Trailer brake problem

glennster

Well-known Member
Put new brakes on enclosed trailer, 18 ft. Dexter axles, 4 drum brake system. Replaces the brake asemblies, including backing plates and magnets. Hve a tekonsha controller in my truck that works fine with my dump trailer. Trailer brakes will activate, but very weak stopping power, even with the manual slidr in the truck. Shoes are adjusted up to where they are barely dragging on the drums. All wiring seems fine, getting voltage to all wheels. Assemblies were marked for left and right side axles, and put on accordingly. At a loss on to what is going on. Any suggestions?? I did try setting the controller to maximum braking, still weak, will not lock the wheels.
 
I agree, check the ground again, as well as all your other connections. If a wire broke down and only one or 2 strands are still together, you would get voltage, but not enough current to make brakes work correctly. Also if you use the trailer in the winter, you might have corrosion from the snow melting chemicals.
 
We're the drums rusty on the inside? Of the old brakes hadn't worked for a while they may have rust that needs to be removed. Whenever I do a brake job after I'm done I always pull the trailer with the brakes on til they get warm to get any rust or oil off. Otherwise make sure you actually got them on right and left. The wires will come out of the backing plate behind the axle when installed correctly. If all that is good and they really are set up tight enough, then the only thing left is electrical. Are they grounded to the frame? If so run a ground from the plug to the wheels to start.
 
Royse and I have fooled with the brakes on my livestock trailer until we just don't even know what to do anymore. We've tried two different pickups and they still act just like yours do. If you ever find the answer,let me know.
 

I always buy a 12 gauge extension cord, and cut it up for trailer brake circuits. One side for the hot, one side for the ground and run both plug to brakes. I solder and heat shrink all connections.

that being said.. most smaller trailers, I can lock the brakes up, if unloaded and set to max braking. However I have a trailer with dexter 10k gd axles that are the worse brakes I have ever used. I have rebuilt them several times and finally had to accept the fact that this model was known for it poor braking. Checking on the internet on this model show the same result for everyone. However an 18 foot should have 7k axles and usually they are known to be very good. You need to figure just a bit less than 3 amps per brake and must have good wire and connections all the way. 16 gauge wire will not work well for this application. And the ground or return side must be wired on both the pickup and the trailer plug to carry both the brake current and also the light current return to the truck. Brakes must have a return wire all the way back to the truck and even better, all the way back to the battery. Coorosion is common on trailer and truck wiring due to taped up connections and the use of very very poor vampire piercing clamps that are known to corrode almost immediately.. Cut all of these connections out, run heavy braking wires and again, solder all connections and heat shrink and then tape. No small wire allowed for brakes.
 
Did you fit the new shoes to the drum? If not they maybe only touching on the middle and not using the full pad.
 
Electric trailer brakes are notorious for not working as they should.
99% of the time the problem is corroded wire(black copper strands) very poor connections especially with the automotive crimp on crappy terminals( i use solder on terminals and connectors and shrink tube) and bad grounds ( I use stainless steel bolts to ground the frame) Trailer plug and plugin can also be the cause more often than not as they are often poor weather proof even when new.
 
The 2 most common problems I have found when trying to make trailer brakes work are.
#1 poor grounds so I run a wire to make sure the ground is good all the way to the brake magnet instead of using the trailer frame.
#2 The wires on most trailers are 14 or 16 gauge which is way to light for the brakes I use a #12 wire and if it has 4 brakes I use #10 so that way you have no or very small line loss
 
Another posibility is that the drums are too worn out. If this is the second replacement or more it's posible the droms aremworn too far for the brakes to work right.
 
The wires exit to the rear, so they are correct. I will re check all thr grounds, and i have another truck i can plug the trailer in to just toneliminate
the tow vehicle. The main brake harness is 12 ga wires, and seems intact. I can access the main junction block under the trailer, maybe i will
run a second ground and see what happens.
 
glennster I take the drums to my brothers machine shop and he puts the drum in a lathe and turns out the armature surface. Then to brake shop to turn brake surface. This is from Dexter axle. Lynn

The machined inner surface of the brake drum that contacts the
brake magnet is called the armature surface. If the armature
surface is scored or worn unevenly, it should be refaced to a 120
micro inch finish by removing not more than .030" of material. To
ensure proper contact between the armature face and the magnet
face, the magnets should be replaced whenever the armature
surface is refaced and the armature surface should be refaced
whenever the magnets are replaced
 

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