WHEEL INDUCED RIDE VIBRATION CHECK WHEEL RUNOUT

VEHICLES AFFECTED: 1985 - 86 M-Vans

On some 1985 and early production 1986 M Vans up to Chev V.I.N. GB141635 and GMC V.I.N. GB509937, equipped with Rally Wheels, RPO ZJ7, a condition may exist where a wheel induced ride vibration is noticed. This condition may be caused by a variation in the wheel runout. The service procedure for diagnosing and correcting this condition is as follows:

1. Inspect the pilot hole area on the Rally Wheels.

2. If the pilot hole has similar appearance as shown in Figure No. 1 then this bulletin does not apply. Follow the procedure in Bulletin 85-3-133 for Measuring and Repairing Tire and Wheel Runout to correct the vibration complaint.

3. If the pilot hole area on wheels is similar to the illustration in Figure No. 2, proceed with this bulletin.

4. The suspected tire and wheel assemblies should first be balanced.

5. If a vibration still exists, follow the procedure in Bulletin 85-3- 133, Measuring and Repairing Tire and Wheel Runout.

6. If this does not correct the vibration, isolate the wheel or wheels which are faulty.

7. Replace faulty wheels as necessary.

A revised wheel of the type shown in Figure No. 1 is currently being offered through WDDGM to alleviate this condition using P/N 9591183. All Rally Wheels, RPO ZJ7, not meeting runout specifications have been removed from WDDGM stock.

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.