Greasing the Wheel Bearings - with Update

[Bill]

Introduction: Most TMs come with Dexter E-Z Lube for greasing the wheel bearings and hubs. Dexter recommends greasing these bearings once a year, or every 12,000 miles. The E-Z Lube design enables you to grease the bearings without removing the wheels and hubs from the trailer. Having done it a few times, I decided to write up a tutorial, with the goal of making it easier for others to do the same. I hope it helps. Comments and corrections by PM are welcome.

Disclaimers: A few TMs are equipped with other types of hubs. This article does not attempt to address those. It should also be noted that some TMO members have not had good luck with the EZ-Lube, with occasional reports of grease leaking past the seals. This is a seal problem, not an EZ-Lube problem, but nonetheless it must be dealt with. Not having experienced this, I cannot address it. But if you have E-Z Lube hubs, and you decide to use the standard Dexter procedure, this tutorial may help.

Time required: Once you have gathered all the supplies, you can expect to spend about two hours on this job. It gets a lot faster if you’ve done it before.

Tools and supplies needed: See Photo 1 below.

• Grease gun. As shown in the photo, I have one of the mini-guns, sold for a few dollars in many stores including hardware stores, Wal-Mart, and auto supply stores. If you have a standard-size gun, so much the better.
• Grease. According to Dexter, you must use a lithium-complex grease labeled NLGI No. 2. There are many greases side-by-side on the shelf – be sure to get the right one. Ignore descriptive words like "High temperature" or "High pressure" or "Extra tough heavy duty". You can buy grease in cylindrical cartridges that fit the gun, or you can buy it in a bulk tub, and load it into the gun by hand. (Hand-loading is sloppy.) Expect to use about 6 oz of grease – that’s two mini cartridges, or 1/3 of a 1-lb tub. Note that the new grease can be found in several colors. If you choose one that is not black, you will be happier, since you can see when all the old grease (black) has been expelled, and new grease has been fed through.
• A can of mineral spirits, aka paint thinner.
• A roll of paper towels. A whole roll. This is a messy job.
• A bucket or cardboard box into which to throw the used towels as you work.
• A hammer or mallet.
• A medium-size straight screwdriver.
• If you are old and decrepit like me, a short stool to sit on while you work. The one that comes with the TM, for getting into the bed, is just right.

Preparation:
Get resigned to the fact that this is a messy job. Until you have done it a few times, you will get lots of grease on your hands, maybe on your clothes, and maybe on your driveway.

Using a paper towel soaked with paint thinner, clean off the bearing cap. The bearing cap is the silvery sheet metal cylinder, about 1½ inches in diameter, in the center of the hub. Photo 2 shows the cap with the center rubber diaphragm.

Remove the bearing cap from the hub. Some people bop it sideways with a mallet, and work it off. As shown in Photo 3, I set a screwdriver in the small gap where the cap meets the hub, tunk it into the gap with a hammer, and twist to get it off. Dexter told me that many people knock it off with a cold chisel! Apparently the method is not too critical, but try hard not to deform the cap, since it functions as the grease seal. If you deform it, grease will leak and and splat onto your wheels. Not a big deal - replacement caps are easily available.*

Clean out the bearing cap with a paper towel, being careful of the sharp edges. Blood is not a good bearing lubricant.

Remove the rubber diaphragm from the center of the cap, and clean it. Set the cap and diaphragm aside. See Photo 4.

Wipe off the grease that has accumulated on the hub under the cap. Cleaning will reveal a big hex nut, and either a sheet steel locking washer (colored yellowish-green in the Photo 5) or a cotter pin. Leave those alone.

The work:

Load the grease gun. To do so, draw back the loading rod, latch it, and unscrew the cylinder from the pump head. If you use a cartridge, insert it into the cylinder in the direction indicated on the cartridge. If you use bulk grease, use a table knife or your fingers to pack grease into the cylinder. Screw the cylinder back onto the pump head, and release the loading rod.

In the very center of the hub, you will find a small metal grease fitting variously called a grease nipple or a zerk fitting. Carefully wipe off the nozzle of the gun - otherwise, if there is crud stuck in the grease at the end of the nozzle, you could pump it into the bearing! Now push the nozzle of the gun onto the fitting until it clicks solidly into place. See Photo 6.

Pump the gun to inject grease into the fitting. After a couple dozen pumps, you should see grease start to ooze out around the edge of the hub. This is the old grease, and it is grubby black from wear. As big globs of it come out, wipe them away with a paper towel, and keep on pumping. Note that you should see grease ooze out more or less equally from all around the hub. If it comes out only in one area, you will need to jack the trailer up enough to rotate the wheel half a turn. Dexter actually recommends rotating the wheel as you work.

Eventually, all the old grease will be gone, and you will begin to see new grease squeezing out of the edge of the hub. If your new grease is any color other than black, it is easy to see. If it is black, it is harder to see, but the new grease does look a bit different from the old. When you have a solid show of new grease, you have pumped in enough. Remove the gun, and clean up the area with a paper towel.

Finish:
Replace the bearing cap. Tap it gently into place with a mallet or a piece of wood and a hammer, again being careful not to deform it.

Put the rubber diaphragm in place in the center of the cap, and seat its groove over the edge of the cap. Depress the little rubber bump in the center of the diaphragm.

Clean up. Have a well-deserved beer. You're done for the year.

Bill

*Edit. The video on the Dexter Axle web site suggests that it is not necessary to remove the cap. Just pull off the rubber plug and insert the grease gun through the hole in the cap. It is messy, because the old grease fills the cap, pushes out around the grease gun nozzle, and drops off in globs. But not having to remove the cap may make it worthwhile. Your choice.