rear brake caliper

[JOHN SOLIDAY]

Yep compressed air is the way to get them out.  If you can soak them in the ultrasonic and somekind of penetrating fluid like WD40 prior that will make it easier.  If the pistons show ANY sign of pitting, they will leak or damage the new seals shortly thereafter.  New pistons are expensive but I've tried reusing pistons and if the surface plating is gone they won't last.

> Date: Wed, 23 Jul 2008 18:43:16 -0500> From: wkdenton at verizon.net> Subject: Re: rear brake caliper> To: gpzlist at micapeak.com; corbie at verizonmail.com> > Bill,> > You can just rebuild the caliper, as long as there's not any significant > corrosion of the aluminum inside the bore of the caliper. If the bore is > badly corroded the caliper is junk. The pistons "may" need to be replaced, > depending on the level of corrosion present, but usually clean up OK.> > To remove the pistons, take the caliper to the bench, wrap it with a towel, > face the pistons away from your body and apply compressed air to the brake > line inlet. Make sure you wear eye protection so you don't get hydraulic > fluid in the orbs. Try 40# of pressure first, but you may have to up the > pressure depending on how gummed up the pistons are. The trickiest part of > this entire operation is getting the "second" piston out of it's bore. Once > the first one pops, clean it up a bit and press it back in far enough to > hold pressure, then wedge a small square of plywood (or something else > softer than the metal of the piston) under that piston only. Then, apply > air pressure again to get the second one to pop out. Once the second one > pops out you should be able to manually remove the first one again.> > Scrub the pistons with hot soapy water and a non-metallic scrubbing pad (or > toothbrush), dry and inspect for pitting or wear. You may have to apply a > little "persuasion" to remove some stubborn deposits, just do it with > something softer than the chrome surface of the piston and you'll be OK. If > they clean up and look good, polish them with a little Mothers mag polish > and reuse, saving yourself ~$50 in new pistons.> > The rest of the caliper assembly can also be cleaned up using hot soapy > water and a toothbrush as well. One exception is cleaning in the groove > where the seal goes, there you're probably going to have to resort to dental > pick work. Work slowly and carefully, doing you best impression of a dental > hygienist scraping plaque off your teeth w/o drawing blood <g>. Those > deposits of aged, polymerized brake fluid are generally tough and non > soluble in anything you throw at it, which is why I clean them this way. > Other than that, the nice thing about working on brakes is that brake fluid > (aka mixed glycols) is water soluble so it's easy to clean them using plain > hot soapy water, which precludes the necessity of using solvents, parts > cleaners, etc.> > Good luck!> > Bill in Yardley, PA> wkdenton at verizon.net> '96 GPz1100> '86 SRX600> '81 VX920RH> '80 CB-X> > ----- Original Message ----- > From: "Bill Magitz" <corbie at verizonmail.com>> > > This is a question regarding the 1984 Sabre my brother gave me. He said the > rear brakes were sticking , but when I removed the caliper I found the > pistons to be frozen in place with corrosion on the exposed sections. Now I > am not even a good shade tree mechanic so i am not sure what my best option > here is. Do I try to free it and clean it up or do I just replace the unit ? > If I try to free it what would be a good method , I have an ultra sonic > cleaner at work I can use if that helps. thanks for any advice---bill m----> > -- > --> you @ usa.com> is available and 170 other free domains.> Sign up at www.mail.com>