Some 1986 Rivieras may experience a shudder or vibration in reverse. This may be caused by contact between the engine mount (Location 1, Illustration) and exhaust heat shield or by a grounded condition of the safety pin in the RH transmission mount (Location 2, Illustration).
If there appears to be contact between the engine mount and exhaust heat shield, the engine mount should be replaced with a new engine mount, part number 17986962, which is available from GMWDD.
If there appears to be a grounded condition of the safety pin in the RH transmission mount, this transmission mount should be replaced with a new mount, part number 1640099, which is available from GMWDD.
Front Engine Mount Replacement:
Operation Number: J1500 Labor Time: .4 Trouble Code: 92
RH Transmission Mount Replacement:
Operation Number: K6723 Labor Time: .5 Trouble Code: 92
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.