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Trailer Brake Love

Discussion in 'Trailers' started by CobraDave, Jun 30, 2019.

  1. CobraDave

    CobraDave Well-Known Member

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    Here is a short write up on my trailer brakes and how brake calipers are rebuilt. I thought on one of my wheels the brakes were dragging so I took it apart and realized the pad contact was normal. Then I got curious of how calipers are assembled and did a quick rebuild for my own knowledge. The parts are really cheap and if you have the time, don’t let a trailer shop tell you you need a new caliper. 9 times out of ten you just have to clean it up and replace a seal if it’s stuck. Disclaimer, I hardly consider myself a mechanic and am sure there is a better way to do things.

    First, I’m dealing with a two year old Extreme Trailer with disc brakes on the front axle. The calipers are UFP dB-35 made
    by Dexter. Take the wheel off and use a jack stand and wheel chocks. This is what it looks like.
    View attachment 769809 View attachment 769811
    Next, there are two bolts holding the caliper on. They have red loctite so prepare for a fight. It takes a 14mm socket. IMG_7236.jpg
    Once off I removed the brake line at the hydraulic fitting using a 5/8. Be prepared for some fluid to come out but it’s minimal.
    IMG_7238.jpg
    From there the caliper is off and taken to the bench. I noticed some rust on the rotor and lugs. I’ll clean that up later. Remove the brake pads and anti rattle clip. IMG_7240.jpg IMG_7241.jpg IMG_7242.jpg
    Pads looked new but very dry.
    IMG_7243.jpg
    From here you can separate the two caliper pieces by sliding them out. The guide pins were a little stuck which could effect braking for sure. Also there was some slight rust on the piston. I sprayed a little brake cleaner which freed them up.
    IMG_7244.jpg IMG_7245.jpg
    Then you can remove the guide pin caps and the rubber guide pin sleeves. They just pull out. Remember how they go back.
    Now it’s time to get the piston out. They’re two seals in the caliper. One is the dust seal which you see on top. Another is the inner seal. The top dust seal pulls right off. Remember the hole where you removed
    The brake line? Use some compressed air to blow in the hole which will force the piston out. You don’t need much so be careful. I’ve seen videos online of using a bike pump. The piston could fly out so use something to take the impact. I used my kid’s sandal. Lol
    IMG_7247.jpg IMG_7248.jpg IMG_7249.jpg IMG_7250.jpg
    Now inside is a squared seal which I removed gently with a small screwdriver.
    IMG_7251.jpg

    So you’re about done with disassembly. You can take the guide pins off but they are one there pretty good and mine were pretty clean. They take an Allen wrench. Might be best to remove them while it’s still on the trailer.
    IMG_7253.jpg
    Also you can replace the metal slides that the pads glide on. I’m just going to clean
    them up. All metal goes into some gasoline for a bit then I’m going to wire brush them.
    IMG_7252.jpg

    To be continued.




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  2. CobraDave

    CobraDave Well-Known Member

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    For some reason the first couple photos did t work. Here they are. Just overalls of the caliper.
    IMG_7234.jpg IMG_7235.jpg


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  3. Shrub Lurker

    Shrub Lurker Well-Known Member

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    UFP parts have gotten so expensive over the past couple years and keep going up. Great money saving how to. Keep it up
     
  4. CobraDave

    CobraDave Well-Known Member

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    Ok. I took my kids Easter basket and filled it with gas. Lol. Let the metal parts soak a couple hours then took a wire brush and sandpaper to them. I bought new seals, guide pin sleeves, anti rattle clips, and dust caps from Eastern Trailer. Cost $30. You can buy a set with pads for about $40. Not bad. The piston is stainless so you should be able to rehab it if it’s bad. Or just buy a new one.
    IMG_7254.jpg
    I inserted the inner seal making sure to lubricate it with brake fluid. Now the tricky part. Getting the piston and seal back in. Grease the dust seal with caliper lube. Here is how you do it. It’s hard to explain but put the seal over the top the way it normally goes. Then slide it down while it turns inside out and have it go past the end.
    IMG_7257.jpg
    Now put it in and make sure the inner portion of the seal is inside the bore. You should be able to compress the piston in by hand now. IMG_7258.jpg
    There are you tube videos explaining this.
    Using caliper lube, lube up the guide pin sleeves and insert them. Install the dust caps. Now lubricate the pins, the pad guides, the ears of the pads, and anywhere metal is being rubbed together. Insert the pads and install the anti rattle clip. I also put the pad lube on the end of the piston. Heard the tip and it made sense.
    IMG_7259.jpg IMG_7260.jpg
    IMG_7261.jpg
    Installed the caliper using blue 243 loctite instead of the red for future work.

    Now is a good time to change the brake fluid since the brake line is off. I knew nothing of trailer brakes so this was all new to me. The brake actuator is up front and there is a cap. Remove the cap and there is another cap. Remove that one and that’s where the Dot 3 fluid goes. IMG_7265.jpg IMG_7266.jpg IMG_7267.jpg
    Put a drip pan underneath the brake line. There is a hole on the bottom of the actuator that you stick a flat head in and pry it forward. This activated the brakes and pushes fluid to the lines. It locks once it gets far enough then you hit the release. IMG_7269.jpg IMG_7270.jpg

    Carefully not to let the master cylinder get too low, but you can pump the old fluid out and watch it drip into the pan. Pump using the screwdriver a few times. Tighten up the brake line.

    Repeat the pumping making sure no air is in the master cylinder. If no
    Air bubbles are present. Close it up. Now to bleed, farthest brake from the cylinder is the driver side. (Port) The brake line runs up the passenger side then crosses over to the driver side. I was not certain if I was correct but it makes sense to me. I used a mitivac kit from Harbor Freight. Pumped it up to 15 psi then broke the bleeder screw using an 11mm open end. IMG_7273.jpg
    Then I repeated in the passenger side. Top off the brake fluid and lastly, I put some copper anti seize on lugs and some on the hub. There is some reasons why they say not to put anti seize on lugs because of false torque readings. I figure better than rust taking over and them snapping off. IMG_7264.jpg IMG_7263.jpg
    That’s about it. Put the wheel back on. I’ll probably rotate them later and call it good.

    Long winded but if you have the time and want to save some money, this shit is not hard. I spent a grand on my previous trailer from brake issues I now know I could have done for a lot less.




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  5. Backlash

    Backlash Well-Known Member

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    These are the informative type of write ups people should be doing more often. Thank you for taking the time to post this info! ;)
     
  6. MagicMan

    MagicMan Well-Known Member

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    Great write up..
     
  7. CobraDave

    CobraDave Well-Known Member

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    Thanks guys. I thought it would be useful.


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