M caliper piston stuck, rebuild or keep trying?

[joehahn]

Hi everybody,
Finaly got around to pads (front) and was moving along at a pretty good clip until I got to last pad (driver side inboard). This pad really had a hard time coming out and was noticeably more worn than the others. I could NOT get the piston to retreat into the caliper either (others were ok using big screwdriver and channel locks all with tape around them). Not sure what I do now???

Should I take caliper off and c-clamp it (while still attached to brake line) or is the consensus that once it's pretty stuck it has to come off for rebuild? Are they hard to get off?

Please help! It will suck if I have to actually have to get a tow to have one pad addressed!


Thanks a lot!

Joe 68 L

[Chuck Moreland]

I'd go ahead a rebuild the caliper. The parts are cheap and the job is easy. You also want to get a look at the piston and bore to see if there is corrosion.

I would rebuild all four as cheap preventive maintenance.

[john walker's workshop]

while it's still attached to the brake hose, block the piston that still moves and pump the brake pedal to push out the stuck one. otherwise you may not be able to get it out on the bench. clean up that bore and reinstall the piston, then do the same for the other side. you don't have to split the caliper unless it's leaking between the halves. unlikely.

[joehahn]

Thanks Chuck and Jon,
Chuck I hesitate to rebuild because I have exactly ZERO experience bleeding brakes, etc. I know it sounds whimpy but I guess I always figured brakes were really important so I shied away from it. Perhaps it's time to step up (weather here finally got nice so down time would suck).

Jon, you mean after I take the caliper off, let it hang there with a hanger (from what I read) and then push brake pedal until it falls out? I did push the pedal last night a little to see if it would clamp closed a little further (while new pad in the other side). It did in fact close a bit more so it is not "stuck" per se, just wont frickin move back! Advise please!

Thanks, Joe

BTW, here is a tip. When washing car put a towel inside engine bay to cover everything. When it begins to rain right after you are done...take towel OUT before starting car to race it back into garage otherwise you will spend a couple hours plucking shredded towel out of the pulley, belt, fan. Ask me how I know.

[Early_S_Man]

Joe ... about that shredded paper towel ...

Before you run the engine again, you should take the fan housing complete with alternator loose and out of the way, so you can get any paper towel bits that are now residing on top of the cylinder fins and cylinders heads. A long ShopVac nozzle will help to get all of the bits that might cause localized overheating and potential damage. There is probably plenty of dust, grass and twigs and dried leaves to be removed, too, that have collected over the years! Be sure to disconnect the battery before taking alternator loose.

[joehahn]

I am afraid to remove ANYTHING! somehow it always results in more work and or breakage. Warren, no opinion on the piston? I can't believe I finally got you and Jon to respond to my question at the same time. If Roland jumps in it will be a triple. Thanks.

Joe 68 L

[steve rush]

I WENT TO NAPA AND GOT A COUPLE OF BRASS FITTINGS FOR MY HAND PUMP PORTA POWER AND JUST POP BOTH PISTONS OUT WITH A COUPLE OF STROKES. A PIECE OF WOOD IN THE MIDDLE WILL KEEP PISTONS FROM HITTING THE DOG

[john walker's workshop]

if it's not stuck solid, try squirting some penetrating oil around the piston and working it in and out a few times to free it up. punch a little hole thru the dust boot and stick the red squirt extender in there and spray lightly. with the one pad out, pump the pedal a couple of times, not enough to totally pop it out, and then work it back in with a long prybar. repete as necessary until it goes back in easy. use a thick, new pad so the piston doesn't sit it the same spot it was stuck in.

[john_colasante]

When rebuilding calipers is there any place that one can send them out to be replated properly? I assume thy should have a nice zinc cadmium finish. Aside from that what's the best way to get them nice and clean?

[joehahn]

Hi Everyone,
I found success with my piston and wanted to post a thanks as well as a follow up for someone who is stuck in the same position searching the bbs in the future.

I took J.W.'s advice and poked a tiny hole in the dust boot and then I found I could get the flexible red tube for the wd-40 almost all the way around (sort of a mini-arthroscopic surgery if you will) the piston. Let it sit approx. 10 mins. Then I detached the caliper (easier than I thought) but not the brake line. That afforded me enough "play" that I could pull it off the rotor and fit a big C-clamp right on the sweet spot of the piston. Then I cranked that Mo Fo! Piston finally went back in.

Admittedly, when I got everything back together the wheel/rotor wasn't exactly loose in the caliper but I am hoping it will loosen up as the pistons find their new resting spots. The pads are also squeaky now?? I am hoping that dies down (it did over the 20 miles I drove last night but still present). I will try to determine if this is common via research here, if I can't find it I will post another question.


Anyway, thanks to everyone and good luck to whomever needs info. in the future.

Joe 68 L.

[Joeaksa]

Joe,

Pls be real careful in a couple of areas here. When you are pushing the pistons back, put a rag or shop towel around the brake fluid container! It will almost always overflow fluid and then its all over the trunk and possibly the fender and this stuff takes paint off!

Also, always pump your brakes several times to get a good pedal when you are done, but not all the way to the floor. Do it in short normal length strokes until the pads are against the brake rotors and you have a normal pedal. Pumping the pedal to the floor sometimes damages the seals in the master cylinder.

Joe