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Why Caravan and Boat Bearings Fail

Stop Catastrophic Breaking Failure distroy your Holidays

Caravan Bearings and Boat Trailer Bearings

Caravan bearings and boat trailer bearings are a combative issue, especially when they fail. Seeing a wheel off a caravan on my way home has triggered this article.

I would appreciate it if you could share this with your mates as many folks forget to do bearing checks.

The premature bearing failure caused a wheel to come off and roll into inbound traffic with truly nasty outcomes.

What are the signs of a failing bearing?

Carbon black is produced when the casting or lining of the bearing is worn. Carbon black mixes with grease and looks like squid ink, black as. This bearing requires immediate replacement and is in imminent danger of complete failure.

Carbon black cannot be inspected using Bearing Buddy or standard dust caps. These products must be removed to check grease. Bearing Buddies can cause improper lubrication, reduce bearing service life and cause bearing damage.

Are the rubber grommet dust caps the answer?

Couplemate rubber grommet insert dust caps allow a visual grease inspection without removing the dust cap.

Another sign of a failing bearing is brown grease caused by water ingress. Water will enter the bearing cavity when a hot hub is immersed in cold water.

The contracting air within the hub sucks water into the hub through the rear bearing seal. This results in early failure when the wheel bearings collapse.

Water ingress is impossible to eliminate, but it can be controlled if boaters wait at the ramp and complete a safety inspection before dunking hot hubs into cold water.

This video will greatly help you understand how to grease bearings.


Surprising, it is not the smaller outer bearing that fails. The larger inner bearing is the load carrying bearing and always the first bearing destroyed.

First, to check the bearings, remove the nuts and remove the wheel, then the bearing dust cover, then split pin and outer washer finally remove the brake drum, hub or disc rotor and inspect the bearings.

Note: Bearing Buddies do not stop bearing failure.

Here is a little-known tip

When replacing bearings, give your axle profile a good clean. If you see a brown or coloured mark where the bearing sits, then it is time to replace your axle.

This bearing journal is worn beyond further use; replacing bearings on this journal will only increase the bearing replacement cycle.

A good axle will produce great mileage.

Installing bad quality bearings causes wear and tear on your axle. When replacing Chinese bearings with Japanese bearing for the first time, make a note or take a photo of your clean bearing journal. Save the photo using the date of the photo.

Bearings causing heat

Danger, danger................

When towing, I religiously touch the outer hub of my wheel to check for heat. Hubs must not be too hot to touch; otherwise, you will soon lose a wheel.

Heat is caused by wear and tear of your bearings or a loose axle profile, causing your bearings to spin and create heat.

The axle profile is the contact surfaces were the bearings connect to the axle.

No amount of adjustment is going to stop your bearings from overheating if your axle is cooked.

Other reasons caravan bearings fail prematurely?

Finally, the lack of high temperature bearing grease will cause failure as the operating temperature rises, low-temperature grease melts. Melted grease does not return to its former state.

© Steve Wotherspoon 26th January 2017