Troubleshooting Continued...
- Gravity Bleeding
- Adjust Caliper Parking Brakes
- Remove Residual Valve
- Installing Rotors
- TSM Tips For A Successful Installation
Calipers, especially rear calipers with all the parts and crevices can trap air inside them. Gravity bleeding is the best method we have found to bleed calipers. To gravity bleed, take the caliper off the bracket but leave the flex hose connected. Take the top off the master cylinder and keep filled. Hold the caliper so the flex hose is going slightly uphill to the caliper. Open the bleed screw so fluid and air will slowly come out of the bleeder. You can move the caliper around, hit it with a rubber hammer to knock air bubbles loose. When the fluid runs clear, do the other side and then do both calipers again. (Do not push the pedal until you install the calipers on the rotors) Remember that air bubbles rise. The bleed screw must be at the top where it breaks into the caliper cylinder to get the air out. (The bleeder might be pointing to the front) Rear calipers have their mounting screws one above the other. Front calipers sit on approximately a 45-degree angle.
Adjust Caliper Parking Brakes The GM rear caliper with integral parking brake is self-adjusting when you use the parking brake. As the pads wear it will click to the next stop, but they do not always work and they will not work if you do not use your parking brake. Back to Top of Page
Rear Caliper Parking Brake Lever Adjustment
Note: This procedure must be performed as part of the rear caliper replacement operation. Failure to adjust the parking brake lever, before you apply the hydraulic brakes, can result in no parking brake and possible premature brake wear or damage. Adjust the parking brake levers by pushing them forward. Each time you push them they should move off of the stop less. To be properly adjusted, they should only move off of the stop 3/8 to 1/2 inch. If they will not adjust try putting a lever between the rotor and the pad and putting pressure on the piston. Now push the lever releasing pressure on the pad as the caliper adjusts. These are the only two ways we know of to adjust the parking brake. If the calipers won't adjust you will have a low pedal and the piston will retract too far and will use up all your hydraulic pedal travel to put the brakes on. Once the parking brake calipers ore adjusted put a c-clamp on between the lever and the bracket to hold the brakes locked up. Note: An easy test for proper lever position is to grasp the brake pad and try to shake it. If any rattling is heard, the parking brake lever requires adjustment. Back to Top of Page
The residual valve holds ten pounds on a drum brake system when the brakes release to keep the spring on the shoes from collapsing the wheel cylinders. Residual valves can be found in the end of the cylinder in ford fruit jar single master cylinders, where the brake lines screw into the master cylinder on some dual cylinders, one in the rear line only on front disc rear drum systems, or in the combination valve rear line only. You can remove the residual valve from the master cylinder where the brake line screws in with a sheet metal screw. Screw it in and then pull. It will come right out. Back to Top of Page
There are times when the rotor won't go on the studs because the studs won't line up with the holes in the rotor. In most cases the studs aren't completely straight. Note the direction the end of the stud needs to go. Put a nut on the stud (to avoid damage) and hit the nut with a hammer. Keep doing this until the rotor slides on without forcing it. Back to Top of Page
TSM TIPS FOR A SUCCESSFUL INSTALLATION
- Pinch off the rubber line between the frame and axle. This will keep the fluid in the lines and make it easier when you bleed the system.
- Grind off any projections on the caliper that might hit the bracket.
- Remove the spring from your parking brake cable, it will coil bind with the rear calipers. Back to Top of Page
