Ford F150 Pickup. Instruction - part 641

With the Traction-Lokohm differential axle, slight chatter noise on slow turns after extended highway driving is 
considered acceptable and has no detrimental effect on the locking axle function. 

Universal Joint (U-Joint) Inspection 

Place the vehicle on a frame hoist and rotate the driveshaft (4602) by hand. Check for rough operation or seized 
U-joints. Install a new U-joint if it shows signs of seizure, excessive wear, or incorrect seating. Refer to 
DRIVESHAFT & UNIVERSAL JOINTS - F150 PICKUP . 

Inspection For Bent Rear Axle Housing 

1. Raise and support the vehicle. Allow the rear axle to be freely suspended.  

2. Use white chalk or paint to mark a vertical line on the center of each rear tire. 

Fig. 8: Inspecting For Bent Rear Axle Housing 
Courtesy of FORD MOTOR CO. 

NOTE:

A gear-driven unit will produce a certain amount of noise. Some noise is 
acceptable and audible at certain speeds or under various driving conditions 
such as a newly paved blacktop road. Slight noise is not detrimental to the 
operation of the axle and is considered normal.

 

2003 Ford Pickup F150 

2003 GENERAL INFORMATION Driveline System - General Information - F150 Pickup

  

3. Adjust both wheels so that the markings face the front of the vehicle. With a tape measure, measure the 

distance between the marks and record this reading (front reading). 

Fig. 9: Adjusting Both Wheels So That Markings Face Front Of Vehicle 
Courtesy of FORD MOTOR CO. 

4. Rotate the rear wheels so the markings are directly underneath the vehicle. Measure the distance between 

the marks and record this reading (bottom reading). 

Fig. 10: Rotating Rear Wheels So Markings Are Directly Underneath Vehicle 
Courtesy of FORD MOTOR CO. 

 

2003 Ford Pickup F150 

2003 GENERAL INFORMATION Driveline System - General Information - F150 Pickup

  

5. Rotate the rear wheels so the markings face the rear of the vehicle. Measure and record the distance 

between the marks (rear reading). 

Fig. 11: Measuring And Record Distance Between Marks (Rear Reading) 
Courtesy of FORD MOTOR CO. 

6. Compare the front and the rear readings (Steps 3 and 5) to find the toe-in or toe-out condition. 

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Toe-in occurs when the front measurement is less than the rear measurement.  

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Toe-out occurs when the rear measurement is less than the front measurement.  

7. To determine camber, find the average of the front and the rear measurements (Steps 3 and 5). Subtract 

the bottom reading (Step 4) from this number. 

Positive (+) camber is when the bottom reading is less than the average of the front and rear readings. 
Negative (-) camber is when the bottom reading is greater than the average of the front and rear readings. 

8. The results of the calculations in Steps 6 and 7 must conform to the following specifications: 

Toe-in: 0 - 1/16 inch. 

Toe-out: 0 - 3/16 inch. 

Camber: 0 +/- 5/32 inch. 

If the axle housing does not meet these specifications, a new housing must be installed. Refer to REAR 
DRIVE AXLE/DIFFERENTIAL-FORD 8.8-INCH or REAR DRIVE AXLE/DIFFERENTIAL-
FORD 9.75-INCH . 

9. After the axle housing has been installed, repeat Steps 2 through 7 . 

 

2003 Ford Pickup F150 

2003 GENERAL INFORMATION Driveline System - General Information - F150 Pickup

  

Analysis of Leakage 

Clean up the leaking area enough to identify the exact source. An axle leak can be caused by the following: 

z

Axle lubricant level is too high.  

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Worn or damaged axle shaft seals or differential seals.  

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Differential housing is cracked.  

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Flange yoke seal is worn or damaged.  

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Pinion flange is scored or damaged.  

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Axle cover is not sealed.  

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Vent is plugged.  

Repair the axle as necessary. Make sure the axle lubricant is at the correct level. Refer to SPECIFICATIONS . 

Axle Vent 

A plugged vent will cause excessive seal lip wear due to internal pressure buildup. If a leak occurs, check the 
vent. Make sure the vent hose is not kinked. Remove the hose from the vent nipple and clear the hose of any 
foreign material. While the hose is removed, pass a length of mechanics wire or a small diameter Allen wrench 
in and out of the vent to clean it. Connect the hose when done. 

Flange Yoke Seal 

Leaks at the axle drive pinion seal originate for the following reasons: 

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Seal was not correctly installed.  

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Poor quality seal journal surface.  

Any damage to the seal bore (dings, dents, gouges, or other imperfections) will distort the seal casing and allow 
leakage past the outer edge of the axle drive pinion seal. 

The axle drive pinion seal can be torn, cut, or gouged if it is not installed carefully. The spring that holds the 
axle drive pinion seal against the pinion flange can be knocked out and allow leakage past the lip. 

The rubber lips can occasionally become hard (like plastic) with cracks at the oil lip contact point. The contact 
point on the pinion flange may blacken, indicating excessive heat. Marks, nicks, gouges, or rough surface 
texture on the seal journal of the pinion flange will also cause leaks. 

Metal chips or sand trapped at the sealing lip can also cause oil leaks. This can cause a wear groove on the 
pinion flange and heavy pinion seal wear. 

When a seal leak occurs, install a new seal and check the vent and the vent hose to make sure they are clean and 
free of foreign material. 

NOTE:

If a plugged vent cannot be cleared, install a new one.

 

2003 Ford Pickup F150 

2003 GENERAL INFORMATION Driveline System - General Information - F150 Pickup