Install and tighten the locknut, but do not over tighten. This can damage the bearing as discussed above. Continue tightening until drag is felt while rotating the hub. The bearing is now in a neutral position.
Speedway Motors offers this ultrasonic cleaner. Image courtesy of Speedway Motors
Use a dial indicator mounted to the axle tube or other suitable surface. Loosen the lock nut slightly. Total free play should be 0.001 inch along the centerline of the axle.
Mark the locknut.
Remove, assemble seal, grease bearings and reinstall.
Tighten locknut to previous mark.
TechnologyTimken Motorsports Products Timken has released a specialized wheel bearing kit with components aimed at reducing friction and increasing reliability. Kits are available for both Wide-5 and 5x5 applications. The kit includes a specialized cup and cone, a low drag seal and grease optimized for racing. The cups feature superfinished surfaces while the cones have a geometry optimized for wheel end usage. The low drag seal is of a two-piece labyrinth design, which means each half of the seal mates directly to the hub and axle and does not contact itself. Less friction is realized due to this design.
In addition to the low-drag wheel bearing kits, Timken has introduced a system called RacePac. The high-end RacePac system is composed of a superspeedway hub pre-loaded with motorsports specific bearings, a low-drag seal and the proper grease. Perhaps the most important aspect of the RacePac system is the spacer package which places an exact amount of preload on the bearing cones. This preload (which is difficult to obtain without specialized tools, measuring equipment or training) makes for a rigid assembly with a good combination of low drag and long life.
Super FinishingThe surfaces of quality bearings are obviously very smooth with regard to the balls, rollers and rolling surfaces. In the quest for speed and reliability, some bearing manufacturers and aftermarket companies have moved into the world of superfinishing. The components of a bearing, when magnified under a microscope, show a world of peaks and valleys. Superfinishing removes the peaks and provides a microscopically smoother rolling surface. The most popular superfinishing process is known as REM finishing-so much so that quite a few racing components are advertised as being "REM'd." The REM ISF (Isotropic Superfinish) process reduces heat and friction due to the microscopic peak removal and also provides a bright and shiny appearance.
Six-pin hub, Holt Precision driver and bearing cup. Ramey Womer
Cryogenic TemperingCryogenic tempering is the process of cooling a material (in this case, a bearing) in a controlled manner to temperatures as low as minus 300 F. The "cryo" process serves to realign molecules in the metal in order to reduce internal stresses and increase durability, scuff resistance and toughness. Bill Groschen, president of Diversified Cryogenics, mentions his company routinely treats a wide variety of racecar parts including bearings, engine parts, and driveline parts. Bearings which have been cryogenically treated tend to show substantially less wear and galling. With this technology, bearings can be treated in assembled condition (i.e. ball and roller bearings) and returned to service with no noticeable difference in appearance but with a substantial increase in performance and service life. It's important to note that some bearings do not respond favorably to this type of treatment. Consult your bearing manufacturer before sending them to a cryogenic treatment facility. Even though they may look the same, bearings are quite often made from substantially different alloys brand-to-brand.