Our subject car was a traditional...
Our subject car was a traditional RWD '84 Grand Prix owned by student Doug Jones. With over 200,000 miles it was an excellent candidate for our makeover. We worked on a lift but the same procedures can just as easily be accomplished with the vehicle securely and safely hoisted on jack stands. HPP suggests that the work be performed in axle sets, instead of jumping around from a front to a rear wheel on the same side of the car.
After changing oil, a brake job is probably one of the first service procedures learned by a Pontiac hobbyist. The only problem is that most of us never learned the proper steps for a professional brake job and thus, have never enjoyed the full stopping power of our Pontiac. This is essential with any vehicle, but a high-powered Poncho needs some good brakes to reign in all of those ponies. While it may be a stretch to call this tuning your brakes, all too often as with engine tuning a substantial amount of the brake system's ability is left on the table because it requires finesse to extract. To this cause, HPP traveled to the University of Northwestern Ohio in Lima and worked with brake system instructor Jim Frueh and students Doug Jones and Louie Messina to show our readers the proper way to do a brake service at home.
Pontiac front brakes are single...
Pontiac front brakes are single piston caliper disc systems from '69 forward. The '67-68 cars used 4-piston calipers. The caliper is what holds the brake pads and squeezes against the rotor through hydraulic pressure created by the master cylinder when the brake pedal is depressed. RWD Pontiacs have serviceable front wheel bearings, while FWD versions use a non-serviceable hub bearing. Before disassembly, do a visual inspection of the rotor, caliper, and brake lines.
A common complaint with Pontiac...
A common complaint with Pontiac disc brakes is a rattle or noise created by a loose fitting outside brake pad or from missing anti-rattle clips. If you can move the pad with your finger than it will most likely make noise over bumps or produce a clicking sound just as the brake pedal is applied. To correct this if the brake pads are still good, pry up on the pad with a screwdriver and using a small hammer bend over the tangs on the pad that ride on the top of the caliper.
Pontiac calipers are a floating...
Pontiac calipers are a floating design. A single piston is used to create force on the inside of the rotor. The caliper moves on the pins as a result, allowing the outside pad to interact with the rotor. If the outside pad is worn more than the inside it is an indication that the sliders are frozen and not allowing the caliper to return after the piston is released. The slider pins hold the caliper to the mounting bracket. Always use the proper tool to remove the slide pins. Early Pontiacs used a hex-head bolt while later versions employed a Torx bolt.
Once the caliper is detached,...
Once the caliper is detached, do not let it hang by the brake hose. Tie it to the frame with no tension on the brake hose. We used mechanics wire. The sign of a poor mechanic is a caliper hanging by the brake line. Inspect the rubber brake lines for cracks and texture. Even though they may look good, over time the rubber becomes softened and allows the line to balloon out slightly as the brakes are applied. This decreases the amount of hydraulic pressure applied to the caliper and greatly impacts stopping ability. The brake hoses should be changed every few years, especially if you live in an urban area with a high ozone content in the atmosphere.
The caliper has a bushing...
The caliper has a bushing that the slider pin goes through. It needs to float in the bore for the caliper to function properly and return when the brakes are released. Remove the bushing by pressing on it with your finger.
Use a pick to remove the O-rings...
Use a pick to remove the O-rings from each side of the caliper. One will be larger then the other. Wash the pin bores with a spray brake cleaner.
A stiff wire brush should...
A stiff wire brush should be employed to clean the slide areas on the caliper and the mounting bracket. Remove all rust and dirt.
The rotor will need to be...
The rotor will need to be measured and if there is enough mass left then turned on a lathe. All Pontiac rotors have cast into the hub a minimum thickness dimension. The mass of the rotor is used to dissipate heat and to minimize warping. A thin rotor will overheat and warp very easily.
Most auto parts stores offer...
Most auto parts stores offer a brake lathe service for drums and rotors. It is essential that the friction surface of the rotor is prepared properly for the brakes to work their best. When cutting drums or rotors, the goal is to remove the least amount of material to create a true surface. If the rotor is warped, it will cause a pulsing in the brake pedal when stopping. A second benefit of turning the rotor is the removal of the glaze that is created by the brake pad. Better brands of new drums and rotors leave extra material so they can be cut before they go into service to guarantee a true surface. If the parts were dropped during shipment they will be warped.