The trailer industry now has a large variety of wheel ends to cater for varying conditions and budgets and conventional wheel end lateral end clearance can be an issue. It is important to identify which wheel end you have, to ensure the correct procedure is followed. This article concentrates on the critical details of a conventional wheel end and the importance of wheel end bearing end clearance on wheel end life.
Measuring Lateral End Clearance
- Basic housekeeping. Prior to assembling the hub onto the spindle, the workshop floor should be free of dust and debris, the hub socket is in sound condition with no damage to the hex corners which could provide opportunity for slithers of metal to enter the outer wheel bearing roller. If you are breaking into a hub, ensure that the anti-mist fibres on the mudguards are free of dust and dirt, the wheel assembly is clean, and the hub cap is thoroughly cleaned particularly around the hub cap gasket interface. Any of these areas are a source of bearing contamination when opening a hub.
- Checking end play through rocking the tyre and wheel assembly with an iron bar is reasonable to get a very general feel for bearing movement but must not be used to gauge end clearance. For example, placing an iron bar underneath a set of dual wheels while rocking the wheel assembly will show movement. But it is impossible to tell whether this is vertical movement (from spindle wear), lateral movement (from end clearance) or a combination of both.
- Lateral end clearance should be measured at the hub assembly. It should only be measured with a dial indicator after rotating the hub at least four times (see images). This is necessary to gauge complete clearance as the bearing rollers must be completely seated against the bearing shoulder.
- The use of a dial indicator to measure lateral end clearance ensures that a clearance of between .001 to .005 inches is set. Setting clearance within this band ensures that the bearing package is stable and will help with inner hub seal life. Refer to chart.
- Bearing life for conventional bearings will decrease with free play greater than .005 inch and degrade even quicker if the bearing is pre-loaded. Conventional wheel ends should not be set in preload, as preload cannot be measured and can cause premature bearing failure.