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© 2000 Brian F. Schreurs
Even we have a disclaimer.

What you'll need to get the boots is a caliper seal kit (GM #18026160). And despite the fact that you have only two calipers on the front of your car, you need four kits. Each kit contains one piston bore seal, one piston dust boot, and two caliper bolts. Thus, yes, you will finish the project with exactly twice as many caliper bolts as you need. Deal with it.

Note the melted and shredded piston boot which prompted this project, and the location of the brake line.

Jack the car up and remove the wheels.

The calipers are gonna come off the car for this project. Therefore, start by removing the brake line at the caliper. It is a 13mm bolt. Be ready with a plug for the brake line, or you'll drain most of the fluid -- not good. We use vacuum hose identifiers, sold in a nice plastic case by Lisle. In addition to identifying vacuum hose, they do a dandy job of wedging into an open brake line.

There are two copper gaskets on the 13mm bolt. One is between the head of the bolt and the line; the other is between the line and the caliper. Keep track of them. In fact put one in your pocket right now coz you're making a trip to the hardware store.

With the brake line plugged you can further discourage leaking by snagging the line around the front spring. That also keeps it out of the way. Meanwhile, the caliper has probably already drained itself all over the garage. If you're reading these instructions before doing the work, have towels ready. If you already have a puddle, that'll teach ya.

The caliper is held to the caliper bracket by two 12mm bolts. Each of these bolts engage a sleeve rather than the actual caliper. This sleeve must be held steady with a 16mm open wrench. It has two flats which can be found between the caliper's ear and the boot protecting the sleeve (technically called a pin guide). Loosen both 12mm bolts before completely removing them. Once the tension is off the bolts, it's a lot easier to get them out without the caliper flopping all over the place.

Plug and suspend the brake line thus.

It may be easier to get the caliper off if you remove one bolt, unhinge the caliper, yank the pads, close the caliper, and reconnect the bolt; loosen the second bolt to hand-loose, and remove the two bolts by hand. That's what we did. Keep track of any anti-rattle clips which sproing out of place. They're easy enough to pop back in.

Now go do the other side.

If you have an air compressor, great! Shoot air through the brake line port to pop the pistons out to the top of their bores. If you don't have an air compressor, there's no good substitute for one; go beg for help from your friendly mechanic.

Note: mechanics seem to be pessimists. Ours told us there was no way we'd get it put back together and that he'd charge us extra for fixing our mess. We're probably not going to use him for this kind of thing anymore, because as you will see, the procedure is no big deal. So if yours gives you some grief, don't pay it any mind.

While you're out visiting a mechanic, pop in to the hardware store and get four copper washers exactly like the one in your pocket. Or, if you forgot it, drive back to your garage, get a washer, go back to the hardware store, and buy four more of them.

With the pistons teetering at the tops of their bores, it's a simple enough matter to wiggle them out with some channel-locks or equivalent tool. When they pop out, they'll take the boot with them.

Rip off the boots and use a dental pick to fish out the rubber seals set in a groove at the top of the caliper bores. Don't have dental picks? Stop right here. You'll need them later. Get a set of picks. Most parts stores should sell them, and once you own a set, you'll wonder how you managed to get so old without them. While you're out, pick up some brake cleaner. If you don't have dental picks, you probably don't have brake cleaner either.

The inner groove is for the piston seal; the outer groove is for the piston boot; the dirt and grime must be washed away with brake cleaner.

When you get back, take the calipers outside and liberally hose them down with brake cleaner. These are your brakes; your life depends on them. This is no place to be cheap! Make those suckers spotless.

Back inside, remove any remaining large grit from the bores. Also carefully clean the outside of the pistons, being especially certain to not scuff them. Clearances are tight in these things.

Now reassemble with the new parts.

Ho ho ho! That would be a load of fun, wouldn't it? Maybe we're stupid but it took us about two hours of fiddling to figure out what the "trick" is to get the boots back in. After all, they're double-sealed and there's no way to get at them from underneath. The factory manual doesn't tell what the trick is either. But we're better than that and we're going to tell you how to do it.

The easy part: take the piston seals (the things that look kinda like O-rings) and use a pick to guide them into the lower grooves in the bores. This shouldn't be difficult at all. Just make sure the seal doesn't get twisted.

This is how the boot should look on the piston just before trying to reinstall it. By the way, that's an original piston; if yours don't look that clean, go back and clean them until they do.

Now for the hard part. First, the boot goes on the piston. It's a very tight fit. If you try to slide it on from the bottom, it'll turn itself upside-down; try from the top and it gets caught in the groove. Leave it in the groove and it won't hold its shape while you try to pry it into the bore groove. The trick?

Pull the boot down from the top of the piston. Yes, it'll snag in the groove. No matter. Gently pry it out of the groove and keep pulling the boot down until it is almost at the bottom of the piston -- and we mean literally just about to pop off the other end. Now hold the piston so that your hand is cupping it from the top, and your fingers are able to both hold the piston and work the boot a little.

Hold the piston just above its bore. There should literally be only a few millimeters between the piston and the bore -- just enough to get a pick in there. Use your fingers to scrunch the boot down away from the piston and into the bore. With your other hand, use a pick to guide the boot into the upper groove in the bore. Start at the back, where the bore is right up against the top of the housing. This area will be totally inaccessible as you progress so it is imperative that the boot gets properly seated there first. As you nudge some parts of the boot into the groove, other parts may try to pull back out. Keep at it and the whole thing will pop in place eventually.

When you think you have the boot sealed properly, gently push the piston into the bore. It will not go in if you messed up. There is just not enough clearance. Keep pushing the piston down the bore, periodically taking the time to scoot the top of the boot up the piston a little. Before long the piston will be far enough in place that the boot will catch the piston's groove. It is sealed. It's probably a good idea to keep pushing the piston in until it is at least 3/4 of the way in. This will reduce the chances of it getting damaged, and you'll have to do it to get the pads back on anyway.

You'll have to seat the pistons by hand, but once seated properly, it's okay to gently guide them into position with a C-clamp. If it requires and substantial force, something's not installed right; it should be a smooth glide.

Do the rest of them. It gets easier with practice.

After that hassle, installing the caliper is easy. Make sure the pads are in position and the anti- rattle clips are where they belong. Set the caliper over the pads. Use a piston compressor to move the pistons deeper if necessary. Hand-tighten the two 12mm bolts; might as well use some of the new ones since you have so many. With both started hand-tight, use the 16mm wrench to hold the sleeve and finish tightening them. The new bolts come with threadlocker pre-installed so it's not necessary to strip the bolts trying to get them back on. A reasonable amount of torque will do.

Unplug the brake line and quickly reinstall it. Use the new copper washers you bought; they're serving as gaskets, and shouldn't be reused.

Once both sides are done, the air needs to be bled out of the system. Start with the passenger side.

The bleeder screw is located on the top of the caliper. It's 10mm, but be sure to use a line wrench to minimize the chances of damaging it. Connect a clear hose to the bleeder, and have some sort of container on the other end. With one person who can follow directions in the car, get ready at the wheel.

Tell the person in the car to press on the brake pedal until it hits the floor. We usually use the "down" command. When he presses the pedal, open the bleeder screw. You'll get nothing and he'll get a pedal that sinks to the floor. Actually what you're getting is air and lots of it. After a moment, close the bleeder screw and tell your assistant to release the pedal. We use the "up" command.

Get this in the right order. If your assistant lets up on the pedal before the bleeder screw is closed, it'll suck air into the system.

Keep doing this until fluid comes out. It may seem like a while, but it will eventually push fluid through the system.

Check the brake fluid level in the master cylinder. This should not be allowed to dip too low. Then do the driver side.

Put the wheels back on and road-test!

Odds are you won't be able to tell any difference. We couldn't. But there's a certain peace of mind in knowing that your brakes aren't about to seize up, and doing this job early enough will save you from buying a whole replacement caliper. Or a replacement fender, if you catch our drift.