Parking Brake Adjust
This procedure covers all ½ ton NBS (’99-’05) GM FS trucks with 4 wheel disc brakes.
This is a very common problem for this vintage truck. Since the parking brake is not self
adjusting, this issue will eventually show up. This is the procedure for adjusting the
parking brake. First inspect cables for damage. If the cables prove to be adequate perform
this procedure.
Tools and supplies needed:
· 22 mm socket (wheel lug)
· 18 mm socket (brake caliper)
· Breaker bar (optional)
· Torque wrench (capable of up to at least 150 lb-ft)
· Drum brake measurement tool
· Flat blade screwdriver
· 3-4 cans of brake parts cleaner
· Open drain pan
· Loctite (green) threadlocker or equivalent
· Jack
· 2 jack stands
· 2 wheel chocks (4 would be ideal)
· Pick or wire brush
· Heavy wire (enough to support the weight of the calipers)
· Dust mask
· Latex or vinyl disposable gloves (optional)
1. Place the wheel chocks under the front wheels towards the side of incline (fully level
surface ideal otherwise 4 wheel chocks would be preferred—2 on front and rear of
each front wheel.)
2. Lift the rear end of the truck and place the jack stands on either side of the rear axle.
3. Check to see whether the parking brake is holding. With the parking brake on, see if
the rear wheels will rotate. If it does, the parking brake is definitely not holding.
4. Remove the rear wheels (Ideal to loosen the lug nuts before lifting the truck unless
you have an air impact wrench)
5. With the rear wheels off, hose the entire rear caliper and disc off with the brake parts
cleaner.
6. There are 2-18mm bolts holding the calipers to the axle. Remove these and the entire
caliper assembly will come off. Here is a picture looking at the backside of the rear
brake caliper. The bolts are (in the picture) the 2 to the left of the caliper housing.
Hang the caliper assembly with the heavy wire. Hang the caliper so that there is little
stress on the brake line. NOTE: Be very careful not to let the caliper hang by the
brake line. This will cause damage to the brake line or damage to the caliper assembly
if dropped.
7. Remove the 2 retainers holding the disc on. Since these are not critical pieces, you
can either use a flat blade screwdriver and carefully screw them out (takes a bit of
patience) or cut them off all together.
8. Make sure the parking brake is off or the next step might be a problem.
9. Carefully remove the brake disc. Be very careful not to drop it. Do not breathe the
dust. Use the brake parts cleaner to hose off all of the dust and debris on the inside of
the parking brake drum and the brake assembly on the axle.


10. Inspect the inside of the drum for unusual wear or heat marks.
11. Inspect the pads on top of the parking brake shoe to ensure even wear and enough pad
material. If the pad material is worn unevenly or very thin, replace the parking brake
pad.
12. Take several measurements of the inside diameter of the parking brake drum over the
widest part. Aligning the measurement tool over the 2 of the bolt holes will ease
finding the widest part.
13. Take several measurements of the widest part of the outer diameter of the parking
brake shoe with the parking brake off.
14. Take several measurements of the outer diameter of the parking brake shoe with the
parking brake on (about ½ way down—pedal pad nearly inline with the door opening
trim.). It should measure larger than the outer diameter of the parking brake shoe with
the parking brake off. If not, check the actuator for binding or for damaged cables.)
15. The clearance of the parking brake shoe to drum should be 0.6604 mm (0.026”) with
the parking brake off. With it on (½ way down), it should be the same (or slightly
larger) dimension as the inside diameter of the parking brake drum. If not, adjust the
adjustment screw until you have the<