Budget GM Rear Disc Brakes

While old muscle cars are cool, drum brakes are not. There probably isn’t a breathed-on Camaro, Cutlass, Tempest, or Buick Special left in the world that doesn’t already have front disc brakes. But we’ve noticed that rear drums are still hanging in there. If it’s the cost involved with a $900 aftermarket conversion that has you clinging to those antiquated rear drums, we have a simple and inexpensive solution. Our pals who prowl purgatory yards have noticed that third-generation V8 Camaros and Firebirds were commonly fitted with generous, 11.5-inch rear rotors and aluminum, two-piston calipers. This caliper and rotor package remained consistent between 1988 and 1997, offering a 10-year span of F-bodies from which to choose.

The simplest plan is to find a donor Camaro or Firebird and yank the calipers and mounting brackets. We’ve found these pieces for as little as $50 at a local yard. The rear axle bolt flange on the third-generation Camaro rear axles is the same as the older 10- and 12-bolt GM rear axlehousings, so these calipers will bolt on virtually any ’64 and later 10- or 12-bolt rear axle assembly. Replacement rotors and pads are inexpensive enough to dismiss those used pieces. A new rotor will measure around 0.790 inch thick, while minimum thickness for a used rotor is 0.720. More than likely, the caliper will be in decent shape, so all you will need is a new pair of rotors, pads, and new hydraulic hose. A new replacement hose will be metric, which will require an adapter fitting to adapt the metric hose to an existing hard line, or an aftermarket AN line can be used. The hydraulic fitting into the brake caliper is a 10mm banjo fitting, and Russell makes a straight 10mm banjo fitting with a male -3 AN fitting on the end. The fitting will use a Russell 10 mm x 1.5-inch banjo bolt and a pair of copper flat washers to seal, then you’re all but hydraulically connected.

Assuming your car is currently rolling on rear drums, it is critical to include an adjustable proportioning valve somewhere between the master cylinder and the rear calipers. This provides a way to custom tune the pressure to the rear brakes to compensate for variables such as adding rear discs, tire diameter changes, and ride height. The key is to adjust the pressure to the rear brakes to prevent premature rear brake lockup that can induce a loss of control. The only other installation issue is the parking brake cable connection that in the interest of brevity we’ll leave to you.

As for pads and rotors, there is a world of options, from basic stock replacement parts that cost almost nothing to drilled and slotted rotors and high-performance pads that are still affordable. We’ve listed a few budget replacement parts, so you have no excuse not to hit the boneyard. Perhaps the biggest hassle in mounting this rear disc brake conversion on an early car is pulling the rear cover to yank the C-clips so the rear axles can be removed. The rest is easy.