summit racing disc brake conversion kit for GM a bodies
axle flange installed with brake mounting bracket
backside of axle flange for a brake caliper install
axle mounting flange and hub with caliper and brakes removed
checking brake pad clearance on a caliper
shimming the mounting bracket of a brake caliper
a close up of a banjo bolt fitting on a brake caliper
tightening a brake line fitting on an axle
rear axle assembled for a disc brake conversion
close up of ring and pinion gears in a rear differential

This is the Summit Racing rear disc brake conversion kit for our ’66 Chevelle conversion. The kit comes complete with all the required fasteners and even a pair of flexible brake hoses that adapt to your original brakes lines. The calipers are two-piston units from Stainless Steel Brakes and we went with the cross-drilled rotors because they look cool.

After removing the four bolts, the drum brake backing plate can be removed. You will also have to undo the 3/16-inch brake line and plug it so it doesn’t leak. On our housing, we removed the lines altogether. Now we can begin by installing the brake caliper brackets. The top of the bracket will face toward the front of car. The kit comes with all new fasteners.

Now slide the axles back into the housing and install the C-clips, cross pin, and tighten the retaining bolt. Do not replace the cover just yet just in case you have to go back in for some reason. We ordered our kit without the splash shields but install them if your kit is so equipped. Now install the thick spacers over the 7/16-inch caliper mounting bolts.

The caliper mounting straps are two different lengths. The shorter straps slide over the top two bolts while the longer straps position over the lower two mounting bolts. Don’t tighten any of the bolts just yet. Also install the parking brake L-brackets on the top front 7/16-inch mounting bolt. This view is from behind the passenger side of the housing.

The calipers are specific left and right side units. Make sure they are correctly mounted with the bleed screw in the highest position. Otherwise you won’t be able to properly bleed the system. Once you have installed the calipers, carefully inspect their position over the rotor. If the caliper is too close to the inboard side of the rotor, you may need to shim the caliper outboard

If you need to adjust the caliper outboard, place the shim between the caliper mounting bracket and the caliper as shown. Once the caliper is positioned properly, torque all the mounting strap bolts. This will properly position the straps and the caliper.

Install the flexible brake hose to the caliper with the banjo bolt. Note that the kits include copper sealing washers that must be placed on both sides of the banjo flange. If not installed as shown, the fitting will leak.

Using adapter fitting supplied in the Summit Racing kit, we made new brake lines between the center inlet and the flexible brake hoses leading to the calipers. If you are a god fabricator, you could also make a small tab that could be welded to the housing to secure this connection. We elected just to zip-tie the hose for the photos.

Here is our finished installation. We also added a Trick Flow Specialties aluminum rear cover just because we could. In the car, you will need to bleed the brakes to complete the install. This is a great time to purge all the old brake fluid with new DOT 4 fluid. You should also bed in the brake pads to get maximum performance out of the pads. A quick search of this website will deliver the proper procedure. Now you’re ready for a test drive!

For our story, we used our freshly rebuilt 12-bolt that is currently out of the car. If you are performing this conversion on your car, make sure the car is secure on jack stands and the rear tires are removed. We pulled the rear cover and removed the cross pin and slid the axles in to release the C-clips. With the C-clips removed, you can slide the axles out of the housing.

Drum brakes have their place—just not on any kind of performance car that’s driven with enthusiasm.

In our experience, drum brakes are good for one and perhaps two aggressive stomps on the brake pedal from speed and then, like Douglas MacArthur’s old soldier, they just fade away. That’s why Summit Racing offers an affordable disc brake conversion kit for most of the popular performance rear axle assemblies including the Dana 60, Mopar 8 ¾, the Ford 8- and 9-inch and the GM 10- and 12-bolt rear-ends. The Summit Racing Disc Brake Conversion Kit is a simple application of adapting a factory style caliper to these early rear-end housings to make the swap a simple one.

We ordered the GM 10/12-bolt kit and spent about 90 minutes carefully installing the system. If you’re good with tools, you could easily do it in under an hour. The kit is a great way to upgrade from those dusty old drum brakes, improve stopping performance, and look good doing it. And all for an affordable price.

What’s not to like?

We didn’t cover the steps involved with removing the axles—a process you must complete to remove the old drum backing plates and install the caliper mounting brackets. This requires draining the gear lube and removing the rear cover. With both the Ford 8.8 and the GM 10- and 12-bolt c-clip axle housings, the cover has to come off to get to the C-clips. Just remove the cover, remove the small bolt that retains the large cross pin, and slide the pin out of the way. This will create enough room to slide the axles in enough to remove the c-clips. Then the axles can be removed.

Unless you’ve done this job before, take the time to read the instructions. They offer plenty of tips on doing the job quickly and efficiently. That leaves you more time to enjoy your ride with its much more reliable stopping power.

Author: Jeff Smith

Jeff Smith has had a passion for cars since he began working at his grandfather's gas station at the age 10. After graduating from Iowa State University with a journalism degree in 1978, he combined his two passions: cars and writing. Smith began writing for Car Craft magazine in 1979 and became editor in 1984. In 1987, he assumed the role of editor for Hot Rod magazine before returning to his first love of writing technical stories. Since 2003, Jeff has held various positions at Car Craft (including editor), has written books on small block Chevy performance, and even cultivated an impressive collection of 1965 and 1966 Chevelles. Now he serves as a regular contributor to OnAllCylinders.