Bearing Lubrication – what are the options?
Many of our clients raise the question of bearing lubrication. People ask us about our thoughts, various options, and of course…what we use for our Spitfire Trailers. Here we are happy to share our observations… even if perhaps a bit controversial for some.
Bearing Buddy
The Bearing Buddy operates by applying steady pressure to the grease that fills a wheel hub. The theory is that this pressure keeps contaminants and water out of the bearings and that somehow, by regularly applying more grease, a boatie is keeping his bearings lubricated.

Over time we’ve seen many useless gadgets and gimmicks. But none have taken off like Bearing Buddies. So they’ve become the standard ‘must have’ for all boat trailers. In fact, a recent survey we did of a boat ramp car park revealed that of the 63 boat trailers in the car park, 51 were fitted with bearing buddies.
Consider this….. You have an axle hub which is a sealed unit – comprising a bearing seal at the rear and the Bearing Buddy being the seal at the front. The Bearing Buddy requires the hub cavity to be 100% full of grease… so that the constant pressure exerted by the Bearing Buddy’s spring-loaded piston will oppose the entry of water, dirt, etc.

A grease nipple allows more grease to be pumped in…but if the hub is already 100% full, where will more grease go?
If you find yourself having to top up the grease in your bearing buddy via the grease nipple… then clearly the grease that was there, is no longer there! We can almost bet you’ll find that grease clustered with dirt on the inside of the wheel and probably all over the trailer chassis near the wheel as well. This is as strong an indication as ever that your grease seal is no longer effective.
Consider the likelihood that you’ve popped the seal while greasing your wheel bearings via your Bearing Buddy. This is the inevitable consequence of filling something that is already full! And worse still, the chances of sucking in seawater at the ramp are suddenly notched higher.
Standard Hubs with pressed metal Hub caps
Most of us have seen the standard hub with the pressed metal grease hub cap.

A correctly fitted grease (or dust) cap makes a pretty good seal. But if the hub cavity is not fully filled with grease, then the free air inside is likely to become a vacuum through thermal reduction every time you launch your boat and immerse your hot wheel hub into cold sea water.
This can, and often does, suck in sea water past the inner bearing seal as the warm hub cools. Thermal reduction will be minimized if you ensure that both the hub and the metal cap are filled with grease before inserting it to seal the hub.
This system has been in use for 100 years and has stood the test of time – but is also the prime reason that trailer makers recommend regular service – including repacking the wheel bearings.
This is a classic lubrication system – and needs regular maintenance.