trailer brake questions

It is also possible that the wire that goes through the back axle to the wheels has become chafed and is shorted out. If your brake assemblies look good upon inspection; you might run a wire on the outside of your back axle to the off side wheel and check for brakes actuating.

I have self adjusting (Dexter) brakes on my 29'Arctic Fox fifth wheel. Absolutely love them. From time to time the brake assemblies are on sale, and you just can't beat the price. My unit came with 6000 lb axles derated to 5300 lbs. When I upgraded to Nev-R-Adjust brakes, I upgraded to 7000 lb brakes. Much better than stock.

themerryjo wrote:


1. When I apply 12 volts to the front 2 drums I can hear the magnets energizing but neither of the back ones sound like they are working, is it ok to just use brakes on one axle or is that going to feel too weak for 7000#?It will feel (and be) too weak for the trailer. Only drive it that way to the repair shop.

2. I am planning on running some 12/2 SO cord from trailer front junction box to a second junction box located between the wheels and from there branching off to each wheel with 14/2 SO cord. Is this sufficient?Yes, that is sufficient, a bit of overkill. As you discovered, SO cord is VERY good in the elements...

3. If I end up buying new brake assemblies, what are opinions on self adjust vs manual? Do they actually work reliably as intended or with a little age do they not self adjust anyway?I have no direct knowledge of self adjusters, but when my manual guys need replacing, I will replace them with auto-adjusters.

My comment on the SO cord is backed up with 30years as a commercial master electrician...but, at the very least, ADJUST Them! If it were me, I would inspect, repack the bearings and go from knowledge.

Tim

Wow, the previous owner didn't bother with trailer brakes. Such irresponsibility. They could be seized from lack of use. I would take them apart and carefully inspect.

Thanks for the replies everyone,

SO cord is a bit more durable than you might be giving it credit for donn, especially when compared to exposed plain insulated wires or even sheathed wire pairs. It may not be the best solution money can buy but it's 10 times better than what comes from the factory. I've used this stuff a lot at a previous machine manufacturing job and it has pretty good impact resistance too where normal unprotected wires would get pinched right in half. Incidentally, isn't the pigtail that plugs into your truck and exposed to all manner of elements a type of SO cord?

Carol Brand Type SOOW Cable Features:

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Water-resistant
UL Listed and CSA Certified for indoor and outdoor use
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TRU-Mark® sequential footage marking

Point well taken about line loss, although I still question if the impact is neglegible over only 20'
However, running 10ga all the way to the brake leads is clearly the top performer!

(online line loss calculator)
12 volts input >>> 14ga@ 12' >>> 16ga@ 8' >>> 16ga@ 1' = 10.84 volts out (factory)
12 volts input >>> 12ga@ 12' >>> 14ga@ 8' >>> 16ga@ 1' = 11.20 volts out (+ .36 volts over factory)
12 volts input >>> 10ga@ 12' >>> 14ga@ 8' >>> 16ga@ 1' = 11.43 volts out (+ .59 volts over factory)
12 volts input >>> 10ga@ 12' >>> 10ga@ 8' >>> 16ga@ 1' = 11.52 volts out (+ .68 volts over factory)

I used 4 amps as the load for each wheel, sounds like it should be closer to 3 amps. Also, volts in should probably be more than 12,
Actual performance for the factory wiring is questionable as the right side has much longer wires than left and, while the hot wire is 14ga the ground only uses 16ga.

Yes I deff need to pull the wheels and inspect bearings and brakes, with the price of etrailer assmeblies it hardly makes sense to repair components

The previous owner only used it a few times a year but I know from pulling my jeep on a trailer with surge brakes that went out, that can be a handful with just truck brakes and that was only about 4000#. Also, in Michigan we have no inspections to worry about!

If you have 4 brakes use 4 brakes. They are there for a reason.

Use the 10 gauge wire as stated before the length is what really determines the wire size.
Look on Amazon for the wire. I just rebuilt a 33' trailer for our ATVs and I bought everything through Amazon as it was considerably cheaper and two day shipping free.

As for the ones that aren't working start by running the right wire and checking connections and work from there. We just had to have 3 magnets replaced on our 2014 bunk house. They just stopped working.

With the wire connections try to use the shrink wrap to seal them up from the elements.
Check adjustment too while your under there.

Our RV Trailers Electric Brakes here in this state are Inspection items for our annual safety inspection.

A clamp-on ammeter like the Sears Craftsman model 82369 model that has both AC/DC 400AMPs is great tool for working on trailer electric brakes. With 12VDC applied each Brake Magnet should draw around 3AMP DC Current if working properly... I can clamp around the single DC wire going into the brake assy and get this measurement real easy... If there is two wires like shown in this photo then one of goes to trailer frame ground somewhere on the outside. You can still measure around either wire to read your 3AMPS DC current. Also the second brake magnet on this axle is fed by wires going through the axle assy. Mine does the same thing here...

google image



ADDED NOTE: Check in with ETRAILER.com on-line and see what they say about wire sizes. They also have a great site and will answer any and all of your questions...

Interesting that someone could get away without working brakes on a trailer that had them installed. Maybe it was never towed over public roads... Perhaps the previous owner State doesn't have a State Inspection program for RV trailers...

I would do whatever is required to get it legal within your State Inspection requirements...

Roy Ken

You probably need to repack the bearings anyway so while you or someone else is doing that they can go through the brakes and make sure they're adjusted and functioning.
Adjust brakes at least once a year (both axle's brakes should work).

Normally it's not the age that gets these units it the inactivity. Everything gets coated in a thin layer of dust which turns to dirt which turns to rust and then nothing works not because of the age but because it just doesn't get used. If it were me I would take them all apart clean them grease the wheel bearings adjust the shoes on them and then see what you got. Once you have them apart you might see some things that need replacing that would be the cheapest way to go. Also like donn0128 said long runs of wire cut down on the electricity try not to do that. Hope this helps and hope you have fun with our hobby.

NO!
Long lengths of wire create resistance, which reduces amps to the magnets. Heavier wire can reduce losses. SO cord is not intended for long term exposure to the outside.
Take your pick. Both will probably need adjusting once in a while.