Easy-Peasy Trailer Hub Replacement

Solid brakes on your trailer and well-operating trailer hubs are no laughing matter. It’s vitally important to ensure the safety of your trailer while towing it down the road.

However, replacing your trailer hubs doesn’t have to be a painstaking process. In fact, with a few hand tools, the job can be completed with relative ease.

In this guide, we’ll go step by step through the process of trailer hub replacement. We’ll cover the tools needed for the task, the steps involved and some tips to make things as easy-peasy as possible.

Need a complete replacement? Shop full axles instead.

The trailer hub is the primary fixture that provides the mounting point on which the wheel spins. There are idler hubs and brake hubs. Idler hubs have no braking capabilities and simply spin freely. Brake hubs contain trailer brakes, whether electric or hydraulic.

Here is what you can expect to see in a typical trailer brake hub.

First things first, it’s important to know what you’re replacing before you dive into the job. Recognizing the various components and overall assembly will make you more confident in your abilities and help avoid mistakes and unnecessary work.

This is the complete trailer wheel hub assembly with the hub installed versus with the hub removed:

Lug Stud

Lug studs are threaded bolt studs that keep the wheel secured on the hub, using lug nuts. Different hubs have different numbers of studs, from four to eight, or even more.

Dust Cap

The dust cap protects the bearings, grease and other inner components of the hub. Typically, the dust cap is mounted in place with a friction fit.

Spindle

The spindle is the threaded end of the trailer axle. It serves as the primary mounting point for the hub and bearings.

Brake Shoes

The brake shoes are pads within the brake hub that create friction when the trailer brakes are activated. The shoes press outward, rubbing against the inner surface of the hub and creating the braking action to stop the trailer.

Brake Magnet

The brake magnet is an electromagnet that actuates the brake shoes. When the vehicle brakes are applied, the brake controller sends a signal to the magnets to activate the outward pressure of the brake shoes.

Spindle Nut

The spindle nut is a large nut that threads onto the end of the axle spindle. On many trailers, it’s a castle nut and is secured using a cotter pin.

Bearings

The bearings allow the wheel and hub to spin freely. Usually there is an inner bearing and outer bearing per hub. The bearings get packed with grease for maximum lubrication.

You don’t need the tools of a fully outfitted mechanic shop to replace your trailer hubs. Typically, all it takes is some common hand tools found in most DIYer garages or shops. However, it should be noted that if you don’t have any of the tools listed below or you would simply prefer to take your trailer to a professional, finding a local installer nearby is an excellent option!

• Floor jack
• Jack stands
• Impact driver or ratchet
• Socket set
• Flathead screwdriver
• Pliers
• Clean rags
• Torque wrench

Start by jacking up your trailer using a floor jack. Place the jack under the trailer frame and make sure the trailer is secured with the proper chocks. Jack up the frame so that the tire clears the floor. Place a jack stand under the frame for additional support.

Next, remove the lug nuts from the wheel using your impact driver or a ratchet. With all of the lug nuts removed, take the wheel off and set everything aside for later.

Using a flathead screwdriver, begin to pry the dust cap off of the hub. Dust caps are typically a friction-fit, so all it takes is a little elbow grease and patience. Slowly spin the wheel as you work, prying at the cap in regular intervals so it comes off evenly. If you pry too much in one spot, the cap might bind up.

Once removed, set the cap aside.

In the center of the hub, after you’ve removed the dust cap, you’ll see a castle nut. This is the spindle nut, holding the hub onto the trailer axle. Before you start cranking away with your impact driver, wait, stop! Take a closer look, and you’ll notice a cotter pin that passes through the castle nut.

First, you’ll need to remove the cotter pin from the castle nut. Use your pliers to straighten out the legs of the cotter pin and then work it back out through the hole. This part can be tedious, so don’t get frustrated! Take your time.

With the cotter pin removed, you can remove the spindle nut with your impact driver and the right-sized socket.

Pro Tip: Throw on some latex gloves or similar at this time. The spindle and other components will likely be covered in grease, and it’s important that you don’t carry that grease (or any other grime from your hands) onto the brake components. This can mess up your ability to brake down the road, literally!

At this point, your trailer hub should come off quite easily (no hammering, blowtorching or cursing necessary! There will be a washer on the spindle that can be removed first, and then you can slide the entire hub off the spindle.

Take care to cup your hand over the opening in the center of the hub to catch the bearings inside. They may be loose inside the hub, and you don’t want them falling on the ground.

Note that if you are replacing your trailer hub assembly with a Lippert model, the bearings will come pre-installed in the new assembly. However, if you need to replace your trailer wheel bearings only, here is a video to walk you through that process.

With the hub removed, you’ll have a clear view of the entire internal brake assembly. Now is a great time to do a visual inspection of each of the components, including the brake shoes, springs, electromagnet and spindle rod. Don’t be alarmed if your brake shoes have some surface rust. This is normal.

Verify that the magnet and brake shoes are free of grease, and clean the shoes with a quality brake cleaner if necessary. Also, clean up the spindle with a clean rag, so it’s free of grease.

If any of the components are damaged or worn out to the point of being ineffective (e.g., the brake shoes are worn too thin), be sure to order any replacement brake parts needed.

Place the new trailer brake hub assembly onto the spindle, firmly pressing it into place. Then, install the outer bearing, followed by the washer.

Next, you need to replace the trailer spindle castle nut. Finger-tighten the nut first to snug it in place. Then, use your torque wrench to tighten the nut down to the specified value (our example is for 55 lb-ft.; be sure to reference the instructions for your specific components).

After torquing, you’ll need to back the nut off again and retighten by hand until snug. 
Why? The purpose of this step is to actually press the components into place, namely the bearings and hub.

To secure the castle nut, install a new cotter pin through the hole, and bend the ends of it into a Y-shape to keep it in place.

With the brake hub properly mounted, the finishing touch is to reinstall the dust cap. This is quite easy. Position the cap over the center hole, and gently tap it into place with a rubber mallet. Be sure to spin the hub as you tap to allow the cap to seat properly within the hole. If it goes on crooked, the cap might get bound up and will need to be reinstalled again.

The last thing to do is to reattach the trailer wheel and tire. Lift the wheel back on, and replace the lug nuts, finger-tightening them first, so you don’t get cross-threading.

Next, snug the hardware with a wrench or impact driver, following a star pattern on the lugs. This will help ensure that the wheel goes on straight and seats evenly against the hub.

With the lug nuts tight, lower your trailer once more, using your floor jack, and torque the nuts to their final specs. Lowering the trailer before you torque makes it easier to tighten the nuts without spinning the wheel.

Also, we recommend checking the torque on your lug nuts after 10, 25 and 50 miles of travel to make sure they stay snug.

Congratulations! You did it! You’ve successfully replaced the hubs on your trailer. Well, to be fair, you’ve replaced one side. Now it’s time to repeat the entire procedure on the other side of the trailer and on any other hubs if your trailer has multiple axles.

If you get stuck at any point during the replacement process, take a break, grab a glass of lemonade, and start again when you’re feeling more confident. And, if you get really stuck, our customer support team is always ready to take your call.

Disclaimer: These photographs, recommendations, and approximations are intended for demonstration purposes only and do not reflect the specifications of any particular tow vehicle, recreational vehicle, or trailer. Always consult the manufacturer’s Owner’s Manual.