What You Need To Know About Trailer Bearing Protectors

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Water contamination and inadequate lubrication are among the biggest causes of boat trailer bearing failure. While it’s relatively easy to diagnose worn trailer bearings by observing any play in the hub, it can be a bit more difficult to detect the early stages of wear or water ingress without removing the wheel and the hub assembly. This is where trailer bearing protectors come in.

What are trailer bearing protectors?

Trailer bearing protectors are accessories that are fitted into the wheel hub. They are inexpensive to purchase, and help protect the wheel bearings by:

  • providing a larger reservoir of lubricant
  • preventing water from entering the assembly

As a result, the wheel bearings have a longer lifespan and require less frequent maintenance.

Trailer bearing protectors generally feature a spring-loaded pressure plate that applies a pressure of around 3psi into the hub assembly. This ensures grease is pushed all the way to the inner bearing and rear seal. Grease is applied and topped up through a grease nipple in the centre of the pressure plate. Excess grease, including old grease during maintenance, is expelled from the assembly at the edge of the bearing pressure plate. This protects the rear seal from blowing out.

Bearing protectors are available in stainless steel, chrome and polycarbonate. Stainless steel provides the best combination of corrosion resistance and durability.


Trailer bearing protectors are sold in pairs to suit various bearing diameters and weight ratings. A good set of bearing protectors should be priced under $30.


Fitting a regular bearing protector is as simple as removing the dust cap from the hub and knocking it in (some hubs are threaded), sealing with Loctite and filling with lubricant with a grease gun. Whether or not the axle is new, any machining or wear lines need to be honed away with emery tape.

While you’re doing this, it’s highly advisable that you take the opportunity to check your trailer bearings and replace themif they exhibit signs of wear.

Finally, a plastic dust cover, sometimes known as a ‘bearing bra’, is placed over the protector to prevent lubricant from leaking onto the wheel. It also prevents brake and dust from collecting in the recess of bearing protector.

Fitting a bearing protector should be a no-brainer – they’re inexpensive, and they’ll save you time and effort when you’re maintaining your boat trailer. What’s not to like?

Your bearings might be safe, but which boat-towing spares should you be looking out for?


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