Trailer brake question
July 10th, 2018, 08:34 AM
#1
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Trailer brake question
I’m not sure where to post this, feel free to move it wherever. I noticed on the way to Norwalk this past weekend the trailer brakes felt lousy. I crawled under the trailer and adjusted them, I did notice it took about 4 turns of the star wheel to get any drag. On a test drive the brakes felt better, but still not right. I had my son sit in the drivers seat of the truck and manually slide the actuation button over while I spun the wheels by hand, only one wheel has brakes. I don’t see any obvious electrical wiring issues, is there a resistance spec on the magnets? I swear, I have friends who NEVER check tires, bulbs, brakes, anything on their trailers. I try to maintain mine and have problems.
Last edited by matt69olds; July 14th, 2018 at 06:05 PM.
July 10th, 2018, 09:18 AM
#3
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I replaced a bunch of trailer brakes at a former job & like 442Harv said, you might want to pull the wheels/drums to see what is going on. I've seen the wires to the magnet get cut/pinched before causing them not to work.
July 10th, 2018, 09:54 AM
#4
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I can power a test light with the brake controller at the 7 pin connector on the truck, and I can feel the brakes come on, but poorly. I assume since the one brake works the controller is ok?
July 10th, 2018, 10:19 AM
#5
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One more thing, year ago, when I bought my first trailer, bought it from a guy who made it. He did a real nice job, and very detailed in what he did. On the wiring instead of just running the wires on the inside rails, he put all the wires in conduit , made nice bends, and good fittings. So I could not see the wires. I finally took some long wire, and had my brother help me, and checked for continuity, and saw I had a problem. I pulled the wires out of the one side, and the wires were all melted together, must of wore off the insulation, and had a dead short. I would check all the wires one by one.
July 14th, 2018, 06:16 PM
#7
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Greetings, have a update with new issues. I pulled all the drums, all the brake hardware was dry and pretty reluctant to move. I took everything apart, cleaned and lubricated all the pivot points and star wheel adjusters. I cleared and repacked the wheel bearings, while the drums were off I decided to check the magnets. I pulled the pin for the brake away switch, and one at a time st each wheel I placed a heavy screwdriver on each magnet. It stayed in place, when I replaced the brakesway pin the screwdriver fell. I reassembled everything confident it was fixed. You can imagine my disgust to find that I still have brakes on only one wheel. GREAT BIG STEAMING PILES OF HORSE EXCREMENT!!!! I’m ready for some other suggestions.
July 15th, 2018, 08:53 AM
#8
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ok lets assume the issue is not electrical but rather mechanical.
when the 'magnet' is energized, it wants to move outward to the drum and stick to it. the rotation of the drums drags the magnet backwards to the rear of the trailer, applying brakes. faster you are going, the more braking action.
so, what is preventing that from happening.
typically when I rebuild a trailer system, I just replace them - everything. for the cost of most shoes anymore, you can get the complete system for a few dollars more. clean the inside of the drums and any scale. on the actuating lever, remove them and wire brush them to clear metal. check for any binding, this magnet and lever have to move outward and back EASILY.
and to be fair, while you did something of an electrical test, you didnt check resistance of the magnet, or continuity of the wiring really. a 4 brake system draws less than 10-15 amps, which means 4 magnets in PARALLEL (important plot point!) only pull that many amps from 12ish volts
when the 'magnet' is energized, it wants to move outward to the drum and stick to it. the rotation of the drums drags the magnet backwards to the rear of the trailer, applying brakes. faster you are going, the more braking action.
so, what is preventing that from happening.
typically when I rebuild a trailer system, I just replace them - everything. for the cost of most shoes anymore, you can get the complete system for a few dollars more. clean the inside of the drums and any scale. on the actuating lever, remove them and wire brush them to clear metal. check for any binding, this magnet and lever have to move outward and back EASILY.
and to be fair, while you did something of an electrical test, you didnt check resistance of the magnet, or continuity of the wiring really. a 4 brake system draws less than 10-15 amps, which means 4 magnets in PARALLEL (important plot point!) only pull that many amps from 12ish volts
July 15th, 2018, 12:00 PM
#9
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Well, I can tell you I removed everything from the backing plates, used a wire brush to scrub off all the brake dust, crud, and other debris. I lubed the backing plates where the shoes ride, all the pivot points, and the place the magnet slides across the backing plate. I’m confident the mechanical part is as good as it can be. It occurred to me while riding the lawn tractor mowing my lawn (I do some of my most creative thinking on the mower!!) that the one brake that does work well is the one closest to the junction block. I’m wondering maybe the crimp connectors used further down the line are possibly corroded. Maybe there is enough correct to activate the magnet, but not enough to drag the magnet enough to actually apply the brakes. I’m going to run a voltage drop test, I will get this fixed!!
July 15th, 2018, 06:27 PM
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Success!!! I HATE butt connrctors or scotch-lock connectors!!! I had to run new wires for side to side, I kept cutting and stripping wire trying to find copper inside that wasn’t corroded, by the time I did the wire was too short. I ran 14 gauge ( bigger than the 18guage on it originally) used solder and marine grade heat shrink, hopefully I won’t have to mess with anything on this trailer for a long time.
Im guessing with all the corroded connections the magnets couldn’t get the current and voltage to really grab onto the drum.
Im guessing with all the corroded connections the magnets couldn’t get the current and voltage to really grab onto the drum.
July 16th, 2018, 05:43 AM
#12
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yep - you found continuity, but high resistance. you got just enuf current to 'hold a screwdriver' but not be a good brake.
another thing I do when I rebuild or rebrake trailers is to replace the wiring from battery box and pigtail to brake units with tinned copper in a gauge higher. tinned copped = the stuff you find at marine stores for boats. and I would rather solder connections with high silver solder and use shrink wrap. for a trailer that should NOT be dunked in water...it holds up quite well. but if you want smashable connectors, just get the ones that are shrink wrap ends and slide over all that a much longer piece of tubing and shrink that as well
another thing I do when I rebuild or rebrake trailers is to replace the wiring from battery box and pigtail to brake units with tinned copper in a gauge higher. tinned copped = the stuff you find at marine stores for boats. and I would rather solder connections with high silver solder and use shrink wrap. for a trailer that should NOT be dunked in water...it holds up quite well. but if you want smashable connectors, just get the ones that are shrink wrap ends and slide over all that a much longer piece of tubing and shrink that as well
July 16th, 2018, 12:58 PM
#13
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agreed when im installing something or wireing it i solder and heat shrink...the butt connectors invite corrosion and poor connections...if i find oxidised copper wires i just replace the whole thing as the corroded copper doesnt take solder...
July 16th, 2018, 03:26 PM
#14
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there isnt enough wite left on the magnets to make another repair, this is it. I was REALLY surprised at how small the wire that they used to power the brakes. It was 10 or 12 gauge to the wheels, but I’m guessing 18 gauge.
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