Inspection of the Wheel End

rv mm 33.04.000

Important: For ZF IFS axles, ZF recommends that all grease fittings be lubricated once a year, preferably before periods of inactivity. The wheel hub should be disassembled, inspected, and the wheel bearings repacked every 1,000,000 miles (1 609 000 km).

  1. Park the vehicle on a level surface, shut down the engine, and set the parking brake. Chock the tires.

    2. Warning: Never work around or under a vehicle that is supported only by a jack. Always support the vehicle with safety stands. Jacks can slip, causing the vehicle to fall, which could result in serious injury or death.

  2. Raise the front of the vehicle and support it with safety stands.
  3. Remove the front wheel and tire assemblies. For instructions, see of the Recreational Vehicle Workshop Manual.
  4. Remove the brake drum. For more information, see of the Recreational Vehicle Workshop Manual.
  5. Check for loose, damaged, or missing fasteners and hubcaps.
  6. Check for lubricant around the hub cap and wheel. If lubricant is present, investigate the cause and take corrective action.
  7. Check for lubricant around the hub, brake hardware, and brake shoes (if installed). If lubricant is present, check the oil seal and replace it as necessary. For instructions, see of the Recreational Vehicle Workshop Manual.
  8. Inspect the lubricant for discoloration. Under normal conditions, the lubricant will darken; a white or milky appearance indicates water contamination. If the lubricant is discolored, service the wheel end. See the Recreational Vehicle Workshop Manual and manufacturer literature for procedures.

    9. Important: Do not mix different types of lubricants.

  9. Inspect the lubricant for the presence of foreign matter. Use a magnet to detect any metallic materials present in the lubricant. If the lubricant is contaminated, service the hub. See the Recreational Vehicle Workshop Manual and manufacturer literature for procedures.
  10. Rotate the hub and check for free, smooth, and quiet rotation. If rotation is hampered, service the hub immediately. See the Recreational Vehicle Workshop Manual and manufacturer literature for procedures.

    11. Warning: Correct wheel-bearing end play is crucial to the safe and sound operation of the vehicle. If the end play is not correct, the wheel bearings could fail and cause the loss of the wheel and hub assembly and result in an accident causing property damage, serious injury, or death. Use a dial indicator to measure the end play.

    Important: Do not measure the wheel bearing end play with the wheel mounted on the hub; you cannot accurately measure or adjust bearing end play with the wheel mounted on the hub. Also, ensure that the brakes are not applied so that that drum and hub can move freely.

  11. Using a dial indicator, measure the end play as follows.
    1. Attach the magnetic base of a dial indicator to the end of the spindle, and place the measuring end of the indicator against the hub cap mounting flange. See Fig..

      Important: Maintain continual pressure on the hub until you have taken both the inboard and outboard measurements. If you release the hub, an accurate measurement is not possible.
      1. To seat the bearings, grip the hub at the three o'clock and nine o'clock positions, and push inward while oscillating it approximately 45 degrees. Maintain pressure on the hub, note the inboard measurement, and then pull the hub outward while oscillating it as before. Maintain pressure on the hub, and note the outboard measurement. See Fig..
        The end play is the difference between the two measurements. The end play limit for PreSet hubs is 0.006 inch (0.15 mm); for non-PreSet hubs the acceptable range is 0.001 to 0.005 inch (0.03 to 0.13 mm) inclusive.
        If the end play does not exceed the limit and no other problems were found in the previous steps, no additional service is necessary. If the end play exceeds the limit, service the hub. See the Recreational Vehicle Workshop Manual and manufacturer literature for procedures.

        1. Hub Cap Mounting Flange

        2. Dial Indicator (with magnetic base)

        Fig. 1, Dial Indicator Setup

        • Pull and push the hub while oscillating it.

        Fig. 2, Measuring End Play

    Note:
    Parent topic: Front Axle
    Document Number: 0000120523
    Manual Publication Date: 2024-05-23
    Topic Publication Date: 2024-11-13