Ford: Shudder on Acceleration, Binding on Slow Turns

Ford: Shudder on Acceleration/Deceleration, Binding on Slow Turns

Ford: 1997­-2008 Expedition, Explorer; 2006­-’08 F-­150; 2007-­’08 Explorer Sport Trac
Lincoln: 1998­-2008 Navigator; 2003-­’05 Aviator
Mercury: 2005­-’08 Mountaineer


Various 1997-2008 vehicles equipped with either 4WD or AWD and equipped with control trac may exhibit a shudder on acceleration/deceleration, binding in slow speed turns or noise from the front driveline and/or transfer case. The shudder/binding will occur with the vehicle being operated in the AWD/auto 4×4 mode. The shudder/binding may be due to incorrect tire circumference or improper tire inflation pressures.

On some 4WD models, the initial shift from 2WD to 4WD while the vehicle is moving can cause a momentary clunk and/or brief ratcheting sound. These sounds are normal as the front drivetrain comes up to speed and are not cause for concern.

0-Lincoln SHUDDER ON ACCELERATION MotoLogic fig 1Action

1. Review the tire label for correct tire size and tire inflation pressures located at the B­-pillar of the driver’s door.

2. If the tire size does not match the label, this procedure does not apply. Follow normal workshop manual diagnostics.

3. If the tire size is correct, ensure tire pressures are within specifications.

4. Raise the vehicle on the hoist.

5. Disconnect all wiring going to the transfer case and road test.

6. Is the condition present?
A. If the shudder/binding is still present, do not continue with this procedure, continue with normal diagnostic procedures in the workshop manual.
B. If the shudder/binding is gone, proceed to Step 7.

7. Raise the vehicle on the hoist and reconnect all the wiring previously disconnected.

8. Using a tailor’s tape or flexible measuring tape, measure the circumference of all four tires and record the measurements. (Fig. 1)

0-Lincoln SHUDDER ON ACCELERATION MotoLogic fig 29. Calculate the average of the circumference of the two front tires and calculate the average of the circumference of the two rear tires. (Fig. 2)

10. If the difference between these two averages is greater than ½-inch (12.7 mm), front to back or side to side, replace the smallest circumference tire(s) and remeasure the tire averages.

Note: This does not apply to the 2006-­’08 Mountaineer with a 4.0L engine or the 2007-­’08 Explorer and Sport Trac with 20-in. wheels.

Note: Vehicles may require tire replacement if the tire circumference average between the front and rear axles are outside of the ½ in. spec or if the tire circumference from side to side on either axle exceeds ½ in. difference. The smaller tire(s) must be replaced.

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