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GM Rear Drum to Disc Brake Swap

Stock Rear Brakes Giving You Fits? Stock rear brakes giving you fits? We show you how to get big brakes for 10- and 12- bolt axles.

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When swapping brakes, the after-market really does come to the rescue. The brake companies have done the legwork, and they know what parts work best with each other and what will fit your car. We talked to the guys at Baer Brakes, Stainless Steel Brake Co. (SSBC), and KORE3 to get their advice.

They were all in agreement. You can see substantial gains in braking performance when switching to a four-wheel disc system. But there are a few key things to pay attention to. First, everyone stressed how important it is to design the rear system based on what brakes are on the front wheels.

"It's got to match the front system," says Bill Cummings of SSBC. Baer's Ben O'Connor agrees, "it's better to have too small a caliper on the rear than too big. With bigger calipers, you get too much clamping force, too much pedal travel, and the system is very hard to adjust." Because braking physics shift most of the car's weight to the front wheels, the rear brakes don't need to do as much work as the front brakes do. if you have too much clamping force on the rear brakes, the rear wheels will lock and the car can easily start to rotate. in other words, the rear caliper piston(s) must be smaller than the front or you'll be doing 180s every time you touch the brake pedal.

All three companies we spoke to offer basic rear disc brake kits that work in conjunction with stock or modified front systems. O'Connor says Baer's rear kits are modestly sized so as not to overwhelm a stock front system, but they can be easily upgraded if the owner decides to go big on the front brakes. SSBC and kORe3 have similar systems, and some can fit inside your stock wheels.

The components used are a second concern. SSBC's kits utilize a caliper similar to what GM offered on the Cadillac Seville and Firebird WS6. These calipers feature an integral, mechanical parking brake mechanism. engaging the parking brake pulls a lever on the back of the caliper that pushes on the caliper piston, clamping the pads to the rotor. Baer's kit uses components similar to C4 Corvettes and '92-'97 F-cars. They consist of PBR calipers with an improved manual parking brake design that engages a pair of pins, which push in the inboard pad, clamping the rotor. kORe3's systems offer a setup using C5 and C6 Corvette PBR calipers and a drum-inhat-style parking brake. The parking brake is actually a separate drum brake inside the hub of the rotor. kORe3's Tobin knighton prefers this system, saying the drum-in-hat system is less complicated and easier to maintain. The guys at Baer and SSBC acknowledge that the mechanical caliper parking brake arrangement is more complicated, but the system is less expensive to engineer because the parts have been around since the late '70s. Originally, the factory system experienced failure due to corrosion and lack of maintenance. The calipers would come out of adjustment or seize up, rendering them ineffective. Baer and SSBC have had lots of time to work most of the bugs out of the mechanism though, and they say their caliper designs are superior to the original GM pieces. Both Baer and SSBC offer higher-end kits that come with drumin- hat-style parking brakes, too.

Which system is best for you?
Obviously that depends on your budget and driving style. We can say with confidence that they all make a good product. Below are kORe3's, Baer's, and SSBC's best-selling kits. Note that these are not their least expensive kits. Go to each company's Web site for options and specific pricing information.

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