Brake Caliper Rebuild - How to Rebuild Your Calipers for Better Performance and Durability

Rebuilding your brake calipers before the start of each racing season—especially if you race on dirt—will not only help improve the useful life of those calipers, but can also increase performance on the track.

Rebuilding your brake calipers before the start of each racing season—especially if you ra

Nothing lasts forever—except for maybe American Idol, which just won't seem to die—and this is especially true in racing. But proper care and feeding of your race car's brakes can help them last longer and perform better. Thus, helping you stretch your racing budget and improve your performance on the racetrack. Most racers regularly work on their braking system, including bleeding and/or flushing the brake fluid, inspecting the rotors for cracks or warping, and deglazing or simply replacing brake pads. But one area that shouldn't be overlooked is the calipers themselves.

Most brake calipers, especially performance-oriented units from reputable manufacturers, are deceptively simple pieces of technology. Essentially, they are a cavity capable of transmitting the pressure of the brake fluid to pistons that squeeze the brake pads against the rotors. And as such, there really isn't a lot that can go wrong with a caliper as long as it's well-built to begin with.

However, rebuilding your calipers before the start of a new racing season is definitely a good idea, especially if you race on dirt. There's a lot of grit, sand, oil dry, and all types of stuff blown around underneath a race car and if it accumulates between the piston and seal it can cause fluid leaks, sticking calipers—which will overheat the brakes and harm acceleration—and premature brake failure.

Rebuilding your calipers is a relatively easy job that can be done by practically anyone with simple handtools. We would recommend having a set of new piston seals on hand but they may not be needed. Following are a few tips for rebuilding your calipers for maximum performance season after season and long brake life. The Dirt Late Model team we worked with uses Wilwood brakes, but the same concepts will work with any brand. You may also notice that the Wilwood Dynalite calipers in the photos are a few seasons old and show signs of use, but simply a testament to the value of using quality products and taking care of them.

Begin by pulling all four calipers off the car and knocking off any loose dirt or grime. Next, remove any hardware so you can pull the pad out.

Begin by pulling all four calipers off the car and knocking off any loose dirt or grime. N
After getting everything out of the way, you can pull the pads out. If they’re jammed in place, that’s a sign that you may have more serious problems to look at. These pads have plenty of material left. After scuffing them up a bit to remove any glazing from the last race, they will go right back in.

After getting everything out of the way, you can pull the pads out. If they’re jammed in p
Now begin the tricky process of getting the caliper pistons out of their cylinders. The pistons move in and out to press the pads against the rotor. One way to do it is to use deep-reach Vise-Grips like these to hold the other pistons in position and then place an air chuck against the brake fluid inlet fitting and blowing pressurized air into the caliper. The air pressure should blow the piston out of the bore.

Now begin the tricky process of getting the caliper pistons out of their cylinders. The pi

With the piston out, you’ll have to gently hold it in place so that the caliper will hold air pressure as you blow out the other pistons one at a time. This is easily the most aggravating part of the entire process.

With the piston out, you’ll have to gently hold it in place so that the caliper will hold
After all of the pistons are out of the caliper, gently remove the rubber piston seals which should be inside a ring in the caliper’s piston bore. Inspect each rubber-like ring. If it’s hard, distorted, torn, or showing other signs of wear, replace it.

After all of the pistons are out of the caliper, gently remove the rubber piston seals whi
Most performance brake manufacturers sell a caliper rebuild kit like this one from Wilwood. It cost less than $20, so it was nice to have a few spare O-rings on hand in case we needed to replace one.

Most performance brake manufacturers sell a caliper rebuild kit like this one from Wilwood

The pistons are steel and should be reusable unless something really wrong has happened to your calipers. Here, ours are scrubbed with a Scotch Brite pad in the parts washer to remove the wear ring that had developed where the end of the piston was exposed to the elements.

The pistons are steel and should be reusable unless something really wrong has happened to
On the left is a freshly scrubbed and polished caliper piston. On the right is what it looked like before cleaning. It’s important to get the pistons clean so that they will slide inside the seal without sticking. If they don’t, the seal can hold the pistons out, which keeps the brake pads from retracting and causes brake drag.

On the left is a freshly scrubbed and polished caliper piston. On the right is what it loo
These are the backing plates that the edges of the brake pad slide along. They not only allow easy movement of the pads as they’re pushed out by the pistons, they also keep the edges of the backing plates from digging into the aluminum caliper. Remove them for cleaning and so that you can inspect the caliper material underneath.

These are the backing plates that the edges of the brake pad slide along. They not only al

On the bottom is one backing plate just as it came out of the caliper, while the one on the top is what it should look like after it has been cleaned. Again, it’s important that these are as clean and as smooth as possible so that the pads will be able to slide out—and back in—without snagging or experiencing drag.

On the bottom is one backing plate just as it came out of the caliper, while the one on th
Now that the caliper has been completely stripped, wash it down with brake cleaner and hose it with dry, clean air. Make sure that any crossover tubes are clear of debris and you don’t leave any cleaning fluids behind inside the caliper that can contaminate the brake fluid when the calipers are reinstalled.

Now that the caliper has been completely stripped, wash it down with brake cleaner and hos
Reinstalling the O-rings dry can cause them to rip the first time the brakes are applied. Lubricate them with some fresh brake fluid.

Reinstalling the O-rings dry can cause them to rip the first time the brakes are applied.

Now you can install the O-rings back into their grooves in the piston bores. Be careful to make sure they are fully seated and don’t get twisted when reinstalling them.

Now you can install the O-rings back into their grooves in the piston bores. Be careful to
The freshly cleaned pistons will be less likely to get hung on the O-ring (and will be easier to slide in place) if you also lubricate it with fresh brake fluid.

The freshly cleaned pistons will be less likely to get hung on the O-ring (and will be eas
The brake bleeders are exposed to the elements and you’ll often find that they are clogged with debris. If you can’t blow air through them, try reaming out the gunk with a small drill bit.

The brake bleeders are exposed to the elements and you’ll often find that they are clogged

Follow that up with a blast of brake cleaning fluid and then dry shop air to make sure they are completely clean and obstruction free.

Follow that up with a blast of brake cleaning fluid and then dry shop air to make sure the
A bit of Teflon sealer on the fluid inlet fitting will help prevent leaks and help keep it from galling to the caliper so you can get it out again on the next rebuild.

A bit of Teflon sealer on the fluid inlet fitting will help prevent leaks and help keep it
Finally, you can complete reassembly of the caliper and reinstall it on your race car confident that it’s ready to provide dependable service for another season of racing. CT

Finally, you can complete reassembly of the caliper and reinstall it on your race car conf