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C5 Parking Brake Adjustment

Some people have experienced slippage with their parking brake. Following are two corrective actions: one from a Corvette forum member, one from GM. I have included the forum member's procedure, but please note, use this repair at your own discretion! I'm not saying this is or is not the way to do it, just someone else's experience. That said, I'm including the by-the-book procedure for this problem straight out of the GM service manual.


From the Corvette Forum:

I posted this fix several years ago, but it was lost in the software upgrade. When My C5 was new, the e-brake barely worked. I took it to the dealer, and was told that brakes are a wear item and that I would have to pay for new shoes. The car had less than 1000 miles on it. The e-brake only engages when the car is stopped so how could they be worn? Anyway, I decided to take a look and see if I could do anything. I was not crazy about the dealer touching my car anyway. OK, here we go…the e-brake works similar to the e-brake on most cars with rear drum brakes. With that in mind, jack up the rear of the car and remove the wheels. Remove the bolts for the calipers, then the calipers and pads. You will see the caliper bracket…it has two bolts that hold this to the brake backing plate, they are very, very tight but they will come off. (They are torqued to 125 ft pounds with loctite). Once the bracket is off you can remove the rotor (make sure the e-brake is not engaged). Next you will see how the system works: it has a set of shoe brakes and the rotor has an internal drum. In the last few years I have found that many, many C5 come from the factory with poorly adjusted e-brakes. Now locate the star adjuster…turn it out to make the shoes grow in diameter (mine were out 33 clicks). I did ten clicks at a time and the slid the rotor back on. I did three sets of ten before I could feel any drag, I then clicked five more and could not get the rotor on. I then backed off two clicks and got the rotor on (it was tight when I started it on the shoes but when I finally seated it, it was perfect). I then did the other side; it was out exactly the same amount, I then put everything back. Now for the test...when I engaged the e-brake, it locked up the brakes at a point about 45 degrees, 90 degrees being straight up. The lock up was so positive, I knew I did it right. Next, to check the release, I took the car to a hill, set the e-brake, put the car in neutral and it stayed there. Then to check on the release, I slowly disengaged the e-brake and found that the shoes where totally retracted after only an inch of lever release.

After this fix I could stop the car using only the e-brake with the car doing ten miles an hour. The e-brake also has an auto adjust feature, but it will only work if your e-brake lever is between 45 and 55 degrees; if your e-brake is out further than that, the e-brake will not auto adjust (AUTO ADJUST feature: roll the car backwards on a hill or in reverse @ 5 mph, pull up on the e-brake lever--this will slam your car to an abrupt stop. The engagement of the shoes to the drum while the car is moving backwards will cause the shoe assembly to flex…it is the flex that causes the blade to click the adjusting star one click). Do this three or four times and it will expand your shoes. You cannot over tighten these shoes...if it needs two clicks to get to max and you do four clicks, it will only adjust the star two clicks. Also remember to use loctite on the brackets and caliper bolts. If you have any questions on this repair, feel free to e-mail me or instant message me.

Good Luck! Many people have e-mailed me with their positive results from this fix.

Bill (Evil-Twin)

from GM :

Park Brake Shoe Adjustment

Tools required:

J 21177-A Drum-to-Brake Shoe Clearance Gauge (or brake shoe caliper from your local auto parts store)

Important:

  • Adjustments are not normally necessary after replacing the park brake lever or cables. The park brake is adjusted automatically by cycling the part brake lever three or four times.

  • Never operate the park brake lever while the rotor is removed.

1. Remove the brake rotor. Procedure:

    1. Raise the vehicle and support.

    2. Remove the tire and wheel assembly.

Caution: Do not place your fingers in front of the piston in order to catch or protect the piston while applying compressed air. This could result in serious injury.

  1. Depress the piston into the brake caliper housing to provide clearance between the brake pads and the brake rotor. When depressing the piston some fluid should be removed from the master cylinder.

Caution: These fasteners MUST be replaced with new fasteners anytime they become loose or are removed. Failure to replace these fasteners after they become loose or are removed may cause loss of vehicle control and personal injury

  1. Remove the brake caliper mounting bracket bolts and discard.

  2. Remove the brake caliper mounting bracket and the caliper as a unit and support it to the vehicle so there is no weight on the brake hose.

  3. Disconnect the park brake cable from the apply lever.

Important:

    • Never operate the parking brake with the rotor removed.

    • Do not force the rotor off. If the rotor is difficult to remove, ease it off by gently rotating it as you pull outward.

    1. Remove the brake rotor.

2. Check if the brake drum inner diameter is within specifications.

Important: If the gap between the adjuster nut and screw exceeds 5mm (0.25 in) during the adjustment procedure, the brake shoe assembly must be replaced.

3. Adjust the parking brake shoe-to-drum clearance to 0.38 mm (0.015 in) using the drum-to-brake clearance gauge mentioned at top.

4. Center the brake shoe.

5. Measure the brake shoe lining diameter across the horizontal centerline using

the clearance gauge. The diameter should measure 189.6mm (7.464 in) to 189.8 mm (7472 in).

6. Install the brake rotor.

7. Install two wheel nuts to retain the rotor.

Tighten: Tighten the wheel nuts finger tight. Do not overtighten.

8. Cycle the part brake lever three times.

9. Rotate the rotor and check for drag.

If drag is present check and adjust the shoe-to-drum clearance.

10. Install the rotor.

Procedure:

1. Adjust the parking brake shoe-to-drum clearance.

Notice: Whenever the brake rotor has been separated from the wheel bearing flange, clean any rust or foreign material from the mating surface of the rotor and flange with a hub cleaning kit. Failure to do this may result in increased lateral runout of the rotor and brake pulsation.

Clean the metal surfaces between the brake rotor and the hub bearing flange.

Install the brake rotor.

Install the disc brake caliper mounting bracket and the brake caliper as a unit.

Install NEW brake caliper mounting bracket bolts.

Tighten: Tighten the brake caliper mounting bracket bolts to 175 N-m (129 lb ft).

Install the tire and wheel assembly.

Tighten: Tighten the wheel nuts in sequence to 140 N-m (100 lb ft).

Lower the vehicle

Check the fluid level.

Caution: Do not move the vehicle until a firm brake pedal is obtained. Air in the brake system can cause the loss of brakes with possible personal injury.

With the engine running, pump the brake pedal slowly and firmly to seat the brake pads.

Burnish the brakes as necessary.