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 > Re-Wiring the brakes.

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mrekim

NJ

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Posted: 04/18/14 04:26pm Link  |  Quote  |  Print  |  Notify Moderator

My 35' ~10,000 lb GVWR trailer brakes were wired with 14 gauge wire and very poor crimps. All the crimps on that I've seen so far are pretty bad...


I'm going to redo it with a quality crimp tool and marine heat shrink connectors.

Does anyone know the wire size of the brake magnets(I need to order crimp connectors....) ? My trailer has 5200 lb Lippert axles. I might have a magnet from a 7,000 lb Dexter stashed away somewhere. Is it likely the magnet wires are the same size?



I've seen a few threads on the topic:

LAdams: I rewired my trailer brakes



JBarca: Independent Brake Wire Feed Upgrade


I like the idea of a star configuration and will go with that. It seems as if running 10G to the axles and then building the star from there is the approach most often taken.

What about running 14 or even 16 Gauge wire from each of the 4 brake magnets all the way from each wheel to the tongue - basically using 4 smaller gauge wires, but only 3 amps per and a "home run" wiring approach back to the tongue. I'm trying to avoid hiding junction boxes in the corplast...

tvman44

Southwest Louisiana

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Posted: 04/18/14 04:43pm Link  |  Quote  |  Print  |  Notify Moderator

I'd stick to #10 all the way. [emoticon]


Papa Bob
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mrekim

NJ

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Posted: 04/18/14 04:51pm Link  |  Quote  |  Print  |  Notify Moderator

Here's a nice voltage drop calculator:


http://www.bulkwire.com/wireresistance.asp

Assumptions:
12.8 Volts at battery
4 Ohm per magnet
25 foot cable run


1 10G case:
If the 4 magnet are at the end of 1 10G wire run the the wire "sees" a 1 ohm resistance.

Wire Resistance: .04054.
Voltage at magnets : 12.3 Volts


4 16 G case:
In this case, since there are 4 wire runs, we use 4 ohms as the resistance at the end of the wire.

Wire Resistance: 0.10211
Voltage at magnet: 12.48

So, it appears that home running 16G wire would produce a somewhat better result than running 10G and then a star configuration from there.

I've simplified things and ignored the star at the end of the 10G wire. I'm hoping that simplification isn't skewing things too much...

[ EDIT ]

I redid the math and assumed a 20' run of 10G and then 4 5' runs of 10G. I got 12.52 volts to each magnet that way. So it still seems that, in theory, I would get the same results as as 10G wire.

I also looked for a 2nd way to check my math. The cross sectional area of the 10G wire is 5.26 mm and 16G is 1.31 mm. Well 5.26 / 4 = 1.315, so it appears that 4 16 gauge wires is electrically the same as one 10 gauge.


[ / EDIT ]

* This post was edited 04/18/14 05:19pm by mrekim *

Gdetrailer

PA

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Posted: 04/18/14 04:54pm Link  |  Quote  |  Print  |  Notify Moderator

mrekim wrote:

My 35' ~10,000 lb GVWR trailer brakes were wired with 14 gauge wire and very poor crimps. All the crimps on that I've seen so far are pretty bad...


I'm going to redo it with a quality crimp tool and marine heat shrink connectors.

Does anyone know the wire size of the brake magnets(I need to order crimp connectors....) ? My trailer has 5200 lb Lippert axles. I might have a magnet from a 7,000 lb Dexter stashed away somewhere. Is it likely the magnet wires are the same size?



I've seen a few threads on the topic:

LAdams: I rewired my trailer brakes



JBarca: Independent Brake Wire Feed Upgrade


I like the idea of a star configuration and will go with that. It seems as if running 10G to the axles and then building the star from there is the approach most often taken.

What about running 14 or even 16 Gauge wire from each of the 4 brake magnets all the way from each wheel to the tongue - basically using 4 smaller gauge wires, but only 3 amps per and a "home run" wiring approach back to the tongue. I'm trying to avoid hiding junction boxes in the corplast...


I would not bother with smaller ga of wires, just not worth the hassle. Even those short runs of lighter ga will cause a good deal of voltage drop and the whole idea of upgrading the wire is to REDUCE the voltage drop.

You are much better off using 10ga or even heavier right up to the backside of the drums.

Do it once and do it right from the start.

Mine I ran TWO pairs of 10Ga wire from the front to the axles, well worth the work! Absolutely priceless! [emoticon]

Peg Leg

Anderson, IN

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Posted: 04/18/14 05:40pm Link  |  Quote  |  Print  |  Notify Moderator

Each magnet will draw about 3 amps. When I had trouble with my old TT I just stripped back the wires and soldered all the connections. Still working great when I sold it after 18 yrs.


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RCMAN46

NorthWest

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Posted: 04/18/14 05:49pm Link  |  Quote  |  Print  |  Notify Moderator

If you are going to go to the trouble of running new wire I would run a separate wires to each side. 12 ga would be OK.

The reason I would do this it would be easy and the hard work done in case you would decide to use the Tuson sway control device in the future. Right now the device is not available to the general public. But if the device does as advertised and goes on the market it should be on all trailers.

A good controller does not really care if there is some voltage drop. The controller should raise the voltage as necessary as required. This assumes the controller can be set at a gain setting less than maximum.

mrekim

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Posted: 04/18/14 06:16pm Link  |  Quote  |  Print  |  Notify Moderator

Peg Leg wrote:

When I had trouble with my old TT I just stripped back the wires and soldered all the connections. Still working great when I sold it after 18 yrs.


Yes, I had been in the solder camp. I'm going to give proper crimps a shot and see how that works. I can't believe that the trailer manufacturer is unable to meet the minimum requirements of the axle manufacturer for wire size....



RCMAN46 wrote:

If you are going to go to the trouble of running new wire I would run a separate wires to each side. 12 ga would be OK.

The reason I would do this it would be easy and the hard work done in case you would decide to use the Tuson sway control device in the future. Right now the device is not available to the general public. But if the device does as advertised and goes on the market it should be on all trailers.

Good point. I was going to home run all the wires to the front junction box (so 4 wires per side).


RCMAN46 wrote:

A good controller does not really care if there is some voltage drop. The controller should raise the voltage as necessary as required. This assumes the controller can be set at a gain setting less than maximum.


Yes, this is part of my problem. I **was** able to run with the gain setting at about 70 percent or so. On my most recent trip, I found I was turning the gain up throughout the day and at one point, with the gain all the way up I felt like I had WAY less brake power than what I expected. It's possible that this braking issue is intermittent. Based on the observations below, I thing a "redo" would be faster and produce better results.

I've already adjusted the brakes. I could hear the pads drag on the high spots on all the drums before adjusting. They didn't take much adjustment either, so that wasn't the issue.

The magnets all took 3 amps and I could not turn the wheels by hand when energized.

As I dug into the brake system I discovered

1) poor crimps
2) under sized wire
3) Wire strands cut to fit the crimp (main junction box joining 10,14 and breakaway (16 or smaller).
4) Bare wire exposed to the elements:

[image]

mrekim

NJ

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Posted: 04/18/14 06:56pm Link  |  Quote  |  Print  |  Notify Moderator

mrekim wrote:


Does anyone know the wire size of the brake magnets(I need to order crimp connectors....) ? My trailer has 5200 lb Lippert axles. I might have a magnet from a 7,000 lb Dexter stashed away somewhere. Is it likely the magnet wires are the same size?


FYI the magnet from the Dexter 7K axle looks to be 18 Gauge.

JBarca

Radnor, Ohio, USA

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Posted: 04/18/14 07:41pm Link  |  Quote  |  Print  |  Notify Moderator

Hi mrekim,

You will be glad you fixed the wiring. While you are at it, for sure abandon the cross over wire inside the axle tube. That setup is the classic, wire insulation gets brittle, cracks, chaffs, skins the insulation and starts shorting out bouncing down the road. If you tie wrap new wires on the axle tube, tie then to the back of the tube. The front gets hit with "stuff". Camp ground branches, brush, anything you drive over that can fling up there.

The sad part of all this is, while what is shipped on day one does meet the minimum standard for working, sustaining working is the issue. It only takes a little more cost in better materials and time to take it from minimal to long lasting. Hopefully some day manufacture will either just fix the issue or at least offer an upgrade. I for one am willing to pay for quality.

Take care

John


John & Cindy

2005 Ford F350 Super Duty, 4x4; 6.8L V10 with 4.10
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21,000 GCWR, 11,000 GVWR
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Gdetrailer

PA

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Posted: 04/18/14 08:47pm Link  |  Quote  |  Print  |  Notify Moderator

RCMAN46 wrote:

If you are going to go to the trouble of running new wire I would run a separate wires to each side. 12 ga would be OK.

The reason I would do this it would be easy and the hard work done in case you would decide to use the Tuson sway control device in the future. Right now the device is not available to the general public. But if the device does as advertised and goes on the market it should be on all trailers.

A good controller does not really care if there is some voltage drop. The controller should raise the voltage as necessary as required. This assumes the controller can be set at a gain setting less than maximum.


Umm.. brake controllers do not "compensate" for any resistance which causes a voltage loss over the length of the wiring.

To have a controller to do that WOULD require some sort of feedback wire from the brake magnets all the way up front that the controller would be able to determine the amount of voltage lost.

Brake controllers are basically zombies, they only output the MAX that you set it to. The absolute max output voltage will be the battery voltage of approx 14V while driving..

Add a few tenths of a volt drop from the vehicle to the brake magnets and you will lose considerable amount of braking power. Brake controllers are not able to sense the losses and you can only compensate so far by taking the gain to max..

Not much difference in cost from 12Ga wire to 10Ga wire but the result will be overall much better brakes.

I have made this the very first upgrade to do on new to me trailers and it really makes a difference..

My 2013 F250 I only set the brake controller to a max of 3.5 out of 10 for output and the trailer brakes are strong enough to be felt engaging before the vehicle brakes on my current setup with two pairs of 10ga wire.

If you going to all the work to replace the wire you may as well make the improvement worth while. 12 ga to me is simply not much of a step up from the OEM 14ga..

10ga is like making a 30ft trailer as if it is only about 12ft long.. two pairs of 10ga will make it as if a 30ft trailer is 6ft long (in other words as if the trailer axles are only a couple of feet from your vehicle bumper..

Small wires = higher resistance = more waste = less brakes

LARGE wires = Less resistance = less waste = MORE BRAKES

While the Tuson device sounds promising, folks need to understand that it may take a long time to get to the market and even if it does how long will it stay on the market and not to mention what happens when the device FAILS and if it fails during a sway event??

First order of business is to setup your braking system correctly so sway is handled easily and swiftly by your brake controller manual override.. Bad, poor, shoddy wiring makes hopes of recovering from a sway event hard to impossible..

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