The Definitive Guide to Grease Trailer Bearings: Step-by-Step Instructions for Safe Towing

Towing a trailer, whether for work or recreation, is a common activity, but it comes with responsibilities. Among the most crucial aspects of trailer maintenance is ensuring your wheel bearings are properly lubricated. Neglecting this simple yet vital task can lead to catastrophic failures, including wheel lock-ups, axle damage, and even accidents. This comprehensive guide will walk you through the process of greasing your trailer bearings, providing detailed steps, safety precautions, and essential tips to keep you rolling smoothly and safely.

Why is Greasing Trailer Bearings Important?

Wheel bearings are the mechanical components that allow your trailer’s wheels to spin freely on the axle. They consist of rolling elements (balls or rollers) encased in a hardened metal race. These components are subjected to significant friction and heat during operation. Proper lubrication with grease minimizes this friction, reducing wear, dissipating heat, and preventing corrosion. When bearings aren’t adequately greased, they can overheat, leading to:

• Increased Friction and Wear: Dry or poorly lubricated bearings experience excessive friction, causing premature wear and damage to the bearing components and the spindle.
• Overheating: Friction generates heat. Without sufficient grease, this heat can build up rapidly, potentially causing the bearings to seize or fail completely.
• Bearing Failure: Bearing failure can result in a wheel locking up, causing a loss of control and posing a significant safety risk.
• Axle Damage: In severe cases, a failed bearing can damage the axle spindle, requiring costly repairs or even a full axle replacement.
• Towing Delays: Bearing issues often lead to inconvenient and expensive breakdowns, disrupting travel plans and potentially stranding you.

Regularly greasing your trailer bearings is an essential part of preventative maintenance that significantly extends the lifespan of your trailer and ensures your safety on the road.

How Often Should You Grease Your Trailer Bearings?

The frequency of greasing your trailer bearings depends on several factors, including how often you use your trailer, the distance you travel, the type of terrain you encounter, and whether you frequently submerge your trailer in water. Here are some general guidelines:

• Annual Greasing: At minimum, you should grease your bearings once a year, even if you haven’t used your trailer much. This helps to ensure that the grease is still effective and prevents corrosion.
• Before Long Trips: It’s good practice to grease your bearings before embarking on long journeys, especially if you haven’t greased them recently.
• Frequent Use: If you use your trailer regularly or travel long distances, you might need to grease your bearings more often – perhaps every 3,000 to 5,000 miles.
• Water Submersion: If you frequently launch a boat or submerge your trailer in water, it’s crucial to grease your bearings more frequently. Water can displace grease, leading to bearing corrosion and premature failure. You may consider greasing after each submersion.
• Listen for Signs: Pay attention to any unusual noises coming from your trailer wheels, such as grinding, squealing, or rumbling. These can be indicators that your bearings need greasing or possibly replacement. Also, if a wheel hub feels excessively warm to the touch, it’s a sign of a problem.

It is always better to err on the side of caution and grease your bearings more frequently than not. A good rule of thumb is to establish a regular maintenance schedule based on your usage and conditions.

Tools and Materials You’ll Need

Before you begin, gather the necessary tools and materials to make the process as smooth and efficient as possible. Here’s a list of essentials:

• Jack and Jack Stands: A reliable jack and jack stands are necessary to safely lift and support the trailer. Never work under a trailer supported only by a jack.
• Wheel Chocks: Use wheel chocks on the opposite wheels of the trailer to prevent it from rolling.
• Wrench Set: You’ll need a set of wrenches or a socket set to remove the wheel and the dust cap or bearing protector. The specific size will vary based on your trailer.
• Screwdriver or Pry Bar: These will help in prying off dust caps or hubcaps.
• Grease Gun: A grease gun is essential for injecting grease into the bearings. You’ll need one with a flexible hose for easier access to the grease zerk (if equipped).
• High-Temperature Wheel Bearing Grease: Use a quality, high-temperature, lithium-based wheel bearing grease specifically designed for trailer bearings.
• Gloves: Wear work gloves to keep your hands clean and protected.
• Safety Glasses: Always wear safety glasses to protect your eyes from dirt and debris.
• Shop Rags or Paper Towels: These will be necessary to wipe away excess grease and clean up spills.
• Catch Pan: Place a catch pan underneath to collect excess old grease during the process.
• Brake Cleaner (Optional): Brake cleaner can help remove old grease and grime if needed, but avoid getting it on rubber seals.
• Hammer and Punch (Optional): May be needed to gently tap stubborn dust caps or hubcaps back into place.
• New Cotter Pin or Castle Nut Retainer (if required): Ensure you have replacements if you remove these during the process.

Step-by-Step Instructions for Greasing Trailer Bearings

Now that you have all your tools and materials ready, let’s get to the actual greasing process. This process assumes that you do not have easy grease fittings and will need to do it manually. If you have EZ-Lube axles, the process is far simpler.

Step 1: Prepare Your Trailer

1. Park on a Level Surface: Choose a flat, stable, and level surface to work on.
2. Engage Parking Brake: If your trailer has a parking brake, engage it firmly.
3. Chock the Wheels: Place wheel chocks on the wheels opposite the ones you plan to work on. This will prevent the trailer from rolling during the procedure.
4. Gather Your Tools and Supplies: Make sure everything you need is within easy reach.

Step 2: Jack Up the Trailer

1. Position the Jack: Place the jack under the trailer axle near the wheel you plan to work on. Refer to your trailer’s manual for recommended jacking points.
2. Raise the Trailer: Slowly jack up the trailer until the wheel is completely off the ground.
3. Secure with Jack Stands: Immediately place a jack stand under the axle near the jack. Lower the trailer onto the jack stand. The jack should remain in place as a backup, but the weight should be supported by the jack stand.

Step 3: Remove the Wheel

1. Loosen Lug Nuts: Use a lug wrench to loosen the lug nuts. Do not fully remove them yet.
2. Remove Lug Nuts: Once the lug nuts are loosened, completely remove them and carefully take the wheel off the trailer. Set the wheel aside in a safe place.

Step 4: Remove the Dust Cap or Bearing Protector

1. Pry Carefully: Using a screwdriver or pry bar, carefully pry off the dust cap or bearing protector. If you are working with a hub that has a bearing protector with a grease zerk, you do not need to remove it; skip to step 6. Be careful not to damage the cap or the surrounding hub. If the cap is difficult to remove, you can gently tap the side of it with a hammer and a punch, working your way around the perimeter.
2. Inspect the Dust Cap: Check the dust cap for damage or corrosion. If it’s damaged, replace it with a new one.

Step 5: Inspect and Remove the Old Grease

1. Examine the Bearings: Carefully inspect the bearings and surrounding area. Look for signs of damage, wear, excessive rust, or heat damage. If you detect any of these issues, it’s best to replace the bearings.
2. Remove Old Grease: Using a clean rag, carefully remove as much of the old grease as you can from the hub. If it is caked on, a small amount of brake cleaner can help, but do not get brake cleaner on the rubber seal(s). Use the rag to remove the grease from the bearings themselves. You will now have access to the outer wheel bearing. Be careful not to dislodge the outer bearing or it may fall out.
3. Remove the Outer Bearing: If it has not already come loose, carefully remove the outer bearing and set it aside.
4. Remove Spindle Nut Retainer or Cotter Pin: You will need to remove the cotter pin or spindle nut retainer to be able to remove the spindle nut.
5. Remove the Spindle Nut: Unscrew and remove the spindle nut from the axle spindle.
6. Remove the Hub and Inner Bearing: Carefully pull the hub and inner bearing off the spindle. It should slide off fairly easily, but may require a bit of wiggle to loosen. Catch any parts that may fall out.
7. Clean the Parts: Use a shop rag to wipe down all of the components you have removed, making sure to remove as much of the old grease as possible. The brake cleaner can be used to clean more heavily caked on grease as long as you do not get it on rubber seals.

Step 6: Pack the Bearings with New Grease

1. Grease the Bearing: Take a glob of high-temperature wheel bearing grease in your palm. Take one of the bearings (either inner or outer) and press it into the grease. Work the grease into the bearing by pushing and rolling it until the entire bearing is completely packed with new grease. Repeat for the other bearing.
2. Grease the Hub: Take a small amount of grease and apply it to the inside of the hub.

Step 7: Reinstall the Bearings and Hub

1. Reinstall the Inner Bearing: Carefully slide the inner bearing back onto the spindle. It will go into place inside the hub.
2. Reinstall the Hub: Slide the hub back onto the spindle.
3. Reinstall the Outer Bearing: Slide the outer bearing back onto the spindle inside the hub.
4. Reinstall the Spindle Nut: Reinstall the spindle nut on the spindle. Tighten the spindle nut by hand until you begin to feel resistance.
5. Tighten the Spindle Nut: Use your wrench to torque the spindle nut to the manufacturer recommended specification. This is typically around 50 ft-lbs to seat the bearings, and is then backed off to just past finger tight and the nut retained using the cotter pin or retainer nut. It is VERY IMPORTANT to get this specification correct or you can damage the bearings. Consult your trailer’s documentation for the correct specification. If your spindle nut is designed to be tightened only and retained, tighten it to the proper torque.
6. Install the Spindle Nut Retainer or Cotter Pin: Reinstall the spindle nut retainer or install a NEW cotter pin. If using a cotter pin, make sure that it is properly bent to prevent the spindle nut from coming loose.
7. Grease the Hub: Even if you do not have an EZ-Lube type hub, add a small amount of grease to the hub, filling the void in front of the outer bearing.

Step 8: Reinstall the Dust Cap or Bearing Protector

1. Reinstall the Dust Cap: Carefully tap the dust cap or bearing protector back into place using a hammer and a punch if needed. The goal is to make it flush with the hub without damaging it. If you have a bearing protector with a grease zerk, this will need to be re-installed by hand or using a wrench to properly seat it back on the hub.

Step 9: Reinstall the Wheel

1. Mount the Wheel: Carefully mount the wheel back onto the hub.
2. Hand-Tighten Lug Nuts: Thread the lug nuts back on by hand.
3. Tighten Lug Nuts: Use a lug wrench to tighten the lug nuts in a star pattern. Tighten them to the manufacturer’s recommended torque specification.

Step 10: Lower the Trailer

1. Lift the Trailer: Using the jack, lift the trailer until the weight is no longer supported by the jack stand.
2. Remove the Jack Stand: Remove the jack stand.
3. Lower the Trailer: Slowly lower the trailer using the jack.
4. Remove the Jack: Once the trailer is fully lowered, remove the jack.

Step 11: Final Check

1. Final Torque: Check the lug nut torque again after lowering the trailer completely.
2. Test Spin: Spin the wheel by hand to ensure it rotates smoothly. Listen for any unusual noises.
3. Repeat: Repeat this process for the other wheels on your trailer.
4. Cleanup: Gather all tools, used grease rags, and dispose of them properly.

Alternative: Using EZ-Lube Axles

Some trailers are equipped with EZ-Lube axles, which have a grease zerk (fitting) on the end of the axle spindle. These make greasing your bearings much simpler. Here’s how to grease them:

1. Clean the Zerk: Clean the grease zerk thoroughly before attaching the grease gun.
2. Attach Grease Gun: Attach your grease gun filled with high-temperature wheel bearing grease to the zerk.
3. Pump Grease Slowly: Slowly pump grease into the bearing while turning the wheel. Continue to pump grease until you see the old grease being pushed out of the hub around the edges of the dust cap or bearing protector.
4. Remove Grease Gun: Disconnect the grease gun from the zerk.
5. Clean Up: Wipe away any excess grease that has been pushed out of the hub.

Important Note: While EZ-Lube axles simplify the process, they may not be suitable for all situations. If your trailer is frequently submerged in water, the pressure of pumping grease through the zerk might force water into the bearings. Also, using the EZ-Lube system exclusively does not allow a complete inspection of the bearings, so you should still consider a manual cleaning, inspection, and repacking at least yearly.

Tips for Success

• Work Clean: Keep your work area clean and organized to prevent dirt and debris from contaminating the grease and bearings.
• Use Quality Grease: Always use a high-temperature wheel bearing grease designed for trailer bearings.
• Don’t Over-Grease: While it’s important to lubricate thoroughly, over-greasing can put pressure on the seals and cause them to fail.
• Don’t Mix Greases: Different types of grease are not compatible and should not be mixed.
• Inspect Regularly: Check your bearings regularly for signs of wear, damage, or overheating.
• Consult Your Manual: Refer to your trailer’s manual for specific instructions and torque specifications.
• Don’t Rush: Take your time and work carefully. This is a job where precision is more important than speed.
• Be Prepared: Keep a spare set of wheel bearings and seals on hand in case you encounter issues on the road.

When to Seek Professional Help

If you are unsure about any aspect of this process or if you encounter any difficulties, do not hesitate to seek the help of a qualified mechanic. It is always better to be safe than sorry, especially when it comes to trailer safety. If you notice any of the following issues, consider seeking professional help:

• Damaged Bearings: If you find significant wear, rust, or other damage to your bearings.
• Damaged Seals: If the seals appear cracked, worn, or are leaking.
• Excessive Play: If you feel play in the wheel when you try to move it from side to side or up and down.
• Unusual Noises: If you hear grinding, squealing, or rumbling noises coming from your trailer wheels.
• Overheating Hubs: If the wheel hub feels excessively hot to the touch.
• Difficulty Removing Components: If you struggle to remove any parts during the process.

Conclusion

Greasing your trailer bearings is a crucial maintenance task that can significantly improve the safety and longevity of your trailer. By following the steps outlined in this guide, you can ensure your trailer is in top condition for your next journey. Regular maintenance and attention to detail are vital to keeping your trailer rolling smoothly and safely. Remember, if you are ever unsure about anything, consulting a professional is always a good idea. Happy towing!