Trailer Brake Burnishing: How to Properly Break In New Electric Trailer Brakes
If you just had new electric brakes installed on your trailer and they don't seem to stop as strongly as you expected, that doesn't necessarily mean something is wrong.
New electric drum brakes need a break-in process called burnishing.
Burnishing helps the new brake shoes properly seat against the surface of the brake drums. This process is an important step after installing new electric trailer brakes, brake shoes, or drums and can make a noticeable difference in braking performance.
At Deer Valley Trailer in Phoenix, Arizona, we want trailer owners to understand not only how their braking system works, but also what to expect after brake repairs or replacement.
WHAT IS TRAILER BRAKE BURNISHING?
Burnishing is the controlled process of repeatedly applying new trailer brakes so the brake shoes and magnets begin wearing into their mating surfaces.
Electric drum brakes work through friction. When the brake controller sends power to the trailer, an electromagnet inside each brake assembly contacts the rotating drum. That movement activates the brake mechanism and forces the brake shoes outward against the inside of the drum.
Those surfaces aren't necessarily a perfect match when they're new.
The curved brake shoe lining needs to seat against the drum's braking surface. The brake magnet also needs to establish proper contact with its mating surface on the drum.
Burnishing begins this seating process.
Think of it as properly breaking in a new pair of trailer brakes rather than expecting maximum braking performance on the first stop.
WHY DO NEW TRAILER BRAKES NEED TO BE BURNISHED?
A new brake shoe may initially contact only a portion of the drum surface.
As the brakes are repeatedly applied, small amounts of friction material wear and conform to the drum. This increases the effective contact between the shoe and drum and helps the brake operate as intended.
This is why brand-new trailer brakes may initially feel weaker than the brakes that were removed.
Brake manufacturer Dexter specifically notes that after replacing brake shoes and magnets, decreased braking performance can occur until the new components have worn into the drum and completed the burnishing process.
The full break-in period can take many stops. Burnishing starts that process in a controlled manner.
HOW TO BURNISH ELECTRIC TRAILER BRAKES
Dexter provides a straightforward procedure for burnishing electric trailer drum brakes.
1. Find a safe location.Choose a safe, open road or area where repeated slowing will not interfere with traffic. Avoid performing the procedure in heavy traffic or anywhere repeated speed changes would create a hazard.
2. Accelerate to approximately 40 MPH.
3. Apply the trailer brakes and reduce speed to approximately 20 MPH.
The goal is approximately a 20 MPH reduction in speed during each brake application.
4. Release the brakes and allow them time to cool.
Do not immediately repeat hard brake applications one after another. Braking converts motion into heat, and excessive heat can damage braking components.
5. Repeat the process approximately 20–30 times.
The repeated applications help the brake shoes seat against the drums and begin establishing the proper friction surfaces.
IMPORTANT: ALLOW THE BRAKES TO COOL
Burnishing does not mean deliberately overheating your trailer brakes.
There should be adequate cooling time between brake applications.
Some heat during braking is completely normal. That's how brakes work: friction converts the trailer's movement into heat.
However, excessive heat is different.
If you notice smoke, a strong burning smell, abnormal brake behavior, or one wheel becoming significantly hotter than the others, stop the procedure and have the braking system inspected.
SHOULD I USE THE BRAKE CONTROLLER MANUAL OVERRIDE?
When performing a trailer brake burnishing procedure, the objective is to make the trailer brakes perform the controlled slowdown rather than relying primarily on the tow vehicle's brakes.
Your exact procedure can depend on the brake controller and braking system installed in your tow vehicle and trailer.
Always follow the brake controller manufacturer's operating instructions and the recommendations of the axle/brake manufacturer.
Never perform the procedure in a way that compromises control of the tow vehicle and trailer.
ARE MY BRAKES FULLY BROKEN IN AFTER 20–30 STOPS?
Not necessarily.
This is an important distinction.
The initial burnishing procedure helps establish the contact surfaces, but complete break-in can take considerably longer.
Dexter notes that after replacement of brake shoes and magnets, the process of bringing new brake shoes back to normal performance may take more than 100 stops, using approximately 20 MPH reductions in speed.
So don't assume something is wrong simply because brand-new brakes don't feel exactly like fully seated brakes after the first few stops.
Continue paying attention to how the trailer brakes perform as they break in.
BURNISHING DOES NOT FIX A BRAKE PROBLEM
Burnishing is a break-in procedure. It is not a repair procedure.
If your trailer has weak or inconsistent brakes, don't automatically assume they simply need more burnishing.
Poor electric trailer brake performance can also be caused by:
Improper brake adjustment
Incorrect brake controller settings
Low voltage at the brake assemblies
Poor electrical connections
Improper grounding
Worn or damaged magnets
Grease or oil contamination on the brake shoes
Worn, glazed, scored, or damaged drums
Incorrectly installed brake assemblies
Mechanical problems inside the brake
Wiring that is too small, damaged, or improperly connected
If the brakes continue to perform poorly after proper adjustment and burnishing, the braking system should be inspected.
BRAKE ADJUSTMENT AND BURNISHING ARE NOT THE SAME THING
This is another common misunderstanding.
Adjusting the brakes establishes the proper clearance between the brake shoes and drum.
Burnishing seats the friction surfaces together through controlled brake applications.
You need both to be correct.
A badly under-adjusted brake may have poor performance regardless of how many times you try to burnish it.
Likewise, correctly adjusted brand-new brakes can still require burnishing before they reach their expected braking performance.
Some electric trailer brakes are manually adjusted while others use self-adjusting mechanisms. Know which braking system is installed on your trailer and follow the manufacturer's service requirements.
WHY CAN BRAND-NEW BRAKES FEEL WEAKER THAN THE OLD ONES?
It seems backwards, but it's possible.
The old brake shoes have spent thousands of miles wearing themselves into the exact shape and surface of their drums. When properly adjusted and in serviceable condition, they may have a large established contact area.
Install brand-new shoes and that established relationship disappears.
The new shoes have to seat themselves against the drum.
As they burnish and break in, their contact with the drum improves and braking performance should improve with it.
That's one reason you shouldn't evaluate a new electric brake installation solely on how the trailer feels during the first few stops.
WHAT ABOUT NEW BRAKE DRUMS?
New drums and new brake assemblies still require a break-in period.
You now have two new friction surfaces establishing contact with one another rather than new shoes seating against an existing drum.
Follow the brake or axle manufacturer's recommended burnishing procedure for the components installed on your trailer.
WHAT IF MY TRAILER BRAKES LOCK UP?
More brake controller gain isn't always better.
Electric trailer brakes are designed to provide controlled braking in coordination with the tow vehicle.
If the trailer tires are locking, grabbing, or braking harshly, check the brake controller setup and brake adjustment rather than assuming maximum braking force is desirable.
The proper brake controller setting can also change with trailer weight and loading conditions.
WHEN SHOULD TRAILER BRAKES BE BURNISHED?
Burnishing may be appropriate after:
Installing new electric brake assemblies
Replacing brake shoes and linings
Replacing brake drums
Certain major brake repairs where new friction components have been installed
Follow the instructions provided by the manufacturer of your particular axle and braking system.
DON'T FORGET THE BRAKE CONTROLLER
Once the brakes have been properly adjusted and burnished, the trailer brake controller still needs to be set correctly.
The controller determines how much braking force the trailer receives.
Too little gain can make the trailer feel like it is pushing the tow vehicle.
Too much gain can cause aggressive braking or wheel lockup.
Trailer weight also matters. A controller setting that works well with an empty utility trailer may not be appropriate when that same trailer is carrying a heavy load.
Brake controller synchronization should therefore be checked under appropriate towing conditions.
THE BOTTOM LINE
New electric trailer brakes aren't necessarily at their best the moment they leave the shop.
The brake shoes and drums need an opportunity to seat together.
A proper burnishing procedure of approximately 20–30 controlled brake applications, reducing speed by about 20 MPH each time and allowing cooling between applications, helps begin that process.
And remember: burnishing is only one part of proper trailer braking.
Brake adjustment, brake controller setup, wiring, magnets, drums, shoes, bearings, and the mechanical condition of the brake assemblies all play a role in how well your trailer stops.
If your trailer's brakes remain weak, pull unevenly, lock unexpectedly, overheat, make unusual noises, or simply don't feel right, have the system inspected instead of assuming additional burnishing will solve the problem.
TRAILER BRAKE SERVICE IN PHOENIX, ARIZONA
Deer Valley Trailer provides trailer brake inspection, service, repair, parts, and replacement in Phoenix, Arizona.
Whether you have a utility trailer, landscape trailer, equipment hauler, car hauler, dump trailer, enclosed trailer, or other towable trailer, our service department can help diagnose braking problems and determine what your trailer needs.
Deer Valley Trailer22228 N 23rd AvePhoenix, AZ 85027623-780-1551
Trailer Sales • Trailer Parts • Trailer Service & Repair
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