GM A-body front disc brake upgrades
Larry Weiner - January 03, 2013 10:30 AM
For Your Information:
Stainless Steel Brakes Corporation
Year One Inc.
Oasis Alloy Wheels
1 SSBC single-piston disc brake conversion kit for early second gen F-body spindles.
2 Now is a great time to do some cleaning if you’re upgrading your brakes. Our suspension was being rebuilt, so all of the parts were cleaned and painted prior to installation.
3 One of the benefits of installing a new kit is that all of the components will be new. Be sure to pack the bearings with a sufficient amount of grease.
4 Install grease seal on the back of the rotor hub.
5 Note that the rotors are directional and are engraved with left and right markings to identify them. Next, install the greased outer wheel bearing, the retaining washer and the spindle nut.
WHEEL STUD INFORMATION
VehicleThread Size1964-1972 A-body7/16
1970-1981 F-body 7/16
1982-2002 F-body12 x 1.50
1977-1990 B-body7/16 or 1/2
1991-1996 B-body12 x 1.50
Stud information courtesy of www.gorilla-auto.com
6 Torque spindle nut to 12 lbs-ft. While turning rotor, loosen nut one flat and insert cotter pin.
7 Install the bracket on the pad that mounts to the caliper piston. The pad is mounted to the piston, and the outside pad clips to the caliper housing.
8 Carefully slip the caliper with pads over the rotor. Note that there are left and right side calipers. The correct caliper will have the bleeder located at the top when installed.
9 The banjo bolt has a passage that allows the brake fluid to flow from the brake line into the caliper. Be sure to use a copper crush washer on both sides of the fitting and screw into the back of caliper.
10 Temporarily connect the flex line and turn steering assembly through a full left to right turn, noting that the flex line does not twist or take a double bend.
11 After bleeding the calipers, and continuing to top off the master cylinder, make 20 to 30 applications of the brake pedal. If the pedal is hard, no further bleeding is required. If the pedal is spongy, repeat bleeding process until a hard pedal is achieved.
12 Our conversion still looks box stock from the outside of the wheel.
13 SSBC two-piston disc brake conversion kit for B-body spindles.
14 As mentioned, this brake upgrade requires updating the spindle to the B-body version. Our spindle is installed and ready for disc brakes.
15 The two-piston upgrade provides better clamping force due to better distribution shared between both pistons.
16 Due to their larger overall diameter, minimum wheel size is limited to 16 inches, which eliminates many factory Rally wheel offerings, but braking is greatly improved.
17 Here is a shot of the GTO with our 18-inch custom wheel. A modern classic!
18 The second gen F-body spindle (right) is designed for 11-inch rotors and the B-body spindle is designed for the 11.8-inch rotor and will require the use of a minimum of 16-inch wheels. Both spindles use the same upper and lower ball joints and tie rod ends.
19 The inside wheel bearings for the both F-body and B-body spindles are the same, but the outer wheel bearings for the B-body spindles are larger.
20 Camaro 1LE rotor has the correct 5x4¾ bolt pattern (but stud thread pitch is different) for GM A-body vehicles. The Caprice/Impala SS rotor has the 5x5 large car bolt pattern and the cogged wheel for the speed sensor.
21 Our 1965 GTO was upgraded with a new dual-chamber master cylinder, a proportioning valve and a power booster from SSBC.
Among the most coveted of all muscle cars are 1964 through 1972 GM A-bodies.
They include the Chevelle SS396, Pontiac GTO, Olds 442 and Buick Gran Sport, and represented the next logical step in the evolution of performance cars at General Motors.
With their reduced weight and smaller size, they were the perfect combination for the enthusiasts of the era. Take the subject of this story, a classic 1965 GTO. Powered by the fabled Pontiac 389 with Tri-Power, this baby belts out 360 horsepower and even has the rare, first-year Ram Air. Backed by a Muncie M20 four-speed, this Goat transmits its power to a Safety Trac limited slip differential. Most muscle car enthusiasts will agree that when it comes to tire smoking performance, a Tri-Power GTO definitely has the right stuff.
But the brakes, well, that’s another story. This GTO was equipped with 9½-inch drum brakes, essentially the same brakes used on a base six-cylinder Tempest. Disc brakes were not available on the early A-bodies, and in most cases, on many of the later cars they were options that were not always chosen.
We replaced the stock upper control arms on the GTO with a set of tubular arms manufactured by Hotchkis Performance that are specifically designed for use with 1970-1976 GM F-body and 1978-1996 GM B-body spindles. This easy, inexpensive upgrade will significantly improve the handling of 1964 to 1972 GM A-body vehicles. We worked with Stainless Steel Brakes Corp, better known as SSBC, to identify several direct bolt-on disc brake kits they offer that are compatible with ’64 to ’72 A-bodies equipped with this suspension upgrade.
In this story, we will be installing two different SSBC disc brake kits on the GTO. The first disc brake kit utilizes a cast iron single piston caliper and 11-inch slotted and ventilated rotors. This kit is compatible with 15-inch vintage wheels, such as reproduction Pontiac Rally I wheels and original Chevrolet Rally wheels along with many ’60s era mag wheels. The second kit utilizes larger two-piston aluminum calipers and 11.8-inch slotted and ventilated rotors. This kit requires a minimum of 16-inch or larger wheels that are very popular today with enthusiasts who prefer vintage muscle accented with a modern flavor.
In both kits, the calipers were powdercoated for long life and are very easy to clean. We will perform both disc brake upgrades in this story to illustrate how easy the kits are to install, regardless of which direction you choose to take with your vehicle.
If you want your A-body to have a vintage, era-correct appearance, the choice is simple; just go with the early style second gen F-body spindle with the smaller disc brake kit. You’ll have improved braking and handling, while retaining the stock outward appearance of your vehicle, including using a period correct wheel style. If you prefer a more modern approach, choose the later spindle, with the larger rotor and two-piston caliper package. Just remember that this kit does require the use of a minimum of a 16-inch wheel. Follow along as we hit the brakes without breaking the bank.