Ford 2003 Mustang Workshop Manual page 276

presence of the vibration. If the vibration is not evident, check the non-driving wheels with a
wheel balancer to rule out imbalance as a possible cause. If required, balance the non-driving
wheels and repeat the road test. If the vibration is still evident, proceed to Step 2.
2. Mark the relative position of the drive wheels to the wheel nuts. Remove the wheels. Install all
the nuts in the reversed position and repeat the road speed acceleration. If the vibration is gone,
refer to the tire and wheel runout procedure in
to Step 3.
3. Inspect the driveshaft for signs of physical damage, missing balance weight, undercoating,
incorrect seating, wear and binding universal joints. Clean the driveshaft and install new
universal joints or a new driveshaft if damaged. Check the index marks (paint spots) on the rear
of the driveshaft and pinion flange. If these marks are more than one-quarter turn apart,
disconnect the driveshaft and re-index to align the marks as closely as possible. After any
corrections are made, recheck for vibration at the road test speed. If the vibration is gone,
reinstall the wheels and road test. If the vibration persists, proceed to Step 4.
4. Raise the vehicle on a hoist and remove the wheels. Rotate the driveshaft by turning the axle
and measure the runout at the front, the center, and the rear of the driveshaft with the indicator.
If the runout exceeds 0.89 mm (0.035 inch) at the front or center, a new driveshaft must be
installed. If the front and center are within this limit, but the rear runout is not, mark the rear
runout high point and proceed to Step 5. If the runout is within the limits at all points, proceed to
Step 7.
5. NOTE: Check the U-joints during re-indexing. If a U-joint feels stiff or gritty, install new U-joints.
Scribe alignment marks on the driveshaft and the pinion flange. Disconnect the driveshaft,
rotate it one-half turn, and reconnect it. Circular pinion flanges can be turned in one-quarter
increments to fine tune the runout condition. Check the runout at the rear of the driveshaft. If it is
still over 0.89 mm (0.035 inch), mark the high point and proceed to Step 6. If the runout is no
longer excessive, check for vibration at the road test speed. If vibration is still present, re-index
the driveshaft slip yoke on the transmission output shaft one-half turn and road test the vehicle.
If the vibration persists, proceed to Step 7.
6. Excessive driveshaft runout may originate in the driveshaft itself or in the pinion flange. To
determine which, compare the two high points marked in Steps 4 and 5. If the marks are close
together, within about 25 mm (1 inch), a new shaft must be installed and the vehicle road
tested.
Section 204-04 . If the vibration persists, proceed