TRAILER BEARING CHANGE–              By Wayne Comben


Trailer bearings are one of those often overlooked maintenance jobs that can catch you out if you have not given them proper attention. If you are at a yard slowly moving the boat round to the slip it can be inconvenient if a wheel falls off – on a motorway doing 50mph it can be catastrophic.

Most small boat trailers are rated at 750kg and below and are usually unbraked, anything over this has to be braked and legally all brakes on trailers used on the highway must be in good working condition. If you have a braked trailer and regularly tow your boat then I’m sure you will already be aware of the upkeep required. I won’t be going into detail on trailer brakes suffice to say that braked hubs require regular checks to make sure everything is clean, free moving, and safely working –

flushing systems and good practice like not dipping hot hubs straight into cold salt water will go a long way in reducing breakdown time.

Here we are looking at the bearings most commonly found on unbraked trailers, these are the tapered type consisting of an inner and outer bearing. They come in various sizes which are often handily stamped on the bearing itself, if your unsure what type you have then take the old ones with you when you renew and they can be easily matched with new ones. Incidentally when purchasing your bearings do so directly from a specialist outlet rather then a chandler or trailer dealer, it will save you a small fortune, believe me the prices can vary wildly and it’s worth shopping around.

When the time comes to gets your hands dirty you will need a few tools – a good jack and axel stands, a wheel brace or socket for the wheel nuts or studs, one also for the castle or retaining nut, some thin nose pliers, a hammer,  and a flat screwdriver.  You will also need a good supply of old rags.


To start crack the wheel nuts on the side your working on and chock the opposite wheel







Jack up the trailer and support with an axel stand.


Remove the nuts and the wheel; note the bearing saver in place on this hub







Remove the dust cap to reveal the cotter pin and castle nut








Straighten the cotter pin and remove using the pliers.


Remove the castle nut and washer







Take the hub off paying attention not to damage the spindle.

The hub may retain the bearings in which case remove them, if they are tight tap them gently out with a hammer and batten.

Give them a clean and examine them for any damage. Check any seals are intact and if they are sound they can be repacked with waterproof grease and re-used (pic 5 outer bearing













Clean off all the old grease from the hub and spindle.

You may find the inner bearing stuck on the spindle, a blow torch directly on the race can be used to free it or better still use a bearing puller.

Coat the inside of the hub with clean waterproof grease.

To reassemble start by sliding the inner bearing back over the spindle, then the hub, being careful to locate correctly, then the outer bearing, washer and castle nut.

Spin the hub to make sure it is moving freely and tighten the castle nut.

When it bites, back the nut off about an eighth of a turn and re-fit the cotter pin bending the ends over to prevent it dropping out.

Pump some grease into the hub nipple and fit the dust cap or bearing saver (bearing savers work by pushing grease under sprung loaded tension into the hub, I have certainly found they help keep water out and prolong the life of the bearing)

Finally put the wheel back on and tighten the nuts well, a little Coppertone on the threads will help the next time the wheel needs to come off.

The wheel should spin quietly with no grinding or vibration.

A few hours on bearing maintenance will be time well spent, and certainly preferable to the hassle involved should your trailer lose a wheel.