The hub mounting face must be cleaned and kept flat. Look for worn or damaged mounting faces by using a straight edge.
Clean hub mounting surface and hub pilots with a wire brush if rust, dirt, paint, grease or debris is present.
Note the condition of the hub and the hub pilots. Replace the hub if a worn hub face is evident or if the hub pilots are worn or broken.
Drum:
The drum mounting face must be cleaned, free of dirt, paint, and grease and kept flat.
Look for worn or damaged mounting faces by using a straight edge.
Clean the drum surface with a wire brush if rust or debris is present.
Ensure the brake drum is positioned on the raised step of the hub pilots and is seated fully against the hub.
Replace the drum if it exhibits a worn mounting face, or cracked bolt holes.
Wheels:
Ensure that wheel mounting faces are free of dirt and grease.
Be sure the wheels are hub-piloted wheels with bolt holes drilled straight through without ball seats. Stud-piloted wheels must not be used as substitutes for hub-piloted wheels under any circumstance. Never try to use a hub-piloted wheel with a stud-piloted hub or stud-piloted nuts. The result could be torque loss, a cracked wheel, or possible wheel loss.
Make sure the center hole of the wheel is clean so it will fit easily on the hub pilots.
Look for worn or damaged mounting faces by using a straight edge.
Replace any wheel that exhibits wear or damage.
Look for damaged metal at bolt and center holes.
Studs and Nuts:
Ensure that studs and nuts are free of dirt and grease.
Wire brush the base of each stud and threads to remove any rust or foreign material that could bind up the wheel nuts.
Check for damaged studs and stripped stud threads as evidenced by shiny threads.
Replace any parts that exhibit wear or damage.
Ensure replacement studs are the proper ones for the system used. Stud breakage can occur if the wrong studs are used.
If a stud is broken, replace it and the stud on each side of the broken one. If two or more studs are broken, replace them all. Use a press to install the studs and be sure the hub flange is supported. Stud heads can be bent from hammer blows, which will prevent the stud from seating properly, and can result in stud failure.
Recommended Mounting Torque For Disc Wheels
Mounting Type
Nut Thread
Torque Level Ft.-Lb. (oiled)*
Hub-piloted with flange nut
11/16" - 16
300-400
M20 x 1.5
280-330
M22 x 1.5
450-500
7/8 - 14
350-400
* Oiled - Apply two drops of oil to a point between the nut and flange and two drops to the two or three threads at the end of each stud.
DO NOT APPLY OIL TO ANY PART OF THE DISC-LOCK SAFETY WHEEL NUT.
NOTE: If using specialty fasteners, consult the manufacturer for recommended torque levels.
Recommended Mounting Torque For DISC-LOCK Safety Wheel Nuts (*Table 1)
Size
Disc-Lock Part Number
Installation Torque Ft.-Lb. (oiled)**
7/8" - 14UNF
NSF-2090-S-GEO
500-550
M22 X 1.5
NMF-2090-M-GEO
500-550
** The above torque levels for Disc-Lock Safety Wheel Nuts are for usage with Grade 8 (Class 10.9 Metric) wheel studs only.
NOTE: DISC-LOCK Safety Wheel Nuts are coated with Geomet Coating, a completely chromium-free coating (no Hexavalent and no Trivalent chromium). 720 hours salt spray corrosion protection, far surpassing the industry standard of 96 hours.
CAM RISE ANGLE - Unlike conventional wheel nuts for hub-piloted wheels, DISC-LOCK Safety Wheel Nuts are made with interlocking cams on the underside of the nut component and top side of the hex flange washer. The angle of the cams is greater than the pitch angle of the threads on the stud, therefore under road shock and vibration, a wedging action takes place and the DISC-LOCK Safety Wheel Nut locks and will not come loose, thus keeping the wheel on the axle.
Aluminum hubs require different stud installation procedures. Consult the manufacturer for recommendations.
Use correct nuts. Nuts used for stud-piloted systems can't be used in hub-piloted systems. Hubpiloted wheels use flange nuts for both single and dual wheel applications. No inner cap nuts are required.
Check the wheel nuts and ensure that multi-piece nuts turn smoothly on their flanges. Discard all nuts with damaged threads and those that fail to turn smoothly.
Apply two drops of 30 weight oil to a point between the nuts and flanges and two drops to the last 2 or 3 threads at the end of each stud. Also lightly lubricate the pilots on the hub to ease wheel installation and removal. Do not get lubricant on the mounting face of the drum or wheel.
NOTE: DO NOT APPLY OIL TO ANY PART OF THE DISC-LOCK SAFETY WHEEL NUT.
NOTE: The use of anti-seize compounds is not recommended for this application.
For DISC-LOCK Safety Wheel Nuts
Use only 6-point, flat-faced (without bevel), flanked sockets to install and remove DISC-LOCK Safety Wheel Nuts (sockets available from DISC-LOCK.)
IMPORTANT: DISC-LOCK recommends DISC-LOCK Safety Wheel Nut usage in COMPLETE WHEEL SETS ONLY (i.e., eight DISC-LOCK Safety Wheel Nuts on an eight-hole mount and 10 DISC-LOCK Safety Wheel Nuts on a 10-hole mount.
Nut Tightening Sequence for Hub-Piloted Disc Wheels
(*Figure 1)
2. Rotate the hub so that one pilot is at the 12 o'clock position. Place the single wheel or the inner dual wheel onto the hub being careful not to damage stud threads. Make sure the wheel is fully seated against the drum.
3. For dual wheels, place the outer wheel onto the hub making sure the hand holes are lined up for easy access to the tire valves. Make sure the outer wheel is pushed fully up against the inner wheel. Install nuts finger-tight at the 12 o'clock position and then at the 6 o'clock position, then apply nuts fingertight to the remaining studs. Snug the nuts to about 50 ft. lbs. following a crisscross sequence as shown in Fig. 1*. Finally tighten all the nuts to the recommended torque (See Table 1*) using the same crisscross sequence.
4. After the wheels are installed, check to see that both wheels are still seated on the pilots and are flat against the drum. This can be done by inspecting the seating of the wheels on all four pilots and by turning the wheels and checking for wheel assembly irregularity.
5. After a wheel assembly has been installed, recheck the torque level between 50 and 100 miles of operation and retighten if necessary to the recommended torque using the proper sequence. It is recommended that a torque check be made as part of a vehicle's scheduled maintenance program or at 10,000 mile intervals whichever comes first. Individual fleet experience may dictate shorter intervals or allow longer intervals.
6. If air wrenches are used, they must be periodically calibrated for proper torque output. Use a torque wrench to check the air wrench output. If output is not correct, take the necessary steps to adjust output. (See "Air System and Impact Wrench Maintenance" section for more details.) "Air System and Impact Wrench Maintenance" section in TMC's User's Guide to Wheels and Rims for more details.)
DISCLAIMER: This information is based on TMC RP 222B, "User's Guide to Wheels and Rims," and the consensus of the members of the Technology & Maintenance Council (TMC) on those items and methods that have delivered the best performance record based on the experience of those present at meetings of the Council. The procedures contained herein are not exclusive. TMC cannot possibly know, evaluate, or advise the transportation industry of all conceivable ways in which a practice may be undertaken or of the possible consequences of each such practice. Other practices or methods may be as good, or better, depending upon the particular circumstances involved. All who use the procedures contained herein must first satisfy themselves thoroughly that neither the safety of their employees or agents, nor the safety or usefulness of any products, will be jeopardized by any method selected. The following procedures are not intended nor should they be construed as an endorsement of any particular person, organization, or product. Technology & Maintenance Council of American Trucking Associations, Inc., 2004
