LOWER CONTROL ARM CONTACTS FRONT BRAKE ROTOR

SUBJECT: NOISE AT FULL STEERING LOCK (PROVIDE ADDITIONAL LOWER CONTROL ARM TO BRAKE ROTOR CLEARANCE)

VEHICLES AFFECTED: 1992 "C1, 2" TRUCKS

Some owners of 1992 "C1, 2" trucks may experience a condition where the brake rotor comes in contact with the lower control arm. This occurs only when the steering wheel is turned to the full lock position and most often on left hand turns. The interference between the lower control arm and brake rotor will cause a screeching noise as metal rubs metal. A gouge on the inner face of the brake rotor is evidence that an interference condition does exist.

On vehicles with this condition, the nose area of the lower control arm should be ground away to provide additional clearance. If a deep gouge is found on the inside of the brake rotor, then replacement of the rotor will be necessary.

VEHICLES INVOLVED:

Certain 1992 Chevrolet and GMC "C1 and C2" truck models built within the following VIN breakpoints are involved.

Plant Beginning Ending Division ----- --------- ------ -------- Pontiac East 1GDJK34K1NE530561 1GDHK34K2NE535279 GMC Truck NE177646 NE190038 Chevrolet

Oshawa 2GTEK19K3N1537709 2GTEC19K7N1543686 GMC Truck 2GCEC19H6N1206608 2CCEC19K7N1221548 Chevrolet

Fort Wayne 1GTDC14Z9NZ530350 1GTDC14K6NZ531815 GMC Truck 1GBDC14K7NZ189800 1GCEC14K7NZ194690 Chevrolet

Janesville None

SERVICE PROCEDURE:

1. Inspect brake rotor for signs of contact with the lower control arm.

2. Replacement of the brake rotor will be necessary if rotor gouge is deeper than 1.0 mm (.039 inches).

3. Siphon 2/3 of the brake fluid from the master cylinder.

4. Remove the wheel and tire assembly.

5. Remove the brake caliper from the brake rotor. Suspend the caliper assembly with a wire hook away from the work area.

6. Remove wheel bearing cap and nut from the spindle.

7. Remove the brake rotor. Care should be used so that the outer bearing and spindle threads are not damaged. Save the bearings.

8. Remove the brake splash shield and gasket.

9. Mark the centre nose portion of the lower control arm. Place another mark 5 cm (2 inches) on either side of centre (Figure 1).

10. Using a die grinder or equivalent, take care not to remove more than 2 mm (.08 inches) of metal from the control arm nose to obtain clearance between the control arm and brake rotor.

11. Inspect the outer nose of the control arm for the flange thickness. The thickness should be 10 mm - 14 mm (.39 - .55 inches). (Figure 2)

12. If the flange thickness is greater than 14 mm (.55 inches), use a die grinder or equivalent to remove excessive metal from the bottom to obtain the proper thickness.

13. Clean the unfinished metal, then paint black.

14. Reinstall gasket and splash shield. Torque bolts to 16 N.m (12 lb. ft.).

15. Install inner bearing to the brake rotor. Apply an additional amount of an approved high temperature front wheel bearing grease outboard of the inner bearing.

16. Install a new wheel seal using a flat plate to press the seal down flush with the hub. Apply a film of wheel bearing grease to lubricate the seal.

17. Install brake rotor to the spindle.

18. Apply grease to the outboard side of the outer bearing. Reinstall outer bearing to the brake rotor.

19. Reinstall nut and washer to the spindle. Tighten nut to 16 N.m (12 lb ft) while turning the brake rotor assembly forward by hand. This will seat the bearings. Adjust the nut to a "just loose" position by hand, then back the nut off until the hole in the spindle aligns with a slot in the nut. Do not back the nut off more than 1/2 flat. Install new cotter pin.

20. Reinstall cap to the brake rotor.

21. Check for control arm to rotor clearance in the straight ahead position and in a full right and left hand turn.

22. Reinstall brake caliper. Torque caliper mounting bolts to 51 N.m (38 lb ft).

23. Reinstall wheel and tire assembly. Torque nuts to 160 N.m (120 lb ft).

24. Refill the master cylinder with Delco Supreme II fluid, Part Number 1052535, or Dot 3, and bleed brake system if required.

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.