ATV Wheel Bearings
Thanks to Ccrane for the writeup
ATV Wheel Bearings are a vital part of the suspension and drive train system and can cause serious damage to your ATV if not maintained & replaced properly.
Most factory wheel bearings are not sealed, they are pre-greased and have dust seals that press into the hub on the inner and outer side to protect from dust/sand/mud invasion.
These bearings are of a high quality Stainless Steel, they incorporate a S.S. "cage" that circumferences the bearing on the inner and outer sides in which there are tracks for the ball bearings to ride along.
The combination of several perfectly round stainless steel ball bearings riding inside the tracks of the "cage" and a high temperature wheel bearing grease allow the axles to smoothly turn inside the housing or "knuckle" without creating friction or marring the axle/housing.
When mud/sand/dirt/water or other foreign matter enters the bearing housing it compromises the grease and creates friction, which slowly and steadily wears away at both the bearings and the "cage". This wear will eventually lead to either the destruction of the bearing (allowing the axle to "flop" loosely inside the hub) or in some cases seizure of the bearing (that can lead to a potentially dangerous situation... harming the rider and destroying the axle).
It is best to periodically raise your ATV off the ground and check your wheels for "slop", physically grab the wheel (one hand on top of the tire, and one hand underneath) and attempt to move the wheel back and forth away from the machine. If the wheel is noticeably loose, typically it means your bearings are worn beyond tolerable limits.
There are two ways to go when it comes to purchasing new bearings for your ATV:
Go back with OEM bearings, this is usually the most simple way to go and OEM bearings are a commonly stocked item at most ATV dealerships. Always purchase new dust seals for your ATV when replacing the bearings (remember... on some models the inner and outer dust seals are not the same!)
Some aftermarket companies offer sealed bearings for ATV's, these are usually constructed of the same S.S. material as OEM or better.... and incorporate built-in rubber seals to further protect the bearing from foreign substances entering them. Just as with OEM bearings, always replace your dust seals... even though the bearings have their own seals the OEM dust seals are still a mandatory part.
There are many ways to remove bearings from hubs, different mfg's machines require a different process.
For the purpose of this article I will use Honda Utility ATV's as my example, they closely match most other brands and are typically the most difficult to remove based on my experience.
Always place your new bearings in the freezer overnight before attempting to install them... this will make them much easier to drive into the housing.
1:Thoroughly clean the machine, making sure to remove all debris around the wheel hubs, axles, a-frames, and shocks.
2:Raise the machine up, and brace it with jack stands or other solid and stable objects.
3:Remove the wheels.
4:Remove the cotter pin.
5:Remove the castle nut (sometimes this requires an impact wrench).
6:Remove the brake hub.
7:Remove the lower shock bolt from the a-arm and swing upwards out of your workspace.
8:Remove the two lower a-arm bolts holding it to the frame.
9:Swing the lower a-arm away from the machine and physically pull the axle shaft out of the steering knuckle.
10:With a shop towel, wipe the excess grease/sand/mud/debris out of the bearing housing so that you can see the bearing.
11:With a large set of Snap Ring Pliers remove the snap ring holding the bearing in place on the outer side of the steering knuckle.
12:Using a pneumatic Air Chisel, (with a flat-blade attachment) knock out the ball bearings and inner bearing cage.
13:With a shop towel, wipe the excess grease/sand/mud/debris out of the bearing so that you can see the outer bearing cage.
14:From the inner side (side closest to the differential) place the flat blade of the air chisel against the inner tracks of the outer bearing cage and pull the trigger... this will slowly (usually) drive the bearing out of the hub without causing damage to the hub.
15:Clean the inside of the hub thoroughly with a shop towel... then with a fine scotchbrite pad.
16:Find a small piece of angle iron, aluminum plate, or brass roughly the size of the outer cage of the new bearings.
17:Remove the new bearings (one at a time) from the freezer (ONLY when you are completely ready to install them into the hub.
18:Gently start the new bearing into the hub by hand, making absolutely sure to keep it square and going straight into the hub just as the old one came out.
19:Once you are absolutely sure the bearing is lined up with the hub and is ready to be pressed in.. place your block against the new bearing and your air chisel against the block... and drive it in.
20:Once the new bearing is in the hub and is flush with the outer edge of the hub... take your old bearing's outer cage and line it up with the new one... and use a ball peen hammer to gently tap it the rest of the way in.
21:Clean and re-install the snap ring.
22:Line up the dust seals by hand making absolutely sure they are square with the hub... and then gently tap them into place with a rubber mallet.
23:Apply a marine-grade grease to the axle (where it will be riding through the bearing).
24:Pull the lower a-arm outward from the machine and slide the axle back through the bearing.
25:Replace the lower a-arm bolts.
26:Replace the lower shock mount bolt.
27:Replace the Wheel hub.
28:Replace the Castle nut. (Sometimes this requires an impact wrench)
29:Replace the Cotter pin.
30:Replace the Wheel.
Only tighten the lug nuts to snug, then lower the machine and tighten them fully once it's sitting on the ground. (I usually re-check them after a test run of about 100 yards).
As said before, different machines require different methods... and different people prefer different ways as well.
I've heard of folks removing the hub from the machine and placing it in a vice to do the work. I've heard of folks removing the hub and buying a new one with the bearings already in it. I've even heard of folks using sockets and 1-7/8" hitch balls to knock the bearings out of the hubs.
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