Diagnosis and Correction

Visual Inspection of the vehicle is recommended prior to the initial test drive. Put the vehicle on a hoist and inspect the following items:








VISUAL INSPECTION

Test Drive the vehicle, in the as received condition, at the complaint speed on a smooth road surface with all accessories turned off. Correct any obvious safety related items identified during the Visual Inspection prior to the Test Drive. It is essential to the diagnosis that the repair facility has identified a smooth road and uses it for the entire diagnosis. A smooth surface will reduce the vehicle response to road inputs and allow the diagnosis to concentrate on the rotating components. If the vibration condition has been corrected due to replacement of component(s) return the vehicle to the customer. If the vibration problem is still present make the following checks:

^ If the vibration changes as you coast in neutral, the problem may be with the driveline, refer to the Service Manual.

^ If the vibration does not change while coasting then the problem may be caused by tires, wheels or suspension.

^ If the vibration increases with increasing vehicle speed, the problem may be with imbalance of rotating components (tires, wheels, half shafts, drums or rotors).

^ If the vibration decreases with increasing vehicle speed, the problem may be with tire/wheel assembly run out.

^ If the vibration is a low-speed lateral wobble of the body and/or steering wheel oscillations at speeds less than 45 mph (72 kph), the problem may be caused by lateral run out of the tire/wheel assembly.

^ If the vibration is a mid-speed vibration and is characterized by vibration in the seat, floor, and/or steering wheel at speeds between 35-45 mph (56-72 kph); the problem may be caused by high 2nd order tire/wheel assembly excitation. If torque sensitive, the problem may be driveline related, refer to the Service Manual.

^ If the vibration is a high-speed vibration and is characterized by vibration in the seat, floor, instrument panel, and/or steering wheel at speeds greater than 60 mph (97 kph); the problem may be caused by high 1st order tire/wheel assembly excitation.








ON CAR TIRE/WHEEL ASSEMBLY RUNOUT

After your initial Test Drive, correct any deficiencies that the initial Visual Inspection identified. Test Drive the vehicle, if the vibration condition has been corrected due to replacement of component(s) return the vehicle to the customer. If the vibration is still present and it was determined that the vibration is not driveline related proceed to the On Car Tire/Wheel Assembly Runout procedure.

Tire/Wheel Match Mounting is a technique used to reduce radial runout of the tire and wheel assemblies. Excessive runout is a source of ride complaints and Match Mounting is a method of reducing runout.





TIRE/WHEEL MATCH MOUNTING








WHEEL RUNOUT








WHEEL BORE PILOT DIAMETERS








HUB WHEEL PILOT DIAMETER








HUB WHEEL PILOT RUNOUT








WHEEL MOUNTING SURFACE LATERAL RUNOUT