Brake Wiring

[Myrjer]

I just bought a 1977 31' Excella. The manual says it has vacuum brakes but evidently it was ordered with electric brakes or was converted at one time. The previous owner is little help on any questions I have so I'm strikeing out on my own here with help from this forum. When I looked underneath I discovered the wires comeing out of the wheels have been cut and have wire nuts on them. ???? Why that is I have no idea but obviously I want to wire the brakes properly. The schematic drawing in the manual doesn't help much since it is for the vacuum type brakes. Does anyone know where to run the brake wiring on this model? Maybe when I get the couch out of the way and get a good look at the fuse terminal the answer will be obvious but I thought I better ask while I was here reading the posts.

[71tradewind]

Here is some info from dexter axle http://www.dexteraxle.com/pdf_files/...c%20Brakes.pdf , most of the electric brake systems are pretty generic . I just completely replaced all of my brakes backing plates and all. When you purchase the comlplete backing plate all you need to do is bolt them on adjust them and connect the wires.My wires were also wirenutted , I have seen SOB use only those 3M scotchlocks which only cut the wire insulation and some of the wire usually.Hard to believe that manufactures would rely on sush a bad connection for an important system like brakes. The wirenut approach is better but still pretty not what I would call a good connection. The best way is to cut heat shrink tubing slide it over the wire, twist the wires ,solder them , slide the heat shrink over the solder joint , shrink it , and put some tape over it to be on the safe side.If you want added saftey put some convoluted tubing over the exposed wires to keep them from chaffing. Oh.... and make sure to leave enough wire for the axles to move , but not so much that they can touch or rb on the tire or wheel. I hope this helps.

[Myrjer]

Thanks tradewind. Good info on Dexter website. However, my real dilemma is the two conductor wire is cut right at the wheel. I'm trying to figure how to and where to run new wiring from the wheels to the 7way connector. In other words, I have no trailer brakes. I assume one wire goes to ground and the other to the brake line from controller.
I have tried to trace the brake wire from the 7way trailer connector but it dissappears into the trailer wall. Again, I assume it connected to the wire that is cut at the wheels at one time. So, I need to run new wiring from wheels to somewhere. Just needing to know where to exactly.

[nickcrowhurst]

We don't know why these wires were disconnected, but I would guess there was a problem with the brakes, the owner

couldn't fix them, so they were disconnected, rather than deal with the matter properly. The fault could have been

with one of the wheels, or one of the circuits could have been defective. I had a similar problem with a broken

concealed brake wire on my Excella. I would do the following:

1. Look under the wheel arches with the wheels off, one at a time, and attempt to find the cut ends of the wires

sticking out of the wheel wells. I am a long way from my trailer, so I don't recall exactly where the wires emerge,

but the wires are close to the frame rails. If you can find all 8 wire ends, you can check with a digital voltmeter

for voltage at the 4 live wires with the tow vehicle connected, then reconnect the wires to the backplate wires.It

doesn't matter which wire is which on the brake plate.

2. If the wire ends cannot be located, I would run new wires from the wheels to the fuse panel behind the sofa. I

would use hard plastic tube as conduits. (plumbing type if there is no suitable electrical conduit in the USA- I'm

from England). The pipe can be attached to the underbelly, probably along the line of the frame, using the usual

plumbing clips. You would want a location where the conduit is least likely to be damaged when passing over rocks or

limbs in the roadway. I would also make sure that the same length of wire runs to each wheel, so the voltage drop is

identical. You may need to coil up some surplus wire to do this. Feeding the wires up from the underneath to reach

the fuse box is a game. I played this passing wires alongside the big bunch of wires forming the cable to the 7 way

connector. You may prefer to do it by drilling a hole , and lining this with a grommet. I then removed the entire

sofa (groan), and used a long stiff wire with a bent hook end, to draw one wire at a time through the floor from

inside. I did it in two stages. One stage from below the trailer to above the internal particle board floor (large

hole to be drilled in the floor), and the second from there, up behind the internal lining, to the fuse box. I also

drilled out a load of 1/8 inch rivetsto peel back the panels here. (more groans!). You then need to ensure you have

the breakaway switch circuit joined to the barke wire live connection at the fuse box, as in the Dexter drawings.

3. If time is no object, you could avoid the exposed wiring by removing the lower decorative strip with the blue

insert, drop the sections of curved underbelly at the bottom edge, and feed the wires, in protective tubing, through

this area. This seems a lot of work, but it turns out to be no big deal, and you could de-rust the outside of the

frame while you're at it.

Let's hope you find the ends of the wires! Good luck. Nick.

[Myrjer]

Thanks Nick. Turns out, all magnets were burnt. I am replacing entire brake assy. on all wheels.

QUESTION: Do I need to run two wires for each wheel to the fuse panel or can I tie all eight, 4 and 4, together near the axle and run two wires the rest of the way? Also , do I just tie into the wire from the brake controller and other wire (wires) to ground on fuse panel? The wire from the brake connector dissappears toward the underbelly so I assume I can just cut it at the connector behind the sofa and splice into it. I hope my question makes sense.

[nickcrowhurst]

Myrjer, I assume you cannot find the ends of the wires which disappear into the underbelly. You have my sympathy. I recommend you buy the complete back plate, brake shoe and magnet assemblies. They are cheaper than buying separate parts, and you will have no incompatibility problems.
1. Yes, you can tie the wires in bundles by running one live wire and one ground wire from the fuse panel back to the axle, and splitting 4 ways from each wire, one live and one ground to each wheel magnet. You need to make sure that the single wires are heavy enough to carry the amperage (about 13 amps, if my memory serves). If in doubt, use wire with twice the copper diameter (4 times the cross-section area), of the individual wires to the magnets. Your Owners Manual should tell you the gauge to use, on the wiring diagrams. The wire runs should be the same length to each wheel, so if you run the main cables down one side, you may need to roll up some surplus wires. You want the same electrical resistance in the circuits to each magnet. I connect the magnet wires usuing wire nuts, back-filled with marine silicon caulk. Ready-filled wire nuts can be purchased at Home Depot. Solder and heat shrink does the top job, but I like to be able to disconnect them easily, perhaps at the roadside.

2. Yes, you can tie your live wire to the wire from the brake controller, and the ground to the ground at the fuse panel. I was relieved to find that the wire was looped up to the fuse box area, rather than going straight through, inaccessibly, to the wheels. You need to cut (and insulate the cut ends of) the old live wire to the magnets, so there is no live wire to short out on the frame. You need to locate the two wires to the emergency break-away pin on the A-frame. On my rig, the blue wire is live power from the fuse box to the pin, the pin forms a switch, and the return white wire is switched live when the pin is withdrawn. The white wire is tied into the wire from the brake controller.

I am 4000 miles from my trailer and Owners Manual, so this is from memory. Perhaps someone with manual to hand may be able to help. Good luck. Nick.

[Myrjer]

Thanks a million Nick. Excellent info. I did buy the complete brake assy. Just now got one on. Three to go ! I'm going to Home Depot though and get a ratchet end wrench since there is no room to get a socket wrench on nuts . Will go much faster.
Should be smooth sailing here on out. Thanks very much for your time and very helpful info.

Best to you.
Jerry

[Marlboro Mafia]

Hep me Karma-filled sages. . .

I have four wires that are supposed to be for the electric brakes. What are they? A ground and a positive for each side?

My trailer is a 1961 Safari. Would electric brakes be standard?

[nickcrowhurst]

Yes, each wheel has an electromagnet. Each electromagnet has two wires leading to it. One is 12v positive, the other is ground. The wires are interchangeable at the connection with the short wires emerging from the magnets. That is, it doesn't matter which of the two is connected to the live wire. For two wheels, you need two live wires, and two gounds. Regarding your question as to the original brakes on the '61, I'm sure one of the more knowledgeable forum members will let you know. Good luck. Nick