Front caliper seized. Help!

[dave Esch]

Last year on the last ride my front caliper seized. She just started squealing like mad. I nursed it home and planned on replacing it. I can't find one though. Dealer says my year K bike caliper is discontinued. I cant even find a rebuild kit for the 76 K. I also cannot find a front rotor (mine is now thouroughly cooked). Today I took the caliper off and the only way I could get it to compress was in a vise. I tried pulling the piston out with pliers but if I try any harder i will screw it up. Any suggestions on who sells these parts? The dealer told me a company called ebc offers them for the newer F series bikes. Will anything else bolt on to a 76 750K? Thanks guys.

[TOOLS1]

I have one I might be persuaded to part with. But first I would hook the break line back up to it, and use the master cylinder to pump the piston out. There are only two parts that can go bad in them. the rubber O-ring, and the piston. tasclassicmotorsports.com has the O-ring's. I think the piston's are still available. I have seen them on e-bay. But they are expensive. Fortunately they hardly ever go bad.  I have bought rotors on e-bay for $20-30. All the Honda rotors from the 70's are the same. Even the CB 350 uses the same one. the only part they used different was the caliper on the 750K models. Go figure? And these are very pricey.
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[dave Esch]

I took your advice and put the caliper back on the bike then pumped the piston out. All in all the piston and caliper look alright. Some minor pitting, but the pits are so shallow that they can't be filled in. Without the ring in the caliper, the piston slides in and out very easily. I stoned the piston and inside bore of the caliper. I found the o-ring was covered in corrosion, picking it up from the caliper. The piston seal seat was also packed full of it. I figure I can clean that seal seat out and be good to go. I ordered a new seal but going to try my luck with the old piston.
So you say i can use any rotor from the 70's bikes? That would be a relief. This brake is the last thing I need to figure out. Other than my rear shocks. But those are just a money issue. Thanks again!

[Re-run]

You may not need to replace the rotor. See what its current thickness is and if it is over the minimum service limit, take it to a brake shop and have them resurface it.

As for the corrosion, get a brass wire brush or a dremel with a brass wire brush and clean out the inside of the caliper, taking special care of the seal groove. Get the new seal and if your pits are not bad, reuse the piston, I did that a few years back and it has been fine.

While you are at it, flush out all the old fluid and put in some fresh stuff. No point in leaving in old fluid.

[dave Esch]

I was told bike rotors couldn't be resurfaced? I have an "I believe" button for occasions like this. When someone who knows what they are talking about tells me something and I have any question, I hit my button and take their word for it. I will measure the rotor for thickness, though it got pretty burnt the last time it seized. If it's ok I will take it in. I was planning on replacing it. I haven't been able to find one for the K bikes, but tools tells me they were all the same in the 70's. "I believe".

[Re-run]

I think the 77/78 changed but 70-76 K should work no problem.

http://cgi.ebay.com/ebaymotors/1973-Honda-CB750-CB750K3-Four-Front-Brake-Rotor-_W0QQcmdZViewItemQQhashZitem588de02856QQitemZ380337399894QQptZMotorcyclesQ5fPartsQ5fAccessories
http://cgi.ebay.com/ebaymotors/Honda-1972-CB500-CB750-Front-Brake-Rotor-_W0QQcmdZViewItemQQhashZitem35b1e2c4e6QQitemZ230617695462QQptZMotorcyclesQ5fPartsQ5fAccessories
I am pretty sure people have resurfaced them, they do it to car rotors but some shops may not, these are hard rotors. Those ebay rotors by just be easier to go with.

[TOOLS1]

Both of the rotors Re-run put links to are the right ones. i would put an auction snipe on the first one, for around $25.00. The second one is a little pricy. Sometimes if you look, for the ones off 350s, and 500s they will be cheaper. Not everyone knows they are the same.
I would still check with an independent break shop about resurfacing your old one.
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[dave Esch]

I will check. And to support re-run, the reasoning behind not resurfacing bike rotors is their density (hardness). I am told the metal does not chip off as car rotors do, but rather peels off in ribbons. I have a brake rotor lathe, but my arbor only supports rotors with round holes in the hub. As you know, my bike rotor does not have a round cut out. Or else I would do it myself.

[dave Esch]

I am an idiot. The mounting hub is round, I just looked at those ebay pics. What have I got to lose? I will try to cut my rotor tonight if the thickness is ok. I'll let you guys know. If it works out, you will know where to turn when your rotors get ugly!