Some early built 1985 Somerset Regals exhibit a sharp cracking noise from the rear of car when driving over moderate to severe bumps. This condition may result from low torque on the retaining bolt and nut which attaches the rear axle to the underbody. To repair this condition, tighten to 80-95 N.m (59-70 lbs.ft.).
The torque is to be applied to the washer side of the axle retaining bolt. See Figure. If the washer is on the nut side, use torque wrench on the nut. If the washer is on the bolt head side, use the torque wrench on the bolt head. After VIN FM405885, the axle retaining bolt washer was moved from the bolt head side to the nut side.
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.