not to be demanding but i gotta leave for a softball game in about 10 minutes!! so here it is.

i'm in the process of replacing the rear pads.  i got all the clips and pins out and pulled the old pads.  i removed the reservoir cover and now i need to push the pistons in so i can fit the newer thicker pads in place.  i cant get the pistons to move in at all! i gently push the brake lever and watch the pistons come out but for the love of god they wont go back in.  i put the old pads in and pushed like hell on them, even jammed a flat head between the pad and rotor and tried using it as a lever.  nothing.  what am i doing wrong?

You are doing nothing wrong, you should not have to move them in very far, though.
Maybe open the bleeder valve up a little?

Or try opening the top of the rear brake reservoir.  That worked for me.

yes open the cap not the bleeder valve or you will have to bleed the brakes which is a pain in the butt just unbolt the caliper and push it in with a G clamp that should do it

i've opened both. neither piston will budge in. its impossible to get any sort of clamp in there.  i've lifted the caliper off the rotor and still no way to get any fuggin thing in there and now im late.

I've never had a problem getting a C-clamp in to compress brake pistons, but I've never done brakes on a GS.  Do you have a set of channel lock pliers?  I've successfully used those to compress pistons before when no clamp was available.

For future reference, don't mechanic on your only transportation unless it's something you know you can finish before you need to go somewhere.

Take a 4" C clamp (get a heavier one than you think you need) and generally, you CAN fit it on there.

The screw portion needs to go on the OUTSIDE of the caliper. I like to use a piece of aluminum or brass shimstock to keep from damaging the paint on the caliper(s).

The clamp portion needs to go on one of the OLD pads. It will just fit, and it takes a couple tries to teach your fingers how to set it without loading the brake lines with the weight of the aparatus.

Turn slowly, while holding the caliper and the pistons will recede quite easily. This is assuming you haven't buggered one of the pistons, and the piston(s) haven't been misaligned.

IF YOU SEE BRASS HALF MOON BRASS SHAVINGS/SLIVERS INSIDE THE CALIPER STOP NOW and ask about how to rebuild stuff proper.

If you really get desperate, take a 6 pack of GOOD COLD beer over to your neighbor that's a welder and ask him if you can please borrow his vise-grip welding clamp. He'll make a fuss about loaning tools, then likely come over and help to boot.

you always want to keep the welder on good terms. those guys rock!

none of my C-clamps, including the 4" variety will fit.  i now have the outboard piston pushed in at an angle.  im selling my bike.

Grease up the pistons to prevent this again?! 

Quote from: weaselnoze on May 22, 2007, 03:49:18 PM
none of my C-clamps, including the 4" variety will fit.  i now have the outboard piston pushed in at an angle.  im selling my bike.

Put the old pads back in the caliper, put a file (or something about 1/4") between the pads, and press the brake lever. It will realign the piston. Then you can attempt to press the pistons into their bores again.

I wouldn't trust the piston to still seal properly after being angled, but it may be fine.

You still have to fix the brakes befor you sell the bike. Ya know, lawyers and all.

i put a file in and 2 c clamps on the sides and it broke my file. wtf.  by fixing the brakes you mean?

Quote from: weaselnoze on May 22, 2007, 06:56:19 PM
i put a file in and 2 c clamps on the sides and it broke my file. wtf.  by fixing the brakes you mean?

ya, you can't twist or bend a file very far. they're hardened, and a little brittle. you can use them as spacers as I suggested, but you can't use them for bending or torquing operations. sorry you broke yours. the idea was to use it in place of the rotor, with old pads installed. then you would just press the brake lever and the calipers pistons would come out a little, and realign.

Quote from: weaselnoze on May 22, 2007, 02:55:47 PM
.........i cant get the pistons to move in at all! i gently push the brake lever and watch the pistons come out but for the love of god they wont go back in.

And that's why I always push them out now when replacing pads.  I had too many pistons that wern't completely cleaned off start sticking on me later because of the hardened crud built up on them that got pushed back into the seals. 

I always push the pistons out, clean them up like new, put them back in, and bleed the brake when putting new pads on.  Works for me.  Those outer piston wipers will begin to twist and also cause binding when the pistons are pushed back into them.  I just throw them away when that happens, they are supposed to wipe the pistons clean when they are pushed back in but won't wipe off hardened crud or rust.  If you clean the pistons and put them back in clean, the outer wipers are not needed.

Someone mentioned lubricating the pistons above, do that only with brake fluid and nothing else.  Other lubes could cause the piston seal to swell and bind later on.

alright. tomorrow i will try and realignt he piston.  then i will attempt to clean it with brake fluid as per jacks recommendation.  its just so stinkin hard to get anything inside that caliper let alone my fingers.  we'll give it another try now that i am cooled off. i appreciate the help guys. i'll keep you updated.