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.
Whenever performing any brake...
Whenever performing any brake work, it is advisable to use new hardware. Pictured here is the hardware for both the front and rear brakes, except for the front slider pins. The paint on the springs is used not only as an anti-corrosion procedure but also as an indicator of the spring's service life. A return spring with missing paint or a rusted surface indicates an overheated part that needs replacement to provide the proper tension. Note the caliper bushings and O-rings.
If new hardware and sliders...
If new hardware and sliders are not available or an emergency repair is being performed, then clean the bushings and pins on a wire wheel. HPP repeats that this is not the desirable procedure because the surface will usually present a high level of friction even after cleaning and lubrication.
FWD Pontiacs use a hubless...
FWD Pontiacs use a hubless rotor and brake pads that require a non-directional finish after machining. It is created after the final cut by spinning the rotor on the lathe while a Scotchbrite pad is brought into contact on a die grinder.
After cleaning, inspecting,...
After cleaning, inspecting, and repacking the wheel bearings, the rotor can be installed. Follow the shop manual procedure for bearing pre-load. THEY ARE NOT ALL THE SAME. A torque specification is usually provided. Remember, the wheel bearing and the race are made as a set. Always keep the wheel bearing with its race, even if the rotor comes with new races. Lubricate the caliper slide points with silicone brake grease. Install the new pads and retract the piston with either a C-clamp or vice grip. You may have to remove the lid from the master cylinder to do this. Before assembly of the brakes, always crack open the bleeder screws and then retighten. If the screw breaks off or can not be opened now is the time to either replace the wheel cylinder or caliper.
Now on to the rear drum brakes....
Now on to the rear drum brakes. Most drums will have balance weights on them, make sure that they did not fall off. To remove the drum the emergency/parking brake will need to be released. If the drum is stuck it may require some force with a rubber mallet to be removed. It is common for the drum to rust around the axle shaft. Use a rust buster such as WD-40 to help the task. Before reassembly always coat the axle hub where it meets the drum with anti-seize compound.
With the drum removed this,...
With the drum removed this, is what you will see. There is a primary and secondary brake shoe. The smaller, shorter of the two is the primary and always goes to the front of the car. It is designed to wrap into the drum and help activate the secondary shoe through leverage. Some linings are bonded to the metal shoe while others are riveted. This is a bonded lining. Before disassembly, match-up the new shoes to confirm they are correct. If you are a novice, as you take apart the brakes, place the old parts in the appropriate place on the new shoe.
With the shoes removed, the...
With the shoes removed, the parking brake cable will be hanging down. Inspect the cable for stretch and pull on it with pliers to make sure it is not seized. If it is stuck, it will need replacing. Wash the backing plate with brake clean.
Use emery cloth to polish...
Use emery cloth to polish all of the shoe slide points and the pivot of the center anchor. That is the round boss above the wheel cylinder. Check the wheel cylinder for leaks. It should be bone dry. If in doubt, now is the time to replace or rebuild it. Lubricate the slide points with silicone brake grease.
Take the adjuster apart, wash,...
Take the adjuster apart, wash, and lubricate it. The oval hole in the backing plate is for access to the adjuster. There should be a rubber plug in the hole. If the plug is missing, water will enter the drum mechanism and create rust and brake fade in wet weather. Plugs are sold at most auto parts stores. Have the machine shop measure and then turn the drums for trueness. Reinstall the new brake shoes and hardware. Use emery cloth or sandpaper to remove any fingerprints and to scuff up the linings. Many old-time mechanics like to take a file and chamfer the leading edges of the brake shoes so they wear in better and do not grab. This is optional. Install the drum and adjust the shoes so there is a slight drag on the drum when it is turned by hand.
Now is time to bleed the brakes....
Now is time to bleed the brakes. Even if the hydraulic part of the brake system was not opened, the lines should be bled. Brake fluid is a desiccant, absorbing moisture very readily. Because of this, brake fluid containers should be closed immediately after use and old fluid should be discarded. When exposed to moisture, the boiling point of the brake fluid is greatly reduced and rust forms in the system. Before removing the lid from the master cylinder, wash it with brake clean. Any dirt entering the hydraulics will cause premature failure. On disc brakes, the fluid level is the adjustment. As the pads wear, the fluid level will drop. With the new pads installed, the fluid level should come up to the proper range. This a quick way to determine the wear of the brake pads. If the fluid is low and there are no leaks the pads are worn.
Two people will be required...
Two people will be required to manually bleed the brakes. Start with the wheel that is farthest from the master cylinder, which would be the right rear. Keep the lid on the master cylinder so that it does not spray fluid on the paint. When pumping the brakes always keep your other foot or place a piece of wood under the pedal to limit the travel when the bleeder is opened. If you let the pedal go to the floor the piston plunger cup seal will go past the bore and will usually result in failure of the master cylinder a short while afterwards. Let your helper pump the pedal until it is hard. With the pedal in the down position open the bleeder screw until a stream of fluid exists. Repeat until there are no air bubbles. Close the bleeder screw with the brake pedal down or the system will suck air. Repeat for the other wheels while keeping mind of the fluid level in the master cylinder. There are three different brake fluids: DOT 3, 4 and 5. Most cars use DOT 3 from the factory.
One-Man Bleeder
Manually bleeding the brakes is an acceptable method for the home mechanic but it is not the most desirable approach. Any debris that has entered the master cylinder ends up being pushed through the entire system, possibly creating a future failure of a wheel cylinder or caliper. Most professional repair shops use a power bleeder that is operated by compressed air. They first suck all of the old fluid out of the master cylinder and replace it with fresh brake fluid before starting the procedure. These units are costly, cumbersome to use, and require multiple adapters for specific cars. Not to mention a power bleeder also requires a compressed air source.
Realizing that there must be a better way, the author got very excited when he stumbled upon this vacuum bleeder from Griot's Garage Priced at a very reasonable $69.99 plus shipping, the unit uses a hand pump to suck the air and old fluid from the brake lines. The kit also includes a bottle that sits in the master cylinder to keep the reservoir full with clean, fresh fluid.
The procedure is very simple. After sucking out and replacing the master cylinder fluid simply pump the handle a few times to create a vacuum and starting at the wheel farthest from the master cylinder, attach the clear flexible line to the bleeder screw and crack it open. When you see clean fluid coming through the plastic line you simply close a valve on the tool and then tighten the bleeder screw. Repeat for the other wheels.
Brake fluid service is something that many of us neglect. With the popularity of ABS on newer Pontiacs, now more than ever a fluid change should be part of your maintenance schedule. Older Pontiacs are no exception; they are just less costly to repair than ABS when they fall prey to old fluid.
With the introduction of Griot's Garage's new tool servicing the hydraulic part of the Pontiac braking system never was easier.
Parts Are Parts, Right?
If you own an older Pontiac then the aftermarket is your only source for brake parts, especially shoes, pads, drums, and rotors. But if your Poncho is on the newer side, I strongly suggest sticking with the factory AC-Delco or GM Replacement Parts components unless you are upgrading the system with improved performance components from a reputable source.
Over the last 20 years, braking systems have undergone many invisible changes, especially to the material used in the pads, rotors, and shoes. Many aftermarket brake companies who supply factory replacement parts to auto parts stores make or buy a generic friction material, and now many rotors and drums are coming from China and are of very poor quality. Not only do these parts affect the brake performance, but also the feel of the pedal and longevity. So if you have a newer Pontiac and it needs brakes, do yourself and the car a favor, and keep it genuine GM.