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GT750 brake caliper problem

Posted: Sun Oct 28, 2012 3:45 pm
by dstegjas
I have a 1976 GT750 that I picked up last year to restore. It had set for over 16 years in a garage. It is in pretty good shape, but still has a few issues. One is the front brake calipers. The pistons have seized, and I'm not sure how to release them. After taking the bleeder valve out. I can see that there is no fluid inside the brake caliper. So I am concerned that things may have rusted up in there.

If anyone has any suggestions. I would appreciate your help.

Jim

Re: GT750 brake caliper problem

Posted: Sun Oct 28, 2012 5:30 pm
by oldjapanesebikes
One way is a grease gun - other folks have had good success that way. I normally use a spare master cylinder and a short hose connection with everything off the bike and on my bench. The key point being to use a liquid rather than air - if you use air then you get a mini-explosion when it lets go and it can get painful. 8)

Re: GT750 brake caliper problem

Posted: Sun Oct 28, 2012 5:57 pm
by dstegjas
Thanks OJB. I didn't even think about the grease gun. I did laugh when I started to read your other option and the mini explosion part. I'm not sure why, but that was funny.

Thanks again.

Jim

Re: GT750 brake caliper problem

Posted: Mon Oct 29, 2012 3:49 am
by titan performance
I'd go with OJB's pump it out with fluid method.....however, I have had some that wouldn't shift, and I've had to use more force. The problem is, it usually damages the piston, and you end up having to buy a replacement.
On the bright side, the Suzuki GT range all used a similar caliper, so they're not rare...

Re: GT750 brake caliper problem

Posted: Mon Oct 29, 2012 4:41 am
by Craig380
As Titan said, even if you have to use a vise / pliers to wrench the piston out, caliper rebuild kits (with new piston, all seals, o-rings etc) are still readily available and are not expensive -- I got one from Crooks Suzuki a couple of years back for under $60.

Re: GT750 brake caliper problem

Posted: Mon Oct 29, 2012 7:40 am
by Pete O'Dell
and if the grease (my prefered method) and hydraulics fail, drill piston with 10 or 12 mm drill, CAREFULLY tap the hole, and screw a bolt in and wind it out, if all 3 fail throw in in the canal and start searching ebay :)

Re: GT750 brake caliper problem

Posted: Mon Oct 29, 2012 11:14 am
by Coyote
I have always had good success with air. Wrap a rag around the caliper and put it piston side down on the bench. Tighten the bleed screw and use compressed air on the line inlet hole while holding the caliper down with your free hand. Yes they make a pretty good pop when they let go. A few I have had trouble with, I pushed the piston in some with the aid of a vise. This seems to get things in motion and the piston usually comes right out after that.

Re: GT750 brake caliper problem

Posted: Mon Oct 29, 2012 7:33 pm
by dstegjas
Thanks guys. The air trick worked to a point. Then I was able to pull the piston out without damaging anything. There was some pitting in the bottom of the reservoir and a couple of small pits in the side of the pistons. It looks like I can get by with just replacing the seals.

Don't be surprised when I come back with other issues. :)

Thanks again for the help.

Jim