Wheel bearings are a real headache for trailerboaters - a proverbial pain in the neck! But you needn't reach for the medicine cabinet as a more palatable remedy exists for the symptoms...

Every couple of trips to the ramp, the wheels should be jacked up and spun. A pitted wheel bearing will rumble, while a good bearing is almost silent. By holding the tyre at the top and bottom, the wheel should be 'wobbled' to feel for any movement.

GREASE IS THE WORD
The cavity in the hub should be filled with high-temperature wheel bearing grease. If using bearing buddies or other devices on the hub that utilise a grease nipple, take care not to over-pressurise the hub with grease as this will force the seal off the back of the hub. The more grease in the hub, the less room for damaging water.

Each time a hub is removed from its journal, the split pin should be replaced with a new one. Split pins are cheap and half a dozen stored in the glovebox will keep you out of trouble.

The outer (small) bearing will fall out when the nut and washer are removed. The wheel and hub will then come off and to remove the inner (large) bearing, the seal will have to be levered out with a screwdriver. Once removed, if this seal is damaged it should be replaced with a new one.

Most modern hubs have two adjacent slots that run into the rear of the bearing cones. Use a bronze drift and hammer to tap out each cone, moving each side a little at a time until completely removed. Do not move one side too far before shifting the other, as the cone metal is forged hard and will dig a ridge into the relatively soft hub metal.

Should this occur, a round file should be used to take the high spot off the divot. Using hard metal tools in this area will pit the sleeve of the hub and jam in the new bearing cone when it is installed.

The inside of the hub should be washed clean with petrol to remove any metal fragments from the drift and damaged bearings.

Apply a thin film of grease on the sleeve, then evenly tap in the new cones until they are snug against their dead end in the sleeve.

Pack the bearing with grease and insert the rear bearing. Double check that this bearing is inserted the correct way around before tapping in the seal or it will have to be replaced if a mistake is made.

Using a finger, install as much grease as possible in the hub around the bearing and seal.

Fit the hub to the journal, then pack the new outer bearing, washer and nut.

TIGHT NUTS
Tighten the nut until there is no sideways movement of the hub on the journal. After spinning the wheel a number of times match the next slot in the nut with the hole in the journal, inserting the pin.

Pack as much grease as possible between the washer and the sleeve of the hub, then install the bearing dust cap.

After a hundred kilometres or before the next trip to the ramp, the hub should be checked for looseness on the journal and it would be unusual not to require tightening after this initial repacking.

If towing over unsealed roads, it is common for the seal to wear a groove in the journal. The deeper the groove, the more water and dust will be allowed in.

A badly grooved journal usually requires replacement, often at the expense of a complete axle. If this is a problem, there is a kit sold by Consolidated Bearing Company (CBC) that alleviates this unnecessary cost.

It comes with a metal sleeve that fits over the journal, covering the groove. The new seal fits over the metal sleeve, which remains fixed on the axle while that seal spins around it.

The best maintenance on wheel bearings is the preventive type. Remember, it is all over bar the swearing when the parts of a hub fly off in transit and the wheel of your trailer overtakes the towing vehicle. An axle hub contacting bitumen at speed causes all sorts of steering problems and if your boat survives the incident, the axle definitely will not.

Here's a summary of important points for effective maintenance of trailer wheel bearings:

• Use good grease and plenty of it.
• Don't let the wheel bearings stay loose for too long as this will exacerbate wear on the components and trailer tyres.
• Don't immerse the journals in water, especially saltwater.
• If you have the time, allow your trailer to sit for a while before reversing it into the water. A hot hub will suck in water when it contracts upon contact with cool water. (This also applies to the rear diff of your vehicle).
• Buy the best quality bearing kits that you can afford. (My trailer has done over 350,000km, had two replacement axles, three sets of springs and quite a few wheel bearing kits). The higher quality kits, such as Timken, will outlive cheaper sets.
• Don't put off replacing a worn bearing. A slightly pitted bearing will damage its cone and the problem can only get worse.
• If replacing a bearing, always replace its cone. They are a matching couple.
• The shorter the distance from your house to the ramp, the more likely you are to have damaged bearings. This comes about because the hubs never get warm enough to dry the water out as they do on a long haul.