Best Grease For Boat Trailers: Keep Your Axle Smooth Sailing

Boat trailer wheel bearings require regular greasing due to repeated submersion in water and exposure to sandy environments. It is important to use the right type of axle grease to prevent wheel bearings from failing, which can cause accidents or damage to your boat. Marine grease is recommended for boat trailers, but regular lithium complex bearing grease is also compatible. It is also important to inspect, disassemble, and grease boat trailer wheel bearings annually as part of a boat trailer maintenance program.

How to grease boat trailer wheel bearings

Greasing your boat trailer wheel bearings is an important part of boat maintenance. It's a messy job, but it can prevent the loss of valuable boating time. Here's a step-by-step guide on how to grease your boat trailer wheel bearings:

Step 1: Remove the Dust Caps

Use a screwdriver to pry off the dust caps. Tap the blade under the lip and rotate the hub as you pry off the cap. If your bearings have bearing protectors, tap the protector as you rotate the hub with a plastic mallet to avoid denting it.

Step 2: Clean the Bearings

Manually remove as much grease as possible from the bearings. Then, wash the parts in a solvent and blow-dry them with compressed air. Be careful not to spin the bearings at high speed with compressed air, as this can cause them to explode.

Step 3: Inspect the Bearings

Check the bearings for any signs of damage or rust. Look for pitting, blue or black discolouration, scoring, galling, or rust. If the bearings show any of these signs, replace them. It is also recommended to replace the bearing races, as they are matched to the bearings. You can remove and install them with a hammer and punch.

Step 4: Grease the Bearings

Greasing the bearings is easier and neater with a bearing packer. If you don't have one, place a dollop of grease in your palm and smush the bearing into it with your other hand. Work the grease firmly into the bearing until it starts to appear on the other side, rotating the bearing as you go to ensure it's filled.

Step 5: Reassemble the Bearings

Tap the greased inner bearing and race into the hub with a mallet until flush. For the rear seal, wipe a film of grease into the bearing races and seat the greased inner bearing into the race. Coat the outer edge of the seal with a liquid sealant, then tap it into the hub until flush with the end of the bore, using a mallet and a socket of equivalent diameter.

Tips:

• If you notice deep scoring, pitting, or rust on the axle shaft where the bearings ride, it's best to replace the axle.
• If your trailer is equipped with bearing protectors, such as Bearing Buddy®, maintenance is minimal. You won't need to clean out and repack the grease for several years, but be sure to check the manufacturer's instructions for the recommended frequency.
• When greasing the bearings, use a marine-appropriate grease, such as Mercury 2-4-C Marine Grease or Mercury High-Performance Extreme Grease, to prevent breakdown in the presence of water.
• To check and top off grease levels, remove the bearing protector cap and press on the edge of the spring-loaded piston. If the piston doesn't move, add more grease with a hand-pump grease gun.

How often to grease boat trailer axles

The frequency with which you grease your boat trailer axles will depend on several factors. Firstly, consider the size of your trailer, the wheel size, and the weight load. Boat trailers with small wheels may require more frequent greasing due to the increased stress caused by faster spinning. As a general rule, boat trailer axles should be greased at least once or twice a year, and some sources recommend greasing every 2,000 miles for small-wheeled trailers to prevent excess wear. If your trailer is exposed to extreme heat or consistently operated at its load limit, you should grease the axles more often, as this will cause the grease to deplete more quickly.

Additionally, the frequency of use, the type of use, and the type of water the trailer is used in (salt or freshwater) will impact how often you need to grease the axles. It is recommended to inspect and repack the bearings and install new seals at the end of every season to prevent mid-season hub failure and catch any seal leaks.

To grease your boat trailer axles, you will need high-temperature grease, a wheel jack, a torque wrench, and a hammer. Basic mechanical knowledge is required for this task. Remember to refer to your owner's manual for specific instructions and torque recommendations.

Best grease for boat trailer bearings

When it comes to choosing the best grease for boat trailer bearings, there are several factors to consider, including the type of grease, its water resistance, compatibility, and maintenance practices.

Firstly, it is recommended to use a marine-style grease specifically designed for boat trailer bearings. These greases are typically blue in colour and are formulated to resist water even under severe conditions. They are designed to protect bearings from corrosion and water washout, which are common issues when boat trailers are dunked in water. Some recommended marine greases include Sta-Lube Marine Grease, Lucas Marine Grease, and AMSOIL Water Resistant Grease.

Secondly, compatibility between different types of grease is an important consideration. It is generally recommended to stick to one brand or type of grease to ensure compatibility. Mixing different types of grease can lead to reduced performance and potential issues with your bearings.

Additionally, maintenance practices play a crucial role in ensuring the longevity of your boat trailer bearings. It is advised to regularly grease your bearings, especially if you use your boat frequently or expose it to saltwater. Proper maintenance includes inspecting and repacking bearings, as well as replacing seals at the end of each season or after prolonged use. This helps prevent bearing failure and catches any seal leaks before they cause significant problems.

Some users recommend using products like Bearing Buddies, which are designed to keep the hub full of grease, preventing water intrusion. However, it is important to follow the manufacturer's recommendations and greasing procedures to avoid over-greasing and potential seal damage.

In summary, the best grease for boat trailer bearings is a marine-style grease that offers excellent water resistance and compatibility. Regular maintenance, including greasing, inspecting, and repacking bearings, is essential to ensure the smooth and safe operation of your boat trailer.

How to remove the bearing to grease it

To remove the bearing so that you can grease it, follow these steps:

First, slightly loosen the lug nuts while the trailer is on the ground. Then jack up the trailer, so the wheel is off of the ground. Ideally, for stability, the trailer hitch should be connected to a vehicle, and the opposite wheel should be chocked. You can also use a jack stand for added security and safety.

Next, remove the wheel. Now you can inspect the hub and look inside the rim to see if there has been any grease escaping. Grease running from the seal means water and contaminants can get in and degrade the bearings.

Now, remove the dust cap with a mallet by knocking it equally from side to side. Once the cap is removed, this exposes the axle nut that holds the hub and the cotter pin that secures the nut in place. Remove the cotter pin, followed by the nut, and then the large washer.

Next, pull the hub toward you and remove the outer bearing. Leave the wheel on the spindle. You can now inspect the outer bearing for any rust, pitting, or deformities on each roller bearing. If the bearing is in good condition, it should be smooth and clean.

If you need to replace the bearings, you can use a special punch to pop out the old inner and outer bearing races. Lay the hub down and use a long punch to reach through to the opposite side. Find the back edge of the race with the punch and knock it out with a hammer, alternating sides of the race's edge. Once removed, flip the hub and repeat the process for the opposite race.

Now, to remove the inner bearing, put the axle nut back on and pull the hub toward you fully. This will cause the inner bearing and seal to pop out. You can then inspect and clean the inside of the hub, checking for any metal shavings or signs of degradation.

At this point, you can begin to grease the bearings.

Please note that this process may vary slightly depending on the specific design of your boat trailer, and it is always a good idea to refer to the manufacturer's instructions or seek professional assistance if you are unsure about any steps.

How to check if your boat trailer axle needs greasing

Boat trailer axles need greasing more often than other trailers because they are regularly submerged in water, which can damage the bearings. Boat trailers with small wheels may need greasing every 2,000 miles, while larger trailers with small axles may need greasing once per season.

Checking the grease level

First, remove the bearing protector cap. Then, check the grease level by pressing on the edge of the spring-loaded piston. If the piston moves, the hub has enough grease and you don't need to add any more. If the piston doesn't move, you need to add more grease.

Topping up the grease

Mount a hand-pump grease gun to the grease fitting (also known as a grease zerk) in the centre of the piston. Pump in grease until the piston starts to move, then continue adding grease until the piston moves about 1/8 inch when you press on the edge.

You can then jack up the trailer and spin the tire to help distribute the grease before towing. Wipe up any excess grease and replace the cap on the bearing protector.

What type of grease to use

Use a marine-appropriate grease, such as a high-quality, waterproof grease that won't break down in the presence of water.

Frequently asked questions