MAINTENANCE MATTERS
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Keeping your wheels in good running order


Sometimes keeping your wheels turning literally means keeping your wheels spinning — smoothly and reliably. And making sure wheels are properly mounted is a crucial part of that process.

Depending on your coach model, wheel-mounting hardware and torques may vary substantially. Factors that can make a difference include where the wheels are mounted (front, drive or tag axle); whether the wheel is painted steel or polished aluminum; and if the wheels are stud-piloted or hub-piloted. But there's one thing they do have in common: Poor mounting procedures can cause wheel-stud failure that can damage the wheel or hub assembly, or, even worse,  cause the loss of the tire.

When mounting wheels, MCI cautions against over-reliance on pneumatic tools; using torque wrenches and proper torque sequences can reduce or maybe even prevent wheel-stud failure. In addition to using proper mounting procedures, inspecting tires and lug nuts before every trip may save you from a breakdown that could cost you time and money.

Proper tightening sequences can be found in your MCI Maintenance Manual, Section 15.  But in general, when replacing wheel studs, it is good practice to replace adjacent studs as well, for they have probably been overloaded. If more than two studs have been broken, replace the entire set.

Stud vs. hub

Stud-piloted wheels use chamfered wheel-stud holes to center the wheel on the hub. Hub-piloted wheels do not have chamfered stud holes and use the center stud hole to pilot the wheels onto the hub and studs. Due to these basic wheel differences, each of these installations use specialized mounting hardware to fasten the wheels to the axle hub and drum/disc assemblies. Steel wheels have a two- or five-hand hole pattern, while aluminum wheels have a ten-hand hole pattern and are fabricated from thicker material than steel wheels.

With stud-piloted wheels, installations require left-hand threaded studs on the left side of the coach and right-hand threaded studs on the right side of the coach. All stud-piloted drive axle studs are fitted with an inner wheel nut to make up the length required for dual-wheel installations. With this configuration, it is necessary to tighten the inner nuts fully before installing the outer wheel nuts.

Hub-piloted wheel installations use right-hand threaded studs on both left and right sides. Stud stand-out lengths for aluminum wheels are longer on all hub-piloted installations.

Conventional ball-seat wheel nuts are used to attach all stud-piloted wheel installations. In some previous installations, special one piece flanged wheel nuts might have been used in place of  the more typical  ball seat nuts. Two-piece flanged wheel nuts are used to attach all hub-piloted wheel installations. Inner wheel nuts are used to attach drive axle stud-piloted inner dual wheels on steel, steel/aluminum, and aluminum/aluminum wheel installations.

Wheel torque nut specifications

Torque all wheels to 450-500 ft. lbs. (610-678 NM). It is recommended that wheel nuts be re-torqued after the first 50 to 100 miles of operation.

Below is the torque sequence for torquing the wheel nuts on all axles. By making this simple template, torquing wheel nuts will be made simple.

Everyday maintenance

Here are some things to look for on your wheels on the pre-trip inspections drivers and mechanics should do each day:

  • On painted wheels, look for cracks between the wheel stud holes. If cracks are present, the wheel should be discarded.
  • On steel wheels, check for rust streaks at each lug nut, as rust streaks may indicate loose wheel nuts. Re-torque as required.
  • On aluminum wheels, check for streaking at each lug nut, as streaking may indicate loose wheel nuts. Re-torque as required.

By following these simple daily checks, you can help make sure your rims, wheel studs and lug nuts will give you years of  trouble-free service, and help your annual DOT inspections to go more smoothly.

You can find more information in Service Bulletin 2676, MCI's definitive reference on wheel studs and nuts If you have any further questions or concerns, please contact the MCI Technical Call Center at 800-241-2947.

The FYI from MCI editorial staff values your feedback. Please e-mail any suggestions, comments, or ideas for future articles to fyi@mcicoach.com

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