POPPING NOISE WHEN BRAKING FORE / AFT SHIFT OF FRAME
FRAME NOISE
1984 OMEGA MODELS, 1984-86 CUTLASS CIERA MODELS BUILT PRIOR TO MARCH 1986
Some 1984-86 Cutlass Cieras and 1984 Omegas may exhibit a popping type noise during braking and acceleration. The popping noise, caused by a fore and aft shifting of the frame, can be felt as "oil canning" in the floor pan. (The popping noise should not be confused with a "click" or "clunk" felt in the steering wheel -- covered in the September 1984 Service Guild). Another similar sounding noise, "crunching", could be caused by loose frame mount bolts. Torque should be 115 N - m (85 lbs. ft.).
If the noise is still present after tightening the frame bolts, it can be corrected by installing shims on both rear frame mount insulators as shown in Figure 1. The intent of this fix is to create an interference fit using shims. Multiple shims may be used if necessary.
Shims may be fabricated from any available steel or bran shim stock. Thickness should be approximately .635mm to 1.02mm (.025" to .040").
The following procedure should be followed when installing shims:
1. Support frame with a jack stand on the rear cross member.
2. Remove one (1) rear frame bolt at a time and lower the jack stand enough to remove pressure from the mount.
CAUTION:
Damage to the steering intermediate shaft could result if the frame is lowered more than required to free the mount.
3. Form shim to mount as shown in Figure 1 and reinstall mount. Some rubber lube may be required to ease assembly.
4. Re-install mount bolt. Torque to 115 N - m (85 lbs. ft.).
5. Repeat above procedure on other rear corner.
WARRANTY INFORMATION
Labor Operation Number: E1040 Labor Time: .5 hrs. Trouble Code: 40
Diagnosis Suggestion:
The above described noise occurs during stop-start (brake-accelerate) vehicle operation. Other conditions such as, for example, frame mount bolt interference to body in cage nut area or suspension component noises may also be heard when driving on a rough road and impacting holes or bumps in the road. If the sound of an uncommon noise cannot be readily determined, a suggested method of diagnosis is to tape a stethoscope to the suspect component and use a long piece of hose between the pickup and ear piece to listen for the noise while driving the car over bumps.
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.
