Technical Service Bulletins
|Publication Date: MARCH 18, 1998|
|1994-1997 F-250 HD, F-350|
A vibration or shudder may be felt during braking on some vehicles. This may be caused by heating of the rear brake drums causing surface roughness and/or distortion of the drums.
The following provides a list of diagnostic Service Tips to help resolve vibration/shudder concerns induced by the rear brakes.
- Determine if the vibration/shudder is being caused by the rear brakes by making a light stop from about 80-55 km/h (50-35 mph) using the parking brake. In order to do this, hold the release handle out while depressing the parking brake with the left foot. If the vibration/shudder continues to occur during the parking brake application, continue with the following Steps.
- Check the vehicle for loose or over-tightened lug nuts.
- Inspect the wheel studs for damage and replace if needed
- Inspect the wheel stud holes to see if they are elongated. If so, replace the wheel(s)
- Retorque the lug nuts on the vehicle using Accutorq® lug nut socket per TSB 98-5A-4. If this tool is not available then retorque the lug nuts with a standard torque wrench to 190 N-m (140 lb-ft) in a double star pattern
- Check tire pressures to make sure they are at the correct setting
- Reverify concern
- If the concern is still present and the vehicle has Ford original equipment tires/wheels, check the tires and wheels for excessive radial and lateral runouts by referring to the appropriate Service Manual, Section 04-04. Service as required.
- If the vehicle has aftermarket wheels and/or tires, replace with Ford original equipment wheels/tires
- If the condition is corrected, explain to owner the effect aftermarket wheels/tires have on vibration/shudder
- If the condition is still present, proceed to Step 5
- Remove the rear brake drums and inspect for axle lube leaks. If present, service the rear wheel seals and brakes as needed. For cold weather operation in sub-zero temperatures see TSB 98-5A-27. If no leaks are present, proceed to Step 6.
- Check adjustment of the rear parking brakes and routing of the cables to be sure excess drag does not exist in the rear brakes. Refer to TSB 98-5A-35 for correct rear parking brake cable routing. If the vehicle is a Crew Cab model, secure the cable midway in the routing to prevent excessive bounce/movement of the cable while driving.
- Inspect the rear drums for signs of excess heating including cracking and glazing of the braking surfaces. Resurface the drums if glazing is present. Replace the drums if any visual cracks/damage appear or if they exceed the maximum diameter listed on the rim of the brake drum.
- Inspect the rear linings for wear or glazing. If the linings show excess wear or glazing, then replace the rear brake shoe and lining assemblies. If the linings have enough material, hand sand them using garnet paper 100A (medium grit) or aluminum oxide 150J (medium grit).
- Adjust the rear brakes by referring to the Service Manual, Section 06-02. Check the self-adjusters to make sure they are working properly.
- Check the rear shock absorbers.
- Disconnect the lower end of the rear shock absorbers
- Extend and compress the shock absorbers as fast as possible, using as much travel as possible. The action should be smooth and uniform throughout each stroke. Faint swish noises and higher resistance on extension than on compression are normal conditions. Service as required. Refer to the Service Manual, Section 04-00, for additional information.
- Torque the lug nuts on the vehicle per Step 2.
- Re-evaluate the vehicle for brake shudder.
OTHER APPLICABLE ARTICLES:
301000, 703000, 703400
Copyright © 1998 Ford Motor Company