Electric Brakes Not Working good

[KCTractors]

Working on a guys tractor hauler, tandem axle single wheel trailer. he had no brakes at all, so I removed the drums. One magnet was shorted out on one side and the brakes were seized up on the other side. Freed up the brakes and magnet arm and put everything together and one new magnet. I tried it on my truck and still very little brakes with the control turned all the way up.
I did noticed that when I hooked a 12 volt battery directly to the brake wire, I only had 7.8 volts back to the brakes, wouldn't I have 12 volts back by the axle? Any thing else to look for?
 

[toolz]

I"ll sit back and read the replies- I just went through the brakes on my 24K gooseneck, and only have about 8 volts at the magnets. Trailer is 4 years old, and all the wiring is in steel pipe. Haven"t started running down the wires yet. Might have to run new wires for power and ground.
 

[Jim in Ma.]

Rule #1. Check the Ground.
 

[Dodgeit]

[toolz]

Complete setups for my 12K axles are about $225 each, but I did it anyway, and cleaned any grounds I could find. Still 8 volts at the magnets. Will go after the wiring this weekend.
 

[mkirsch]

The wiring is no good. Probably corroded. Certainly not heavy enough.

Trailer companies tend to cheap out and put 14ga wire in for brakes. Sometimes they splurge on 12ga. Brakes really need 10ga wire.

Zip tie the brake wiring to the outside of the axles. Sleeve them in PVC or something but don't thread the wires inside the axles. What happens is the wires rub on the holes they pass through, and short out. They might rub on the PVC but even if they rub through PVC is non-conductive.
 

[LBSMJS]

The brakes all needed redone on my 34ft dual tandem trailer.Replace all 4 electric backing plates with hyd ones.Installed pump and lines.Now I have brakes like you need on a big trailer.No magnets or arms to freeze up.Have pulled it about 30000mi in 2yrs with out a problem.
 

[scotc]

Is there a breakaway kit on it? Could the battery be pulling some of the power somehow?
 

[FC Andy]

I've been going through a similiar problem on my 20' 14k Gooseneck. I had little braking action just like you're seeing. I was beating my head against the wall. I checked my connections, cleaned gounds, even replaced the Cable from the truck to the Junction box that my trailer has. I still could only get around 10.5 volts to the junction box, and I know all is well with the truck, as I can lock up my friend's brakes, just not the brakes on my own trailer. I opened up the brakes, thought the magnets may be bad, didn't find anything wrong with the magnets or the mechanism.

What helped my trailer the most was making 5 or 6 20 mile runs hauling machinery home from the Lenawee County Fair for myself and a freind. After that, I could lock the brakes up and drag them on the gravel in my driveway, at least. I've decided to leave them alone at that. When they don't at least function that well I'll probably be forced to spend the big bucks and start from scratch with wiring and brakes.

I should probably add that My trailer sits most of the time. I don't make many trips, mostly local stuff, with my own couple tractors. No regular long trips hauling tractors or hay, and I'm not commercial. My longest trip will probably be going up to the Mackinac Bridge with 2 tractors in a few weeks. About 300 miles. Honestly, I'm more concerned about melting down my old 6.5 than I am stopping the trailer.

My trailer is new to me this spring. It was pulled commercially by the previous two owners, and then sat for a year or two I believe before I bought it. Mine is about 10 years old. Mine just seemed to need to be used. I'm still learning, this is my first expirence with owning my own trailer with electric brakes. Hope my expirence this year helps you. -Andy
 

[rustyfarmall]

[cd1]

Are you testing the voltage with the magnets still hooked to the wires? If you are it would not surprise me that the voltage was lower. You are putting a load on the battery and are temporarily lowering the voltage (either from the wiring resistance or battery itself) Make sure your brake shoe adjusters are adjusted right.