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How to Bleed your Trailer Brake System

You ordered a complete brake backer for your trailer and installed it. But now what? How do you bleed the brake system on the trailer? Good question. Felling Trailer is here to help you learn how to bleed your trailer brake system. Here’s what you need to do next.

Bleed your Trailer Brake System

After replacing the backer and tightening the brake line to the wheel cylinder, follow these steps to bleed your trailer brake system.  

Remove the master cylinder cap and fill the reservoir to three-quarters full with brake fluid.

Note: To manually bleed the system, you will need two people to make the job easier.Bleed your Trailer Brake System

With a Demco or Dexter brake actuator, pulling the breakaway cable lever will actuate your brakes. While one person is slowly pulling the breakaway lever, the other should loosen the bleeder screw on the back of the wheel cylinder, then tighten the bleeder screw back before pulling the breakaway lever back to its normal position (You will need to repeat this procedure several times until you have fluid coming out of the bleeder screw with no air bubbles visible in the fluid). After you have a steady flow of fluid coming out of the bleeder, as the breakaway lever is pulled forward, you can then switch to the next wheel and repeat this method until all brakes have been bled.
 As you move around the trailer, you should continue to check the fluid level in the reservoir as the fluid level will drop as you pump fluid back to the brakes.

Note: Brake fluid will damage any painted surface. If you happen to get some fluid on your trailer’s painted areas, be sure to wipe the fluid off immediately.

  • If your brakes feel spongy and faint or are not working properly, there may still be air in the brake system and the system will have to be re-bleed.

Break-In Period for Brakes

When brakes are new, there is a break-in period to burnish the brakes in. This will usually take 15 to 20 stops (while pulling the trailer) to have the shoes fully wear into the drum. It’s a good idea to adjust the brakes after they are burnished.          

Trailer Parts Store

If you are in need of a complete brake backer or other trailer parts, please visit Felling Trailer’s Parts Store Online. If you have questions on how to bleed your trailer brake system or another topic that Felling Trailers can assist you with, please contact us at 800-335-5464 or fill out this simple form.


  1. Alllen Pearson says

    Having trouble bleeding brakes on Felling F10 drop axle tandem trailer. Put on new master cylinder, lines and all wheel cylinders. Noticed the fitting on master cylinder has a extremely small hole in center where it connects to brake line. Not sure I can get enough fluid passed through to fill everything. I assume this is right fitting and meant to be small to help control speed of actuation of brakes. Do I need to find a fitting without the orfice just for bleeding purposes?

    • Good Morning Allen,
      The orifice in the fitting is the correct part, this does control the speed of the brake application. As far as bleeding get brakes, this fitting shouldn’t be removed when bleeding the brakes.

      Hope this helps,
      Felling Trailers

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