Wheels/Tires - Vibration/Shake Diagnostic Procedure
87ford22
Article No. VIBRATION AND SHAKE - STEERING
87-22-10 WHEEL NIBBLE - DIAGNOSTIC PROCEDURE
LINCOLN-MERCURY: 1987 COUGAR
ISSUE: Vibration and shake felt as a steering wheel nibble may be caused by wheels that are out-of-balance or excessive wheel runout. The potentially affected vehicles are 1987 Cougars with aluminum wheels.
ACTION: To correct this, use the following diagnostic service procedure.
Road test the vehicle with the owner and make note of the following items:
^ What is the critical speed of the vibration?
^ Does vibration get worse as speed increases?
^ Does vibration occur over a small speed range?
^ Does vibration phase in and out?
If one or more of the above symptoms are found, proceed as follows:
1. If vehicle is equipped with a locking lug nut, it should be checked to make sure the correct wheel balance weight is used. Refer to TSB 87- 14-7 dated July 16, 1987.
2. If balance weight is added or changed, road test vehicle at the critical speed. If vibration is gone, STOP HERE. If vibration is still present, measure both front wheel's runout by proceeding to Step 3.
3. Warm up the tires for about 20 miles of highway driving before taking measurements to eliminate any chance of slight flat spotting.
4. Raise the vehicle on a hoist.
5. Select a wheel position. Mark a stud bolt and the corresponding wheel hole to make sure the wheel can be replaced on the vehicle in its original position.
6. Remove the tire and wheel assemblies from the vehicle. Carefully mark the location of the wheel valve stem on the tire. If tire has a yellow sticker on the sidewall indicating the highpoint, go to Step 8.
7. Mount the tire and wheel assembly to the cone of a dynamic balance machine. Place a runout gauge in position to measure the radial runout of the center rib of the tire while mounted on the dynamic balance machine. Rotate the assembly to find the high spot. Rotate again to make sure the high spot has been properly located. Mark the high spot on the sidewall of the tire for future use.
8. Dismount the tire from the wheel and install the wheel on the vehicle in its original position securing it with lug nuts (use the marked stud bolt and wheel hole to line up).
Figure 7:
9. Place a runout gauge in position to measure the radial runout of the outside wheel bead seat, Figure 7. Rotate the assembly to find the low spot. Adjust the gauge to read zero (-0-). Rotate the wheel once to make sure the low spot has been located and that the dial returns to zero runout. Mark the low point on the wheel.
10. If the runout is not within the guideline specified, proceed to Step 12.
RUNOUT GUIDELINES
Radial Runout
Thousandths 64ths
Outside Wheel Bead Seat .008 0.5
11. If the runout is within the guideline specified, remount the tire to the wheel in the original position matching valve stem to mark on tire. Install assembly on the vehicle lining up marked stud bolt and wheel hole. Road test vehicle. If vibration is gone, STOP HERE. If vibration is still present, proceed to Step 15.
12. Remount the tire to the wheel orienting the tire so that the high point mark on the sidewall of the tire (yellow sticker) matches the low point mark on the wheel. Inflate the tire.
13. Remove balance weights and rebalance the assembly.
14. Install the assembly on the vehicle, lining up the previously marked stud bolt and wheel hole.
15. Repeat Steps 5 through 11 for the rear wheels.
OTHER APPLICABLE ARTICLES: 87-14-7
WARRANTY STATUS: Eligible Under Basic Warranty Coverage
OPERATION: SP872210A - Steps 1 and 2 - Includes initial road test
TIME: 0.5 Hr.
OPERATION: SP872210B - Steps 3 through 10 and 12 through 14
TIME: 1.1 Hrs.
OPERATION: SP872210C - Steps 3 through 11
TIME: 1.0 Hr.
OPERATION: SP872210D - Step 15
TIME: 1.0 Hr. DLR. CODING: Basic Part No. 1007 - Code: 67