Electra V8-350 5.7L DSL (1983)
Wheels: Customer Interest
Wheels/Tires - Tire Radial Force Variation (RFV)
INFORMATION
Bulletin No.: 00-03-10-006F
Date: May 04, 2010
Subject: Information on Tire Radial Force Variation (RFV)
Models:
2011 and Prior GM Passenger Cars and Light Duty Trucks
2010 and Prior HUMMER H2, H3
2009 and Prior Saab 9-7X
2000-2005 Saturn L Series
2003-2007 Saturn ION
Supercede:
This bulletin is being revised to considerably expand the available information on Radial Force Variation (RFV) and should be reviewed in whole.
Please discard Corporate Bulletin Number 00-03-10-006E (Section 03 - Suspension).
Important
-
Before measuring tires on equipment such as the Hunter GSP9700, the vehicle MUST be driven a minimum of 16 km (10 mi) to ensure
removal of any flat-spotting. Refer to Corporate Bulletin Number 03-03-10-007E - Tire/Wheel Characteristics of GM Original
Equipment Tires.
-
Equipment such as the Hunter GSP9700 MUST be calibrated prior to measuring tire/wheel assemblies for each vehicle.
The purpose of this bulletin is to provide guidance to GM dealers when using tire force variation measurement equipment, such as the Hunter GSP9700.
This type of equipment can be a valuable tool in diagnosing vehicle ride concerns. The most common ride concern involving tire radial force variation is
highway speed shake on smooth roads.
Tire related smooth road highway speed shake can be caused by three conditions: imbalance, out of round and tire force variation. These three conditions
are not necessarily related. All three conditions must be addressed.
Imbalance is normally addressed first, because it is the simpler of the three to correct. Off-vehicle, two plane dynamic wheel balancers are readily
available and can accurately correct any imbalance. Balancer calibration and maintenance, proper attachment of the wheel to the balancer, and proper
balance weights, are all factors required for a quality balance. However, a perfectly balanced tire/wheel assembly can still be "oval shaped" and cause a
vibration.
Before balancing, perform the following procedures.
Tire and Wheel Diagnosis
1. Set the tire pressure to the placard values.
2. With the vehicle raised, ensure the wheels are centered on the hub by loosening all wheel nuts and hand-tightening all nuts first by hand while
shaking the wheel, then torque to specifications using a torque wrench, NOT a torque stick.
3. Visually inspect the tires and the wheels. Inspect for evidence of the following conditions and correct as necessary:
-
Missing balance weights
-
Bent rim flange
-
Irregular tire wear
-
Incomplete bead seating
-
Tire irregularities (including pressure settings)
-
Mud/ice build-up in wheel
-
Stones in the tire tread
-
Remove any aftermarket wheels and/or tires and restore vehicle to original condition prior to diagnosing a smooth road shake condition.
4. Road test the vehicle using the Electronic Vibration Analyzer (EVA) essential tool. Drive for a sufficient distance on a known, smooth road
surface to duplicate the condition. Determine if the vehicle is sensitive to brake apply. If the brakes are applied lightly and the pulsation felt in the
steering wheel increases, refer to the Brakes section of the service manual that deals with brake-induced pulsation. If you can start to hear the
vibration as a low boom noise (in addition to feeling it), but cannot see it, the vehicle likely has a first order (one pulse per propshaft revolution)
driveline vibration. Driveline first order vibrations are high enough in frequency that most humans can start to hear them at highway speeds, but
are too high to be able to be easily seen. These issues can be caused by driveline imbalance or misalignment. If the vehicle exhibits this low boom
and the booming pulses in-and-out on a regular basis (like a throbbing), chances are good that the vehicle could have driveline vibration. This type
