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SOHC Brake Caliper Piston

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hc243102

SOHC Brake Caliper Piston

I've been fighting with my K8 front brake for a few years now (off and on) and have never been able to get it to retract. Currently if I torque down the caliper bolts the front wheel will not even spin a whole revolution, so I've been running it with them each a half turn out and even still I have some drag. I researched the heck out've the system and tried numerous things to no avail. Rebuilt MC, SS line, cleaned caliper piston seal groove with wire wheel and lubed the bore, I've put so much fluid through the system there's no way it could have contaminates in it. I feel the only thing left to do is try a new caliper piston. There are several SS aftermarket pistons available, but from what I've read SS will not play nice with my aluminum caliper. Does anybody have any suggestions on what to replace the piston with?

TOOLS1

Re: SOHC Brake Caliper Piston

Administrator

Stainless steel will not hurt your caliper. Go to vintagecb750.com and get a new piston. However I had this same problem not long ago, and it turned out to be the brake pads doing it. They must have been binding, because as soon as I installed a new set, no more problem.
TOOLS

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shinyribs

Re: SOHC Brake Caliper Piston

Administrator

Do you have the swinging arm adjusted right? Kinda hard to get to through the spokes,but very important.

hc243102

Re: SOHC Brake Caliper Piston

Yeah I forgot to mention I took the swing-arm apart and cleaned, lubed and replaced both orings. Floats nicely now.

hc243102

Re: SOHC Brake Caliper Piston

In reply to this post by TOOLS1

Does it matter that vintagecb750.com's only piston says its for 69-76 and unlike mine looks to be hollow.

TOOLS1

Re: SOHC Brake Caliper Piston

Administrator

In reply to this post by hc243102

They have one for the 77-78 K, 75-76 F, and the 76-78 A. The part# is: 29-0531
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hc243102

Re: SOHC Brake Caliper Piston

Update. I purchased a nice new shiny piston and installed it into my caliper, put it all back together, bled it and...................same thing. Guess I'll try some new pads. Are some better than others? Any to stay away from? Also my current setup has a pad, a plastic washer thingy, and then then piston. I'm having a hard time understanding how the pad would retract with the piston since its not really attached in any way to the piston.