Heard some metal grinding so I took off the front caliper and the pads are gone. The pistons are maxed out and they won't go back in even with a C-clamp. I cracked the bleeder valves and no help. Any ideas out there?

Pop them all the way out and inspect for corrosion

PMB Performance. Send them in and get them rebuilt.

--DD

The pistons have stuck in the caliper bores,that will do it.

Round file it,, lottsa parts in the portland area..

you should be able to wrap the top area with a few rounds of duct tape, then use vice grips to get the piston to turn back and forth just a little bit to free it up.

You can also use a high pressure air hose through the inlet and blow the piston out...but it may not work with too much corrosion.

Try not to put teeth marks in the piston, but if you must just grab the top 1/8 that never goes into the cylinder area.

rich

Please try to avoid the vice grips -- only as absolute last resort. If high pressure air won't blow them out they are in really bad shape anyway and then at that point, you're probably in for new calipers.

I've never found the duct tape thing to be that much help it's far too soft. Thin 0.040 - 0.060 copper strip will work much better to prevent vice grip jaw teeth markings and metal deformation on the top of the piston.

Its all in the technique I guess.
YMMV.