Trailer hubs shedding grease caps

[California]

I had hunted for replacement caps at auto parts stores and they didn't have any.

I recently went to a RV trailer specialty shop for the 2" replacement cap I needed.

Caps are also on Amazon but this place had a better price.

 

[jyoutz]

Maybe replace the grease caps with some bearing buddies?

 

[Silvic]

Agreed. This is weird. Just to be clear, you're saying these are EZ Lubes, with the usual rubber center plug in the cap, but you're losing the steel stamped housings that hold the rubber caps?

I've owned a lot of EZ Lube hubs, and I've never seen anything like that. The rubber plugs are leaky enough that there's no real chance to build pressure.

For anyone who doesn't know what we're talking about, look up EZ Lube hubs. They're a great rig, and they're already vented by means of a rubber cap with a grommet ring, which never fits air-tight. They're also unlike normal hubs, in that you end up totally filling the cavity with grease after a few maintenance cycles, as the new grease pushes the old grease out into that cap space, and eventually out around the grease gun fitting.

Yes they are EZ lubes. I redid all four hubs with new brakes assemblies and new inner and outer bearings and races. Reused all four grease/dust caps. Three have remained on and one was shed on the first day. Replaced with a new cap twice on return trip and shed again. Have now lost three all on the same hub. The other three original reused caps are holding just fine, at least so far they are holding after 1000 miles.

 

[flyerdan]

Empirical evidence indicates that this is a problem with the hub itself. Maybe there is a hairline crack in the outer bore that allows the cap to work out due to force redistribution during rotation.
If close inspection and a dye pen test doesn't show anything, swap sides and see if the problem stays with the hub (I'd probably strapping tape a lanyard to the cap so it doesn't get lost) or with the original axle location. The spindle could have a slight bend that would set up harmonics that worked the cap off, but that's admittedly getting into the weeds theory wise.

 

[nisaacs]

Maybe drill an 1/8" hole in the edge of the hub and hub cap and secure with a roll pin or sheet metal screw.

 

[WinterDeere]

Empirical evidence indicates that this is a problem with the hub itself.

^ This. If three of your four hubs are fine, and just one keeps ejecting caps, it's obviously time to pull that one apart and figure out what's happening. I can't believe anyone would actually suggest mod's like pinning the cap or venting the hub, EZ Lubes are a well-engineered system that should work without DIY mods, and it's clear there's a problem with just this one hub.

I can't agree with the recommendation to try Bearing Buddies, either. They're great for boat trailers, esp. those without brakes, but tend to create more problems than necessary for trailers with brakes. Plus, if you're not dunking the thing in the water (boat ramp), Bearing Buddies really hold no advantage. EZ Lube really is the superior system for landscape and utility trailers.

For those who don't know, Bearing Buddies are a closed cavity system with a spring plunger that maintains constant positive pressure on the cavity. This is supposed to be only 2-3 PSI, if used correctly, although way too many people over-charge them with grease to where the rear seals completely fail. But even if used correctly, their main method of venting grease is thru the rear seal, into your brake drums, making your brakes ineffective. They also have to be completely removed from the hub, if you ever want to clean out old grease and re-pack. Lots of disadvantages, with their only advantage being that their positive pressure prevents water intrusion on a hot bearing, when you dunk them in the lake or ocean on a boat trailer. Boat trailers are really the only appropriate place to use Bearing Buddies.

Conversely, EZ Lubes have an open-loop system. You inject fresh grease thru a zerk drilled into the center of the axle stub end, and there's a channel thru the axle stub to the back of the inner bearing. Injecting fresh grease pushes the old grease out around the axle stub, in FIFO fashion, making it very easy to replace old grease with new with just a few pumps of the grease gun. They can work on boat trailers as well, by pushing milky water-laden grease out, but they're really best for land-based trailers.

 

[ruffdog]

Yes they are EZ lubes. I redid all four hubs with new brakes assemblies and new inner and outer bearings and races. Reused all four grease/dust caps. Three have remained on and one was shed on the first day. Replaced with a new cap twice on return trip and shed again. Have now lost three all on the same hub. The other three original reused caps are holding just fine, at least so far they are holding after 1000 miles.

Are you losing the rubber cap that you remove to grease the zerk or is the metal ring holding the rubber not staying in?

 

[WinterDeere]

I was out mowing this morning, and happened to notice how badly one of my EZ Lube hubs was deformed. Still no issue staying together!

 

[Silvic]

Are you losing the rubber cap that you remove to grease the zerk or is the metal ring holding the rubber not staying in?

No it is not the rubber inner plug it is the entire metal grease/dust cap. Now having said that the rubber plug I presume went with the cap

I was out mowing this morning, and happened to notice how badly one of my EZ Lube hubs was deformed. Still no issue staying together!

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That is for a much lighter weight axle and hub but the principle is the same. Never had this problem before and I have seen them beat up before as well

 

[zzvyb6]

The wheel bearing may be too tight, producing more heat that normal. Supposed to be 1 flat off from slightly tight. Make sure the Cotter pin isn't interfering with the cap.