i've been fixing up my old '84 245 for my brother to drive recently and have been doing some brake work. i got most of the way done but was stopped by the inner side pistons on the passenger side calliper being stuck. this car had been sitting about 3 months so i unbolted it and got in and jammed on the pedal to pop the pistons out...they came out pretty far but then i had a heck of a time getting them to slide back as far as i did... now i'm trying to put the new pads in and the pistons still arent back far enough to slide them in....any advice on how to get these moving correctly? thanks in advance!

Chris,

You might try Advance Auto parts for reasonably priced calipers. They sell rebuilt ones for around $50 each. I just replaced my front ones on my '86 and it made a huge difference. Just make sure to check and see if your car has solid or vented rotors before ordering calipers.

Cheers,
Dave

Chris Mooney is quite right -cleaning is a temporary fix at best until you replace/rebuild the calipers. If time is not an issue and the calipers are otherwise in good condition, it's not expensive or overly difficult to rebuild your own calipers with a seal kit. Search the site for additional details. If all you can manage is a cleaning and replacement is simply not on the horizon then I can give you a more involved method of cleaning from my starving student days that will help things last longer:

Initially push the pistons out as far as they'll go using the backing of an old set of pads (or equivalent thickness minus up to about 3/32" max) as a stop to prevent the pistons popping out. Unbolt the caliper and hang it or rest it on something for proper access to the pistons. Carefully pry off the dust boots so you can properly clean and check the pistons. Scrub the pistons with brake fluid using a toothbrush, cleaning in close to the seals. Flush and wipe the pistons clean (flush only with clean brake fluid or disc brake spray cleaner). Inspect pistons carefully for scoring or rust stains (use a mirror if needed). You really should replace the caliper unless the pistons are in fairly pristine condition. Lube the pistons with clean brake fluid. Retract the pistons about half way (channel lock pliers or a c-clamp are good for this). Push both pistons back out until the ring of dirt and fluid that collected at the seal is accessible (temporarily re-installing the calipers as needed to prevent a piston popping out). Wipe the pistons clean again. Re-lube the pistons and retract them fully. Any residual brake fluid external of the seal will just become a dirt magnet and start caking the pistons sooner, so finish by flushing with spray disc brake cleaner. Re-install the dust covers (replace any punctured/torn ones). Re-install the calipers and pads (use high temp grease between back of pads, shims and pistons to prevent squeeling). Apply full brake pressure to seat the pads hard and release. The pads should retract enough to allow the rotor to be turned by hand, albeit with some difficulty. On rare occasions the brake warning light may end up on in which case you would need to reset the switch at the brake line distribution box.
--
Dave -own 940's, prev 740/240/140/120's & quasi-expert only on a good day

Determine if the hoses suffer from stenosis by attempting to move the piston back with its bleeder open. If you meet the same resistance, count on rebuilding or replacing the caliper. If not, you will be replacing the flex hoses.

well i had removed the calliper entirely from the hoses and all when i pushed them back in when it was a pain....so it is the pistons. i just replaced that calliper 2 years ago so that is disheartening to hear that i'll have to replace it..the boots are in very good condition still....would it be possible that they are just a bit stiff from sitting that long (with the wheel off) and with use they'd lube back up and work ok? Thanks though

Correct answer is no, replace it. That being said I suspect you're in the same boat I am, not enough money & willing to try a halfway measure to buy a few more months' driving before the next big expenditure... Here's what I've done many times: take a syringe, fill with clean brake fluid & inject it around the dust boots, and with the caliper installed pry the pistons as far back in as you can. Then pump them back out with worn pads installed to keep the pistons from popping past the seals. Pry back. Repeat. Repeat. Etc, etc, until they move freely. They will seize up again, no doubt, and the seals may get nicked & start leaking. Keep a close eye on them. I've got away with it for months at a time though. But remember, for the purposes of litigation & liability, I didn't tell you that this is a good idea!
-Chris