Stuck Piston-any ideas?

IAN · 12-03-2005, 03:36 PM

I took everyone's advice and purchased a compressor.

I tried blowing out my pistons on my calipers and got one side to move but not the other. I have been holding the non-stuck side with a clamp but still no movement.

Can anything else be done to help get the one side moving? How much is the max force of air I should use?

I would like to avoid splitting the piston.

Thanks,
Ian

on-ramp · 03:46 PM

get C-clamp and push piston all way to the back. then use air gun..is should come out a little to where it was. (other side must be clamped when using air gun) keep repeating until it pops out. watch your fingers, you can get seriously hurt doing this.

make sure you have all hydraulic fluid out of there or this method doesnt work.

DohertyCM · DohertyCM's Garage

I had to use a pair of vise grips the first time.
But this time I removed pads from the strut and put 2 pieces of cardboard in their place. Then I pumped the brakes until both of the pistons were all the way out. This is how i got mine unstuck. I then removed the caliper and used a flat head screw driver and gently pryed on the piston. Since you are going to rebuild them tear the rubber off, this will allow the piston to move alittle more.
When I got them apart I found it packed with dirt. Not a good thing.

Evans, Marv · 12-03-2005, 07:31 PM

Agree with on-ramp about trying to push the stuck piston in with a C-clamp. I would also soak the piston & bore with PB-Blaster or something similar for a day or so before trying to move it. Also, make sure the piston is not cocked to one side in the bore. You can also use a C-clamp to gently straighten it out if you need to.

dtw · 12-04-2005, 01:48 AM

I squirt penetrating oil in there. Next day I heat cycle a few times with a torch. Next day oil. Repeat, trying the compressor each night. They'll be out sooner or later.

rcaradimos · 12-04-2005, 04:54 AM

Question, can you replace dust boot with calapers still bolted to strut and brake pads out? cleaning wheel wells and noticed dust boots are torn. Took pads out for replacement, pistons move free and are clean.
Thanks

Early_S_Man · 12-04-2005, 06:12 AM

rcaradimos,

If the dust seals are torn or cracked ... the calipers [all four] need to be removed, cleaned, and rebuilt!

Trying to replace one or two dust seals with calipers on the car is a Band-Aid fix with bad long-term repercussions!

rcaradimos · 12-04-2005, 06:43 AM

Warren,

I will order the rebuild kits, working on cleaning all four calipers and lines up before removing from struts, if you know of any tips/tricks that help, please post.\

Thanks
Bob

john walker's workshop · 12-04-2005, 09:19 AM

hang the caliper back on the brake hose, bleed, clamp the free piston and pump the other one out with the brake pedal.

sammyg2 · 12-04-2005, 01:43 PM

You would be surpised at how much pressure a cheap grease gun can put out. Hint, the cheap ones will do around 2500 psi.
You can either use one you have, or get a new cheep clean one and fill it with brake fluid or whatever.
Figure out what it will take to hook it up to the caliper and pump away. Use eye protection and make sure you have something to contain/limit the travel. Get as much air out of the caliper as possible.
If it is completely air free it won't shoot. If it has air in it the piston might end up a block away. Either way, you will get the piston out.

Early_S_Man · 12-04-2005, 02:02 PM

Bob,

Get a good quality set of metric flare-nut wrenches, such as Craftsman.

If the fittings are corroded and stubborn ... an acid brush and 9% pickling vinegar ... applied every five minutes or so for an hour ... will sometimes aid in disassembly. Stronger acids such as oxalic or phosphoric tend to remove any finish such as cadmium plating or anodizing, but sometimes can help with really badly stuck threaded fittings.

rcaradimos · 12-04-2005, 04:30 PM

Warren,

Thanks for the tip, the fittings don't look to bad, but I will take your advice and apply the acid. I read on the board that flare nut wrenches are a must and plan on picking up a set. I don't want to rush anything so each day I have been working moving pistons so they are nice and free, spraying with wd-40. I think my next step will be to free the caliper bolts before disconecting any brake lines. Plan on using the braking system to push out pistons to rotor or very close before removing line and caliper. It seems to be the right way.
By using that method will i have to add brake fluid as I go?
Thanks,
Bob