Knowing how much play you need in your wheel bearings is critical, whether you have a boat trailer or a travel trailer. Especially when going down the freeway at 60 mph, your bearings are holding all the load and spinning thousands of times a minute. Too much or too little play will cause heat, premature damage, and even spindle failure.
So how much play do you need? It would be best if you had a maximum of a 1/16″ when you move your entire trailer tire. Any more, and that can cause a potential for heat and added wear and tear.
So how do you ensure you get the right amount of play in your wheel bearing? This post will review the following:
- How to Check Wheel Bearing Play
- How to Adjust
Also, another thing to remember is that you don’t want your bearings too tight, either. This will also generate friction and wear and tear to your bearings. When the castle nut is set too tight, the inner bearing and out bearing compress to the spindle. This will cause added friction and heat to your trailer. This could also prematurely break down your bearing grease and cause added wear on your trailer.
Table of Contents
How to Check Wheel Bearing Play
When you check for bearing play, you will need to ensure no load on the trailer. The best way to do that is to jack up your trailer. This will work with a travel trailer and a boat trailer. For a boat trailer, if you can remove the boat when doing, it would be a good idea to avoid any potential issues.
Any time you raise your trailer, use wheel chocks on the opposite trailer tire (the one staying on the ground). Any unlevel ground could cause the trailer to move when jacked up, so it’s a good idea to use the wheel chock.
Raise the trailer tire enough that you can spin freely. Once it can spin, it’s free enough to check for bearing play. This is an excellent time to ensure that your bearings are not too tight. Your tires should spin freely enough that your tires rotate at least a few times around, giving a normal spin. If the wheel spins around barely once, your bearing could be too tight, or you could have an issue with insufficient grease.
If you have a grease issue, check out my post on how often to grease trailer bearings. You will learn more about trailer-bearing grease and how to remove old grease and replace it with fresh grease.
Grab each side of the tire (3 and 9 o’clock work) and push one hand in while pushing one hand out. You should feel the play between the bearing and the spindle. The ideal situation is no play, and your wheel does not move at all and still spins freely.
The most you should play when moving in and out is 1/16″. Some recommend a max of 1/8″ play. That is fine for a lighter trailer with not much load. But if you have a travel trailer or a boat trailer going at high speeds, I would stick with the tighter tolerance of 1/16″ max.
If there is more play than that, there can be added stress and friction to your axle, spindle, and bearings, especially when your trailer is loaded with weight and travels at high speeds with thousands of revolutions a minute.
What happens if you have too much play? The good news is that you should be able to adjust easily. If your wheel bearings are still in good shape, it’s simple to make a readjustment.
How to Adjust
If you are slightly over this amount of play, you can easily adjust and get the play back into tolerance. Here are the steps to adjust play in your trailer wheel bearings:
- Remove the grease cap. This is usually set in by compression. A small standard (flat) screwdriver should work to pry it off.
- Remove your cotter pin. The best way is to bend the pin with pliers so the pin is straight and will slide out of the hole.
- Loosen your castle nut. Loose enough that you can get a little more play on the bearing. Why? Because we are going to re-seat the bearing, we want to ensure the bearings are not bound in their current position or off-center on the axle.
- Spin your wheel hub assembly. Since the castle nut is loose, it should spin freely.
- Tighten the Castle nut. As the wheel hub assembly is spinning, start to tighten the castle nut. Give it just enough tightness, so it slowly stops the spinning hub. Loosen the castle nut slightly, so the hub spins freely again. Then tighten the nut again, just like before. Finally, lightly loosen the nut again when the wheel can spin freely.
- Set Cotter Pin. Get a new cotter pin and set it in the hole without adjusting the castle nut position you did in step 5. I always like to set my cotter pin from the top and have the bent prongs on the bottom. It’s easier as the pin doesn’t keep trying to fall out as you bend the prongs.
You want to keep trailer wheel bearings play at a maximum of 1/16″. It’s ideal not to have any play, but having a little should not be an issue. Also, it’s important not to have your wheel bearings too tight. You should have enough play to spin the wheel freely a few times with a normal rotation.
Tony is an avid camper and RV traveler. He fell in love with camping on his first RV trip with his wife over 25 years ago. Tony loves sharing lessons learned and tips about RV maintenance and safe traveling.