Caliper Correction

Turning back time on ’65-’82 brake calipers

Andrew Bolig Jul 1, 2000 0 Comment(s)

Step By Step

The worst enemy of your Corvette’s brake system is water. Water in the lines causes them to rust. Rust can work its way into the piston bores and begin to work on the anodizing on the pistons. When this happens, it’s only a matter of time before the calipers will have to be repaired. Once the rust gets under the seal, there’s no way to keep it from leaking. This is the main reason it’s so important to keep good fluid in the system and to change out the fluid annually.

Once you get the calipers apart and cleaned, check the inside bores of the caliper for scoring or scratches. Dewey suggests that if there are any large imperfections, the calipers will need to be resleeved. If the caliper has only small imperfections, you can clean them up using 600-grit emery cloth.

Make sure you get the proper springs for the pistons. When we took this caliper apart, we noticed that there were two different springs. The smaller spring is the original—the larger spring shouldn’t be used because of the increased pressure on the piston, which will make the pad drag more on the rotor.

To install the seals on the pistons, place a little bit of the appropriate brake fluid on the piston to lubricate the seal. You simply have to slide the seal into the slot provided. There is a raised surface inside the groove—make sure that the seal passes that raised surface and seats securely on the bottom of the groove. If you have to use a screwdriver to maneuver the seal in the groove, be careful not to scratch off any of the anodizing on the piston. This is what keeps the piston from oxidizing and seizing in the bore.

Once the seal is installed, hold the piston in one hand and spin the seal with your fingers. This will ensure that the seal is seated properly, and you’ll be able to feel any scratching or dragging.

Before installing the pistons into the caliper bores, put a little brake fluid on the inside surface. This will help protect the seals.

There are two ways to install the pistons and springs into the calipers: One is to put the spring into the bore of the caliper and then install the piston, using a sleeve the same size as the one used in the caliper and simply pushing the piston through the sleeve and into the bore of the caliper.

Or, you can also use a screwdriver to work the seal into the bore, but you must be very careful not to score the inside surface of the bore or scratch off any of the piston’s anodizing.

You’ll have to keep the piston pushed down into the bore or the spring will push it right back out. The next step is to install the outside seal. While holding the piston in, place the seal around the piston.

Then, with a soft hammer, gently tap the seal into place around the diameter of the piston bore. Take your time and don’t damage the seal or piston.

With the pistons installed, we were ready to put the caliper halves together. Dewey puts some synthetic grease on the forward surfaces where the brake pads will ride in the caliper to keep it riding freely.

Don’t forget the little O-rings that go between the two halves.

Put the locating pin into the caliper and then slide the brake pad onto the pin. Dewey takes an old ignition condenser and uses that between the pads to keep them apart. You can also use the same size socket or wooden dowel pin.

Install the other brake pad and caliper half (after applying synthetic grease). Run the bolts through and torque them to 70 lb-ft. Then install the cotter pin, which should always go on the inboard side of the caliper.

When you install the caliper, the rotor will push out the condenser. The springs behind the pistons keep the pads against the rotor.

You should fill the calipers with fluid before you hook up the brake lines. This will shorten the time needed to bleed the brake system. Dewey uses a small squeeze tube of brake fluid and a flexible hose. For the front calipers, squeeze fluid in the line until it comes out the bleeder, and for the rear just squeeze fluid in one bleeder until it comes out the other bleeder.

While driving our Corvettes, we often forget about all of the components that consistently operate without giving us a lick of trouble. That is, until they no longer perform as they should. Like the often-overlooked disk brake calipers on ’65-’82 Corvettes. These forgotten-till-broken components can be restored to like-new operation but, depending on what components need to be replaced, you may be further ahead financially if you buy remanufactured calipers. If you want to keep the original calipers, you can rebuild them yourself. There’s a right way and a wrong way to rebuild calipers, so we went to Dewey Hendricks of Dewey’s Just Vettes in Longwood, Florida, to find out the right way to do it.

Once you have the entire brake system hooked up, you can start to bleed the system. Dewey suggests opening all of the bleeders and filling the master cylinder. Let the system gravity bleed for about half an hour, and keep checking so the master-cylinder reservoir doesn’t go empty of brake fluid. Close all of the bleeders and then bleed the system as usual. For that added protection, Dewey goes around and taps each caliper with a plastic mallet, and then bleeds the system again just to make sure no air bubbles are stuck to the inside of the calipers.

If you follow these steps and exhibit care and patience, you’ll have a set of binders that will be as good as the day GM built them.

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