My brake pistons are rusted in, please help
 

Okay, first of all I have an 88 Turbo II with the stock brakes.

So today I took the wheels off to change the brake pads. I started on the driver's side front brake. I disconnected the pad springs and removed the caliper pins and then I squeezed the two outermost pistons back into the housings and removed the brake pad no problem. So I try to do the same thing with the innermost pistons and they won't budge. I took off the dust boot and found them to be completely rusted. They are rusted fast to the piston housing and won't move.

Anyway, I was wondering if I can simply spray it with something to eat through the rust overnight. I know it is not rusted past the piston seal so would the piston seal keep the brake fluid from being contaminated by the rust remover? If the pistons are rusted past the piston seal do I need new pistons? Do I need new calipers maybe?

Thanks in advance. I wish the previous owner would have looked at his brakes once in awhile...

$36 + core per caliper, easier to just replace them.

where can I get calipers from?

Chances are the pistons are rusted inside the caliper bores from condensation. Best thing to do is rebuild the calipers...Both front- kit is probably @ $25/30 total. That is if you can do the job yourself. You can get the piostons out by blocking the outside pistons with wood, the step on the brake pedal to force the inners out. Put some wood in front to allow them to move out a slight bit at a time. You don't want to "blow" them out. I, preferred method, remove the calipers and use compressed air to remove the pistons. Clean up pistons and bores with crocus cloth. If bores are nicked, etched by rust, buy rebuit units from a local parts store, or used ones. Any "rust" cutter would not penetrate past the "O" ring, and that is where the rust is.

Try local parts store e.g. Pep Boys, Auto Zone, Advanced Auto. Give 'em a call.

I agree with turbonut, but it's suggested to do it with the compressed air. you can by a nozel (sp?) with a nipple on the end and attach it to an air compressor and blow those babies out! Figuratively speaking though, if the innermost pistons didn't move, then you wouldn't have to change the inner most pads, would you? ;)

Hah, i had one piston stuck on each side, talk about a weird shaped brake pad! I'm replacing them, rebuilding those rusted things is outta the question.

I just bought a caliper for $50 + core charge. Thanks for the help.

those pads were a bitch to get out too. I thought changing the pads was going to take me 20 minutes. Took me 3 and a half hours and I still only got one brake done... d'oh. I'll have the brake caliper on friday though. Comes with everything but the pads... I already have the pads.

Yeah, I had an unpleasant experience changing brakes... thought I could push the piston back in with a steel forged C-clamp... When really all I had to do was screw the piston back in... bent the clamp....

Heh, I love knowing everyone at the autoparts store, they give me a discount & don't charge me the core, I got em at $36 a pop.

Funny, the local place here wants 160$ canadian / each + core. :mad:

swap caliper and pad in rear = 15 minutes

It probably wouldn't have taken me so long but I couldn't figure out what the hell the problem was. At first I just thought that maybe I wasn't pushing them in hard enough and I did use a C clamp (didn't bend it thankfully). Still no go. Then I thought maybe from compressing the first set of pistons there was too much pressure in the brake lines so I opened up the brake fluid resavior and drained some brake fluid. Tried it again, still nothing. Then I decided to give the other side a try (I had left it alone so that if I couldn't remember how the pad pins went in I could just look at the other one). All 4 pistons went in fine and then I knew I was screwed. Removed the dust boot and it was rusted right to the housing. It was not the 20 min job that I was expecting...

do NOT just break them loose. If they're rusted in, you should definitely just get rebuilt calipers, they're not that expensive and you don't want to screw with brakes.

Just a helpful hint-----Check the rears also. If you have a problem with the fronts, who knows after all the years, if the previous owner has done anything to the rear brakes. Just remember, the rear pistons TURN in. They are not "pushed" in.

in the past when I have used the C-clamp to loosen a frozen or rusted caliper when the new bads get worn to that same point you might have the same problem. That spot on the caliper gets scored and once it hits that spot again it freezes. Best to just replace the caliper.

I am going to check the rears but the car has to remain on jack stands untill I can put the wheels back on. And I won't put the wheels back on untill tomorrow when I get the new caliper.

I broke to c clamps trying to move my frozen calipers. Not fun...not fun at all.

That's why it's easier, and worth it just to get rebuilt ones already, nice and cheap at local auto stores.

get real ones.. matter of fact, if you've got a lot of miles and are doing the whole braking system, you SHOULD probably just get rebuilt calipers to begin with.. not to mention they'll be nice and shiny.. mmmm...

opening the resevoir doesn't relieve any pressure. That crappy plastic cap couldn't hold 2 psi. When you force the pistons in, it just pushes the fluid back into the resevoir. The only thing you have to worry about is making the resevoir overflow (like if you change all 4 at once). That Brake fluid works wonders taking off paint. Luckily it's water soluble so you can just douse the area with water.
Oh yeah, pump the brakes before you start moving! otherwise you'll get a pleasant brake pedal to floor feeling the first time you try to stop :).

I got the caliper that autozone ordered me and it was a single piston caliper. I told them I don't need it and got my money back and then went through the ordering process with them again and the guy told me they don't carry and cannot order a 4 piston caliper. Where else can I find them?

I've got the same problem, one piston on each caliper is rusted in. i've put 150 psi through each caliper but the last two just won't budge. they've been soaking in wd40 all night so i'm gonna have another go now but i'm not holding my breath:(

Eh, I wouldn't exert the needed energy. Buying a new/used one would be worth the money.