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View Full Version : GMA Master Cylinder trouble



krisc1008
06-30-2014, 7:54 PM
Picked up a used GMA front MC on here a while back and the thing has given me nothing but grief. Made sure it was DOT5 in it before and got it hooked up, brakes bled. All good. Few days later I pull on the brake and it just stays plunged. Piston won't return. It came with a rebuild kit so I tore it down, cleaned it thoroughly,and installed new piston, seals, spring. I go to bleed brakes again and I can't get piston to seal and push fluid through. Tore it down again. Upon inspecting the old seals I see they have o rings inside them. Rebuild kit did not have those with it so I pulled them out and put them in the new seals. Lubed with a little fluid, and there is no way hell the piston will go into the bore. So without o rings it won't seal properly, and with, piston won't go in. Finally got it in by taking the o ring out of the outer seal. And now it's getting fluid past the piston.
So I have two questions. Is this thing even worth rebuilding again, only to maybe have the same issues? Can anyone recommend a good front brake 5/8 bore MC that won't cost me an arm and a leg? I just want to ride, don't care if its ugly. Thanks