Caravan Bearings and Boat Trailer Bearings
Caravan bearings and boat trailer bearings are contentious issues, especially when they fail. Seeing a wheel off a caravan on my way home 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 bad 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 for grease. Bearing Buddies can cause improper lubrication, reduce delivery 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 corner 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.
Surprisingly, it is not the smaller outer bearing that fails. The load-carrying bearing is the more significant inner bearing, and permanently the first bearing is destroyed.
First, check the bearings, remove the nuts and wheel, then the bearing dust cover, then the split pin and outer washer. Finally, remove the brake drum, hub or disc rotor and inspect the bearings.
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.
You are installing bad-quality bearings, which causes wear and tear on your axle. When replacing Chinese bearings with Japanese ones for the first time, take a note or take a photo of your clean bearing journal. Save the image using the date of the picture.
Bearings causing heat
When towing, I touch the outer hub of my wheel to check for heat. Hubs must not be too hot to handle; 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 surface where 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 and low-temperature grease melts. Melted grease does not return to its former state.
© Steve Wotherspoon 26th January 2017