2012 22.3 Ask Albert!
Dear Albert,
I was recently moving a piece of equipment from one field to another and heard a crunchy sound near the wheels. When I looked back, I saw one of the wheels was wobbly. I stopped and went to inspect it. There was some movement – about 1/2” – when I grabbed the top of the tire and moved it. The other side did not have the movement. I’d gone about ½ mile and noticed the hub was warm. What’s going on?
Stalled in the road
Dear Stalled,
Good noticing the noise, wobble, movement of the tire, and the warmth on the hub. These are all signs of a wheel bearing going out. Noises like the screechy growly type and vibration when rolling down the road are clues that wheel bearings need inspection. When a worn wheel bearing is on a steering axle, one side will drag and pull and there is movement when the tire is pushed or pulled. It’s worth noting that tow-behind implements also have wheel bearings.
To best inspect the wheel bearing, lift and securely block the implement so the wheel is off the ground. Depending on the size and weight of the tire, the tire doesn’t always need to be removed from the hub in order to service the wheel bearings.
Removal
Most implements have a stamped metal cup that presses into the center of the hub, while others have a threaded cup. The stamped cup can be removed with a straight slotted screwdriver (prying) or large pliers (gripping the cup), or hammer (tapping lightly around on the sides). A cotter pin and a castellated nut will be visible through the axle after the stamped cup has been removed. Take the pin out and remove the nut with its accompanying washer. Put them inside the cup and set them aside. Wiggle the wheel a bit and the inner race will move outwards, pushing the bearing out. Grab the bearing off the spindle and place it in the cup with the pin and nut.
Now grab the hub and pull off the axle. The inner bearing will come out with the hub, retained by the axle seal. This is a classic removal description. If the bearing has been spun and overheated the spindle, they’ll have fused and it will be a lot harder to remove. Obviously, this is another reason to avoid overheating the wheel bearings (more reasons later). Maintenance (see below) will help avoid this situation.
Returning to the hub, turn it inside down and block it off the floor a couple of inches. Go through the outer hub with a drift punch and hammer and tap the inner bearing and seal out of the hub. Clean off the bearings and inner races (which will still be inside the hub). Check for pits, cracks, scrapes, or discoloration on the race. The desired outcome is smooth, clean, shiny, uniform, and silvery-colored races. If there is a gray wear line around the center, it means there has been normal wear, in which case it might still be serviceable. If a groove can be felt by touch, it’s time to replace the race. If there is no groove, it can be re-packed. If the outer race or hub has defects or rollers on the inner bearing are pitted, cracked, deformed, chipped, or rusty, then the bearing needs to be replaced.
To remove the outer race, block the hub up off the floor. Looking at the opposite side of the race, tap the drift punch at 180 degrees alternately until the outer race drops out of the hub. Once one side is out, turn the hub and tap out the other outer race. Thoroughly clean the hub with solvent and a brush removing all old grease, metal filings, rust, et cetera.
Finding Replacement Parts
The bearing part number is printed on the wide thrust side of the roller on the inner race. The outer race part number can be found on the thrust end or outer perimeter of the outer race (another reason not to “spin” or heat the bearings – as it grinds the numbers off). There are five replacement part numbers in total: inner race, outer race, inner bearing, outer bearing, and seal. If the numbers are not on the parts that have been removed or are missing due to damage, re-ordering can be done by application – make, model, year, and serial number.
Replacement
With clean hub, press new races (make sure they’re facing the right direction) into the hub with press and correct sized plates (called “cookies”). If no press is available, place hub on piece of wood (2 x 6) on bench or floor. Then, evenly tap the races into the hub with a brass drift punch. Make sure race is seated all the way into the hub. Turn over and repeat.
Find the inner race with rollers. Place about three heaping tablespoons of wheel bearing grease in palm of left hand. With right hand, hold bearing with index finger through the center with the large end of the bearing roller retainer (cage) facing out. With scraping action, start at the edge of the grease and force the grease through the cage and rollers. Grease will extrude out of the small cone and bearing cage. Rotate bearing and continue to pack with grease until bearing is full. Place the excess grease onto the outer race and into the hub. Place the bearing in the hub, then take the seal and press into the hub also. Usually the shell of the seal is to the outside. The seal prevents grease from leaking out, but more importantly from dirt getting into the hub, destroying bearings, spindle, and hub.
Next, pack the outer bearing in the same manner. Set them in a clean place (in the cap). Now, carefully place hub onto spindle, taking care not to damage the seal. Hold in place and seat outer bearing, washer (where applicable), and nut. Tighten the nut hand tight then with pliers or wrench tighten enough to remove any endplay without putting torque on the nut. Finally, back off nut 1/8 to 1/6 turn and insert cotter pin through nut and spindle.
Maintenance
Wheel bearings should be checked and re-packed yearly. While operating machine during the season, go around and check hub temperature by hand, and shake the wheel to check for wear and possible failure.
It’s amazing how important wheel bearings are, and yet they are often overlooked and ignored. I congratulate you on your alertness to the noise and other clues. Hopefully, you have averted larger damage by this intervention.
Yours in the shop preparing the swather for first cutting of hay,
Albert
