Tired of Throwing Money away on Caravan and Boat Trailer Bearings?

Boat Trailer bearings have been a contentious issue for a long time and will continue to be for many boat owners.

Bearings are not only a problem for boat owners but Caravan owners with bearings due to high-speed, highway usage.

Worn bearings and even damaged stub axle journals are a result of water ingress into the bearing cavity.

Water entry into hubs is generally through the back seal and is a common boaties problem.

I need a better marine seal, yes that is a FURPHY.

Current Australian marketing recommends pressurising Bearing Buddy® 3 psi via pushing grease into the hub via a grease gun.


Did your bearing buddy fall off or was it stolen?

Water Ingress

Statement: You will not get water intrusion into the hub because the tension in the bearing buddy® spring will counteract the contraction in the cavity due to cold water immersion. That is also a FURPHY.

Pressurising bearing buddy® at three psi in a cold hub only results in that pressure being released on the highway when the bearing housing is hot.

Have you noticed the grease marks on the inside of your wheel? Impossible to remove? As the hub gets hot, air expands. Remember that spring was under full tension at three psi when cold?

Now the expanded grease isn’t going back inside the bearing protector or bearing buddy® because the bearing buddy® is already loaded and under full tension. The only place where grease/oil can escape is through the back seal.

Walla, grease over the inside of our trailer hub.

In fact, as the hub grease/oil gets hot and fluid, the grease in the bearing buddy® is starting to escape into the bearing cavity and then out through the back seal?

There is a lot of talk from experts about putting good quality bearings into your boat trailer, and THAT IS the remedy for failed bearings. Another FURPHY. Right, bad bearing FAIL, but it is not the root-cause of boaties bearing problems.

Another Prime cause of bearing failure is pumping new grease ON TOP OF OLD or contaminated lubricant?

If you have BAD lubricant, this bad grease/oil needs to be removed, and bearings checked for wear. The old lubricant is a light tan grease or black grease.

Tan coloured grease is water in the grease. Black grease is carbon black in the grease.

Bearing Buddy®

Bearing Buddy is the trademark that belongs to Couplemate. This device has a place in the marine industry for folks who want to expel water from their hubs.

Pumping fresh grease into the bearing buddy will certainly expel old contaminated grease (brown grease out the rear end). Be sure to recheck after you hit the highway because more grease will be found on the inside of your wheel after a trip on the motorway.

Caution: Bearings with water contamination will cause the coating on bearings to wear more quickly. This can accelerate bearing failure.


Bearing BuddyAustralian company Couple-mate has found the science to the BEARING FAILURE SOLUTION

Couple-mate discovered that putting a hot trailer hub into cold water causes the air inside the hub to contract. This contraction causes water to be sucked in through the back seal. Simple as that.

After years of testing, it has been found that water enters the hub through the marine seal and more precisely water enters around the outside of the marine seal. (given there is no wear on the bearing journal)

Couple-mate inserted a rubber diaphragm on the outside of the dust cap (or rubber grommet). The rubber grommet is pushed out as Air Expands and then is sucked into the bearing cavity when contraction occurs. It is the rubber grommet that expands and contracts due to dramatic changes in air temperature.

50mm Square Hydraulic Disc Braked Axle

50mm Square Hydraulic Disc Braked Axle

Boaties still check their wheels and apply regular maintenance, but they are not buying bearings.

Bearing failure is being minimised in the Australian market for boaties using Couple-mate Premium Dust Covers. Grommet dust covers are standard equipment on American trailers, especially boat trailers.

Couplemate have produced a set of dies to suit Australian hubs and produced a stainless Grommet dust cover.

Helpful TIPS:

  • Remove the grommet to inspect bearing grease. Simply replace grommet after inspection.
  • Black grease is caused by bearing wear. The black component of the grease is carbon that has worn from your bearings. Remove and re-pack bearings with high-temperature grease (recommended)
  • Dirty, gritty brown grease indicates water contamination. Remove and re-pack bearings with high-temperature grease (recommended).
  • Once you have reached the boat ramp, wait 15 minutes for your hubs and bearings to cool down.

Using the grease nipple on bearing protectors to insert fresh new grease on top of OLD DIRTY grease is NOT recommended as this will accelerate bearing wear.

Read more on caravan and boat trailer bearing failure here.

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