Grease is applied to marine seals and bearings for one reason only, to reduce friction. Friction produces heat, excess heat through incorrect installation destroys bearings.

Wow, you said that I need to apply grease to my marine seals!

Is it true that 40% of all bearings do not live their full engineering life due to bad installation practices?

Australian Marine Bearing Seals

Marine Seal LM suit Holden ProfilesFirstly, Australian marine seal is a significant cause of friction and must be greased. Surprised?

Secondly, the ID of a Marine grease seal is a shrink fit and very tight fit on an axle.

Thirdly, the ID of a marine seal does not spin, only the OD of this seal spins.

Friction is created between the rubber seal and the metal housing.

There are two lips on the inside of the rubber seal. Apply ample grease to these lips to significantly reduce friction and greatly increase bearing life.

As a result, water ingress does not continue to be a significant problem.

In 90% of cases, grease is not applied to the inner lip of a marine seal. No grease assists air being sucked into the bearing cavity when the hot hub is immersed into hot water.

A greased marine seal provides an additional barrier to help prevent water ingress.

Couplemate sells NSK bearing kits and seals.

Bearing Buddies

Can over lubrication of bearings by boaties fix the problem of water in the grease. How?

New grease pushes out the old grease through the back grease seal.

This method is dangerous and should be avoided.

  1. The ideal amount of grease in your bearing cavity is approximately 50%.
  2. Excess grease is spilt over the inside of your wheel
  3. More excess grease is spilt over the inside of your wheel as the bearing cavity heats up.
  4. Excess grease is ‘flung’ onto the road surface during transit.
  5. Grease stains on the springs, wheel rims and undercarriage of your boat trailer are almost impossible to clean.

The very best way to check and clean bearings, for me, is to use an axle jack to easily lift my boat wheels. Then inspect every bearing set for carbon black in my grease and check adjustment.

On one occasion at the Hawkesbury River, I was preparing my boat for the return home to Brisbane.

While checking the bearings, I found one bearing journal so worn; it would not have successfully make the trip back.

Robert Huston at ISP Islington had 45mm Square axles, the correct length on the shelf.

Disaster saved, all through checking my bearings before the long trip home.

Frequent Bearing Checks

Increase the frequency bearing checks greatly avoids disasters.

Over time, the outside casting on your bearing wears. This wear creates carbon black. Worn bearings also cause heat and accelerate bearing failure.

Are you bearing buddies being stolen? Maybe they are not being stolen, find how why.

I invite you to leave a comment if you find the above tips useful. If you find errors in any of the above, I would love to hear from you.

Finally, here is another good article on why caravan and boat bearings fail.

How to Correctly Grease a Marine Bearing Seal

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