For the rear caliper, remove the two little hitch pins....

....and the two pad-holding pins.  Hold your fingers over spring clips, as they have an affinity for shooting across the room never to be seen again.  Don't ask me how I know this.

Here's what comes out after the pins are removed. 

How's this for a crappy pad?  Almost to the backing plate.

Separate the two halves, and peel off the rubber dust boots.  Aren't you glad you loosened the bolts outside?

As you can see, the fluid goes into the caliper on the right side, travels through a tiny passage across from one side to the other, and then to the other piston.  The spot where the little passage meets the gap between the two halves, there is a little rubber o-ring (shown laying on the left half).  The manual says that you should always replace it, but I've put it back, with no problem, during a previous caliper cleaning.  YMMV.

To get the pistons out of the caliper, use of compressed air is the most common method and the method described in the Suzuki service manual.  I used a SCUBA air tank as an air source since I don't have a compressor.  I suppose one of those little 12v compressors (used for air mattresses, flat tires, etc..) might just work too.  Clark Ball reports success using an off the shelf can of compressed air, the kind used for cameras and computer components.  Apparently this method involved duct taping the little red spray straw to the nozzle and to the caliper hole.  Good thinking Clark!

I've read that if you have no source of compressed air, you can "pump" the pistons out using the brake fluid.  Of course this means you'll be doing this on the bike, and will likely make a godawful mess when the piston pops and sprays brake fluid all over the place.  Also, once one piston pops, I can't figure out how you would get the second one out, due to the fact that it would be nearly impossible to get any sort of hydraulic pressure.  I guess the trick is to hold the one piston that is coming out in order to divert a bit more pressure to the other piston.  this way they would both be close to popping at the same time.  This method is DEFINITELY NOT for me, but I suppose it would work OK on brakes that have only one piston.

Lay one half of the caliper on a pile of rags.  GENTLY apply some compressed air into the brake line hole to force the piston to pop out.   The passage that would be going to the other half of the caliper will let all the pressure escape, so put you finger over that hole.

Keep you fingers and other body parts well away from the piston because it can pop out with quite a lot of force if you are not careful.  Make sure any openings are facing away from you as any foreign matter in the caliper could be shot out as well.  Use small increments of air so that you can gauge the progress.

As you apply air, the piston will slide out of it's bore with a resounding POP.  

Do the same with the other half of the caliper.  Apply air into the bleeder valve hole.  Cover the "passage" with your finger, as before, and keep your hands away from the piston.

POP!

Using a dental pick or jeweler's screwdriver, pick out the rubber seal that is sitting in the groove cut around the circumference of the cylinder.  If it's in good shape, and picking it out didn't damage it, you might feel comfortable reusing it. 

Over time, lots of gunk can accumulate in here.  The big problem is when the gunk accumulates on and around the rubber seal.  The build-up can actually distort the seal to the point that it cannot release properly, resulting in a dragging brake.  

Clean out the cylinder walls and the groove as best as you can, using whatever tools you can dig up (dental pick, jeweler's screwdriver, toothbrush, an extra fine Dremel wire wheel brush, etc...).   Make sure that you don't gouge or scratch the groove or caliper wall.  If possible, use tools made of softer metals, or similar materials.   If there is some particularly resilient corrosion, I've heard that people use 600 grit sandpaper or fine steel wool to hone and polish the walls.  Fortunately, my cylinders were fairly clean and smooth inside, so I didn't have to do much here. 

To clean and wipe down the inside, use only clean brake fluid.  Don't use any solvents since residue could later interact with the seals and metal parts.  We also already know that water should be avoided in the brakes.

If necessary, recondition the piston in a similar manner, or replace it.  Since the piston directly rubs against the rubber seal, it's important that it be nicely polished.  Any substantial pitting or rusting will just cut the seal and interfere with proper sliding and retraction.  You don't want that.  Some minor rusting or pitting can generally  be tolerated if it's buffed smooth.  Since I got new pistons with the kit, I skipped the piston re-conditioning step.  

Put a new seal into the groove.  

I have read once that the seals are generally  asymmetrical; slightly angled one way to help the rubber pull the piston back in slightly when the fluid pressure is released.  This implies that there is a "this side up" for installing the seal.   When I examined both the new and old seals, I could find no discernable difference either way.  The seal had a seemingly perfectly square profile all the way around.   Eventually I just took a chance and put it in.  I figured if it was important to get the orientation right, Suzuki would have put a paint dot or ridge or something to identify the right way.   Maybe only other manufacturers use asymmetrical seals, or maybe I just misunderstood the whole idea.  Come to think of it, I'm starting to think that it is the groove itself that is angled, not the seal.  If anyone can clarify further, please email me at etzfish@optonline.net. 

Either way, the idea is that the seal deforms itself as the piston slides out to apply the brakes.  As the pressure is released, the twisted seal tries to right itself, pulling the piston back in the process.  

Lubricate the piston with clean brake fluid only, and slide it halfway into the cylinder.  It may take a bit of jiggling to get it past the new seal.  

When installing the dust boot, I found it easer to get the boot on if I attached it on the ridge on the piston first, before pushing it all the way in.  Then push the piston the rest of the way down and pull the dust boot over the outer edge of the cylinder.  There's a little ridge there to hold the boot.

Do the same thing for the other half of the caliper.

Re-combine the two caliper halves, and hand-tighten the connecting bolts.  Remember to put the little o-ring in between the two halves in the appropriate place.  The manual advises to always use a new one.

Back to main brakes page
Rear caliper removal
Front caliper removal
Rear caliper disassembly and repair
Front caliper disassembly and repair
Installation and testing