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How To: Un-Trash Your Trailer Bearings Cover Image
091604 ::.

How To: Un-Trash Your Trailer Bearings
...And Keep'em Rolling!

Editor: STILFX

Not long ago, on a short trip to the infamous Rausch Creek MX park, a lack of simple maintenance crept up to bite me in the pants; well in this case, trailer. Through years of neglect, plenty of rain, and dirty stone filled parking lots our poor 4x8 folding trailer finally lost the race; literally, it was a bearing race seizure. Luckily, it happened less than a mile from the track, I was able to re-grease and limp home - after a full day of riding nonetheless.

In this step by step guide, we'll explain a workaround for such a failure and provide a bit of insite on how to prevent a future breakdown.

A bit of background:

Typically, trailer wheel bearings are the roller bearing type with a series of rollers in a cage. These roll inside a race or cup that is a strip of metal press fit into the hub. There is an inner bearing for the part of the hub towards the middle of the trailer axle and an outer bearing which is the one you see when you remove the nut under the dust cap. A grease seal is press fit into the hub over the inner bearing. The seal keeps bearing grease from leaking out of the hub onto the brake surfaces. Grease leaking past the outer bearing is controlled by a washer, nut, and dust cap.

The hub and bearing assembly slides onto a spindle attached to the axle with the grease seal on the inside and a washer and nut on the outside holding it in place.

The standard recommendation is that you re-pack your trailer wheel bearings once a year. This is because trailers tend to sit a lot and that can contribute to condensation inside the wheel and that can lead to rust - which, in turn, leads to particles - which can score surfaces and cause friction and bearing failure. Re-packing the bearings also makes it easy to inspect your brakes and running gear in order to detect and fix potential problems before they become a hazard.

Re-packing wheel bearings means removing the hub, pounding out the old grease seal, cleaning the bearings and hubs of all old grease, cleaning the spindle, packing the cleaned bearings with new grease, 'painting' all inside hub surfaces and the spindle with new grease to help prevent rust, and reassembling the hub on the spindle with the right tension.

“The repack” is not that complicated or sophisticated a task and can easily be done by amateurs willing to wrestle with awkward and heavy tires and hubs. Plan on an hour or so for each wheel (under half hour if you are serious and have everything figured out).

Be sure to take appropriate safety measures. Set up a spot with plenty of working room that is well lit and free of dust and grit. Keep wheels chocked to limit any trailer motion. If using jacks to lift the trailer be sure to use jack stands as a backup. Eye protection will be needed. Plan ahead and plan for safety.

Let's Un-Trash:

After I limped my poor 4x8 home, I had a quick bite to eat (always a good idea before starting a project) and then returned to the garage and the carnage.

Jack it - safely!
1) Park the trailer on firm and level ground.
2) Block the trailer tires to prevent forward or rearward movement.
3) Jack up the trailer following the manufacturers instructions.
4) Secure the trailer on jack stands of adequate capacity front and rear.

It may be easier to flip the trailer over rather than jack it up. Be sure you won't damage the trailer if you try this technique.

Remove the wheel and hub
1) Undo the wheel nuts and remove the wheel.
2) Pry off the dust cap using a flat bladed screwdriver.
3) Straighten out the cotter pin that holds the bearing nut and remove it.
4) Remove the bearing nut and washer.
5) Place the front bearing, bearing nut and the bearing washer in a clean container.

Since our trailer was experiencing a bearing failure, the tire didn't want to come free so easily. A little elbow grease and a rubber mallet convinced the tire/hub to let loose.

Inspection
Thoroughly clean the bearings and other parts in a solvent (not gasoline!) until all the old grease is removed. Set the race aside to dry completely or blow it dry with compressed air. Don't use the air pressure to spin the bearing, as damage could result to the bearing or to you!

Clean the hub and spindle. Inspect the bearing races for heat discoloration, pitting, scoring and any unevenness. Inspect the bearing for damage as above. Any out of round rollers, cracked roller cages and rough running will indicate replacement is required. The bearing and both inner and outer races must be replaced as a set.

With the wheel removed, we noticed the inner race collar was siezed to the axle. After a few solid wacks from our sledge we knew there was only one alternative - the Dremmel! We ground a cross cut into the collar to avoid damaging the axle any more than we had already. 10 minutes later we were back on track.

Hand packing the bearings
Place a walnut sized gob of wheel bearing grease in one palm. Grasp the bearing with the other hand so that the wider end is facing the grease. What you want to do is force the grease into the gap between the inner race and the outer cage so that it squeezes up through the rollers and out the top. Press the bearing down into the grease in a rocking motion and continue until the grease oozes up. Rotate the bearing 1/4 turn, at a time, and continue until the bearing is completely filled with grease.

Reassembly
Put some grease into the interior of the hub with your fingers. A walnut sized amount is sufficient. Spread it around the circumferance of the hub. Place the inner packed bearing into it's place in the hub. Place a new seal on the hub and tap it into place with a hammer until it seats fully. Be sure to wipe off any grease that finds it's way onto the outer flat surface of seal. Replace the drum onto the axle spindle, insert the outer bearing, thrust washer and axle nut.

Replacing the bearings
The bearing must be replaced with a complete new bearing with the inner and outer races. The inner races are pressed into place in the hub and must be driven out. Use a brass punch to catch the edge of the race by passing it through the inverted hub. A few good whacks with a hammer should drive out the old race. Place the new race into position and tap it in with the hammer and punch. Take care not to mar the surface of the race. Pack, reassemble, and preload the bearings.

Preloading the bearings Tighten the axle nut by hand until it is tight. Tighten another 1/4 turn with pliars or wrench. Spin the drum several times to distribute the grease evenly in the bearings. Back off the nut with the pliers or wrench, until loose and then retighten finger tight. Insert a new cotter pin to lock the nut in place and bend it over the spindle. Re-install the dust cap, wheel and tire, and hubcap - whaaalaa, you're done!


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