January 23, 2017 By 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 SystemAfter 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.  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.
Break-In Period for BrakesWhen 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 StoreIf 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.
BLEEDING THE BRAKES You have now completed the hardware installation and are ready to bleed the brakes. First fill the brake coupler master cylinder reservoir with DOT type 3 brake fluid (not provided with kit). Next go to the brake cluster wheel cylinder farthest from the master cylinder in the tubing sequence. Open the barbed bleed valve on that wheel cylinder one turn, with a 3/8" open end wrench. Obtain a piece of 5/16" plastic hose about two feet long, push the piece of hose onto the bleed valve barb. Now you will need a clear container (BRAKE FLUID IS TOXIC. DISPOSE OF PROPERLY.) to use as your fluid receiving container. Set the fluid receiving container on top of the trailer fender or at some point above the wheel cylinder. Now route the plastic hose from the bleed valve barb to the fluid receiving container. NOTE: The fluid receiving container must be above the wheel cylinder so that any bubbles trapped in the bleed hose will flow up away from the wheel cylinder, not back towards it, which would be the case if the fluid receiving container were lower than the wheel cylinder. Going back to the brake coupler, insert a large screw driver into the 1/2" dia hole in the coupler under the nut on the pushrod which extends out the front of the brake coupler housing. With your screw driver in place in this hole, you can use a back and forth motion to apply levered pressure directly to the master cylinder pushrod, by passing the coupler and shock damper mechanism. Remove the cap on the master cylinder reservoir and using small 1/2" forward and backward strokes on the screw driver, you will begin purging air from the piston portion of the master cylinder assembly. Bubbles will rise from a small hole in the bottom of the reservoir. As you continue with the 1/2" back and forth motion, bubbles will continue to rise until the piston portion of the cylinder is full of brake fluid. Only when you have No more bubbles rising in the master cylinder reservoir should you begin long strokes on the screw driver to pump fluid toward the wheel cylinders. NOTE: Once you have the piston portion of the master cylinder full of brake fluid and no more bubbles are rising in the reservoir, USE CAUTION. Do not look directly down into the reservoir while pumping the push rod. The brake fluid will squirt up with considerable force during the first part of each pump stroke. Don't let it hit you in the face. Set the filler cap on top to control this squirt. Now as you pump brake fluid into the system, you will begin to see it arrive at the fluid receiving container. (CAUTION - Never let the reservoir fall below 1/2 full during the bleeding process) If the fluid gets too low and sucks air down into the piston of the master cylinder, you must start over and the new air just sucked in and all brake fluid already in the system will need to be purged out. As you pump fluid thru the system, the bubbles you have been seeing in the fluid receiving container will cease. This indicates that you have completely filled the system with brake fluid. Now, with the bleed hose still on the bleed valve barb, close and tighten the bleed valve. Remove the hose and go to the wheel cylinder on the other side of the trailer and repeat the process. After completion of the bleeding process, refill the master cylinder reservoir and reinstall the reservoir fill cap and tighten. Next, apply pressure to the push rod and hold hard pressure on the screw driver for five or ten seconds. This will develop maximum hydraulic pressure on the system, and make it easy for you to see fluid if you have any leaks. After totally checking the system for leaks, you are now ready to adjust the brakes.
Registered Join Date: Jan 2001 Location: Holland MI Posts: 3,140 Likes: 0 Received 0 Likes on 0 Posts
Easiest way to do it yourself is to bleed from the bottom up. Get a CLEAN oil squirt can filled with brake fluid (with another quart to complete the job) and a piece of small neoprene hose, small enough to fit over the bleeder on the wheel cylinders and the oil can nozzle. With the cap removed from the master cylinder, crack open a bleeder fitting on the wheel farthest away from the master cylinder after slipping the hose on the bleeder and the oil can and start pumping the lever on the oil can. I usually empty about half of the contents of the master cylinder out so that I can watch for overflow as I fill the system from the bottom. Repeat the process on all brake-equipped wheels. Just make sure you don't completely empty the oil can before refilling it. Believe me, this system works. Page 2
Registered Thread Starter Join Date: Oct 2000 Location: Greenwich CT. U S of A Posts: 1,845 Likes: 0 Received 0 Likes on 0 Posts
Crazy, good idea! I have been thinking in the opposite direction. I have a plastic 2 gal garden sprayer which I could put the fluid in & then pump it up. The hand vac. pump isn't working too well. I like your idea! Thanks
Charter Member #232 Join Date: Oct 2000 Location: Carlisle, MA USA Posts: 18,414 Received 6 Likes on 4 Posts
I am with Nort but since it is you DJD how about you get some help from your pickle park friends!!!!! Jon __________________
Registered Join Date: Jan 2001 Location: Holland MI Posts: 3,140 Likes: 0 Received 0 Likes on 0 Posts
BRAKES!!!!???? WE DON' NEED NO STINKING BRAKES!!!!! Damn the torpedoes! Full speed ahead!!! Hammer down! LOOK OUT FOR THAT ICEBERG!!!
Registered Join Date: Apr 2001 Location: beaumont tx Posts: 1,703 Likes: 0 Received 0 Likes on 0 Posts
Well like Crazyhorse said,Reverse bleeding works every time and on hard to bleed brakes, slave cyl.ect., and other operations, if all else fails the reverse bleeding will get it done, but any of the above will work most of the time
Charter Member#157 Join Date: Oct 2000 Location: Minneapolis, Mn, Usa Posts: 1,859 Likes: 0 Received 2 Likes on 2 Posts
year before last at the start of the season my resivior was empty Lines were empty. not sure how but they were. I took the boat and trailer up to my local Firestone shop and asked if they could power bleed them. 2 axles, all 4 corners they took about 45 minutes and I was on my way for 60 bucks best money spent over the time it would have taken me by myself Call around, you just never know. I would not have thunk they could do it. But it has been great since __________________
Registered Join Date: Jan 2001 Location: Holland MI Posts: 3,140 Likes: 0 Received 0 Likes on 0 Posts
Yup. MnFastBoat's got it. Easiest way is to take it to your local brake shop and pay them to pressure-bleed it. Have a cup-o-coffee in the waiting room and pay on the way out. Screw this hands-on bullspit.
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