VCCA Home Forums TECHNICAL - GENERAL Mechanical - Engine, Trans, etc Removing brake pistons

Well, tonight's job was going to be taking the brake cylinders apart and cleaning them up. I got the end caps off and then hit a snag. The pistons are frozen in place. I've tried some PB Blaster and some heat, and maybe I just need to give them some time. There's nothing to get a good grip on.

I also tried to push them out. First, with compressed air in the brake line hole (nothing budged) and then by putting a bolt in to seal the hole and gently heating so the inner gas would expand. To be honest, the latter approach felt way too much like I was toying with a pipe bomb, so I didn't pursue it very far.

I see rebuild kits at the FS and Chevs40s, but they don't include the pistons in this size, so I don't want to drill them out.

Suggestions?

Paul
A trick I have used is to fit a grease nipple (zerk) into the pipe entry point and pump grease in.
Tony

Paul,

Easy. Just get a suitable size deep-well socket and a hammer. Socket should be about the same size as the cylinder, the closer the fit the better. Hammer should be a small one increasing in weight to sledge-hammer. Just heavy enough to do the job and be easy on your wrist. Drive the pistons out from either end.

If they still don't budge then take the two retaining bolts out of the backing plate and tap the unit out. Take them fishing the next time you go and don't bring them back.

Charlie

Use a "C" clamp to get the cups in as far as possible and then clean the exposed part of the cylinder. Then try Tonys suggestion.

You could soak 'em in a 50-50 mix of old type ATF and Acetone. Good stuff. Just keep 'em wet with it and be patient.

When you get the pistons out, I hope the bores will hone to a smooth surface.

Check your cylinder casting numbers and see if NAPA can possibly find new ones (they might fit another vehicle).

Good luck - -

Well, Paul that brings up another thought on the subject...There is a chance they might "clean-up" with a light honing...My experience is that it's "iffy"...Secondly, do you really enjoy what your doing...? Or, are you cash strapped...? Time on your hands...? What I'm getting at here is that the time and aggravation is sometimes not worth the going...Those parts are not that expensive...I order new one's and "chuck" the old, these days...When I was younger I'd rebuild them myself...Now, I'd prefer spending that time with family and friends...Your dog misses you...

Thanks for the great suggestions. Kevin, you make a good point. On the other hand, I do seem to have more time than money these days, AND I like the challenge of keeping as much of the original stuff as I can.

I'll play around with them a bit using you guys' suggestions. It is a good feeling though, to know that new ones are only a click away.

I hear ya, Paul. I also have more time than money these days...On the other hand I recall one time that I removed too much material honing out the pits and later on, the cylinder failed because the bore was too big...As luck would have it I was only going a few miles an hour, but still, the pedal went straight in the floor and I ran in to my closed gate (no damage) I was to close to grab the parking brake in time...If you can't remove all the pits there is a good chance it may start to leak down the road, also something that you wouldn't want to happen...Good luck

As often happens when they've been stuck for a while the water has caused pits that can't be honed out...And if it's the originality you want to keep you need to send the cylinder out to be "sleeved"...Which can cost as much as a new one, easily...I personally prefer not to "sleeve", if the original one lasted this long...I get a new one, I won't be around to worry about it happening again...

You can drive out the pistons with a punch. The aluminum pistons should be replaced as once the surface is roughed up or oxidized they will never be the same and will rust to the cylinder in a short time. There was like an anodized surface on them. I would get new cylinders or have the originals resleved.
Years ago if you purchased a wheel cylinder repair kit from Chevrolet it came with new pistons , spring, and cups.

Kevin, I hear ya. Some parts just aren't worth saving, particularly something kind of important, like brakes! The master cylinder isn't looking too good either.

Ouch...I just checked for the wheel cylinders, master cylinder and rubber replacement lines...I bought thru old.parts, on eBay...$400 includes shipping...But, I was satisfied with the parts they sent...

You couldn't spend $400.00 any better on an old car than the brakes.

Again, you might try a NAPA store to see if they can supply these parts. They can still get a lot of "older" stuff. If so, they'll be more reasonable and no freight to pay.

Yup, NAPA has them. 74 for the rear and 89 for the front. They look awfully good. Clean and new.