What to do about ancient brake callipers?

[martinclan56]

Robin , it is recommended not to split the 2 halves of the Calliper although the Bid Redd Kit does include those seals also. I got my pistons out without splitting them.

The way I got the pistons out is as follows: Find a 3/8" Unf bolt and a ball bearing e.g. from a cycle hub. Remove all the rubber dust boots from around the pistons Using a syringe or small funnel , fill through the brake nipple hole and brake pipe holes with water, replace the nipple and place the ball bearing down the hole where the pipe went and lighly tighten the bolt onto it.

Get a strong G clamp and compress each piston in turn so they are rocking in and the other out a bit. It will take 5-8 goes at that. If they won't move . Place on the gas hob and heat up with the G clamp on one of them and you will hear the pistons creak as they start to move. When it gets hot enough the water will boil and force the piston out.
Wear Goggles and have an old coat on so you don't get scalded if the piston flies out.

The reason I recommend using water is that the pistons can fly out suddenly and spray your kitchen with fluid . At least water won't damage like brake fluid . The second piston if it was moveable can be blown out with 115psi using your air compressor.

That sounds like a good trick. I managed to "blow" one piston partially out using compressed air. The other refused to move. So I should be able to fill the caliper with water and use a G Clamp on the piston that moved to loosen the other.

Cheers, Robin

[Ye Ol Ripper]

Hi Robin
I previously forgot to mention using GT85 with the straw to run , that fluid contains some ptfe around the diameter of the pistons to help free them off prior to "rocking them"with the G clamp and heating up.

[martinclan56]

Thanks for the advice. The "filling up with water" trick worked. See my rebuild diary.