Drive Axle - Premature Wear

CHEVROLET NUMBER: 87-T-85

SECTION: 4B - Rear Axle

DATE: March, 1987

SUBJECT: AXLE VENT MODIFICATION

MODELS: 1982-1986 C/K AND 1987 R/V MODELS

Some 1982-1986 C/K and 1987 R/V trucks used in severe duty/off road operations may experience premature axle wear due to dirt and water entry through the axle tube vent. Modifications to the vents for both the front and rear axles can reduce the amounts of dirt and water entering the axle housing and decrease the chances of premature axle wear in severe duty/off road operations. Prior to modifying the axle vents, remove axle cover and inspect for contamination. If water or dirt are present, flush out axle housing, ring and pinion with a suitable solvent such as choke cleaner (GM Part Number 1050494) or equivalent Reinstall housing cover and gasket and refill housing with the lubricant specified in the light Duty Truck Service Manual or Maintenance Schedule. If the axle lubricant does not show signs of contamination, reinstall housing cover and gasket, and refill the housing with the lubricant specified in the Light Duty Truck Service Manual or Maintenance Schedule. The following service procedure should be followed for the modification.

VENTING REAR AXLE ASSEMBLY

1. Disconnect rear axle vent hose and vent at attachment to box floor cross sill or frame and axle housing. Typical attachments are shown in Figures No. 1A and 1B. Various other attachments are possible depending on axle size and model year.

2. Replace vent with filter, P/N 25055032, and secure to vent hose with a screw clamp, P/N 797923.

3. Install clamp on the body of the filter and install filter on the box floor (body floor) cross sill one rib REARWARD of the axle housing using the existing bolt. Filter outlet should face rearward. See Figures No. 2A and 2B.

4. Install 38 inches of 5/16 inch hose, P/N 9438315, on the filter securing with a screw clamp.

5. Route the hose REARWARD to the left side frame rail and secure using plastic fasteners (ties). Let hose hang downward within left frame rail.

VENTING FRONT AXLE - K/V MODELS

1. Remove clamp holding the vent hose to the radiator support. See Figure No. 3A.

2. Remove the plastic vent from the hose and install filter, P/N 2505532, and secure with screw clamp.

3. Install six inches of 5/16 inch hose, P/N 9438315, on the filter with a screw clamp and relocate the filter to the canister attaching bracket. Let end of hose hang downward from filter. See Figure No. 3B.

The time required to make this inspection and modificatation is as follows:

K/V Models
(Both Axles) 1.2 hrs

C/R Models 0.7 hrs