Back Stops

Building fast cars has traditionally involved adapting or modifying factory parts that were never intended to go fast. These parts, after being subjected to a hot rodder’s adaptation, usually end up on someone’s vehicle trying to perform a task they were never designed to accomplish. Nowhere is this more prevalent than with rear disc brakes. If your early musclecar came with front discs from the factory, or you have previously upgraded your front brakes, now’s the time to put discs in the rear.

In the past, if you wanted rear discs for your car you had two choices: spend six-month’s salary on the baddest racing rear-wheel disc brake setup, or custom build your own brake system using obscure factory rear discs and calipers from something like a Corvette. Since then, automotive enlightenment has progressed into braking systems. Today, you can upgrade any vintage GM car or truck with a brand new rear disc brake system starting around $500.

Aftermarket To The Rescue

The performance aftermarket has blessed us with the development of rear wheel disc brake kits designed as direct bolt-on replacements for early GM iron. You can now install a properly engineered rear disc brake system using all new components that will not only improve your car’s braking ability, but look hot as well. We found several rear disc kits offered for early musclecars such as Chevelles, Camaros, Novas, and trucks too that can be installed in a day without special tools or equipment. All the kits featured here have parking brake capabilities, and most even work with the factory parking brake cables. Beware of less expensive kits that don’t offer parking brake capabilities.

Most kits we found do not come with an adjustable proportioning valve. We recommend purchasing one separately if that’s the case. An adjustable proportioning valve can even improve the braking ability of a stock drum brake–equipped car and is a requirement for fine tuning a new four-wheel disc–equipped brake system.

Affordable Rear Disc Brakes

We researched the market and found rear disc brake kits ranging from a low of $499 up to about $800. The lower-cost kits we found usually included cast-iron calipers, vented steel one-piece rotors, steel or cast-iron caliper-mounting brackets, and all the hardware and brake hoses needed for installation. The higher-cost kits include cast or billet aluminum calipers, vented-steel rotors (some mounted on aluminum hubs to save weight), high-performance brake pads, and all the necessary hardware and stainless brake lines. The most expensive kit we found cost $795 from Master Power and uses cast-aluminum calipers made by PBR of Australia, which were originally designed for fourth-generation Corvettes and the 1LE Camaro. Baer Racing also offers the PBR calipers in its new Rod & Drag rear disc brake upgrade kit for 10- and 12-bolt rearends starting at around $600.

Big Wheels

One of the biggest concerns—and expenses—when upgrading your brake system is whether the new components will clear your wheels. Big brakes mean tall rotors, calipers, and headaches if they rub on your 15-inch billet wheels. Well, there’re no worries about that in most of the kits we found. Most inexpensive rear disc brake upgrade kits are designed to fit inside a minimum 15-inch wheel. Some, like the Baer kit, will even clear those 14-inch Rally wheels you are so attached to. It would be wise to check directly with the brake kit manufacturer before making your purchase, otherwise you may end up spending more money on new wheels and tires just to clear the brakes.

Properly Proportioned

Some really inexpensive kits are designed to adapt factory front disc brake calipers to the rear axle using steel adapter plates. Not only is this a bad idea because front brakes don’t have parking brake capability, but front calipers are designed for the front of cars where about 60 to 70 percent of all the braking effort takes place. The heavier the car, the more braking the front does. When you adapt a front caliper to the rear, you’re going to overpower the rear brakes by virtue of the large piston calipers, which could cause rear-wheel lock-up.

One manufacturer we spoke with, who was against this practice, admitted they tried using identical front and rear calipers on a road race test car. It took three adjustable proportioning valves mounted in series to reduce rear brake pressure enough to keep the rear wheels from locking up. A good rule of thumb for properly proportioned brake calipers is to use rear calipers with a total piston surface area less than 65 percent of the front calipers. Today’s new rear disc brake kits are safe and trick. When installed and valved properly, they help your car stop better and improve braking consistency, which is critical to high-speed cornering and road race performance. They also let everyone know you’re serious about stopping.