Special Tools
J 38792-A Electronic Vibration Analyzer (EVA) 2
If after following the tire and wheel vibration diagnostic procedures, some amount of tire and wheel vibration is still evident, an on-vehicle high speed spin balancer may be used to perform an on-vehicle balance in an attempt to perform finish balance for the tire and wheel assemblies, wheel hubs, brake rotors, brake drums, (if equipped) and wheel trim cover simultaneously. On-vehicle balancing can also compensate for minor amounts of residual runout encountered as a result of mounting the tire and wheel assembly on the vehicle, as opposed to the balance which was achieved on the off-vehicle balancer.
To perform on-vehicle balancing procedure, carefully follow the on-vehicle balancer manufacturer's specific operating instructions and carefully consider the following information before proceeding:
| • | Vehicles equipped with low profile, wide tread path and high performance tires and wheels are susceptible to small amounts of dynamic imbalance. |
| • | When performing on-vehicle balance, great care must be taken when placing the wheel balance weights on the wheels. If the wheel balance weights are not placed accurately, they can actually contribute to dynamic imbalance and thus increase the severity of the vibration. |
| • | Inspect the wheel bearings to ensure they are in good order. |
| • | Thoroughly check all on-vehicle balancing equipment and ensure that it is fully within the manufacturer's recommended specifications. |
| • | Do not remove the off-vehicle balancing weights. The purpose of on-vehicle balance is to perform the assembly fine balance already achieved by the off-vehicle, rather than restarting balance. |
| • | Leave all wheel trim installed whenever possible. |
| • | If the on-vehicle calls for more than 56 g (2 oz) of additional weight, split the weight between the inboard and outboard flanges of the wheel, so as not to upset the dynamic balance achieved in the off-vehicle. For wheel balance weight information, refer to Tire and Wheel Assembly Balancing - Off Vehicle. |
| • | If equipped, tape-off an area on top of the fenders and the quarter panels, then place the J 38792-A on the fender or quarter panel above the corresponding tire and wheel assembly while it is being on-vehicle balanced. |
| J 38792-A - A will provide a visual indication of the vibration amplitude and the effect that on-vehicle balance has on it. |
