Axles

[Frank P]

Unit is a 2019 Momentum 395 M. I noticed there were zert fittings on the axel hubs. Will keeping those greased eliminate having to remove wheel and repacking bearings.

[FT4NOW]

Not recommended. Best bet is to do a visual inspection and hand pack the bearings, or you could use the zerk and take a chance of adding too much grease and have it leak by your grease seal and contaminate your brakes.

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[Grammy&Grandad]

Not recommended. Best bet is to do a visual inspection and hand pack the bearings, or you could use the zerk and take a chance of adding too much grease and have it leak by your grease seal and contaminate your brakes.

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Been there done that! Good way to get to buy all new brakes, not to mention the severe safety concerns until you find out you did it! Unless you are pretty experienced working with packing bearings and greasing hubs, it’s pretty inexpensive to have a technician do a brake inspection and hub service for piece of mind. It’s not rocket science, but it’s very easy to make a costly mistake. I’ve seen a bit of press also in recent years about converting to oil bath systems. I wonder about the benefits of that for 5ers?

[Second Chance]

... I wonder about the benefits of that for 5ers?

True oil bath bearing systems like used on tractor-trailers are good. Stay away from the Nev-R-Lube bearings touted for RVs, though. They have a pretty high failure rate.

Rob

[jmbopp]

If I don't put many miles on the trailer in a season I'll admit to using the zerk fittings to give the bearings a few shots of grease. Caveat - I use the same grease I used to pack the bearings, remove the dust cap to check the bearing play, and jack up the wheel and rotate the tire while I slowly pump the grease in. If I do this I'll do a full repack the following year.

[Second Chance]

True oil bath bearing systems like used on tractor-trailers are good. Stay away from the Nev-R-Lube bearings touted for RVs, though. They have a pretty high failure rate.

Rob

OK - thought I'd update this information with some things I learned in a conversation with a MORryde engineer on Wednesday.

I had the wheels off my trailer Monday to move the inner sheer spring plate down one set of holes to get the ground clearance back up to where it should be (MORryde independent suspension). The naval engineer across from me in the military FamCamp where we're staying looked at the hubs (hydraulic disc brakes from MORryde) and said, "Hey, those are oil bath hubs but they've greased the bearings rather than fill the hubs with gear oil." He was basing this on the fact that the hubs had the clear screw-on caps with the black rubber plug in the center and we could see through to the outer bearings with grease.

Armed with this new-to-me information, I called MORryde to ask about converting to oil bath. The response was a pretty emphatic, "We recommend against doing that." Here's how the engineer explained it to me - using a tractor trailer axle and hub as a comparative example: the internal volume of the tractor trailer hub and axle is much greater, with both a much greater volume of oil and air. Due to these volumes, the oil in the tractor trailer hub doesn't heat up as much and, when it does, it has more air volume to compress and expand into. The smaller oil volumes in our RV hubs would heat up to a higher degree (more rapidly) and have less air to compress and expand into. This would result in pushing the gear oil out the back seal or, more likely, the black rubber plug in the center of the outer cap. The resulting loss of oil would cause bearing failure and likely damage the spindle and/or hub.

You're probably already asking yourself the next question I asked: Why install the clear oil bath cap on the hub, then? It seems that the manufacturer of the previously-used opaque grease cap had changed plastic compounds. The new material degraded rapidly and became brittle. The cap would then crack, fall apart, and expose the inside of the hub, spindle and bearings to contamination. The strongest cap they could find to fit that hub was the clear, oil bath style that came on my hubs.

I'm not an engineer, though I've had many years of mechanical experience including building and rebuilding cars, motorcycles, and all types of motors. The explanation I was given makes sense to me, but I'd be interested in the thoughts of any engineers who'd like to chime in.

Rob

[huntindog]

I dunno... I would think that the tractor axles especially the diffs should be vented.
Dexter had a totally different reason not to do it. IIRC, they said that long periods of sitting in RV axles would leave the upper portion of the bearings dry, and that would cause damage. I am doubtful of that theory as well... The best reason I coud think of not to do it is the plastic cover degrading and cracking leaving the bearings dry.