Also pick up a tub of wheel bearing grease. Regular mineral-based grease will work fine, but
synthetic grease will last longer and tolerate water better. Lastly, a bearing packer will make
filling the bearings with grease a much easier job.
While the article suggests that most trailer/marine stores carry spindle seals, be prepared for some empty looks when you ask. Critical to obtaining the right kit is the number on the inner bearing; pry off the existing seal and you'll have access to it. The spindle seal kit I bought had sufficient parts for a complete axle; i.e., two of each. Of interest also was that the instructions that came with the spindle seal stated: "Tighten the nut to seat components, until the wheel will not spin freely (20 foot lbs). Next back off the adjusting nut 1/6 to 1/4 turn until the cotter pin can be inserted into a locking hold (20 inch lbs.)". Worked well for me.
We want to thank Kristen Hamper, TBM's Advertising Production Manager, for granting permission to reprint this article on the MC Web site.
1 November 2003
The subject is as old as trailer boating itself, but keeping wheel bearings properly greased
and maintained is a ritual many still forget to perform. The evidence is clear when you find
a family sitting dejectedly on a grassy roadside, as Dad goes off to find a mechanic to replace
the trailer's damaged wheel bearings. While servicing wheel bearings isn't glamorous, it can
prevent the loss of valuable vacation time.
Today's wheel-bearing assemblies are no different than those of 50 years ago. Most still use grease as lubricant and coolant, employ caged rollers and pressed-in races, and use rubber-lipped seals to keep grease in and water out. What's changed is the grease used to lube them. Today's synthetic greases offer longer bearing life and more protection against roller failure.
In addition, there are methods for greasing the bearings without actually removing them from the wheel hub. While the venerable Bearing Buddy protectors have been available for years, they've since been improved and met many forms of competition. In addition, new types of hub/bearing systems have been introduced in recent years — including oil-bath systems.
While bearing protectors can help keep water and corrosion at bay, the most effective way to ensure long bearing life is to change the grease at least once per season.
Changing wheel-bearing grease is a messy, but easy job. You'll need pliers (side-cutting pliers
work well when removing stubborn cotter pins), a wrench to fit the lug nuts on your trailer wheels,
a jack, jack stand, ball-peen hammer, rubber mallet, large flat-bladed screwdriver, and a 6-inch
long two-by-four. Of course, a grease gun will be needed if your wheels have bearing protectors.
A large pair of pliers may also be needed to remove the large castle nuts securing each hub. If you don't have them, this is the time to fit your wheel hubs with bearing protectors. They are available from just about any trailer dealer, hitch installer or auto parts store. The most common sizes are 1.780 and 1.981 inch inner-diameter. If in doubt, take your dust cap to the store to match up the inner diameter. A pair of bearing protector covers will only add a few bucks to the tab and they'll protect your wheels from excess grease that may escape the hubs at highway speeds.
Also pick up a tub of wheel bearing grease. Regular mineral-based grease will work fine, but
synthetic grease will last longer and tolerate water better. Lastly, a bearing packer will make
filling the bearings with grease a much easier job.
To service the bearings, jack up the trailer's axle, one side at a time. A floor jack is best,
but a bottle jack will do fine. A jack stand is also needed to secure the trailer in the raised
position. Jack the trailer up until the wheel can spin freely. Remove the lug nuts and the wheel,
exposing the hub assembly. Check the back side of the hub, wheel and tire for grease spatters.
If you see grease, the rear seal has failed and will need replacement.
You can now remove the hub. The dust cap or bearing protector must come off first. A dust cap
has a small lip that can be pried off by carefully using a flat-bladed screwdriver; lightly
tap it under the lip with the hammer, rotating the hub as you pry off the cap. Bearing
protectors have no lip to pry under, so you'll have to tap the outer diameter of the protector
as you rotate the hub. Use a rubber mallet instead of a hammer, and you won't mar or dent the protector.
After you remove the protector/cap, rotate the hub slowly and listen closely for irregular noises.
You should hear nothing as the hub spins. If you hear grinding, scratching or rattling noises,
or if the hub moves excessively on the axle shaft, you probably have bearing problems. Brown or
reddish grease is also a bad sign. It indicates water has gotten to the bearings, and they are rusting.
A cotter pin keeps the castle nut from loosening. Bend the pin straight and remove it with pliers. If it's been bent too many times, replace it. Remove the castle nut and washer, and then remove the outer bearing. Keep plenty of rags handy to catch loose globs of grease as you remove the hub assembly.
Remove as much loose grease as possible from the outer bearing, hub and inner bearing. If the
rear seal is damaged, or if you detect problems with the inner bearing, pry out the seal with a
flat screwdriver and discard it. Remove the inner bearing. If the grease is still in decent
condition and you can inspect the inner bearing by feel and a flashlight, it doesn't need to
be removed and cleaned. You can leave it in place along with the rear seal —just be sure to
wash out all the old grease and dirt.
After washing all parts, blow-dry them with compressed air to remove remnants of old grease,
dirt and washing fluid. However, do not spin the bearings at high speed with compressed air.
This can cause the bearing to explode in your hand, causing severe injury.
After cleaning and drying, inspect all the parts closely. If the roller bearings appear pitted, scored, galled or rusted, replace them. Replace the bearing races, as well. These are press-fitted into the hub. They can be removed with a hammer and screwdriver, but have a dealer do it while you're buying new bearings. It's easier for him to do it with a shop press, and you won't risk damaging the hub.
Packing the bearings with grease goes quickly with the bearing packer. Place the bearing on the
bottom cup, screw the top cup down snugly over the bearing, attach a grease gun, and pump grease
into the bearing until it just begins to flow out the sides of the rollers. If you do it by hand,
place a gumball-sized dollop of grease in the middle of your palm, and firmly wipe the edge of the
bearing through the grease.
Do this repeatedly until grease begins to appear on the other side of
the bearing. Rotate the bearing as you go, ensuring that it's completely filled.
If you removed the inner bearing and seal, now is the time to reinstall them. Check one more time to ensure that the inner bore of the hub is completely clean and dry. Place the greased inner bearing into the hub, seating it in the race securely (the grease will hold it there.)
Now, replace the rear seal. Clean the hub bore where it seats, making sure there's no grease,
old sealant or dirt there. Select a short socket wrench that matches the seal's outer diameter.
Coat the outer edge of the seal with liquid sealant, and gently tap it into the hub with a
rubber mallet, using the socket as an installing tool. Seat the seal flush with the end of the
hub bore; don't tap it any deeper.
Clean the axle shaft and inspect it for damage. If there's deep scoring, pitting or rust where the bearings ride, it may be time for a new axle spindle. This can be an involved job, best left to a good trailer mechanic. If the area where the seal rides (called the shoulder) is scored or pitted, you can easily solve the grease leakage problem this causes by fitting the axle with a Spindle Seal -- a stainless steel seal and O-ring kit that fits over the inside of the axle stub, forming a smooth sealing surface for the hub seal to ride on. Spindle Seals are manufactured by Bearing Buddy, and are available at most marine and trailer dealers.
Coating the axle shaft with grease before installing the hub will help ensure that enough grease is
in the hub before it turns its first revolution. Put a healthy dollop of grease inside the hub,
then slide it onto the axle shaft. Next, install the outer bearing, making sure it's seated in its race. The outer
washer fits in next, then the castle nut. Tighten the nut down as you spin the hub, ensuring
that you don't tighten it so far that it slows the hub or stops it from turning. Grasp the hub's
outer diameter and try to move it back and forth; if you can, the nut is not tight enough. Tighten
the nut to the point that it slows the hub from turning, then back off 1/4 turn and check for
side-to-side movement again. After you've found that sweet spot, turn the nut slightly to expose
the cotter pin hole and insert the cotter pin, then bend the ends out and around the nut. Make
sure the ends don't impede installation of the bearing protector.
[HvB: Instructions that came with the spindle seal stated: "Tighten the nut to seat components, until the wheel will not spin freely (20 foot lbs). Next back off the adjusting nut 1/6 to 1/4 turn until the cotter pin can be inserted into a locking hold (20 inch lbs.)"]
Using the grease gun, pump grease into the bearing protector as you spin the hub to distribute the grease inside. Yet, don't overfill the hub or you'll blow grease through the rear seal. Some bearing protectors have an indicator that tells you when the hub is full.
Without that indicator, watch the spring inside the protector carefully as you fill. When it
fully compresses, stop pumping grease. Wipe any excess away, reinstall the wheel and tire,
and you're done -— at least with one wheel. Now you can repeat the process for the other wheels
on your trailer.
As mentioned, the bearing packer is a worthwhile tool for less than $20. Time involved is approximately one hour per wheel, so for a tandem-axle trailer, expect to devote the afternoon.
Good luck and...See you on the starting line!