Fulltext TSBs

Technical Service Bulletins

TSB
98-5A-23
  • BRAKES – PULL OR DRIFT – DIAGNOSTIC AND SERVICE PROCEDURES – 4X2 AND 4X4 MODELS OVER 8500 LBS GVW
  • STEERING – PULL OR DRIFT – DIAGNOSTIC AND SERVICE PROCEDURES – 4X2 AND 4X4 MODELS OVER 8500 LBS GVW
Publication Date: MARCH 18, 1998

LIGHT TRUCK:
1995-1997 F-250 HD, F-350

ISSUE:

A comprehensive pull and drift diagnostic procedure has been developed to assist technicians in helping to resolve pull or drift conditions.

ACTION:

Use the following Service Procedure, guided by the flowchart in Figure 1, to help resolve drift and pull conditions.




Figure 1 – Article 98-5A-23

NOTE:IT IS POSSIBLE THAT THE VEHICLE MAY HAVE MULTIPLE SYMPTOMS. THEREFORE, IT IS NECESSARY TO USE THE FLOWCHART IN FIGURE 1.

DEFINITIONS PERTINENT TO THIS TSB ARTICLE:

  • BRAKE PULL: WHEN DRIVING ON A FLAT, STRAIGHT ROAD (WITHOUT A CROWN), THE VEHICLE ALTERS FROM A STRAIGHT COURSE DURING APPLICATION OF BRAKES WITH TORQUE FELT IN STEERING WHEEL.
  • STEADY-STATE DRIFT: WHEN DRIVING ON A FLAT, STRAIGHT ROAD (WITHOUT A CROWN), THE VEHICLE ALTERS FROM A STRAIGHT COURSE WITHOUT APPLYING THE BRAKES.

THE CUSTOMER ROAD TEST

Test drive the vehicle with the customer to understand the pull or drift condition. Sometimes they may mistakenly call a clear vision condition a pull or drift condition because the steering wheel is not straight.

  • The road test should be done on a flat, straight road (with no crown) and should be done in both directions to account for wind.
  • Tire pressure should be checked and adjusted, if necessary.
  • On vehicles with automatic locking hubs, it is necessary to drive 6m (20 ft) forward and then 3m (10 ft) backward to unlock the hubs.

NOTE:THIS TSB ARTICLE SHOULD BE READ COMPLETELY BEFORE PERFORMING DIAGNOSTICS OR REPAIRS.

DIAGNOSTIC PROCEDURE #1 – STEERING GEAR MESHLOAD

MESHLOAD CHECK/RESET

If the steering system exhibits on-center free play, or in general displays a vague on-center feel or lash, this may contribute to reduced straight-line stability and a customer perception of drift or pull. In these cases, a fall-off in factory-set levels of steering gear meshload may be the cause. Setting meshload too high may result in customer dissatisfaction with higher efforts and overall steering feel.

ADJUSTMENT PROCEDURE

  1. Adjust the steering wheel to be at center position.
  2. Disconnect the battery.
  3. Raise the vehicle and disconnect the steering gear sector shaft arm from the steering gear sector shaft using Pitman Arm Puller T64P-3590-F.
  4. Lower the vehicle.
  5. Remove the steering wheel hub cover and air bag as required.

    NOTE:REFER TO THE APPROPRIATE SERVICE MANUAL, SECTION 11-04, FOR REMOVAL AND INSTALLATION OF THE AIR BAG.

  6. Attach a pound-inch torque wrench to the steering wheel nut.

    NOTE:USE OF A DIAL-TYPE POUND-INCH TORQUE WRENCH IS RECOMMENDED. DO NOT USE A N-m (LB-FT) OR CLICKER-TYPE TORQUE WRENCH.

    1. Determine the torque required to rotate the steering gear sector shaft back and forth across the center position (90).
    2. Loosen the adjuster locknut and turn the sector shaft adjuster screw until the total on-center torque reading is 1.7-1.9 N-m (15-17 lb-in).
    3. Hold the sector shaft screw in place and tighten the locknut to 46-61 N-m (34-45 lb-ft).
  7. Recheck the steering gear on-center torque readings and reinstall the steering wheel hub cover and air bag as required.

    NOTE:REFER TO THE APPROPRIATE SERVICE MANUAL, SECTION 11-04, FOR REMOVAL AND INSTALLATION OF THE AIR BAG.

  8. Raise the vehicle and reconnect the steering gear sector shaft arm.
  9. Lower the vehicle and reconnect the battery.

    NOTE:WHEN THE BATTERY HAS BEEN DISCONNECTED AND RECONNECTED, SOME ABNORMAL DRIVE SYMPTOMS MAY OCCUR WHILE THE POWERTRAIN CONTROL MODULE (PCM) RELEARNS ITS ADAPTIVE STRATEGY. THE VEHICLE MAY NEED TO BE DRIVEN 16 KM (10 MILES) OR MORE TO RELEARN THE STRATEGY.

  10. Perform road test, referring to Figure 1 for further procedures.

DIAGNOSTIC PROCEDURE #2 – TIRES

  1. Spin the front tires to be sure the front hubs are unlocked.
  2. Set tire pressures to values listed on the certification label.
  3. Swap the front tires from side-to-side and road test. If the condition is not corrected, proceed with Step 4.
  4. Swap the rear tires from side-to-side and road test. If the condition is not corrected, continue with the next Procedure.

    NOTE:IF THE VEHICLE DRIFTS IN THE OTHER DIRECTION AFTER SWAPPING THE TIRES, REPLACE BOTH AFFECTED TIRES.

DIAGNOSTIC PROCEDURE #3 – ALIGNMENT

Wheel Alignment – Measure the front wheel alignment. For out-of-specification vehicles, align to the specifications found in the following two charts.

NOTE:DIAGNOSTIC PROCEDURE #1 MUST BE PERFORMED BEFORE ALIGNMENT. TEST DRIVE VEHICLE AFTER ALIGNMENT IS PERFORMED.



OPTIMUM TRUCK ALIGNMENT SERVICE SPECIFICATIONS
MODELCAMBER AVERAGE*CASTER AVERAGE (minimum)CASTER AVERAGE** (maximum)
4X2
F-2500.5 (0.5)26
F-350 SRW0.5 (0.5)26
F-350 DRW0.5 (0.5)0.54.50
4X4
F-2500.5 (0.5)26
F-3500.0 (0.5)25


OPTIMUM TRUCK ALIGNMENT SERVICE SPECIFICATIONS
MODELTOTAL TOE**** (optimum)CAMBER SPLIT (optimum)CASTER SPLIT*** (optimum)
4X2
F-2500.06 (0.25)0 (0.5)-0.0 (0.5)
F-350 SRW0.06 (0.25)0 (0.5)-0.0 (0.5)
F-350 DRW0.06 (0.25)0 (0.5)0.0 (0.5)
4X4
F-2500.06 (0.25)0 (0.5)0 (0.3)
F-3500.06 (0.25)0 (0.5)0.1; +0.5, -0.4

* CAMBER AVERAGE is the sum of LH camber plus RH camber divided by two (2). Vehicles set to this specification, as measured with the vehicle loaded to normal loading conditions, may result in optimum tire wear.

** CASTER AVERAGE is the sum of LH caster plus RH caster divided by two (2). These are not recommended values for settings. They are only maximum and minimum limitations.

*** CASTER SPLIT is LH caster minus RH caster.

****TOTAL TOE is the sum of LH toe plus RH toe angles.

  • Vehicles which exceed the maximum average caster value shown above may result in shimmy conditions.
  • Vehicles operated below the minimum average caster value shown may result in wander and poor steering returnability conditions. If appropriate, reset nominal LH/RH caster to the high end of the specification.

DIAGNOSTIC PROCEDURE #4 – BRAKES

  1. Raise the vehicle and spin the front tires to be sure the front hubs are unlocked. If the hubs are unlocked, the axle shaft will not rotate with the wheels.
  2. Check for front wheel rotational drag with warm/hot brakes.
    1. Make a series of 10 stops from speeds of 48 km/h (30 mph). Make the stops with no more than 30 second intervals between stops. This generally will induce a maximum pull if there is a drift/pull condition.
    2. Raise the front end of the vehicle so that both tires are off the ground.
    3. Rotate the front tires by hand.
    4. Both tires should rotate with about the same effort with little brake drag occurring. Some brake drag will naturally be present.
  3. If the vehicle has excessive brake drag, proceed as follows:
    1. Open the bleed screw on the affected wheel to check for residual pressure in the brake lines. If there is a squirt of brake fluid out of the bleeder screw and the drag is reduced or eliminated, the master cylinder may not be allowing the brake fluid to return to the reservoir.
    2. Check the master cylinder push rod adjustment. Refer to the appropriate Service Manual, Section 06-06 for details.
    3. Check the brake pedal to determine is it is returning fully.

      NOTE:FOR ALL 4-WHEEL-DRIVE VEHICLES, MAKE SURE THE HUBS ARE DISENGAGED.

  4. Remove both calipers and check piston retraction using a C-clamp and a wooden block. The piston should move easily back into the bore under force of the clamp. Inspect and clean any corrosion buildup under and around the knuckle rail and spring clamp. Lubricate between knuckle rail and spring clips using Silicone Brake Caliper Grease and Dielectric Compound (D7AZ-19A331-A). Repair calipers as required.
  5. If Steps 1 through 4 have not determined the source of the condition, swap rotors and linings from side-to-side.
  6. Test drive the vehicle with 10 or more stops from 64 km/h (40 mph). If there is no change in the drift/pull, the front brakes are not at fault.
  7. Check the rear brakes.
    1. Check for contaminants such as grease, axle lube, leaking brake fluid, etc.
    2. Check for damaged or broken components such as, frozen parking brake cables, improperly installed parts, etc.
    3. Check the rear wheel cylinders by the following method:
      • Reinstall one of the brake drums
      • Have someone apply the brakes very slowly while watching for movement of one of the brake shoes on the side without the drum installed
      • Reapply the brakes while holding the shoe that moved first. The other shoe should now move. If no movement is observed, repair or replace the wheel cylinder
      • Reinstall the drum and repeat the procedure on the opposite side of the vehicle

PART NUMBERPART NAME
D7AZ-19A331-ASilicone Brake Caliper Grease And Dielectric Compound

OTHER APPLICABLE ARTICLES:

93-23-24

SUPERSEDES:

97-24-19

WARRANTY STATUS:

Eligible Under The Provisions Of Bumper To Bumper Warranty Coverage

OPERATIONDESCRIPTIONTIME
985A23ATest Drive0.3 Hr.
985A23BMeshload Adjustment0.6 Hr.
985A23CTire Swap0.4 Hr.
985A23DCheck For Brake Drag, Check And Adjust Master Cylinder Pushrod Length, Check Calipers, Clean And Lubricate Slides1.0 Hr.
985A23ETAdditional Time To Overhaul Calipers – Both0.9 Hr.
985A23EAdditional Time To Overhaul Caliper – One0.5 Hr.
985A23FSwap Rotors And Linings – 4X21.0 Hr.
985A23GSwap Rotors And Linings – 4X41.5 Hrs.
985A23ITReplace Wheel Cylinders – Both0.6 Hr.
985A23IReplace Wheel Cylinder – One0.4 Hr.

DEALER CODING

BASIC PART NO.CONDITION CODE
LABOR OPERATION A – FRONTW6
LABOR OPERATION B – 3L547D4
LABOR OPERATION C – TIRE42
LABOR OPERATION D – 200142
LABOR OPERATION E – 212041
LABOR OPERATION ET – 212041
LABOR OPERATION F – 200142
LABOR OPERATION G – 200142
LABOR OPERATION I – 212841
LABOR OPERATION IT – 212841

OASIS CODES:

301000, 303000, 304000


Copyright 1998 Ford Motor Company