Parking Brake System: Adjustments
Parking Brake Adjustment (2500/3500 SRW)
Special Tools
* J-21177-A - Drum-to-Brake Shoe Clearance Gauge
* J-28662 - Brake Pedal Effort Gauge
Warning: Refer to Brake Dust Warning (Brake Dust Warning).
Note: The park brake cable adjusting nut is a nylon lock type. Use only hand tools whenever loosening or tightening the adjusting nut.
Note: The park brake cables may appear slack after performing the complete adjustment procedure. After completing the entire adjustment procedure and verifying proper adjustment through park brake system performance testing, do not attempt to remove the park brake cable slack by tightening the adjusting nut. This is a normal condition.
1. Identify if the vehicle is equipped with a first-design or a second-design park brake pedal assembly:
* First-design park brake pedal assemblies have the brake pedal pad positioned inboard of the pedal arm, and have no holes in the pedal arm near the pivot. The upper and lower formed edges of the pedal arm face inboard.
* Second-design park brake pedal assemblies have the brake pedal pad positioned outboard of the pedal arm, and have an 8 mm (0.315 in) diameter hole in the pedal arm near the pivot. The upper and lower formed edges of the pedal arm face outboard.
2. Apply and fully release the park brake 2-3 times. Verify that the park brake pedal releases completely.
3. Turn the ignition switch to the ON position. Verify the red BRAKE warning lamp is not illuminated.
4. If the red BRAKE warning lamp is illuminated, verify the following:
* The park brake pedal is in the fully released position and against the stop.
* There are no binding park brake cables preventing full release of the park brake pedal.
5. If the red BRAKE warning lamp remained illuminated and there are no other visible causes, refer to Symptoms - Hydraulic Brakes (Symptoms - Hydraulic Brakes).
6. Turn OFF the ignition.
7. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle (Service and Repair).
8. With the park brake lever in the fully released position, loosen the adjusting nut at the park brake cable equalizer enough to completely relieve the park brake cable tension.
Park Brake Shoe Clearance Adjustment
1. Without disconnecting the hydraulic brake hoses, remove the brake calipers and brackets as an assembly and support with heavy mechanics wire or equivalent. Refer to Rear Brake Caliper Bracket Replacement (JD9) (Rear Brake Caliper Bracket Replacement (JD9))Rear Brake Caliper Bracket Replacement (JH6, JH7) (Rear Brake Caliper Bracket Replacement (JH6, JH7)).
2. Remove the rear brake rotors. Refer to Rear Brake Rotor Replacement (JD9) (Rear Brake Rotor Replacement (JD9))Rear Brake Rotor Replacement (JH6) (Rear Brake Rotor Replacement (JH6))Rear Brake Rotor Replacement (JH7) (Rear Brake Rotor Replacement (JH7)).
3. Set the J-21177-A - Drum-to-Brake Shoe Clearance Gauge so that it lightly contacts the parking brake shoe friction surface of the brake rotor (1) at its widest point.
4. Position the J-21177-A - Drum-to-Brake Shoe Clearance Gauge over the park brake shoes (1) at the widest point.
5. Rotate the park brake shoe adjuster until the park brake shoes just contact the J-21177-A - Drum-to-Brake Shoe Clearance Gauge.
6. Using a feeler gauge, set the parking brake shoe clearance to 0.66 mm (0.026 in).
7. Repeat steps 3-6 for the opposite side.
8. Install the rear brake rotors and secure with hand tightened wheel nuts installed with the cone facing outward.
9. With all tension relieved from the park brake cables, rotate the rear brake rotors. Observe the amount of effort required for rotation, and the amount of drag, if present.
10. If drag is present, repeat steps 3-6
Cable Tension Adjustment
1. Remove the wheel nuts.
2. Install the brake caliper and bracket assemblies. Refer to Rear Brake Caliper Bracket Replacement (JD9) (Rear Brake Caliper Bracket Replacement (JD9))Rear Brake Caliper Bracket Replacement (JH6, JH7) (Rear Brake Caliper Bracket Replacement (JH6, JH7)).
3. Install the tire and wheel assemblies Refer to Lifting and Jacking the Vehicle (Service and Repair).
4. With the aid of an assistant, rotate both rear tire and wheel assemblies while slowly tightening the park brake cable adjustment nut.
5. Tighten the adjustment nut until both rear tire and wheel assemblies cannot be rotated.
6. Slowly loosen the park brake cable adjustment nut while simultaneously attempting to rotate the rear tire and wheel assemblies.
7. When the rear tire and wheel assemblies just begin to move, loosen the park brake cable adjustment nut the additional number of turns specified:
* 2500 series with first-design park brake pedal assembly: 20 additional turns
* 3500 series with first-design park brake pedal assembly: 16 additional turns
* 2500 and 3500 series with second-design park brake pedal assembly: 12 additional turns
Park Brake Adjustment Verification Check
1. Apply and release the park brake lever 3-5 times.
2. Install the J-28662 - Brake Pedal Effort Gauge to the park brake lever pedal.
3. Observe the number of detents required to apply the park brake pedal to the amount of force specified, as indicated on the J-28662 - Brake Pedal Effort Gauge.
* 2500 series with first-design park brake pedal assembly: 9-10 detents to apply the park brake pedal to 400 N (90 lb) of force
* 2500 series with second-design park brake pedal assembly: 6-8 detents to apply the park brake pedal to 300 N (67 lb) of force
* 3500 series with first-design park brake pedal assembly: 6-8 detents to apply the park brake pedal to 400 N (90 lb) of force
* 3500 series with second-design park brake pedal assembly: 4-6 detents to apply the park brake pedal to 300 N (67 lb) of force
4. If the number of detents required to achieve correct force is less than the specification, then the cable tension is too high. Repeat adjustment steps as necessary.
5. If the number is detents required to achieve correct force is greater than the specification, then the cable tension is too low. Repeat adjustment steps as necessary.