Seff

I've had a myriad of problems with the front disc brakes on my 72 Cutlass. Most of the problems are caused by the outer rubber cover for the brake piston, which has either been broken, thus allowing water into the caliper and letting the piston rust (and thus the brake to bind), or by the outer rubber cover being "sucked into" the caliper, laying between the inner rubber o-ring and the piston, again making it bind and overheat.

Any good tips for installing the outer rubber cover so it doesn't do any of this?

Octania

following the piston is normal I think
breaches of the seal are bad

Replace with a rebuilt unit or rebuild yours with a kit. Silicone grease on the boot.

Seff

CSrfJbN.jpg


Shown here is what I mean when I say that the boot (as you call it) is sucked into the caliper too far. It lays between the piston and the o-ring.

mrolds69

There is something wrong there. The boot should not be between the o-ring and piston like that. You need to clean all the rust off the piston with steel wool, crocus cloth or something. Make sure the piston is not pitted. The boot should be almost flat at the end of the caliper. Could your boot seal be in backwards? As the pads wear, the seal (boot as you call it) would extend outward not inward like your pic. I realize you are in Denmark, here we would just get a new caliper. Maybe you should get a new seal kit, if your piston looks good. Like Chris said, use a little silicone grease. You also need to check to make sure your caliper bolt o-rings + pins are good, lubed, and that the caliper moves in and out smoothly.

mrolds69

BTW...1st you put the piston in and then you put the outer seal (boot) on. You can't blow out the piston with air, and then push it back in, because it would end up looking like your pic.

Seff

I agree that it's wrong, I'm just having a lot of trouble installing it right - I even tried pressing the piston all the way in, using pressurized air to push it halfway out (to make sure the boot was "out" and not "in"), but to no avail.

Piston is clean and pit-free. The boot seal has a metal backside, which I've been facing inwards, towards the caliper. I was gonna get a new seal kit in either case, since this is a DD and I need to be able to fix it during weekends, if a problem arises. caliper bolt o-rings are newly replaced and lubed with silicone. Caliper moves freely, and the piston moves "freely" too.

What I CAN say is that I've been using brake fluid as assembly lube, not silicone.


EDIT: AHA, saw your second post - that's what I've been doing wrong. I thought the lip on the piston was for the boot to ride in. I think the mystery's solved. :P

mrolds69

Right, the o-ring is the main seal, and the outer seal is just for dust and water. It might be ruined now...or not! Let us know if it works for you.

Seff

The ones I have are most certainly ruined, but still good enough to be a temporary solution - it takes a few weeks for parts to arrive from the US.

joe_padavano

This isn't physically possible.

Seff

I didn't think so either. The only things I can say for certain are:

That's what I based my statement on, anyway.