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Old 07-14-2009, 06:34 PM   #1
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Can you lock up your trailer brakes?

The first Sunline I had, I could lock up the trailer brakes during the adjustment process for my Prodigy brake controller. Both Sunlines since then won't even come close, though the trailer brakes will eventually stop the entire rig given enough distance.

It really feels like my truck is stopping my fifth wheel. I've tried another brand-new prodigy already, so it's not the brake controller. And both Sunlines have had the brakes looked at, so I know they're good.

I'm just wondering if everyone else has brakes like mine. I can lock them up on very loose gravel, but not even close on concrete.
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Old 07-14-2009, 07:12 PM   #2
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I'm not a brake wizard but I thought to stop most effectively that you don't want to lock your brakes hence the invention of anti-locking brakes.

It seems to me that if the brakes are locked the stopping function consists of scrubbing rubber off the tire rather than by disappating energy between the brake pad and the engaged metal surface.

Norm
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Old 07-14-2009, 08:44 PM   #3
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Jeff

You said the last 2 Sunlines, what was the other TT size?

I can add some to what you are seeing as mine will not lock either at medium speed wiht the manul lever even at full ppwer. It comes from a few areas. The bigger the camper the worse this may get.

1. Brake controller not givning enough power. This is a cause but I think you already adjusted past this one so in your case this is not and issue I think.

2. Getting full power to all 4 wheels. You may or may not be reaching full amperage at all 4 TT wheels. A rusty ground, TV 7 wire connection and small gage wire are issues sometimes. On mine I upgraded the wire. Sunline at least ran number 10 from the front to the back. Some brands do not even do that. However once at the back they split into 14 awg feeders going thru the axle tubes and then there is the splice at the ends. Each splice can loose a tad of voltage drop and then the wire is marginal.

I upgraded to no 10 cross wires, outside the axle tube, and a no 10 ground. Each brake is totally independent of each other and all joints soldered, shrunk wrapped and taped. This helped get full power to the wheels thru the brake controller.


3. Next is the brake itself. Are they all adjusted dead on and up tight where they are suppose to be? I’m assuming you have the std TT/5er brakes that are not self adjusting. If you do no crawl under and tweak them about every 3,000 miles they loose braking strength or you keep up’ing the brake controller to compensate. Well full power may not mean full braking if they are out of adjustment. And all 4 the same. Do you adjust your own?

To help solve that problem I upgraded to self adjusting ones. Looks like this.

The old standard ones 12 x 2 brakes



The new self adjuster Dexter brakes 12 x 2 brakes






This gets what you have about as good as it is going to get. The weight and size of the camper along with the speed can also change if you can lock the brakes. Dexter states in there application guide and manuals that brakes will not lock when close to full load on all sizes. They will brake within acceptable parameters.

A 10,000# flat bed trailer loaded to 4,000# will have a good chance of lock up. A 10,000# GVWR TT loaded to 9,200# is not going to lock with 12 x 2 drum brakes at much above 20 mph. They will brake real hard they will not lock and they are not oversized enough to hold the truck too. Id the truck weighs 8500# and the TT 9,200# that is 17,700# trying to stop. No way are they strong enough to stop that kind of load. They are only sized to the GVWR of the TT. The truck stop the truck, the TT stops the TT.

In my case what drove me to those upgrades was a few things. Not having self adjusting brakes in the year 2009 is truly a miss on the part of the RV industry. There is only about $5 worth of parts when building new to make them self adjust. We are riding around on 1950 brake technology.

Next was the brittleness in the wire inside the axle tube. It can crack and short that one brake intermittingly. My wire was so brittle I flexed it about 30 degrees and it cracked in my hand. So out it went and I can get better amperage at the wheels now.

My F350 has the Ford Tow Command integrated brake controller. I know my truck was doing more stopping as the rear wheels dusted like heck when I towed. The Tow Command is so sensitive that the TT will not lead or lag the truck, but the truck will do more stopping. Ever since upgrading the dusting went away. Having your brakes adjusted up to snuff all the time makes a difference.

You may not be able to ever lock yours doing more then 30 MPH but you can make them the best they can be.

Hope this helps

John
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Old 07-15-2009, 07:20 AM   #4
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John,

The last sunline was a 25 footer, T-2570. The one before that was a 1996 Saturn T-24A. Now that one could lock the brakes on command, but it was a lighter unit.

The fiver's brakes are probably equivalent to the T-2570's, which I always found inferior coming from the first Sunline. That T-24A combo with my 2500 Chevy Duramax/Allison tow/haul mode made braking feel just like it did without the trailer. That is most certainly not the case now.

The tow/haul mode does an excellent job of downshifting smoothly to aid braking. Planning ahead takes care of 95% of braking issues. It's that emergency stop that I'm dreading and I want as much brake power as possible.

I think the wire upgrade is definitely in order on my rig. That's a great idea. Did you do that upgrade in concert with the new brake linings, or did you change the wires first by themselves and could you tell a big difference?

Sunline is known to do goofy things in my experience. For instance, the wire to my main slideout runs first from the battery all the way to the back of the trailer by the door, to the switch, then BACK up front to the battery, then BACK to the slideout, AND there was about 30' extra wire coiled up near the slide motor. That's about 60' too much wire and caused a decent voltage drop. So much in fact, that on 110AC the slide could not come up out of the hole it sits in to retract. The place I bought it from noticed this before I got there, and removed the extra 30' of wire and now it comes out OK, but boy does it work hard for those first 2 or 3 seconds. I'm thinking of re-wiring this also to a heavier gauge wire, and the shortest possible run.
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Old 07-15-2009, 10:20 PM   #5
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Quote:
Originally Posted by ihsolutions
John,

The last sunline was a 25 footer, T-2570. The one before that was a 1996 Saturn T-24A. Now that one could lock the brakes on command, but it was a lighter unit.

The fiver's brakes are probably equivalent to the T-2570's, which I always found inferior coming from the first Sunline. That T-24A combo with my 2500 Chevy Duramax/Allison tow/haul mode made braking feel just like it did without the trailer. That is most certainly not the case now.

Jeff, the T2570 is a 7,000# TT in the newer ones. The older ones may have been 5,500# but regardless they are smaller braeks then your 5er. Same concepet but smaller braking torque. They are like 10” x 2 ¼ brakes. Looking up your 5er, is it 12,000# GVWR?

Most likely you have what I have, 12 x 2 brakes good up to 6,000# each axle. My TT is 10,000# GVWR


I think the wire upgrade is definitely in order on my rig. That's a great idea. Did you do that upgrade in concert with the new brake linings, or did you change the wires first by themselves and could you tell a big difference?

The brakes where parts of an over all new axle install. See here: TT axle alignment - Details (long with lot's of pics) Since I had everything off and the price on the complete self adjusting brake plate with shoes was on sale for $39 per wheel I upgraded when I had it all apart. And since I had to redo the brake wiring I upgraded the wires at that time too. So no I never had one without the other.

I have a camping buddy who owns a Skyline that did the wire upgrade. In his case he had #14 feeder from the front of the TT to the axles on a 34 foot TT. His cross over wires where 14awg and they used skotch splices…. The push in pierce type connectors. He picked up 3 amps more power in his conversion. My Ford brake controller does not have amp output on it like my prior Jordan did. Only a bar graph. So I do not know the total amp draw before.

But I do know the combo is working a lot better then it ever did. If you want to put the data to this do you have an amp meter? I can measure total amps in the 7 wire plug going to the TT and you can compare to yours. Or you can check the actual voltage at the brake plate even better. Check it at the 7 wire plug as a reference point with a digital meter, 2 decimal places, Then check it at the farthest wheel magnet thru the splice. With only 13.2 ish volts to work with at the truck it does not take much to loose full power at the wheel


Sunline is known to do goofy things in my experience. For instance, the wire to my main slideout runs first from the battery all the way to the back of the trailer by the door, to the switch, then BACK up front to the battery, then BACK to the slideout, AND there was about 30' extra wire coiled up near the slide motor. That's about 60' too much wire and caused a decent voltage drop. So much in fact, that on 110AC the slide could not come up out of the hole it sits in to retract. The place I bought it from noticed this before I got there, and removed the extra 30' of wire and now it comes out OK, but boy does it work hard for those first 2 or 3 seconds. I'm thinking of re-wiring this also to a heavier gauge wire, and the shortest possible run.
The slide wire is odd…. Mine comes out of a junction box on the header off the battery, Thru a 30 amp auto reset circuit breaker, 30 feet back to the switch then up to the slide motor in the middle of the camper.

I can’t figure out why yours is going BACK up front to the battery a 2nd time…. What is it doing up there?? 30’ of coiled up wire by the slide motor…. This is a pure miss.

Hope this helps

John
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