Electric brakes troubleshooting

Discussion in 'Tires / Brakes / Bearings / Axles' started by Ourkid2000, Jun 11, 2019.

  1. Ourkid2000

    Ourkid2000 New Member

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    The brakes are 7" and I installed the brake controller myself. With the trailer connected and full gain on the brake controller it barely slows the vehicle down. If I come to a stop and leave the vehicle in gear then press the override to full, it wont hold it back. It just barely grabs. Is this the best I can expect from it or something? Seems awfully weak. TV is 2012 Hyundai Santa Fe.

    Quick rundown:
    - Installed Curt Venturer brake controller. Used 10ga wire, a 30A CB, and crimped all connections with good heat shrink splices and ring terminals.
    - Hooked up to trailer on jacks with the drums off and energized the electric brakes. The magnets held a big wrench and then fell off when I de-energized them.
    - Put the drums on, adjusted the shoes out until the drum was locked solid and backed off just a little bit so that there's just a bit of drag.
    - Go for a drive, barely any braking from the back. Tried pulling the safety braking pin on the trailer, still the same......barely any brakes.
    - Tested the brake controller output with my Fluke in between the tow vehicle and the trailer - pulls about 6amps at max gain. I can watch the amperage vary nicely while adjusting the gain. Starts around .5A and goes up to 6A at max.

    I dunno, I'm at a loss. Everything in the drum looks good and I cleaned the heck out of everything. I cannot understand what could be wrong.

    Brakes really aren't rusty, pretty clean actually. I did use the breakaway switch to apply full battery voltage to the brakes. No change, still weak. I put two brand new magnets in it yesterday.....no change. Same as before with the old magnets, still weak. I did the vehicle side wiring myself. It's all new wiring and I cleaned the ground connection to bare metal before attaching. Trailer side grounds have been cleaned to bare metal. I replaced all corroded looking ground ring terminals
     
  2. silvermickey2002

    silvermickey2002 Morris County, NJ

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    Did you check the voltage at the connection to the magnets?

    When I test the brakes in our driveway (long driveway) and manually apply the brakes from the brake controller it definitely tugs the SUV and slows it down.
     
  3. Ourkid2000

    Ourkid2000 New Member

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    Well the connections at the magnets are actually sealed, not sure how I can check that but I will look.
     
  4. tombiasi

    tombiasi Well-Known Member

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    Do you have the shoes adjusted properly?
     
  5. Ourkid2000

    Ourkid2000 New Member

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    I adjusted the shoes out until I could no longer move the drum. Then backed them off a touch so that there was drag but I could still turn it.
     
  6. silvermickey2002

    silvermickey2002 Morris County, NJ

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    Check the voltage at the splice
     
  7. McFlyfi

    McFlyfi Active Member

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    Brand new brakes have to be bedded in.
    Prior to being bedded in, they have virtually no stopping power. The braking power then gets gradually better as you use them.
     
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  8. Ourkid2000

    Ourkid2000 New Member

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    The brakes are not new. I adjusted them right up until they were locked up solid and backed them off just a bit. They couldn't be adjusted any tighter because it would be too tight.

    See video of the action:







    Anyone spot anything out of the ordinary?
     
  9. Sjm9911

    Sjm9911 Well-Known Member

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    Mine arnt that strong either, i had a shop re calabrate them. But my tv is also a full size pick up. Tbh, not sure how much they will stop a vehical, more like an added assist. I feel mine when i hit the break controller though.
     
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  10. mv520

    mv520 Member

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    I'm assuming the brake shoe friction surfaces are not glazed (i.e, it is clear you know what you are doing from your write up, so I suspect you've looked at that)

    As you now have new magnets, how about trying to de-glaze the armature surface (the flat inner surface of brake drum that the magnet contacts) with sandpaper, etc. Assuming these are Dexter brakes, the manual calls for refacing to a 120 micro inch finish. Off the top of my head (this is a guess) that sounds pretty rough, maybe about 60 grit? (Remember to protect the bearings from contamination with a rag, etc.)

    I personally wouldn't worry too much about checking voltage at the magnets themselves if it is not convenient as you know the current, 6 A total, which is a good # for a 7" Dexter brake. (Again I'm assuming/guessing this is Dexter, which for 7" is 2.5A/magnet, the magnets are 3.9 Ohms each). Maybe just measure the overall resistance at the 7 pin connector of the 2 magnets in parallel, 3.9/2 = about 2 Ohms +/-, etc. But with 6 A into that magnet resistance you know your wiring/connector resistance is negligible and not the problem.
     
  11. jckele

    jckele Member

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    I put 7" drums on my 89 Starcraft tent trailer. Towing with a 89 Chevy Vandura 2500. Could hardly feel the brakes when manually hit to try to stop both the van and trailer. But then the 7" brakes are designed to brake a 2200 lb load, not an added 6800 lbs!. After doing some brake tests with and without the trailer brakes connected, there was a definite difference in stopping distance. Not as much as I thought it would be but then my trailer was probably pushing the limits of its 2500 lb capacity. Still worth the investment imho.
     
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  12. xxxapache

    xxxapache Well-Known Member

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    I agree. You can't expect those little brakes to suddenly stop the trailer and TV alone.
     
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  13. Ourkid2000

    Ourkid2000 New Member

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    So an update. I got a good deal on a set of made in the USA Dexter replacement brake assemblies so I replaced them straight away and set them up the same as before. I didn't find that they were much stronger, maybe 20% which was very disappointing. I ended up finding the service manual for the axle in the paperwork that came with the camper and in it there was some valuable info. I mistakenly thought the manufacturer was Dexter but it's not. It's some other company, the name escapes me now. Anyway, the brake setup procedure specifically stated that you must do the shoe adjustment with the wheel ON. This adjustment made a significant difference as it requires the shoes to be adjusted way further out than when the wheel was removed.

    After I did this adjustment, my brakes are much much better and I'm assuming they will get even stronger after I bed them in.
     
  14. Spridle

    Spridle Active Member

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    I forget what size I put on my Coleman. It did not come with brakes to begin with, but had the mounting flange and wiring. I was disappointed with the braking, but it was still far better than nothing. Two years later, it's better now than when I installed it. Took a LONG time to bed in.

    A quick look at the controller, I suspect the Primus IQ is a better value overall. I do use the different braking curves depending on which trailer I'm towing and sometimes switch curves depending on highway or in town. I also fine tune the braking pretty regularly. The Curt looks to have less control.
     
    Last edited: Jun 16, 2019
  15. Anthony Hitchings

    Anthony Hitchings Active Member

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    Nope - that's a fallacy for drum brakes and disc brakes. They may improve slightly - but they work right out of the box. I have been doing my own brakes (drum and now disc) since about 1973.
     
  16. Anthony Hitchings

    Anthony Hitchings Active Member

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    Sounds like you have most everything as it needs to be. Based on the video - the actuating lever (with magnet on it) seems too sloppy before any brake shoes start moving. Check that out.
     
  17. Ourkid2000

    Ourkid2000 New Member

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    Well I did check that out......I replaced both assemblies. Those videos show the old brakes, full set of new ones on there now.
     

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