It is a paradox of sorts, adjusting self-adjust brake mechanisms. But, in some cases it is required and the procedures are in the service manual. The case in point here was a 2004 Chevy Trailblazer I was working on that needed pads and rotors.
After all the new parts were installed, I went for a test drive. The parking brake on this truck is a drum in the rotor’s hat. Since the rotor and shoe surfaces were not mated, it decided to do a few parking brake stops from 15-20mph. After the second stop, the amount of force and travel in the pedal did not feel right.
The Trailblazer is equipped with a self-adjusting parking brake mechanism designed to take up the slack in the cables. To perform a final adjustment, the shoe can be adjusted at the actuator via an adjusting nut. The clearance between the rear park brake shoe lining and the rotor should be 0.25 mm (0.010 in).
If you have to replace the cables, actuators or the shoes, you have to disable the self-adjusting mechanism.
1. Place the park brake lever in the full release position.
2. Raise and suitably support the vehicle.
3. Pull the park brake cable equalizer toward the rear of the vehicle and place a locking pliers with protected jaws on the cable to hold the cable in an extended position.
4. Lower the vehicle.
5. Rotate the self-adjust clip into the lock position with a flat-bladed tool.
6. Raise the vehicle.
7. Remove the locking pliers from the park brake cable.
8. Lower the vehicle.
9. Partially raise the park brake lever, stopping prior to the self-adjust clip (1) activating on the mount bracket tab.
10. Insert a flat-bladed tool behind the self-adjust clip and twist the tool 90 degrees to raise the self-adjust clip over the mount bracket tab.
11. Raise the handle until it is fully applied and remove the screwdriver.
After component replacement, to reengage the the automatic adjuster complete the sequence below:
1. Lower the park brake lever.
2. Raise the park brake lever.
3. Lift the park brake lever boot to gain access to the multiplier lever at the front of the park brake lever assembly.
4. Pivot the lever up and down 3 times.
5. Cycle the park brake lever up and down three times for auto adjustment.
6. Lower the park brake lever boot.
After this was done the parking brake felt just like new!