The RV season is fast approaching and for many, it’s already here so it’s time to talk about brakes, bearings, and axle maintenance. Although there is not a lot of maintenance that is required, it is important to do periodic inspections to know what is happening to the brakes and inside the hubs and there are different procedures depending on your type of RV such as a trailer vs motorized.
Typically trailers will have electric brakes designed into the hub of the axle that is activated by a brake controller inside the tow vehicle as the brake pedal is applied. Most larger trucks will have a brake controller built into the dash and electrical system while smaller units will need one installed.
Trailer brakes should be visually checked at least once a year and spring is a good time. Most trailer brakes will have a magnet and brake pads that push against the drum.
First, inspect the brake pad to ensure there is enough material still available to stop the rig. Most axle manufacturers such as Dexter recommend replacing the shoes if they are less than 1/16th of an inch thick. At the same time, the drum surface should be inspected for scratches or grooves.
If there are slight grooves, the drums can be “turned” which is a process of grinding or cutting the metal smooth however, this can only be done to a certain thickness and needs to be done by a professional.
This whole process requires some DIY ability, tools, and a place to work on it and the average RVer will probably just take it into a service center. Check out the video at RV Repair Club to determine if you want to tackle this yourself here.
What you can do on a regular basis is check the braking resistance and manually apply the trailer brakes with the brake controller a few times a year. Start by driving with the trailer connected at a speed of 10 mph in a parking lot and apply the brake controller manually without pressing the tow vehicle brake. You should feel resistance and the higher you set the controller, the more resistance.
If you do not feel a resistance, you can check to see if there is electrical power getting to the magnet in the hub. This can be done with a multimeter or expensive break force meter but a simple test is to use a compass placed next to the hub, apply the brake of the tow vehicle as it is connected to the trailer, and watch for the compass to spin. If the magnet is energized, the compass will go wild. If not, there is no power going to the magnet.
Over the years there have been great changes in the bearings used in trailers as well as the way we lubricate them. Dexter has a great product called EZ Lube with a grease fitting on the outside that channels grease through the shaft to the inner bearing and pushes it through to the outer bearing. This applies new grease and pushes out any contaminated or overheated grease. However, they do still recommend repacking the bearing every 12 months or 12,000 miles.
The main thing to remember is, as the wheels turn going down the road, the bearings are exposed to extreme heat and friction and they must be lubricated no matter what type you have. Periodic inspection is a must and a good practice is to use an infrared temperature sensor to check the temperature occasionally to know what is happening behind the hub.
It is not uncommon to see 20-30 degrees higher temperatures than ambient however if there is a spike you know the bearings are starting to get dry and need to have them looked at before needing to have them replaced on the side of the road!
There is virtually no maintenance needed on a trailer axle however, there are a few important weight considerations and jacking procedures. Axles have specific weight ratings termed Gross Axle Weight Rating (GAWR) which is the maximum weight that should be on an individual axle. It’s important to have your rig weighed to ensure you are not exceeding the GAWR or Gross Vehicle Weight Rating (GVWR). Otherwise, the excess weight can make the axle bend and cause issues with tire wear and braking.
Most axle manufacturers do not recommend placing a jack on the axle or braces to fix or replace a tire as it could bend the axle. RV manufacturers have specified jack points on the frame for this purpose.
Most trucks today have sealed bearings that can not be lubricated or visually inspected, but rather need to be replaced when they start to grind. Typically this is at a very high mileage. Over the past 5 trucks, I have had, I only replaced one bearing assembly with approximately 140,000 miles. You do however need to check the brakes occasionally and there are quite a few opinions on how often. Some say every 6 months while others say at every oil change. I typically like to check the brakes when I rotate the tires at approximately 5,000 miles. It all depends on the amount of driving/towing and the weight or severity of braking.
Most tow vehicle brake systems have a wear indicator that will start to squeal as the pads get low. You can also see an accumulation of brown brake pad dust on the rim. Less than ¼” of pad is typically when they should be replaced and inspect the rotor for grooves.
Most truck manufacturers recommend changing the brake fluid every 3 years as condensation can build up in the system. This is not an easy procedure and I have been using this tool for several years to determine the moisture level and quality of brake fluid.
Motorized vehicles utilize a hydraulic fluid braking system that pushes the brake fluid through tubes to extend the brake pads to the rotors at the individual wheel positions. Larger units such as “Diesel Pushers” have air braking systems. It is important to inspect the pads for appropriate and safe thickness yearly.
Most chassis manufacturers recommend checking the braking system once a year and as you can see, not an easy DIY job! Also, most larger chassis manufacturers such as the Class A gas and diesel models do not recommend rotating tires unless there is extensive wear on one so annually is a better schedule.
These also have sealed bearings so there is no inspection or lubrication recommendation for them.
Check your chassis manufacturers recommended maintenance schedule for specific details regarding your brakes and bearings.
About the author: Dave Solberg: Managing Editor, RV Repair Club
For the last 25 years, Dave has conducted RV maintenance and safety seminars, developed dealer and owner training programs, written RV safety and handyman articles authored an RV handbook reference guide, and logged over 100,000 miles on the road in an RV.
RV Repair Club is your go-to online resource for enthusiasts who want quality RV maintenance, repair and upgrade information – a community where passionate RVers can come together to gather knowledge and share their experiences.
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