How to Adjust Your Trailer Brakes | The Ultimate Guide

If you’re a frequent tower, you probably know that owning a trailer or camper is a lot more work than you anticipated. And if you’re new to the towing world, you’ve probably realized there’s a lot you don’t know—adjusting your brakes being one thing.

Adjusting your trailer brakes is a necessary task because it ensures that the brakes don't drag, drawing unnecessary power and wearing them down faster than you can say replacement.

How do I adjust my trailer brakes?

There are 3 basic steps for adjusting your trailer brakes, which I’ll describe in a step-by-step tutorial for you below. If you’re putting brand-new trailer brakes on your trailer, there’s an additional 4th step that you’ll need to do to “break-in” the brakes. The whole adjustment process is very easy to do on your own and can typically be accomplished in less than 30 minutes, depending on how many axles/brake assembles are on your trailer.

Below you’ll find a step-by-step tutorial on how to adjust them the right way. After I describe the steps, I'll dive into some more questions you may have about adjusting your brakes so that you can tackle it with confidence. After this, you’ll be a pro at adjusting your brakes! (Okay, maybe not a licensed professional, but you get the point.)

Secure and Jack Up Trailer
Remove Adjuster Plug and Locate Adjustment Screw
Spin Wheel and Start Adjusting
"Break-in" New Brakes

Skip to 12:25 to watch video demonstration of how to adjust your brakes.

Step 1: Secure and Jack Up Trailer

Chock your trailer wheels so the trailer doesn’t roll out of place. Jack up the trailer/camper high enough so the wheel you’re starting with can freely spin (it doesn’t matter which wheel you start with).

Chock wheels to secure trailer.

Jack up trailer so wheel can spin freely.

Step 2: Remove Adjuster Plug and Locate Adjustment Screw

Find the adjuster plugs on the backside of your brake assembly, located on the bottom. Remove the plug(s) with a screwdriver or pliers and look inside for the adjustment screw. If your brake has two plugs, the screw could be on either side, depending on what side of the trailer you’re on. You can identify the screw by looking for the small teeth that go all the way around it.

Remove adjuster plug(s).

Locate adjuster scew.

Step 3: Spin Wheel and Start Adjusting

Spin your trailer’s wheel or drum (you can do it with the wheel on or off), and while it’s spinning, place your screwdriver or adjustment spoon on one of the ridges. Start moving the tool up so that the adjuster's teeth are moving away from you. This will expand the shoes and create more drag.

Keep moving the adjuster until the wheel is difficult to turn. Then start turning the wheel in the opposite direction and back it off about 10 notches until you can feel only a slight drag/resistance. It's important to have a little resistance, but not too much otherwise your brakes will lock up.

Repeat this method on all remaining brake assemblies, making sure to adjust all in the same manner.

Use adjustment spoon to expand the brake shoes.

Step 4: "Break-in" New Brakes

If you’re installing new brakes on your trailer, this step is for you. The break-in process applies to both manual adjusting and self-adjusting electric brakes. It's necessary to do this step when you install new brakes because it allows the brake shoes and magnet to seat into the drum.

Drive the trailer out into an open area, like an empty parking lot. Get up to around 40 MPH and apply the manual override on your brake controller. Make sure the brake controller is set high enough where it will fully engage the trailer brakes (usually the middle setting will be just fine). Do not hit the brake pedal during this time, as you want to slow down your vehicle and trailer with only the trailer brakes. You’ll most likely have to do this about 20 to 30 times to properly seat the brakes.

When you feel like your brakes are properly seated, pull over and check for signs that you're done: a bit of smoke is normal and your brakes should be very hot (brakes should read 350-400 degrees with a temperature gun). If you don't see these signs, then keep repeating the process until your brakes are properly seated.

Adjusting Trailer Brakes: Common Questions

How do self-adjusting trailer brakes work?

While all brakes need to be adjusted, some require very little work from you – these are called self-adjusting brakes. When the brake shoes move more than a set amount to touch the drums, this implies that they need to be adjusted. The linkage arm is then activated and spins the star wheel. This process happens with each brake application until the brakes are properly tensioned.

There is an initial set-up process for self-adjusting trailer brakes to work their best. It is rather simple and consists of a few steps.

Pick an open stretch of road that will allow you to stop multiple times
Adjust the brake control power to MAX
Speed up to 40mph, then use the manual override on the brake to reduce speed to 20mph
Repeat 12-15 times, allowing time for your brakes to cool (remember the more times you do this the longer they might need to fully cool)

If you’re not sure if your brakes are self-adjusting or not, just look for the adjuster cable that stretches across the brake drum.

You can identify a self-adjusting brake by looking for the brake adjuster cable.

How often do I need to adjust my trailer brakes?

After the initial adjustment, we recommend adjusting newly installed brakes again after 200 miles. After that, you should adjust the brakes every 3,000 miles to ensure they are engaging properly.

How to adjust disc brakes

Easy answer, you don’t. All trailer disc brakes are self-adjusting. If your trailer has disc brakes, you probably just let out a sigh of relief.

About Olivia M.

My journey with etrailer started in Customer Service, where I went through months of product training to make sure that I had all of the knowledge I needed to help our neighbors find a solution to any situation. I helped them with technical questions, troubleshooting, product information, and anything else they needed. Since it has always been my passion to write and express myself through words, I made the transition over to the content side of the website so I could combine my product knowledge and passion for writing.

In order to make sure that I am giving you the most accurate, current information, I am constantly doing research and talking with people who are doing what I am writing about every day. I am constantly striving to find out what questions you are asking, and to give you an answer to every one of those questions, plus answers to questions you haven't even asked yet - yes, I'm that good. Plus, I am constantly getting hands-on training with our vendors and asking them all of the hard questions, that way you can have all of the information you need before making a decision.

Trailer Drum Brakes vs. Disc Brakes: Making the Decision

How to Bleed Surge Brakes

Testing Trailer Brake Magnets for Proper Function

Related Products

Shop Trailer Brakes

Shop Trailer Brake Replacement Parts

Shop Trailer Bearings, Seals, Caps

Written by: Olivia M.

Last updated on: 8/1/22

Jim

12/2/2021

Some brake controllers do not put out voltage unless the vehicle is moving above a certain speed. This can be worked around by using the manual activation bar.

Les D.

12/3/2021

@Jim, yes some built in factory controllers operate that way, but the majority work in typical fashion. However, as the article suggests, you need to manually adjust new trailer brakes, and then set them using what ever controller that you have. If you have one of the few affected vehicles, then you can just start with a higher speed when setting them.

Jim T.

6/28/2021

Hi. I have a 2009 Heartland Cyclone toy hauler with three axles. and tow it with a 2006 Volvo VNL630 tractor, and have recently noticed that the brakes are not working. The Volvo has an air/electric brake controller, which works. I have tested it with another trailer and a controller tester. On the trailer, I have measured the resistance between ground and the brake (blue) wire, and get 1.8 ohms. According to your chart, the resistance of a brake magnet should be between 3.0 and 3.8 ohms. Using 3.4 ohms, six of these in parallel should result in a resistance of about 0.567 ohm. 1.8 ohms would closely relate to only two brake magnets in parallel Applying trailer battery voltage (appx 13.4 volts) between ground and the brake wire, I measure about 10A +/-. Your chart shows that it should be between 22.6 and 24.5 amps, which would be more appropriate for a resistance of about 0.6 ohms. This too would almost relate to only two brake magnets in parallel (I=13.4 v/1.8 ohm = 7.45 A). Question is, is it possible to have four brake magnets go bad? Does my analysis make sense, or am I missing something? Thank you for your help.

Jon G.

6/28/2021

It could be possible to have a number of brake magnets go bad all at once, but for something like that I would think that a wire is damaged somewhere. I would check all of your wiring and all of your ground for your brakes. You might be able to tell which brakes are having issues by having someone manually apply the brakes for the trailer and then listening for a humming noise.

Jim T.

6/29/2021

Hi Jon. Thank you for your reply. After submitting the question, I measured the voltage from both sides of each magnet to trailer ground, but did not measure the voltage directly across each magnet. Found that the voltage on one side was 8.3v, and voltage on the other side was 1.3v. This was consistent across all six magnets, which indicated that the wiring was intact. Then, measured from the ground wire on the plug to trailer ground and found that there was about 0.8 ohm resistance between the two, which could account for the 1.3v. I am still trying to understand this. I did not disconnect each magnet, as there is not much wire left to reconnect. So then, I raised one wheel off the ground (the last one on the parallel connection), rotated it, and hit the brake (blue) wire with the battery voltage. It stopped immediately. Then, backed up the Volvo, connected the trailer to it, rotated the same wheel, and hit the brakes on the Volvo. Once again, it stopped immediately. At that point, I gave up!! We are taking it out this weekend, so will see..... I have not heard any humming noise, but the next time I am under it I will pay more attention. Thanks again.

Jon G.

6/29/2021

@JimT Usually when we measure the power like what you're talking about it's because we are testing the magnet. If the magnets are good then you should be able to troubleshoot your wiring without testing it with the meter like you're doing. Spinning the tire to check for a standard slight drag without the brakes applied is another good way of testing the brakes to see if they are adjusted properly.