Vehicle Lean Correction

Front Lean

Measure the left and right front wheelhouse openings to ground as depicted in Vehicle Lean under the Diagnosis and Testing portion of this section. Refer to Specifications, Lean (Side-to-Side Height Difference) in this section for the specified limits on their side-to-side difference or lateral tilt. A vehicle within these limits would not have an objectionable lean appearance. However, if the lean is objectionable, perform the following to adjust.

Vehicles with Front Coil Springs

If the side-to-side difference is less than 19mm (3/4-inch), install a 6.35mm (1/4-inch) Service Shim (P/N 389117-S2) under the lower spring seat on the low side. No more than one shim is to be added.

If there is a side-to-side difference of 19mm (3/4 inch) or more, remove the high side front coil spring (5310) from the vehicle and compare it with a service replacement part having the same part number.

If the free height of the original equipment front coil spring exceeds the free height of the service part by 13mm (1/2 inch), install the service part in this location. If the free height of the original front coil spring is smaller by at least 13mm (1/2 inch), remove the low side front coil spring. Compare the service front coil spring to both of the original front coil springs and select the two front coil springs most evenly matched. Install the higher front coil spring at the low side.

Vehicles with Front Leaf Type Springs

A service shim (D7TZ-5742-A) is available that installs between the spring and the axle.

For F-Super Duty Commercial and Motorhome Chassis, follow instructions provided with Vehicle Attitude Kit F1TZ-5A581-A.

Rear Lean

A side-to-side lean at the rear of the vehicle can be adjusted by approximately 10mm (3/8 inch) by installing a shim between the rear spring (5560) and rear axle (4001) on the low side of the vehicle. A "low at the rear" vehicle can be raised approximately 10mm (3/8 inch) by installation of one shim on each side. Use the following procedure to install the shim (D7TZ-5742-A).

1. Raise the vehicle frame until the weight is off the rear springs but with the tires still touching the floor.

2. Loosen the spring U-bolts to allow the rear axle to separate from the spring approximately 13mm (1/2 inch).

3. Position the shim (D7TZ-5742-A) between the spring and the spring seat and with the tie bolt head through the hole in the shim. On 4x4 vehicles, position the shim between the rear spring and axle spacer. Tape may be used to hold the shim in position.

4. Make sure the spring leaves are properly aligned and the spring U-bolts contact the edges of the spring assembly or axle seat.

5. Tighten the spring U-bolt sufficiently. The spring bolt end should extend through shim into axle seat hole.

6. Tighten U-bolt nuts to the following torque specifications:

   • 102-135 Nm (75-100 lb-ft) on F-150 4x2 and 4x4 and Bronco.
   • 204-282 Nm (150-210 lb-ft) on F-250, F-350 4x2 and 4x4.
   • 299-406 Nm (220-300 lb-ft) on F-Super Duty vehicles.

   For F-Super Duty Commercial and Motorhome Chassis, follow instructions provided in Rear Spring (Raise) Kit F1TZ-5A581-A.