Mark VII V8-302 5.0L VIN F FI (1987)
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braking. That fact can be used to correctly determine that the customer is not experiencing brake-caused roughness. If however, there is brake roughness
in addition to tire problems, then both problems must be repaired. If the inspection shows that tires are contributing to roughness (vibration or roughness
present in all driving conditions, not just braking) they should first be balanced and rotated using normal maintenance procedures then follow the steps
below to correct the brake roughness.
2.
Check the Wheel Lug Nut Tightening Torque
Uneven and/or out of specification torque on the wheel lug nuts will cause the brake rotors to warp. Up to 0.005 inch rotor runout can occur due to
improper lug nut tightening. The first thing to check for is the consistency of torque of the lug nuts on each wheel. If the torque readings are not within
20% of each other, that gives an indication of a cause of the concern of brake roughness. Improper lug nut tightening can have the following order of
effects:
1.
Rotor runout
2.
Rotor thickness variation
3.
Brake torque variation
4.
Brake roughness
Ultimately, the rotor may be damaged and must be resurfaced. Follow the procedure in the Service Manual for resurfacing the rotors. Proper torque must
be used when a resurfaced or new rotor is installed. Use of a torque wrench is again stressed, or as an alternative, the Rotunda "ACCUTORQ"
164-R0314 or equivalent must be used. When installing a new rotor, do not machine the rotor on a bench lathe. Any surface contamination can be
removed with grease solvents or with very light hand sanding. Refer to # 3, CHECK FOR RUST/CONTAMINATION...
3.
Check for Rust/Contamination on Mounting Surfaces
Surface rust or contaminations on the wheel-to-rotor and rotor-to-hub flange surfaces should be cleaned with very light hand sanding. Use garnet paper
100A or aluminum oxide 150J grit. DO NOT USE HARSH, ABRASIVE TOOLS. If the cleaning is not done, it will contribute to the runout of the rotor
when assembled, which will cause brake roughness later on.
Any removal of rust on the rotor braking surfaces using harsh abrasive tools is not approved by Ford. The on-car turning procedure is the only sanctioned
method at this time to deal with repairing rusty rotors. Since the thickness of the rotors are manufactured to less than 0.0004 inch tolerance, using hand
held tools on the rotor surfaces can not guarantee maintaining the tolerance. Concerns will occur of brake roughness with rotor thickness variation of
0.0008 inch or less on certain very sensitive vehicles.
4.
Check for Runout of the Front Rotor on the Car and Front Hub Mount
Runout of the rotor mounted on car should not exceed 0.003 inch. With the wheel off, fasten the lug nuts back on to hold the rotor onto the hub. The
fastening torque should not exceed 81 N.m (60 lb-ft) and should be even. With the dial indicator attached to the spindle, slowly rotate the rotor to get the
total indicated runout. This value should not exceed the Total Indicated Runout (TIR) as specified in the appropriate Service Manual. If it exceeds
specification, first index the rotor one (1) wheel stud at a time. If the readings still exceed 0.003 inch, then the hub face runout should be checked. Repeat
the runout check procedure on the hub face. If the runout exceeds 0.002 inch, the hub must be replaced, otherwise the rotor must be resurfaced on the
vehicle or replaced.
5. Check for Rear Brake Roughness
Except for the vehicles with separate drum in disc parking brake (e.g., Crown Victoria, Grand Marquis and Town Car) the rear brake can be actuated by
actuating the parking brake. Attempt to slow down the vehicle from 48 km/h (30 mph) with the transmission in neutral using the parking brake. If
roughness is present, then the rear brakes need to be serviced. If roughness is not present, then front brakes need servicing. To service the rear brakes
follow the procedure above for servicing the front brakes.
6.
Check for Proper Caliper Operation
Inspect the calipers for leaks and brake fluid contamination. Any leaks from the wheel cylinders and seals must be repaired per the Service Manual. Also,
inspect for glazing of the brake pads which may indicate a seized caliper piston, frequent severe or unintentional brake dragging by the customer. Repair
as specified in the Service Manual.
OTHER APPLICABLE ARTICLES: 92-12-4, 92-19-2, 92-4-3, 93-16-2, 93-26-2, 93-6-3, 94-25-1, 94-25-2, 95-6-4
WARRANTY STATUS: INFORMATION ONLY
OASIS CODES: 301000