1968 Corvette: Service Bulletin: Driveline Clicking or Snapping Noise

Subject:  Driveline Clicking or Snapping Noise
Model Year:  1968 Passenger Cars and 10 Series Trucks
Date:  September 3, 1968
Bulletin Number: 68-T-61, Section IV

TO:  ALL CHEVROLET DEALERS

Driveline click or snapping type sounds have been encountered on 1968 Passenger Cars and 10 Series Trucks when the direction of torque input to the axle is changed, such as driving forward after reverse operation.  This noise is primarily noted on Chevrolet equipped with the 10 bolt ring gear and Hydra-Matic Transmission.  It originates in the rear axle as a result of pinion bearing spacer movement, which is not detrimental to axle operation or durability, when the direction of driving torque is changed.

A new spacer with a phosphate coating was installed in production axles to correct the noise condition starting with the following build dates:

On a complaint basis, the noise may be corrected by installing the pinion bearing spacer with the phosphate coating as listed on Page 2 of this bulletin.  These spacers can be identified by the dark grey finish as compared to the uncoated steel of the prior spacer.

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.

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