Fulltext TSBs

Technical Service Bulletins

TSB
05-26-24
  • VIBRATION DIAGNOSIS – TIRE/WHEEL RUNOUT
Publication Date: December 23, 2005

FORD:
2003-2006 Expedition
2004-2005 Excursion, Explorer Sport Trac
2004-2006 Escape, Explorer, F-150, F-Super Duty, Ranger
LINCOLN:
2003-2006 Navigator
2006 Mark LT
MERCURY:
2004-2006 Mountaineer
2005-2006 Mariner

ISSUE:

Some vehicles may exhibit a tire/wheel vibration caused by excessive runout.

ACTION:

The following procedure should be used if normal diagnostics lead to a potential runout issue. The procedure is intended to assist with the diagnosis of tire/wheel assembly runout and/or force variation issues. To diagnose and correct the concern, refer to the following Service Procedure.

NOTE:FOLLOW THIS TSB PROCEDURE ONLY IF THERE ARE NO SPECIFIC TSBs/SSMs RELEASED FOR THE VEHICLE SYMPTOM BEING EXPERIENCED.

GENERAL INFORMATION

NOTE:MEASUREMENTS ARE TO BE COMPLETED ON THE BALANCER AND NOT ON VEHICLE.

NOTE:A DIAL INDICATOR IS TO BE USED IF A HUNTER GSP9700 BALANCER IS NOT AVAILABLE.

ROAD FORCE

Hunter Engineering has developed a service balancer line (GSP9700) that includes an assembly uniformity feature that they call “Road Force”. This Hunter system measures the assemblies loaded runout, measures the tires radial spring rate and then converts the runout into pounds of Road Force. The value that the machine displays is a reasonably close equivalent of the R1H (see below) from a force machine. The term “Road Force measurement” has been trademarked and registered by Hunter Engineering.

FORCE VARIATION

The industry standard for a tire’s or an assembly’s uniformity is expressed as “force variation”. Force variation is the variation in the load at the footprint while the inflated tire is rolled at low speed against an instrumented drum at a fixed deflection and also at a predetermined load. Ford Motor Company has specifications for force variation that all tire suppliers must meet. The information that is output from a “Force” machine is usually Radial Force Variation (RFV), Radial First Harmonic (R1H), Radial Second Harmonic (R2H), etc. These are the total variation (RFV), the once per revolution (R1H), and the twice per revolution (R2H), variation, respectively, in the radial load at the footprint.

SERVICE PROCEDURE

  1. Measure the assembly runout, or R1H Road Force, and mark the magnitude (Road Force reading if using the Hunter GSP9700; amount of runout if using a dial indicator) and location on the tire. As the assembly is reworked, the value and location on the tire are important.
    1. If using a Hunter GSP9700 balancer, the following road force values are effective guidelines for acceptable assembly runout:
      • F-150/Expedition/Navigator/Mark LT – Road Force of 25 lbs (11 kg) or less (check with tire pressure at normal level on P metric tires; check with tire pressure at normal level or 50 psi (345 kPa), whichever is lower, on LT type tires)
      • F-Super Duty/Excursion – Road Force of 35 lbs (16 kg) or less (check with tire at 50 psi (345 kPa))
      • Escape/Mariner – Road Force of 18 lbs (8 kg) or less (check with tire at 30 psi (207 kPa))
      • Explorer/Mountaineer/Sport Trac/Ranger – Road Force of 25 lbs (11 kg)or less (check with tire at 35 psi (241 kPa)

      NOTE:AFTER TESTING ROAD FORCE AT THE TIRE PRESSURES RECOMMENDED ABOVE, ENSURE TIRE PRESSURE IS RESET TO PRESSURE INDICATED ON VEHICLE LABEL. IF THE TIRE PRESSURE IS NOT RESET, IT MAY LEAD TO ROUGH RIDE, STEERING WHEEL OSCILLATION, OR OTHER ISSUES.

  2. If assembly runout (or Road Force) is high, evaluate effect of re-indexing the tire and wheel.
    1. Mark the tire at the valve stem. This is to reference the original indexing location.
    2. Deflate the tire and break down both beads from the wheel. Rotate the tire 180 degrees on the rim, rather than following the Hunter GSP9700 balancer’s routine for indexing (see note).

      NOTE:THE HUNTER GSP9700 TIRE WHEEL MATCHING ROUTINE WORKS WELL WHEN THE “TIRE ON” WHEEL RUNOUT MEASUREMENTS ARE GOOD. ON MANY MODERN WHEEL DESIGNS THIS “TIRE ON” WHEEL MEASUREMENT MAY NOT BE A GOOD APPROXIMATION OF THE “TIRE OFF” WHEEL MEASUREMENTS. THIS IS ESPECIALLY TRUE FOR THE STEEL WHEELS WITH CHROME CLADDING, AND ALSO FOR THE “FULL FACE” STEEL WHEELS. THEREFORE IT IS MORE RELIABLE TO USE 180 DEGREE ROTATION IN THE FIRST STEP, AND THEN FOLLOW THESE GUIDELINES.

    3. Re-inflate the tire to the measurement pressure and measure the assembly runout again.
    4. Mark this second high spot of runout on the tire.

      NOTE:IF THE RUNOUT GOES DOWN SIGNIFICANTLY, THEN THE ORIGINAL TIRE WHEEL ASSEMBLY INDEXING WAS NOT OPTIMIZED.

  3. Review the following guidelines, based on the outcome of the second assembly runout (or Road Force) measurement.
    1. If the second measurement is still over the guidelines and it is also close to the first one, (that is the two measurements are within about four inches on the tire) then the root cause is probably the tire (Figure 1). To be SURE that it is the tire causing the high runout, you must have the two runout measurements over the guideline, and they must be in about the same location on the tire’s sidewall. In other words, the high spot followed the tire when you turned it on the rim.


      Figure 1 – Article 05-26-24

    2. If the second high spot is still high and it is within four inches of being opposite the first high spot (Figure 2), then you may have a high runout wheel. In other words, the high spot followed the wheel. Dismount the tire and put the bare wheel back on the balancer. Measure the wheel runout on the bead seat surfaces with the tire off. Check the service manual for wheel runout guidelines.


      Figure 2 – Article 05-26-24

    3. If the second high spot did not follow either the tire or the wheel (Figure 3), AND the runout is still over the guideline, then you can probably improve the assembly by another one quarter turn. Draw an arrow on the tire sidewall from the second high spot toward the first high spot, and turn the tire 90 degrees in that direction. It is very likely that the assembly runout will drop to a lower number.


      Figure 3 – Article 05-26-24

OTHER APPLICABLE ARTICLES:

703300

WARRANTY STATUS:

Eligible Under Provisions Of New Vehicle Limited Warranty Coverage

DEALER CODING

BASIC PART NO.CONDITION CODE
ALBALd9

NOTE: The information in Technical Service Bulletins is intended for use by trained, professional technicians with the knowledge, tools, and equipment to do the job properly and safely. It informs these technicians of conditions that may occur on some vehicles, or provides information that could assist in proper vehicle service. The procedures should not be performed by “do-it-yourselfers”. Do not assume that a condition described affects your car or truck. Contact a Ford, Lincoln, or Mercury dealership to determine whether the Bulletin applies to your vehicle. Warranty Policy and Extended Service Plan documentation determine Warranty and/or Extended Service Plan coverage unless stated otherwise in the TSB article. The information in this Technical Service Bulletin (TSB) was current at the time of printing. Ford Motor Company reserves the right to supercede this information with updates. The most recent information is available through Ford Motor Company’s on-line technical resources.

Copyright 2005 Ford Motor Company