See Figures 1, 2 and 3
FRONT DRUM BRAKES
The brakes should be cool before adjustment.
- Raise and support the front end on jackstands.
- Remove the adjuster slot plugs from the backing plates.
- Insert a brake adjusting tool in the slot and engage the starwheel. Rotate the starwheel until the drum is locked by the brake shoes, then back it off 5 notches. Repeat this for each starwheel.
- When adjustment is complete, check that the wheels rotate freely, with no drag.
REAR DRUM BRAKES 1972-78 Vehicles
The brakes should be cool prior to adjustment.
- Raise and support the rear end on jackstands.
- Release the parking brake.
- Disconnect the parking brake equalizer clevis pin.
- Remove the adjusting slot plugs from the backing plates.
- Insert a brake adjusting tool into the lower slot and engage the starwheel.
- Turn the starwheel until the brake shoes lock the wheel, then back it off 5 notches.
- Repeat this procedure for the top starwheel, then continue on to the other wheel and adjust those brakes in the same sequence.
- When adjustment is complete, make sure that each wheel rotates freely, with no drag.
The rear drum brakes are self-adjusting on 1979 and later models. Manual adjustment is required only when the brake shoes have been replaced, or when the length of the self-adjusting rod has been changes for some reason. The brakes should be cold (room temperature).
- If the shoe retaining spring has been removed, first retract the pushrod fully (drum removed).
- Raise and support the rear of the truck. The wheels must be free to turn.
- Make sure the parking brake is fully released.
- Remove the two adjusting hole plugs from the brake backing plate.
- An arrow stamped on the backing plate indicates the direction to turn the adjuster starwheel to expand the shoes. Insert a brake spoon through the adjuster hole and turn the starwheel until the brakes are locked.
- Insert a drift through the other adjuster hole. Use the drift to hold the pole lever of the self-adjuster firmly. Back off the starwheel three or four notches; the wheel should rotate freely (no drag).
- Repeat the adjustment on the other wheel. Make sure the adjustment is exactly the same. Road test for equal brake action and readjust as necessary.
Disc brakes require no adjustments.
BRAKE PEDAL FREE-PLAY
See Figure 4
On trucks with power brakes, depress the pedal a few times to dispel all vacuum from the booster.
Using the top of the pedal pad as a reference point, there should be 7.0-9.0mm (0.276-0.354 in.) on trucks through 1984 with power brakes, 4.0-7.0mm (0.157-0.276 in.) on 1986 trucks with power brakes, and a little less than 3mm (0.118 in.) free-play before the pushrod contacts the master cylinder piston on models with non-power brakes.
- Loosen the locknut on the master cylinder pushrod at the clevis.
- Turn the pushrod to obtain the proper free-play, then tighten the nut.
BRAKE PEDAL HEIGHT
Pedal height is measured from the center of the pedal pad surface, horizontally to the firewall. On the Rotary Pick-Up, pedal height should be 190mm (7.48 in.). On piston engine trucks through 1984, pedal height should be 205mm (8.07 in.). On 1986 pick-ups, pedal height should be 209-214mm (8.23-8.43 in.).
If not, loosen the stop light switch locknut and turn the switch until the proper height is obtained. Tighten the locknut.