Left or right side
Confirm which side needs replacement. The brake actuator and hardware are arranged differently for each side, so left- and right-hand assemblies are not interchangeable.
Electric trailer brakes
Trailer Brake Assemblies: Left & Right Brake Kits
Replace a worn or damaged electric trailer brake assembly with the correct side, size, and axle fit. Northline carries left- and right-hand assemblies for compatible trailers and can help confirm the details before you order.
Start with the brake itself
Get the right assembly behind the drum.
A trailer brake assembly is the working brake unit that mounts to the axle behind the drum. On an electric-brake trailer, it receives power through the trailer wiring and uses an actuator to press the brake shoes against the drum. When an assembly is worn, contaminated, corroded, or damaged, replacing the complete unit can be more practical than rebuilding individual pieces.
The important word is correct. Trailer brake assemblies are not one-size-fits-all, and a part that looks close in a product photo can still be wrong for the axle, brake drum, mounting flange, or side of the trailer. Starting with the old assembly and the trailer's actual brake dimensions gives you a much better chance of ordering the replacement that belongs there.
Northline's current selection includes matching left- and right-hand electric brake assemblies. Review the product details, then keep the trailer's axle and brake information nearby while you compare. If the markings are unclear, a clear photo of the old brake assembly and the axle tag can give the conversation a useful starting point.
Match before you order
Four details that separate a fit from a guess.
Brake size
Match the brake diameter and shoe width to the existing drum and backing plate. Use the old assembly, drum marking, or axle information instead of estimating by trailer length.
Axle and flange
Check the axle capacity and the mounting flange pattern on the axle. The replacement backing plate needs to align with the existing studs or bolt holes behind the drum.
Electric brake setup
Make sure the trailer uses electric brakes and inspect the magnet wires, connector, and brake controller setup. A new assembly still needs a sound electrical path to work properly.
When a complete assembly makes sense
Replace the brake unit when the old parts are no longer worth chasing.
Brake shoes, magnets, springs, adjusters, and backing plates all work together. When several pieces are worn or when corrosion, heat, grease, or road damage has affected the assembly, a complete replacement can simplify the repair. It gives you the major braking components already matched on the backing plate, rather than asking one new part to work around several tired ones.
Before removing anything, inspect both sides of the axle. Uneven shoe wear, damaged wiring, leaking grease seals, a scored drum, or a brake that has been dragging can point to a problem beyond the assembly itself. A new backing plate does not correct a damaged drum, loose bearing adjustment, contaminated hub, or a trailer-side wiring issue. Address the condition that caused the failure so the replacement is set up for a longer service life.
For a single failed assembly, identify the exact side first. For a trailer that has seen similar use and wear on both sides, inspect the matching assembly closely before deciding whether to replace one or both. Keeping the braking system balanced helps the trailer respond more predictably when the brake controller sends power to the axles.
Do not choose by trailer weight alone. Axle ratings, brake dimensions, and the flange behind the drum are the details that determine whether an assembly can mount and work correctly. The trailer may be a tandem axle model, but the axle capacity and brake hardware can still differ from one build to another. Compare the existing parts and manufacturer information before treating two trailers as the same.
When the trailer has been stored outside or used in wet conditions, take extra time to look for corrosion around the mounting studs, backing plate edge, wire connections, and brake drum. A replacement assembly needs a clean, secure mounting surface and protected wiring. Sorting out those conditions before installation helps avoid a new part being asked to work around an old connection problem.
Compare Trailer Brake Controllers ›Before the trailer returns to the road
Make the repair part of a complete brake check.
Inspect the drum
Check the brake drum for scoring, cracking, heat damage, or an internal surface that is no longer suitable for the brake shoes. The drum and assembly need to work as a matched braking surface.
Check bearing and seal condition
Grease on the brake shoes often points to a seal or hub service issue. Correct leaks and inspect the bearings before fitting a new brake assembly behind the same drum.
Protect the wiring
Route and secure the electric-brake wires away from moving parts and sharp edges. Check the connector, axle wiring, and grounds so the new assembly can receive dependable power.
Adjust and test safely
Follow the assembly and trailer manufacturer's instructions for adjustment and break-in. Test braking response in a safe, open area before loading the trailer or heading onto the road.
Trailer brakes work as one towing system with the brake controller, breakaway equipment, hub and drum, bearings, tires, coupler, safety chains, and trailer connector. A quick review of the whole setup before the first trip after a repair can prevent a small parts job from becoming a roadside problem.
Shop Trailer Brake Assemblies
View All Trailer Brakes ›Northline's current brake assembly selection includes matching left- and right-hand electric brake kits. Compare the product details with the trailer in front of you before adding an assembly to your cart.
Electric brake assembly
Dexter 7K Electric Trailer Brake Assembly, Left-Hand, 12" x 2"
Left-hand Dexter electric brake assembly for compatible 7,000 lb trailer axles. Measures 12" x 2" and includes brake assembly 023-180-00 with instruction sheet 059-726-00. Confirm axle capacity, brake size, and left or right side before ordering.
$111.96View Assembly ›
Electric brake assembly
DEXTER 7K Electric Trailer Brake Assembly, Right-Hand, 12" x 2"
Right-hand Dexter electric brake assembly for compatible 7,000 lb trailer axles. Measures 12" x 2" and includes brake assembly 023-181-00 with instruction sheet 059-726-00. Confirm axle capacity, brake size, and left or right side before ordering.
$111.96View Assembly ›Need help sorting the details?
Bring the old brake information. We will help narrow it down.
Call Northline with the trailer's axle information, brake size, the side that needs replaced, and a photo of the old assembly. Those details make it easier to confirm the correct left- or right-hand brake kit before an order is placed.
Frequently asked questions
Trailer brake assembly questions.
What is a trailer brake assembly?
A trailer brake assembly is the brake backing plate and the working brake components mounted to it. On an electric-brake trailer, it attaches to the axle flange behind the brake drum and uses the trailer's electrical system to apply braking force.
Do I need a left-hand or right-hand trailer brake assembly?
Yes. Brake assemblies are side-specific. Confirm which side of the trailer needs the replacement and compare the old backing plate, actuator arm, mounting pattern, and product details before ordering.
Should I replace both trailer brake assemblies at the same time?
That depends on the condition of the other side. If both brake assemblies have similar age, wear, contamination, or corrosion, replacing the pair can help keep braking response consistent. Inspect both sides before deciding.
How do I know the replacement brake assembly fits my trailer?
Start with the brake type, brake size, axle capacity, mounting flange pattern, wheel bolt pattern, and whether the assembly is left- or right-hand. A photo of the old assembly and its markings can help Northline confirm the next step.