Towing trailers adds so much functionality to our vehicles, but it also comes with its own set of responsibilities—chief among them maintenance. One often overlooked but crucial aspect of trailer upkeep is the greasing of trailer bearings. Neglecting this simple task can lead to a host of problems, from reduced fuel efficiency to catastrophic bearing failure that could leave you stranded or cause an accident.
We have towed trailers of all sizes and shapes full-time, and In this comprehensive article, we’ll guide you through the ins and outs of greasing trailer bearings, a preventive measure that can save you time, money, and a whole lot of stress. Whether you’re a seasoned road tripper or a towing novice, understanding the importance of well-lubricated bearings is essential for a smooth and safe journey. So grab your grease gun and let’s get started—your trailer will thank you.
What Are Trailer Bearings?
Trailer bearings are specialized metal components that allow the smooth rotation of the trailer’s wheels. All vehicles have bearings to allow wheel rotation. They are located in the wheel hub and work in conjunction with other parts like the axle, grease, and seals to ensure that the wheels turn freely with minimal friction. Properly functioning bearings are essential for the safe and efficient operation of any trailer, as they bear the load of the trailer and its contents while reducing wear and tear on the wheel assembly.
The design of trailer bearings depends on the design of the trailer. The most common type is a tapered roller bearing. These look like cylinders trapped in a conical-shaped metal housing. The weight is actually transferred to the cylinders that are held in place by housing.
Less common are ball bearings or cartridge bearings. Ball bearings do not work as well for vehicles because of lateral stresses. Cartridge bearings are all-in-one units that are installed in the hub with a press. These bearings are frequently considered sealed and are the most common type used on passenger cars and trucks. However, some higher-end trailers will use sealed bearings. Sealed bearings technically never need grease, but some types can still be serviced.
Why Should You Grease Trailer Bearings?
The more you use your trailer, the more dirt, water, and debris from the road can reach your trailer bearings. These can contaminate the grease, which can cause increased friction, overheating, and total failure. In extreme cases, the overheating can cause components to reach dangerous temperatures. Over time greases also break down due to heat and can eventually fail to provide the required lubrication.
When these components reach dangerous temperatures, they can ignite. Unfortunately, it could be too late by the time you realize what’s happening. If you don’t have a fire extinguisher handy, your trailer could be in flames in minutes. If you cannot unhitch quickly, you could lose your trailer and tow vehicle simultaneously.
Complete failures can also lead to your wheel actually locking up or even falling off while driving!
Pro Tip: Make sure you know these 10 Camper Towing Rules You Should Never Break before you hit the road.
How Often Should You Grease Trailer Bearings?
The frequency with which you should grease your trailer bearings depends on several factors, including the type of trailer, the weight of the loads you’re carrying, and the conditions under which you’re traveling. However, there are some general guidelines that can serve as a starting point:
Annual Inspection: At a minimum, you should inspect and grease your trailer bearings once a year. This is a good rule of thumb for light to moderate use.
Every 10,000 Miles: If you’re using your trailer more frequently, consider greasing the bearings every 10,000 miles.
Before Long Trips: If you’re planning a long journey, it’s a good idea to grease the bearings before hitting the road, even if you haven’t reached the 10,000-mile mark.
After Submersion: If your trailer has been submerged in water (common with boat trailers), you should inspect and grease the bearings a few times a year. If using a trailer that gets submerged regularly, we highly recommend the use of a bearing buddy or trailer buddy system. These systems store extra grease and keep it under slight pressure on the bearings to prevent water ingress.
- MODEL: Bearing Buddy 1980A (Chrome Version) / Protective Bra 19-B
- SIZING: 1.980 inch (inside diameter of hub) See secondary...
- CONTENTS: One Pair of 1980A Chrome Bearing Buddy(s) with auto...
Seasonal Use: If your trailer is used seasonally, grease the bearings at the beginning and end of the season.
Heavy Loads: Trailers carrying heavy loads may require more frequent greasing. Check your owner’s manual for specific recommendations.
Harsh Conditions: If you’re traveling in harsh conditions such as dusty roads, muddy terrains, or extreme temperatures, more frequent greasing may be necessary.
Signs That Bearings Need Greasing
Recognizing the signs that your trailer bearings need greasing is crucial to prevent catastrophic failure. Unusual noises such as grinding or squealing emanating from the wheel area are often the first indicators that the bearings require attention. Additionally, if you notice excessive heat coming from the hub after a trip, it’s a strong sign that the bearings may be lacking sufficient lubrication. We always carry a thermal gun and shoot the hubs occasionally to check temps. If there is one hub running significantly warmer than the others, something is up.
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Visible signs of wear or corrosion upon inspecting the bearings also signal the need for immediate greasing. Ignoring these warning signs can lead to premature bearing wear, reduced fuel efficiency, and even catastrophic failure, making it essential to grease the bearings as part of your regular maintenance routine.
Consult Your Owner’s Manual:
Always consult your trailer’s owner’s manual for manufacturer-specific recommendations on greasing intervals. Failure to maintain your trailer bearings can lead to premature wear, reduced fuel efficiency, and even catastrophic failure, so it’s crucial to make this a regular part of your maintenance routine.
What Tools and Materials Do You Need to Repack Trailer Bearings?
Before you can start repacking your trailer bearings, you’ll need to gather your supplies. There are a handful of items you’ll need and a few others that are good to have close by.
For tools, you’ll need an adjustable wrench, a socket set, a flathead screwdriver, a hammer, a jack, jack stands, needle-nose pliers, and a wrench. If you’re a DIYer, you likely have most of these on hand.
You’ll also need a few materials like bearing grease, brake cleaner, clean rags, kerosene, penetrating fluids, and a small pan. You’ll need all of these during the process.
Ensure you have all the tools on hand before you start. You don’t want to make multiple trips to your favorite auto parts store to get items. This can make the process take much longer than necessary.
How To Grease Trailer Bearings With A Grease Gun
Not all trailers have grease gun fittings for greasing bearings. Some smaller trailers and many boat trailers have these fittings (called zerk fittings), however. Greasing trailer bearings equipped with a Zerk fitting is a relatively straightforward process that can be done with a few simple tools. The Zerk fitting, also known as a grease fitting, allows for easy lubrication without the need to disassemble the wheel hub. Here’s how to grease trailer bearings with a Zerk fitting:
Steps For Grease Gun Bearings
- Safety First: Park the trailer on a level surface and chock the wheels to prevent any movement.
- Lift The Wheel: You need to lift the wheel that you will be greasing off the ground.
- Locate the Zerk Fitting: The Zerk fitting is usually located on the wheel hub or the end of the spindle. It’s a small, protruding nipple-like fitting where the grease gun will attach.
- Clean the Zerk Fitting: Wipe off any dirt or grime from around the Zerk fitting using a rag to prevent contaminants from entering the bearing.
- Prepare the Grease Gun: Load the grease gun with the appropriate grease if it’s not already loaded. Attach the hose or nozzle to the Zerk fitting.
- Pump Grease While Spinning Wheel: With the grease gun securely attached, start pumping grease into the fitting as you slowly rotate the wheel. You should see old, discolored grease being pushed out of the bearing as the new grease enters. Continue pumping until you see fresh grease coming out. Make sure you pump slowly and only when the wheel is turning. The wheel needs to turn to allow the grease to move through the bearing properly.
- Clean Up: Wipe off any excess grease that has been pushed out during the process. It is usually a big mess.
- Test: Spin the wheel by hand to ensure that the grease has been evenly distributed within the bearing.
- Repeat: Perform the same steps for all other wheels equipped with Zerk fittings.
- Final Check: Once all the bearings have been greased, take a short drive to ensure everything is working smoothly.
Always Spin The Wheel!
I want to reiterate that you need to spin the wheel slowly as you pump in grease. Pumping grease in with the wheel on the ground can immediately mess up your brakes and cause bearing failuer. I made this mistake early on as well, and it’s not fun. This happens because the grease seal at the back of the hub will get pushed out. While zerk fittings can be great to make the process easier, they can also make a lot more work for you if you overpressure your grease seal.
These are general steps for grease fittings, but always consult your trailer’s owner’s manual for any manufacturer-specific guidelines.
How to Manually Grease Bearings on a Trailer
The specific process to grease bearings may differ a bit from trailer to trailer, but many of the tasks are the same. Once you do one trailer, you can figure out pretty much any other type. However, be sure to take your time and do it right. While it may be tempting, this isn’t a task you should rush to complete. If you do, you could make a dangerous and costly mistake.
I made a video a long time ago about replacing trailer brakes but it also includes greasing trailer bearings. Its a long video, but you can watch the entire process in real-time. Below is a summary of what is needed to grease bearings.
Lift the Trailer
The first step in the process is to lift the wheel. To do this, you’ll want to park on a level surface. Use wheel chocks on the opposite side to prevent any movement. Ensure your jack has the appropriate weight capacity to safely and efficiently lift the wheel.
Before lifting the wheel, it’s best to break free the lug nuts on any tires you’ll be removing. It allows you to get much more torque without the tire spinning. Don’t loosen them too much but just enough; make it easy once the wheel is free. Lift the trailer until the tire is two to three inches off the ground. Place jack stands under the frame to provide additional support during the process.
Remove the Wheel
With the tires off the ground, it’s time to loosen the lug nuts further. Having a bowl or other container to place the lug nuts and any small parts into is a good idea. They’re typically relatively small and round, making them hard to find if they roll away.
Once all the lug nuts are off the wheel, pull straight out on the wheel to remove it from the hub. Depending on the conditions, it may need a little assistance from a rubber mallet. Be gentle but firm. You don’t want to cause damage to any of the components in the process.
Disassemble the Hub
You’ll now have unrestricted access to the wheel hub. The first thing you need to do is remove the dust cap. Use a flathead screwdriver to pry it off. Next, remove the cotter pin and spindle nut that keeps the wheel hub in place. After removing these, you can slide off the hub and drum assembly from the spindle.
The hub on most trailer brakes is part of the brake drum assembly. The bearings will sit inside the hub portion of the drum brake.
You should now see the inner and outer trailer bearings and the grease seal. Carefully remove them from the hub and store them in a clean and safe spot. With all the components extracted, it’s an excellent time to inspect all the pieces for any signs of damage.
The bearings will most likely be held in place by the grease seal that is set in the back of the hub. I usually remove the grease seal by setting the drum/hub on a bucket and tapping the seal down and out. The bearings usually fall out with the seal and into the bucket.
If there are no apparent signs of damage or abnormal wear and tear, you can clean the bearings instead of replacing them. If the grease looks okay and is not dirty (dark is ok), then you can add new grease and push the old stuff out. However, if dirt, water, or grease is milky, it needs to be fully removed.
Use a solvent or degreaser to dissolve the old grease and dirt. Soak the bearing and spindle nuts in gasoline to help remove stubborn gunk and spin the bearings in a solvent. Additionally, wipe down the bearings and spindle with brake cleaner. If you use solvent, you need to make sure the bearings are completely dry of solvent before adding new grease. If you add grease too soon, the solvent will damage your new grease and can cause a failure.
This is also the perfect time to inspect the grease seal. Generally, it’s best to replace it with a new one each time you do this process. However, if there’s no evidence of damage or wear, you can put it back.
Pack Grease into Bearings
Now comes the tricky part of packing the grease into the trailer bearings. For this messy job, you’ll want to wear gloves. There are two techniques you can use for packing bearings, by hand or using a bearing packer.
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To pack by hand, place a generous amount of bearing grease into your palm. Use gentle pressure to work the grease into the bearing and roll it between your palms. You want to coat the grease to work into the rollers and cage so it’s evenly lubricated.
Continue this process until you see fresh grease squeeze between the rollers. Once you see this, it indicates that you’ve fully packed the bearing. You’ll need to repeat the process for each wheel’s inner and outer bearings.
To use a grease packer, you will install the bearing between two plastic plates that screw down on the bearing. You then pump grease into the bearing. Its a bit confusing, so I recommend watching our video above as I use a packer.
- Universal Bearing Packer, Plastic, Bearing Size : 1/2" ID/4-1/2"...
- For use on all Grease Guns
- Lightweight yet rugged construction
While your hands are greasy, apply a thin layer of grease to the races in the hub and grease seal. These will help prevent contaminants from getting into the assembly while you travel.
Reassemble the Hub
After packing the bearings, it’s time to reassemble the hub. You’ll place the greased trailer bearings into their races in the hub assembly. They should fit snugly. You’ll then install the grease seal and slide the hub and drum onto the spindle. Reinstall the washer and nut on the spindle and tighten them. Now you can reinstall the cotter pin to keep everything in place.
Align the wheel with the studs and slide it back onto the hub assembly. Hand-tighten the lug nuts in a crisscross pattern. You’ll want to tighten these as you work your way around the lugs. While it may be tempting, don’t rush the process by over-tightening immediately. Provide even pressure around the tire to ensure it sets properly on the studs and hub.
Once you’ve tightened the lug nuts, remove the jack stands and lower the trailer. Use a torque wrench to finish tightening the lugs to the proper torque. Check your owner’s manual if you’re unsure of the appropriate torque for your lug nuts. Additionally, checking your lug nuts every 50 to 100 miles on your first trip after completing this process is a good idea.
Pro Tip: Towing a big rig can be intimidating, so we found 10 Ways to Make Towing a Big Rig Less Dangerous.
Can You Grease Sealed or Cartridge Bearings?
While less common sealed bearings like the NevR lube system are used on larger or higher-end trailers. Like cars, these bearings tend to last longer without service. However, because of the nature of trailer service, we have seen plenty of failures of these bearings. Because they are not completely sealed, you can add some grease to these types of bearings once the hub is removed. The bearings need to be pressed out for full disassemble and cleaning, but you can add a blob of grease with the bearings installed in the hub. I regularly added grease to these bearings (about once a year) for full-time travel. We put about 150k miles on a trailer with this type of bearing and never had a failure doing this.
Grease Your Trailer Bearings Like a Pro
Now you know how to grease and repack your trailer bearings like the pros. While it may not be the most fun or glorious task, it’s necessary. You can hit the road and know that your bearings are in excellent condition for your planned adventures. This isn’t a task that you want to ignore or put off. So get the supplies and tools and repack trailer bearings.
Are you due to maintain your trailer bearings? Tell us in the comments!
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