dcmusch

I just rebuilt the calipers and replaced the master cylinder on my 77. I'm working on bleeding the system with a vacuum bleeder. I cant get the Pistons to stay in? I can push them in but they won't stay. Is this because I still have air in the line? I thought it would improve as I got more air out of the line but it hasn't. May be a dumb question but any insight would be great.

Easy Mike

I'm lost. The brake pads will keep the pistons in. A caliper clipper helps when installing the calipers over the rotors, but isn't a necessity.

dcmusch

The calipers are installed, the pads are tight to the rotors and won't retract unless I move them manually. When I push the brake pedal they engage but don't retract. I've never done this and they were in pretty rough shape when I took them apart, is why I'm concerned. They do have the stainless sleeves though.

revitup

They won't 'retract'. They normally are in very light contact with the rotor. The light springs behind the pistons hold them there. Are they ALL tight to the rotor? If it's just one I'd say the rubber line on that caliper is collapsed internally but if it's all of them I don't think it likely all the rubber lines are bad.

Easy Mike

Yep. Corvette brake pads are in contact with the rotors at all times. They do not retract.

bazza77

can you turn the rotor at all ? ,is it hard to turn ?

the pistons don't "back away" at all , the rotor can be turned by hand and with the road wheel on ,the front rim/tyre can be turned with one finger .

dcmusch

I'll have to take another look at it. I replaced all the rubber hoses also. The fronts have a small gap and when the brake pedal is engaged they compress. I'll work through finishing bleeding the lines and see if anything changes. Its my first stab at this so I was questioning whether or not I had the seals on the pistons correctly.

jnb5101

All Gm discs "dragged" on the rotors (1/60 of a horsepower). If your front pads are not contacting the rotors, something is amiss. What do you mean "the hoses compress"? The hoses will only collapse if there is a blockage in the system that is preventing the flow of brake fluid into the pistons when the pedal is released.

dcmusch

They are in contact with the rotors, I may have been over analyzing it thinking there was supposed to be a gap between the pads and the rotors.

bazza77

What type of seal did you put in there? Was it an "O" ring type or the original style lip seal ? AND most importantly did you follow any written instructions or diagrams on how to do it..

Easy Mike

There should be no gap.

68notray

Corvette calipers have springs behind the pistons pushingles out - you saw them when you rebuilt the calipers, right? And did you have the tool to install the seals? Otherwise you probably tore them

gg521

Throw that vacuum bleeder in the trash. It is notorious for pulling air right around the bleeder threads.