What type of maintenance is required for RV brakes? This is not a tough question to answer, rather a lengthy one as there are several different types of RVs and therefore, several different brakes that need to be covered so it warrants a forum like this to be able to answer it properly.
Types of Brakes
Motorhomes will typically have hydraulic brakes used on the smaller units and air assist brakes for the larger diesel pushers.
A hydraulic brake system uses hydraulic or brake fluid pushed by a master cylinder when the brake pedal is applied that goes to the brake pads at the wheels and applies the pressure to either a brake drum in older units or the disc/rotor. This is a closed system, however, it can still absorb moisture through humidity and condensation that can contaminate the fluid. Brake fluid can withstand very high temperatures, however, if contaminated the moisture will boil at a much cooler temperature and vaporize causing poor brake performance. Therefore it’s important to not only check your brake fluid levels at every oil change interval or as recommended by your chassis manufacturer, but also change the brake fluid approximately every three to five years! Again, check with your chassis manufacturer for specific recommendations.
Brake pads, rotors, and drums on older units should be inspected periodically by a trained professional looking for the proper thickness of the pads, even wear pattern, and grooves or excessive wear on the metal components of the rotors and drums. You will notice a slight brown or rust colored “dust” forming on the rims which is normal as the pads are applied to the rotors or drums and wears off. Excess dust forming is a good sign to have the brakes inspected sooner than the chassis manufacturers recommended maintenance schedule. A “safe” thickness of the brake pad will vary with the type and weight of the rig as larger vehicles will require more pad than your car or truck. Most states have a DOT requirement of 3/16” from the center of the pad, however check with your chassis manufacturer and a certified technician for your safe thickness recommendation.
Air Assist Brakes
Larger motorhomes with air assist braking systems use air to apply the brake pads so there is no master cylinder and no fluid to check or replace. However, condensation and moisture can still form in the system and cause a weak braking condition. These systems have an air reservoir tank to store the compressed air and a filter to help collect moisture and oil. It is recommended to drain the reservoir tank regularly, typically every six months as water and oil will collect near the drain valves. Some have an automatic drain valve feature, check with your chassis manufacturer for specific draining instructions. The filter in the cartridge should also be checked periodically and changed every two-three years as a clogged filter can reduce airflow and weak braking. Pads and rotors should also be inspected periodically by a trained professional looking for safe pad thickness, even wear, and excessive wear on the rotors.
Fifth Wheel And Travel Trailers
Fifth wheel and travel trailers have electric brakes that are operated by a controller located inside the tow vehicle. This can be an add on system mounted under the dash or an Original Equipment Manufacturer (OEM) system designed into the dash of the tow vehicle.
With electric brakes, there is no brake fluid to check and flush, however, there are several areas that need maintenance and even adjustments.
As with any braking system, the pads and drums should be inspected periodically for wear and grooves. Verify the brake pads are wearing evenly and have the “safe” thickness to stop your rig. Most manufacturers recommend replacing the pads if they are less than 1/16” thick, however, for larger rigs, it’s a good idea to replace them a little sooner than that! Also, inspect for cracks/chunks of pad missing as well as any moisture that would prevent the pad from gripping the rotor. If you do need to replace pads, it’s a good idea to replace all at the same time so there is a consistent thickness all around.
When the brake pedal is applied on your tow vehicle, a signal is sent from the brake controller to a magnet on the bottom of the brake assembly which activates the brakes. This brake controller can be set from 0-10 depending on the amount or pressure required to slow the trailer down. It should not be set high enough to stop the truck when braking as this would cause a breaking loose condition when braking in adverse weather conditions. Most experienced service technicians will use a gravel portion of their lot to set up the brakes, starting with the controller at about 4-5 and moving at a slow speed to manually apply the brake controller. Adjust the pressure to the point the trailer skids on the loose gravel but does not pull the tow vehicle much. Your brake controller owner’s manual should also provide information on proper setup.
With the wheel off and the hub removed, inspect the pads as mentioned above and also check the electromagnet. Make sure it can move in and out of the cradle but is not loose or disconnected. There are also wear indicators on the magnet that will show when it is time to replace it. You can also check the magnet for proper amperage and resistance with a multi-meter. Consult your brake manufacturer’s service manual for specific information.
With the wear of the brake pads, you will need to occasionally adjust the brakes with the star adjuster which is accessible through the slot on the back side of the hub. This will provide the proper gap between the brake pad and the drum without needing to set the brake controller to a higher setting. It is also a good idea to use an infrared thermometer to check the temperature of the brakes and hub while driving. Once a day check the hub, brake drum, and tire to see what temperatures you have. If the outside ambient temperature is 70 degrees, it’s not uncommon to register temperatures up into the high 80’s or even 90 degrees F. However if the temperature spikes high, it’s a good indicator that the brakes are being overworked and need to be addressed.
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.
Jim G. ~ “The young lady who assisted us was very kind, she listened to our needs and passed along the specific RV information to the service provider. The service provider used was local to us and very good. The service was efficiently, safely and expertly given.”