Bearings are usually taken for granted-until the bearing comes out in more pieces than when it went in. We'll explore the selection, installation and maintenance of various bearings which will allow you to keep your racer in top condition and give you a better shot at seeing that checkered flag.
Ball bearing for Muncie transmission. Ramey Womer
Types Of BearingsBall bearings Used in transmissions and differentials where minimal side loading is present.
Roller bearingsAlso used where minimal side loading is present. They can carry more load than ball bearings but do not tolerate misalignment as well. A roller bearing on the nose of a quick-change ring and pinion is a popular application.
Tapered roller bearingsThese are used for wheel bearings and as the main bearings on pinions. Another common name is "cups and cones." Tapered rollers are the only bearings that come apart readily.
Off-Season MaintenanceBearings require simple, yet critical routine maintenance to perform at their best. They can often be cleaned, re-lubed and reinstalled. But how do you know when to maintain them or when to replace them? Things to look for include:
DiscolorationAn overheated bearing will have a dull appearance, a black appearance or occasionally a rainbow effect. Don't even think about it-if you see discoloration replace the bearings.
Tapered roller bearing cup and cone. Image courtesy of Timken
Pit marksPits on balls, rollers or races indicate a need for replacement. One of the best inspection items for your toolbox is a 10x loupe or a spark plug reading tool. Close inspection with magnification can give you a good idea of a bearing's true condition.
RoughnessRoughness in a bearing invites failure. Bearings should roll without any skips or bumps. Blemishes in the raceway or on the moving components give problems a place to start. If you can detect roughness, replace the bearings.
Normal wearNormal wear in a bearing is shown by shiny balls or rollers moving in shiny or slightly satin-like raceways. A smooth running bearing in this visual condition can be safely reused.
Cleaning A BearingBearings are precision instruments and should be treated as such. In most cases, off-the-shelf bearings are more precise than the parts in the engine. Begin by wiping excess grease, oil and dirt from the bearing using a lint-free cloth. Industrial wipers are becoming increasingly popular.
Immerse the bearing in a parts cleaning solution and brush until all traces of grease and dirt are gone. Keeping a separate container of "clean" solvent is a good idea for final rinsing. Speedway Motors offers an ultrasonic cleaner which is fantastic for removing the last traces of solvent from the bearings. Ultrasonic cleaners use sound waves to dislodge dirt from hard-to-reach places. You'd be surprised at what comes out of a supposedly clean bearing.
Blow the bearing dry using properly dried shop air or nitrogen from your tire tank and let drain on a lint free wiper or on an industrial absorbent mat. (Note: All of us have spun a bearing with compressed air to hear that cool spinning sound. Be advised this is very dangerous and can cause the bearing to come apart with great force. Always hold the bearing against a clean wipe while blowing it dry.) Cover the bearings if not installing them right away, as grinder dust has a way of sticking to everything. For best results, grease only the bearings you plan to immediately install. Spending some extra time and taking the proper precautions now will make a difference in how long your bearings last later.
Bearing InstallationBearings should never be forced into position in an uncontrolled manner. When installing races (cups) into hubs, the race should be pressed against the outer edge. Never use the bearing cone to press the race into position. Excess pressure, such as required to press a race into a hub, can cause microscopic indentations in the race and accelerate the failure process. Bearing cups should be installed using a dedicated installation tool or a properly sized socket.