In this post, we will be going over how to grease a Bearing Buddy lubrication system on your boat or caravan trailer the correct way without blowing out your hub seals.
I have been using the Bearing Buddy grease system for over 20 years on all of my trailers. It was good to see that when I purchased my last Jet-ski trailer that it came pre-installed with marine Bearing Buddies. They do have a great name in the trailer industry.
Table of Contents
- 1 What grease for boat trailer bearings?
- 2 Bearing buddy maintenance
- 3 How often do you need to grease bearing buddies?
- 4 How do I know what size bearing buddy I need?
- 5 How do you put bearing buddies on?
- 6 Bearing buddy vs dust cap
- 7 Bearing buddy problems and solutions
What grease for boat trailer bearings?
The first thing you will need is some high quality, synthetic, no. 2-grade grease which is designed for trailer wheel bearings, and a grease gun with a zerk fitting flexible hose.
Start by removing the grease cartridge end caps and insert the tube into your grease gun. Prime the grease gun and bleed out any air pockets.
Now jack your trailer up one side at a time enough so you can rotate the wheel. This will enable the grease to flow completely around the bearing without any air pockets.
Press the trigger to pump some grease out of the nozzle. Once you can see that grease is flowing out wipe off the excess and push the hose onto the zerk nipple on the Bearing Buddy.
I like to use a flexible hose on my grease gun so that I have room to work in my garage. If you have plenty of room a solid metal grease hose is fine.
Pump a few squirts of grease into the Bearing Buddy and rotate the trailer wheel a few times. Continue to pump grease until you see the front piston on the Bearing buddy start to push out a little. If you find that grease is starting to come out from either the front or back of the axle you have too much grease in the system. That is enough.
Bearing buddy maintenance
The next thing you can do for your trailer is to go over your Bearing Buddies after every trip. But like any consumable, these need to be maintained. Maintenance on these Bearing Buddies are really easy.
- Wash them down after every trip
- Wipe them down
- Put a few squirts of grease into each Bearing Buddy
- Check for leaks and worn dust caps.
- Check for correct grease level.
- Check for grease leakage from axle seals.
- Clean the Zerk fitting nipple.
- Replace zerk grease nipple if rusted.
- Check for water behind the dust cap.
How to unclog grease fittings
Usually, you can use a small pin to push in the center spring-loaded ball to unclog the grease fitting. If this fails it will be best to take out the Zerk grease fitting and clean out all the old hard grease with some penetrating oil and a small flat blade screwdriver. replace the grease fitting if it is rusted or has a damaged end ball.
If you find that your Bearing buddies are leaking grease check that the zerk grease fitting is tight. You could also have a damaged piston or faulty spring.
How to remove the Bearing Buddy Piston.
The only reason I removed the bearing piston was that I was unable to tighten the grease nipple. There is a locking nut behind the grease piston that holds the 6mm grease nipple in place. I would like to see the locking nut spot welded to the piston for future upgrades.
In some cases you will want to remove the piston and spring to tighten this nut.
First, remove the large circlip and pull out the Bearing Buddy spring and piston. Be sure to wipe down all the excess grease and inspect for damage.
Retighten the grease fitting locking nut and place the piston back into the bearing buddy along with the spring and circlip.
As you can see you don’t have to remove the whole Bearing buddy unit to repair it. You can actually just pull it apart with it still connected to your trailer axle.
How often do you need to grease bearing buddies?
It is best to grease bearing buddies every 3 months or 3000km whichever comes first. Be sure to use a quality axle bearing grease and rotate the wheel as you are pumping some bearing grease in.
You should be able to push the internal Bearing Buddy piston in a few mm from side to side if it is full of grease. If it is empty the piston will sit flush against the inner metal stop race and will not move. Pump some more grease in to push out the piston.
Can you over grease a bearing buddy?
Yes, you can over grease a bearing buddy but all that will happen is you will pop out the rubber inner seals. If you find that grease is coming out of either the front or rear axle seal you must stop pumping grease in.
Try to push the rubber seal back in after rotating the wheel. If the axle bearing seal is not able to be pushed in go for a long drive to heat up the axle grease a little. You will be able to push the seal back in.
An automatic pressure relief feature should prevent over-filling and over-pressurization but sometimes this gets full of dirt and mud.
Does bearing buddy grease the inner bearing?
Yes as you pump grease into the front piston nipple the grease will work its way down the axle shaft until it reaches the rear bearing. Be sure to spin the wheel while you are pumping grease to work it into the whole bearing and fill in any air gaps. The grease is kept in place by the rear rubber axle bearing seal.
How do I know if my bearing Buddy has enough grease?
Once you start to feel some resistance in pumping the grease pump and you can see the piston coming out you have enough grease. You may also start to see a small amount of grease coming out of either the front piston or at the rear rubber bearing seal.
The front of the piston will come out as you pump grease in. You should be able to wiggle it slightly from side to side. This is the simple way on how to check grease level in s bearing buddy.
While you have your grease gun out add a small dab of grease onto your trailer hitch point. It will stop your trailer hitch from rattling.
How do I know what size bearing buddy I need?
You will need to work out the inside diameter of your hub dust cap. This has to be an exact measurement as the Bearing Buddys are a compression press fit.
- Remove the old metal dust cap by using a large flat screwdriver. Measure the dust caps outside diameter.
- Measure the inside diameter of the HUB using a vernier caliper or a micrometer.
- Use the bearing buddy size chart shown below to get the model number required.
Bearing Buddy Selection Chart Sizes
|Model||Inches||Metric||Outer Bearing Cup|
threads = 1
|24 threads |
threads = 1
threads = 1
How do you put bearing buddies on?
Bearing buddies must be hammered in as they are a compression fit. To protect the outer casing of the bearing buddy it is best to use a thick piece of wood such as a 2×4 pine wood which has been cut to a 15cm length. Use a rubber mallet to hammer the small block of wood, and drive it into place. Drive them in until they are at the required depth according to the installation instructions.
If the Bearing Buddy cannot be driven into the hub, measure the hub and the bearing buddy. Send them back to the place of purchase if they don’t match in size.
If you dont have a rubber mallet you can use a nail hammer hitting the centre of the wood plank.
To remove a Bearing Buddy, you must lay a thick block of wood against the side of it and hit the wood with a hammer. Place the wood on the opposite side of the Bearing Buddy and hit it again.
This action will wobble the Bearing Buddy out side by side.
Are bearing buddies worth it?
Yes, they will prevent your trailer bearings from running dry and seizing over time. They are especially useful for long trips and boat trailers that are submerged in the sea.
It will save you time from having to repack your trailer bearings every 6 months. Just get out the grease gun and pump a few squirts of grease into each bearing buddy.
Bearing buddy vs dust cap
All that a dust cap does is protect your wheel bearings from dirt and dust from entering. Water will still enter through the dust cap and enter the wheel bearing if you don’t have bearing buddies installed.
So if it is a choice between Bearing Buddy vs Dust cap go for the ever popular bearing buddy.
Bearing buddy problems and solutions
I have had no issues with my bearing buddies in over 20 years of using them except for a leaking zerk grease fitting.
Another issue I have seen with other boat trailers is the dust caps come off if they are not put on properly. It is best to push the rubber dust cap on and then lift an edge slightly to release any air pressure that is stuck inside. Then press in the center of the rubber dust cap to create a vacuum.
A small bead of silicone will also stop the cap from coming off at high speed.
If you loose a Bearing Buddy it could be because it was not installed correctly. Be sure to hammer them in correctly.
Now that you know how to grease a bearing buddy system easy & fast get out there and do it. You will now have peace of mind that your wheels will not fall off your trailer due to a bad bearing. Check out some of our other trailer mods.
I am a qualified Industrial Electrician for the past 20 years and I love to share my knowledge on home repair jobs.
I love fast toys like Motorcycles, Cars, Jetskis, and Boats so writing about them is easy.
To keeps costs down I do all my own mods, repairs, and servicing. These skills I want to share with everyone. DIY is a skill everyone can learn.