then apply air though the interconnecting chamber which runs between the piston chambers, this should force the smaller out.
Checking the Condition
On looking inside I could see debris (the small back stuff) This could have been affecting the movement of the piston and explains why this piston was difficult to remove. You will see the remaining fluid. Again rag over the caliper and shake it gently to remove. On looking at the inner chamber the surfaces seem to be smooth and undamaged.
Removing the Old Seals
The Black Ring is a seal. There are 2 seals. The larger the oil seal, the smaller and dust seal. Use a tool that will not scratch or damage the inner surface. Take care and time and you will find they will 'pop' out quite easily. Then check the seals for signs of wear and tear. Doesn't matter too much as they are getting replaced. However if you see tears or nicks then check the pistons and surrounds for any sharpness. If there is then the new seals will suffer the same fate.
Cleaning
Don't short cut this as this is the action that will prolong the life of the seals plus make the while component operate efficiently. I use Motul brake cleaner, green plastic scourer, cotton tips, finger nails behind a cloth then finish with a blow though with air.
Reassembly I
You work in reverse to the way you dissasembled. Lube the inner piston chamber using Brake Fulid I use Motul 5.1 then put in the seals applying some brake oil to the seal surface face the piston. You can use fingers fitting these, pretty easy to do. Then gently insert the cleaned pistons, do not damage the uter surface. Do not forget the small o ring between the two facing fluid 'holes'. TOP TIP Fully depress the pistons at this stage, makes life easier later on.
Reassembly II
After cleaning the pad tension plate, fit this. All fasteners finger tight at this stage.
Reassembly III
Fit the two new brake pads with the pad material 'meat' facing inwards and towards each other. Don't laugh people do put it in the other way. Finish by fitting the pad retainer pin.
Reassembly IV
Fit the caliper back onto the front fork then tighten to manufacture specs. Do not over tighten. TOP TIP Try and make sure the pads are apart and pistons fully depressed before sliding over the rotor.
DO NOT FORGET TO BLEED AND PUMP THE BRAKES
Things you will need or find useful
- Rick
- February 23, 2021
- 8:31 am
- No Comments
