AlabamaIceMan

i got a 89 formula.......... my front brakes are locking up and not releasing i done replaced front calipers my brake peddal is real hard ...i checked my booster and vacum lines to the booster are connected and no air is leaking from it ....also my right front rotor is real thin gonna replace that too does anyone have any other ideas what it can be???.... not sure if that valve under my master cylinder could be bad?? think it is a anti lock valve of some sort...but thanks for the help......

volkerc

most of the time it is always a stuck piston in the calipers.are both sides locking up or just one?

AlabamaIceMan

it started out being both side and i lossend the alimite and let it free and then tightend it back up then i checked the left side and it was stuck so i tryed the same thing and it didnt work . i replaced the right caliper and still locking up...i just got my rotor in a few minutes ago.. could my rotor being wore down to much cause it to lock up?? when i mash the brakes it feels hard and the car wont stop at all..(tryed when i freed the front brakes but as soon as they grabbed it wouldnt let loose)

volkerc

ok, not sure what you mean by "lossend the alimite", but if both sides are affected then it is probably not in the calipers, even though new calipers could be stuck also.i don't think your rotor has anything to do with it. your piston would have to travel so far out that it gets stuck again and won't go back. that would mean that your brake pads are completely gone, and you rotor also, but i guess you have good brake pads. Now I had a similar problem on my 79. I drove through deep water a few times, thanks to the rainfall in Florida, that would cause water coming between the piston and the caliper, which in turn made the piston build up some rust which then made the piston stick.When you say your brakes are locking up, I assume that you can't drive the car, and the wheel will not turn at all, ...
See if there is a rubber cover on the side of the proportioning valve below your master cylinder, if so press it in while somebody else is pumping the brake this might get the valve unstuck ,just in case it is the proportioning valve...

AlabamaIceMan

sorry bout the type-hold...lol i ment loosening the alimites (where you bleed the brakes at) i didnt know what that valve was called but it is really expensive. not sure it has a rubber piece on the side of it.. but ill loook and see what i find. my cousin has a few firebirds at his junk yard if that is the problem but my master cylinder wont be in till like tuesday..thanks for your help man. ill let ya know if that stuff helps....

volkerc

The master cylinder won't be the problem if you ask me, you can check by taking it off, in case you want to replace it anyways, on the back of the master, the inner piston is held by a ring, just remove it, and you can slide the piston out, pull it out carefully, if it moves freely, than it ain't the master, just think of the master as a rod that pushes the fluid..that is all it does, and if they go bad, all they do is leak out the fluid(most of the time) ...

AlabamaIceMan

Aight ill check that too but i already ordered a new master cylinder so i reakcon ill just change it too im really starting to think about that being the valve..

volkerc

I'd still go with the calipers, if the piston is just a little off, that what causes it, then I'd go for the proportioning valve,chances are if you bled your brakes and did not push on the side of the valve it might be off center...anyways, good luck!

AlabamaIceMan

thanks man i try to bleed them one more time when i put my master on