Subject: | Suspension Vibration or Frame Beaming at 40-60 mph (64 - 80 km/h) |
Models: | 1999-2007 Chevrolet Silverado Classic |
1999-2007 GMC Sierra Classic |
This PI is being superseded to update Recommendation/Instructions. Please discard PIT3009D.
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Beam shake vibration is usually felt in the seat and occurring at speeds between 40-50 mph (64 - 80 km/h). Hertz readings using an EVA tool are normally between 8-24 Hz. This condition is most common on extended cab and crew cab models but has also been noted in other models.
The severity of beam shake may vary from vehicle to vehicle. To determine if the concern is beam shake, please perform the following:
Note: Tires with excessive Radial Force Variation (RFV) or out-of-roundness can intensify the frame beaming concern. The following radial force variation numbers should be used as a guide:
P-Metric tires (2wd 1500) | 12 lbs or less |
P-Metric tires (all others) | 24 lbs or less |
LT-tires | 30 lbs or less |
If the concern is determined to be beam shake, this is a characteristic of the vehicle and currently no repair attempts should be made. GM Engineering is currently working on reducing this concern for the 1500 Models. There will be no changes made to the 2500 and 3500 models.
Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.