How To Determine If Your Trailer Has Free-Backing Brake Assemblies When Replacing a Surge Coupler

Updated 03/14/2018 | Published 03/12/2018

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Question:

How do i know if my trailer has free backing brakes? I need to replace surge brake coupler but need to know which one to buy. I bought a used boat and trailer but need to replace coupler.

asked by: Johnny N

Expert Reply:

To find out if you have free backing brakes, there are really only two ways I can think of to test. First, if your coupler works, you can push your surge coupler to move your trailer in reverse. If the brakes apply, then you know you do not have free backing brakes. If you can move it easily, then your brakes are free backing.

If your coupler is broken and thus the reason you are replacing then you will need to go to the second testing option. You will need to pull one of your hubs for a visual inspection. If the hydraulic cylinder on your brake assembly has one piston like # AKFBBRK-7, then it's a free backing assembly. If it instead has two pistons like # DMSB18794M-93M, then you do not have free backing brakes. I've attached a photo to assist.

If you have free backing brakes then you can use a surge coupler like the Demco Hydraulic Trailer Brake Actuator # DM72VR without a lockout. If you do not, then you will want either a manual lockout coupler or add an electric lockout to your coupler like # T4748800.

expert reply by: Jason S