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5th wheel JLUR flat towing build (my very own road train)

wtbman

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So far:
Installed LOD destroyer front bumper with frame tie-in brackets.
Purchased Road Master Falcon 2 6k two bar.
Purchased Road Master 3/4" d-ring end connections.

Jeep Wrangler JL 5th wheel JLUR flat towing build (my very own road train) canva2s



Jeep Wrangler JL 5th wheel JLUR flat towing build (my very own road train) canvas


Yes I know it's upside down in the pic and my safety chains aren't crisscrossed.

First road test: It's real interesting because I don't really feel the extra weight. I don't have a brake controller in the Jeep yet but it doesn't overwhelm the truck. Around town the whole setup drives great. The long butt of the trailer drags the jeep so far out around corners I don't have to compensate too much on turns.

I've had it up to 70mph on the freeway and that's where I am having concerns. The jeep seemed to wander a bit from side to side, almost bouncing off some play in the hitch back and forth occasionally. I need to figure out why this is happening because I'm worried it could get out of control.

I can thrash the truck back and forth across the road at slower speeds and and you can tell the corrections you make will be exaggerated by the time it reaches the end of the train. The trailer however did seem to be able to command the jeep with ease.

Next step is to install the jeep lighting wiring harness and do some freeway testing with just the truck and the jeep to learn the quirks of flat towing and find where the slop is.

There really isn't a lot of information out there from people who have attempted flat towing behind a 5th wheel so I feel like I'm blazing a trail, or maybe I'm just crazy and there's a reason it isn't done. Either way the numbers work: GCVWR/payload/towing cap./length/doubles laws, so I thought I would give it a shot. If you've done this before please share your experience.
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oscarvan

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There's a lot of states you can't bring that in to. Also, did you put the hitch on the fiver yourself? Surprised anyone sells/installs something that's 5K plus rated. Fiver frames are generally not designed to do that. Not saying it's unsafe, just questioning the legality. Other than that.... have fun, I'd keep it under a hundred.
 
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wtbman

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I am aware of the laws. It will probably never leave Utah where it is legal. I just want to take it to my favorite camping spots and down to the Moab area. The hitch is a custom job from the previous owner. Some combination of a Reese class III square tube hitch combined with a boxed frame extension all welded onto the 12" i-beam frame. You should see the reinforcement he made to the gooseneck conversion. He sold the trailer and got a toy hauler because he was cited for being too long because he was towing an enclosed utility trailer and was exceeding 65'. I'll post some pictures of the hitch setup to let the internet tear apart. At least it was road tested by the prev owner.
 
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wtbman

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Installed Demco Stay and Play Duo braking system. It applies vacuum to the brake booster while using an air actuated cylinder to apply the brake pedal. It taps into the left and right braking/turn wires and uses inertia to sense when it needs to apply brake. In my testing it does a good job. It's permanent so the only setup you need to do is flip the switch to "on" and off you go. The big box (velcroed to the fuse lid) essentially houses a mini air compressor that applies both vacuum and air pressure for the pedal actuator.
Jeep Wrangler JL 5th wheel JLUR flat towing build (my very own road train) 20210501_182005

Jeep Wrangler JL 5th wheel JLUR flat towing build (my very own road train) 20210501_182044
Jeep Wrangler JL 5th wheel JLUR flat towing build (my very own road train) 20210501_182059
Jeep Wrangler JL 5th wheel JLUR flat towing build (my very own road train) 20210501_110544
 

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wtbman

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Double towing length laws:
Wyoming 85'
Idaho 75'
Utah 65' or 105' with a $90 permit (apparently paying money = safety)
Colorado 70'
Nevada 70'

Pretty much everywhere else it's 65' and forget about states on the coasts.

Just bought this to tighten up the tow bar (remove some slop side to side and up and down).
https://www.amazon.com/dp/B08X19NK21
Jeep Wrangler JL 5th wheel JLUR flat towing build (my very own road train) 41GfROBQsML._AC_SL1080_
 
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wtbman

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Hooked it all up and took it for a test drive Saturday. The braking system works great. The mopar jeep wiring harness worked great to provide lights/brakes/signals on the Jeep. I had to jump the taillights from the trailer to the accessory power pin on the wiring harness to get the Jeep lights to turn on. Maybe I'll run a proper 12v line from the trailer to the plug on the hitch and see about an rvi charger for the Jeep because right now the brakes are running off battery.
 

MtCamper

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We've double towed ours now for a couple of years. My set up is similar, I'm using a 5000# Curt RV hitch on a 27-5 arctic Fox. Foxes are noted for their strong frames but of course what I'm doing is not recommended by the manufacturer. I've converted the Fox to disc brakes and use a Brake Buddy on the Jeep. I kept the wiring simple, I just use HF magnetic lights stuck the the rear bumper of the Jeep and a simple four flat plug in the trailer. All hitched up with the bike rack on the Jeep, we're just under 70'. Totally legal in all the states we travel through. We see a lot of doubles here in Montana, mostly with boats behind both bumper pull and 5ers. In Arizona we see a few Jeeps behind 5ers but trailers with UTVs seem to be the most popular. Many appear to exceed the legal length limit without getting stopped. To be honest, I don't really notice the Jeep back there. Costs just under 1 mpg near as I can tell. The only thing I have noted is I can get a strike between the Jeep bumper and the trailer in a very tight 360˚ turn. My solution is to not do tight turns. We did get into a dead end once and had to unhook the Jeep. Once out of thousands of miles isn't too bad. I added a camera to the rear of the trailer so I could monitor the Jeep, but now I don't even hook it up. It was totally boring back there, the Jeep just keep tailgating us everywhere we went. I usually travel at near 60 mph, but am very capable of maintaining 70+ if I need to keep up with traffic. All said it works for us.
 
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wtbman

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We made it back from a 600 mile round trip to Sand Hollow state park truck+5th wheel+jeep. The setup performed wonderfully and was very stable. We experienced all of the hazards I was afraid of, strong winds, construction with deviated lanes, traffic with sudden stops. Not one bit more difficult than the truck+trailer other than giving a bit more room for lane changes. With my camera setup I can see everything and get where I need to in time. The Demco brake system performs excellently. We lost 1-2 mpgs on flat road and 2-3 going up hill in the wind. With 4:30 gears and duallys mpg was already not great so whatever, at least we had plenty of power and could maintain 75mph comfortably most of the trip (with the speed limit at 80 mph people were still flying by us at an alarming rate). We had a wonderful time 4-wheeling around with the Jeep and I'm glad I can now take it along with us. After our inaugural trip I can conclude that I'm definitely going to keep doing this.
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