Calipers have siezed up!!

stephenlynn98 · Posted: April 9, 2008, 11:58 am Post subject: Calipers have siezed up!!

I went to move my 81 Special to a more secure location after it sitting for a few months and the calipers wont open back up. I was told that it was most likely cause by corosion somewhere in the brake system and it was best to rebuild to be safe. Im trying to find out what parts I need to order. He said I need a master cylinder rebuild kit and a kit for the calipers but the pistons in the calipers most likely are still good. Can someone help me out here with a parts list of must haves and maybes. Also just as a sidebar when I pulled the cover off of the MC it was bone dry inside. Could it be just that they locked up because of lack of fluid and will free up if I get some fluid pumping through there? Thanks in advance for all help!!

5twins · Full Member Joined: Aug 05, 2006 Posts: 1616

I always just clean and rebuild using the old parts. If it leaks afterwards, then I'll spring for rebuild kits. If it wasn't leaking to begin with, there's a good chance you can reuse all the parts. If the caliper is frozen on, that usually indicates the piston is stuck in the bore. A good cleaning of the groove on the piston that the seal rides in usually cures it. They get crud built up in them which pushes the seal against the bore too much and binds the piston up.

TheDude · Posted: April 9, 2008, 4:49 pm Post subject: Re: Calipers have siezed up!!

The same thing happened to me two months ago when i purchased a non running xs650. It rolled fine until pushed it down my driveway and the wheel lock up and stayed that way. Upon inspection, I found the piston to be very rusty (I didn't have to remove them from the caliper to see this).

First off, I don't think adding fluid is going to free up the piston. I would say at a minimum, you will need to remove the piston and seals. If they are in good condition (they probably won't be), you can polish the piston and scrape off the corrosion from the inside of the caliper. Replacing the seals would be a good precession. I wouldn't rebuild the master cylinder unless it's not pumping fluid.

I did this with my RZ350 that had the same problem, and it worked. The cleaning was a pain in the ass however and the brakes never worked great.

In the case with my XS, I knew I would need a new piston and seals at a minimum. I am trying to get this bike super clean, so I decided to replace the whole system. I purchased a whole new caliper from Mike's $99 (not that much more than a piston and seals). I also got a mew master cylinder for $35 on ebay, and a $35 steel braided one piece brake line from Dennis Kirk. Now I don't have to worry about it. Plus, I can run dot 5 fluid which won't absorb water or trash the paint in my calipers.

So, at a minimum, you need some elbow grease and some brake fluid, and at a maximum, you need $200 for a new system. You will just have to tear into it to find out.

royfisk · Posted: April 9, 2008, 6:25 pm Post subject: Re: Calipers have siezed up!!

the brake lines themselves will sometimes not allow the fluid to retract back to the master cylinder.

stephenlynn98 · Posted: April 10, 2008, 8:27 am Post subject: Re: Calipers have siezed up!!

Thanks for all the help guys! Im going to take the cailipers off, take em apart and see what happens. The MC should be ok so worse case I'll have to rebuild the calipers and maybe throw some new lines on while im in there. Thanks again for all responses!

~Stephen

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