Rewiring Trailer Brakes - How to Allow for Axle Movement?

I would place the junction close to the axles, less wire to run and if one short section fails it is easy to repair or replace. Eventually the wires will fail due to flexing and abuse from road debris, salt etc, regular inspection is the key.

Make sure you use the appropriate shielded wire anchors spacing them frequently along the run. Use strap ties to hold groups of conductors together. Allow plenty of wire in the flex areas and secure each end using the appropriate connectors. Whenever the wire changes direction, place an anchor at the beginning and end of each radius. Do not bend the conductors sharply. When the conductors are subject to flying debris, heat, moisture, dirt protect them with an additional corrugated plastic shield. For examples of what to do and how to do it, just look under the hood of any trucks with factory wiring. You'll immediately notice the difference between that and when trunk monkeys have been at work. Do it like the factory to minimize future issues.

Chum lee

If spring ride, or torsion, follow the spring. The only place you need slack is the "hinge" area, and not a lot of movement there. Seal the water out...

A smooth curve will flex just fine. Allow just enough slack to be jacked up by the frame. I would keep the wire away from the tire in case of failure.

Being basically lazy I would make the axle loop about the same length as the old wires.

Jack trailer up by FRAME so wheels/suspension is fully extended
Wire up brake lines.....
Then lower back onto wheels

Check wiring for pitch spots/hung up spots

Why not run the wire through the axle like the factory? - half as many flex points.

Joe,

I had wires inside my axle's originally - and they don't provide mounting points inside the axle to stop the wiring from flopping around.

After a number of years, I got a short in my second axle and couldn't figure out why - Until I put a post up here. Someone else had the same issue and suggested I break the circuit and figure out which axle and which wheel.

Turns out the wire inside had chafed itself down to bare wire and was shorting out.

I rewired with zipties and check it annually for wear to ensure it doesn't happen again.

Just my two cents

Old-Biscuit wrote:
Jack trailer up by FRAME so wheels/suspension is fully extended
Wire up brake lines.....
Then lower back onto wheels

Check wiring for pitch spots/hung up spots

This is a given, do it with full extension. But if you run the shortest distance, from frame above the axle down to the brake, you have a chance of that wire catching anything as it is blowing in the wind. Follow the suspension, keep it tied tight except a little slack at the pivot points.

Here's what I did recently. I ran a #12 ga. brake cable along one side of the frame and tie-wrapped it to the propane pipe. I ran the new brake cable across each axle tube and secured it with tie-wraps every 6". The cable is on the trailing side of the axles and not likely to be hit by road debris.

I soldered all the splices, used shrink wrap and then electrical tape over that for more physical protection. The splices are well-secured to the U-bolts with tie-wraps. The brake wiring installed by the axle manufacturer is tiny #18 ga. (in our TT anyway) and the holes into the axle tubes are waaay too small to get a #12 ga. brake cable into. The alternative is to run new cable above the coroplast but that's a heck of a lot of work for little gain, plus the wiring will be a bit longer.

I bright the brake cable up from the backing plates and forward about 1.5' to 2' forward and tie-wrapped it to the propane pipe. This allows for a lot more vertical movement than will ever occur under normal road travel or jacking the frame up to re & re a wheel.

I have to say the improvement in braking with the new #12 wiring is absolutely amazing. The original splices by the TT manufacturer were really sh!tty - not only added to a poor connection but there was the possibility of the splices pulling apart. See the photo below for one example. The crimp connectors are designed/approved for one wire only in each end and note how only a few strands were pushed into one end. ALL of the other splices were equally bad.