3RD GEAR 'HOP-OUT' ON ACCELERATION OR DECELERATION

3RD GEAR HOP-OUT (2ND GEAR ON THE GEAR SHIFT KNOB) 1985-88 HM 117 MANUAL TRANSMISSION (RPO M20) 1985-88 CH/SM 465 MANUAL TRANSMISSION (RPO MC8)

VEHICLES AFFECTED 1985-86 C/K TRUCKS; 1987 R/V TRUCK; ----------------- 1988 C/K TRUCK; 1985-88 P-CHASSIS; 1985-88 MEDIUM DUTY TRUCKS

TRANSMISSION MODELS:

ALL MODELS

BULLETIN COVERS:

Some 1985-1988 R/V, C/K AND P Trucks equipped with a HM-117 (CH/SM 465 in 1985-88 Medium Duty Trucks) 4-speed manual transmission may exhibit 3rd gear hop-out on acceleration or deceleration.

SERVICE ACTION:

If 3rd gear hop-out occurs, it can be repaired by installing the service part package listed below.

SERVICE PARTS INFORMATION:

P/N 8672944 Service Part Package contents:

Quantity Part Description -------- ---------------- 1 3rd Speed Gear 1 3rd-4th Synchronizer Hub 1 3rd-4th Speed Synchronizer Sleeve 2 3rd and 4th Speed Blocker Rings 3 Synchronizer Keys 2 Synchronizer Springs

SERVICE NOTE:

Refill the transmission with only SAE 80W-90 gear lubricant. Do not use automatic transmission fluid or engine oil. This will cause foaming out the vent and durability concerns.

SERVICE MANUAL REFERENCE:

Refer to the Unit-Repair Section of the appropriate Service Manual for the procedures.

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.