Seized Brake Caliper

[BrianH]

Hello everyone. I need some guidance for re-building my front caliper on my GS425. The caliper is seized up. I've taken th piston out and cleaned it up a bit. I put it back together and it seems that the rubber seal ring that rests inside the cylinder piston is creating a lot of resistance preventing the piston from sliding in and out freely. The seal ring seems old and has some un-eveness to it. I've never re-built a brake before so I don't really know what to expect. Is a lot of resistance normal? Should i replace the seal ring in order to correct the problem?

[DanTheMan]

You need to buy a caliper rebulid kit. It comes with all new parts, replacing that stretched out old ring. If you've never rebuilt brakes before, get to the section in your repair manual (Haynes, Chilton, Suzuki shop or whatever) and follow all the instructions there. Hydraulic brake parts must be kept scruplelously clean, no bits of dirt, sand and absolutely no petroleum products can be introduced into the system. If you've used WD40 or any other petroleum based solvent to free up the piston in the caliper, you now need to clean everything up completely, using Brakleentm, or a similar brake parts cleaner, or you can clean it all up in brake fluid. Check out BassCliff's page, I believe he has a section on master cylinder and caliper rebuilding.

[BrianH]

Thanks that is good info. Any suggestions on where to purchase one of these re-build kits from. Also when it is rebuilt, how easily should the piston slide in and out?

[hampshirehog]

If you're in the UK you can get a stainless steel piston plus the rubber bits here: http://www.wemoto.com/bikes/Suzuki/G...Front_Caliper/

Even if you're in the US I'd still look at buying a stainless piston (apparently they're not available over there?). Almost, but not quite, fit and forget.

When you reassemble smear some fluid on the seal and the piston. You should be able to slide the piston back in with a good bit of pressure on your thumb and it should feel really smooth.

[doctorgonzo]

If you're in the UK you can get a stainless steel piston plus the rubber bits here: http://www.wemoto.com/bikes/Suzuki/G...Front_Caliper/

Even if you're in the US I'd still look at buying a stainless piston (apparently they're not available over there?). Almost, but not quite, fit and forget.

When you reassemble smear some fluid on the seal and the piston. You should be able to slide the piston back in with a good bit of pressure on your thumb and it should feel really smooth.

Good one!

I did my rear with an OEM not too long ago, but when my front need it, this sounds like the way to go.

[Nessism]

The piston does not slide freely through the seal, it should take a pretty firm push to get it to slide. Most of the time the seals can be reused so I’d try that first.

[dirtyfingers]

Make sure to pull out the seals and make sure no crud has built up in the groove. A dentist pick, or similar tool should scrape it out. And like mentioned by dantheman, use ONLY brake fluid as a lubricant on the seals and piston when assembling.

[BrianH]

Thanks for the good info guys. The info about the resistance of the brake piston slideage is interesting. It's amazing to me that the force of the brake fluid can move that piston so easily.