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Pontoon Trailer: Axles, Hubs & Bearings cont...
Hubs and Bearings
Trailer wheels turn on spindles and hubs. The end of the axle has a polished shaft with a threaded nut on the end. This is called a spindle. Bearings rotate in polished units called races. A hub that has wheel studs is attached by a bolt and covered with a cap. About the only variation in these assemblies is the type of dust cap. Some pontoon trailers have a grease zerk designed into the dust cap (sometimes called a Bearing Buddy). Others have a grease zerk beneath the dust cap, often under a protective rubber cap.
Pontoon Trailer Axle "End Unit"
1. Seal  | 2. Inner Bearing | 3. Inner Race | 4. Outer Bearing | 5. Outer Race | 6. Hub | 7. Dust Cap | 8. Spindle | 9. Lug nut
Hubs are rated by their carrying capacity and have to meet certain Department of Transportation requirements for the rating. Thus a “cheap” hub with imported bearings (and most of them are imported) will do what its supposed to do, even though it’s not a known “national” brand.
Size Matters
Some manufacturers are always cutting corners on pontoon trailers: bias ply tires, incandescent lighting, and cheap axles. It’s my opinion all pontoon trailers should have 3500 lb. axles. But 2700 lb. or sometimes even 2000 lb. axles are used. The cost difference isn’t substantial but a fishing boat trailer manufacturer that builds pontoon trailers may use axles they have in stock. The difference is in the size of the hubs and bearings. A comparison of the 2700 lb. hub and 3500 lb. hub, shown above, reveals the difference. Larger hubs and bearings dissipate heat better, they run cooler, and don’t burn up grease as fast. If you’re running small tires on 2700 lb. axles you’ll need to grease the bearings more often than bigger tires. Most trailer owners forget about maintenance and if you don’t grease the bearings you’ll realize you have a problem when you start seeing smoke. When buying a new trailer it’s a good idea to pop the dust cap and check the grease. You won’t actually be able to see grease inside the hub but a little residue on the zerk is reassuring.
Oil Filled Hubs
I’m one to embrace new technology, LED lights, radial tires, disc brakes, etc. We experimented with the oil filled hub and decided that it didn’t make sense for most pontoon trailers. You can search the internet for the benefits and disadvantages. If you are towing frequently and require excellent bearing lubrication, oil filled hubs have benefits. When not towing, condensation can form. They require maintenance and most pontoon trailer owners are not looking for something extra to do.
The problem with oil filled hubs on an 8’ wide pontoon axle is they are easily knocked off. The oil reservoir sticks out from the hub. Wide axle trailer can hit a curb or dealers moving a trailer will damage the reservoir. This is a common occurrence, we sell dozens of inexpensive replacement dust covers for grease axles a year. When you knock the end unit of a oil filled hub off, it’s a trip to a mechanic to replace the system, (Vault Service kit $219.57 on eBay).
How to Grease the Bearings
Most spindles have a grease zerk on the end for easy maintenance. There are varying types of dust covers. The common style has a rubber cap that covers a hole, you pop out the rubber cap and the grease zerk is beneath. Some manufacturers have special designs and you don’t need to remove the rubber cap. I prefer the style where you put the grease gun directly into the grease zerk. With the “zerk in the dust cap” style there can be doubt if the inner and outer grease zerks are lined up properly. If they are not lined up all you do is fill the dust cap with grease. Some manufacturers have a closed dust cap that you have to remove to grease the bearings. A word of advice in case of a break down. Brand names are usually reassuring to the consumer: Reliable, Dexter, etc. There is however a catch. If you break down and damage the bearings you may have a difficult time finding parts. You may need to contact the trailer manufacturer and have them send you the parts. Many manufacturers buy parts from large distributors. If you breakdown in some remote area you can often go to an auto parts store and buy bearings and a hub. If you have a brand that uses proprietary (hubs made special for their trailers) you may have a wait for repair parts. If you’re going on a long trip, smart individuals will take a spare tire. But a spare hub is a better idea. Hubs cost less than a spare tire and if you have trouble on the road almost any handyman or repair shop can replace trailer bearings or a hub.
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