ROAD WHEEL BALANCING WITH HUNTER ROAD FORCE(R) GSP9700 TIRE BALANCER
This bulletin has been amended in the SERVICE INFORMATION section. Tire warm-up time has been increased. Discard all previous versions of this bulletin.
APPLIED VEHICLES: All Nissan
The most common cause of vehicle vibration at highway speeds is tire/wheel assembly (or road wheel) non-uniformity. There are three primary contributors that affect tire/wheel assembly vibration:
Tire Road Force Variation (RFV, or Radial Force Variation)
The Hunter Road Force(R) GSP9700 tire balancer (GSP9700) has the capability to measure tire Road Force Variation (RFV).
When measuring RFV, it is important to look at both the RH1 and RH2 values.
This bulletin will instruct you how to:
Prepare the tire/wheel assemblies for balancing on your GSP9700
Measure and display RH1 and RH2
Determine if the tire/wheel assemblies are within specified limits
Road Force Variation
Radial Force Variation (RFV) is a measurement term. Tire RFV is a measure of the variation (up and down) of the load action on the spindle, the force applied to the suspension as the tire turns. This measures the tires uniformity under load.
The primary measures for RFV are 1st harmonic, once per revolution, or RH1, and 2nd harmonic, twice per revolution, or RH2.
Tire/wheel assembly uniformity can only be measured under load.
The GSP9700 measures uniformity by using a load roller. The load roller simulates a load on a tire similar to when it is mounted on a vehicle and driven on the road.
Most road wheel vibration issues are due to road force variation of RH1 or RH2. Of the two, RH1 is more common.
RH1 vibration causes the road wheel to hop/bump once per revolution. This creates a vibration similar to an imbalance condition.
RH1 can cause steering wheel shimmy or shake, and/or body vibration.
RH1 may be caused by:
Tire uniformity, or RFV
RH2 can be the primary cause of vibration, although it is not as common as RH1.
RH2 vibration occurs twice per revolution and may be caused by:
Radial run-out of tire and/or wheel (i.e., oval or egg shaped)
Preparing Tire/Wheel Assemblies before Measuring Uniformity (RFV)
Check (and adjust as necessary) all tire pressures.
Warm up the tires by driving the vehicle a minimum of 15 minutes at highway speeds.
This will remove any temporary flat spots prior to testing (refer to NTB11-027).
Verify the incident after performing the 15 minute warm-up.
If the incident is verified, check uniformity of all tire/wheel assemblies.
Mounting a Tire/Wheel Assembly to a GSP9700
Follow all applicable instructions in the manufacturers operators manual.
Make sure to:
Use the correct collet and flange plate (refer to NTB11-044)