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Discussion Starter #1 (Edited)
This is an update and re-post from Pirate 4x4 on my flat tow setup using my Xterra.

I developed this setup over the last 15 years of owning and flat towing my CJ. But before I get into it let me provide a few disclaimers:

1. Flat towing is not for everyone. If your pile doesn't steer well, has bad bearings, bad tires or has less than adequate brakes, then it shouldn't be flat towed.
2. Generally, trailering a rig is a better choice, especially if you are taking it to the trail whether it may be damaged beyond the ability to be towed back. But for dropping the rig off for work, or getting it to the trailer, a proper flat towing setup is a good choice.
3. Some transfer cases don't take well to extensive flat towing due to lubrication issues (Dana 300) so the rear driveshaft may need to be removed. For long distances, it's a good plan to completely remove the rear drive shaft, or unlock the rear hubs if equipped.
4. No matter what you tow with, your flat towed vehicle should have a supplemental braking system. Not only is it the law in most states, but without it, you are an accident waiting to happen.

As for me, I live in a neighborhood where having a trailer handy is not an option. I also have friends with large diesel trucks, gooseneck trailers and extra space for my Jeep. So I generally don't flat tow long distances these days. But over the years, I have flat towed for thousands of miles without incident. I will admit that in the past, my setup was not always the safest (no brakes, etc.) but I have a setup now that is safe and works quite well.

Spoiler: If you want to know how well it works, see this thread: http://www.thenewx.org/forum/9-general-xterra/376-flat-towing-jeep-xterra.html#post5952
 

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The Setup:

My tow vehicle is a 2006 Nissan Xterra. Now I know that some of you think that there is no way an Xterra could safely flat tow a CJ, but it does.

First, the Jeep weighs substantially less than the Xterra's 5000# tow rating. And the Xterra rating is rather conservative at that. It's limited by the tongue weight the Xterra's CGVW can support, not the engine driveline or brakes. An identically equipped Frontier can tow an additional 1600 lbs. The Xterra is based on the Titan's frame and shares its rear axle, a 32 spline Dana 44 variant (coincidentally the same axle housing as the JK Rubicon). So the CJ is not stressing the Xterra. My Xterra is a 6 speed manual, so I am not concerned about transmission heat, only clutch wear.

The largest concern is the difference in weight between the Xterra and the Jeep. Many people will tell you that there is a magic formula for the ratio of the towing vehicles weight to the towed vehicles weight. While in general, the heavier the tow vehicle the better, the safety of the towing setup is more dependant on how the towed vehicle reacts to the motion of the towing vehicle and vice versa. For example, tow vehicles with a long distance between the hitch ball and rear axle tend to be more influenced by the towed vehicle than vehicles of similar weight with a shorter distance between the hitch and rear tires.

The amount of weight over the rear tires also determines how much the towed vehicle influences the towing vehicle. This is especially true of pick-ups which generally have a minimal amount of weight over the rear tires. I found that an extended cab p/u would not flat tow my CJ as well as the Suburban I used to tow it with, even though they were generally similar in size and not that far off from each other in weight. But keep in mind that an out of control towed vehicle will wreck anything towing it short of a bus. It doesn't take much lateral force at the bumper of any vehicle to spin it out. But this is no different than a bumper pull trailer.

Among other factors that effect a towing setup is the rear suspension of the towing vehicle. A rear track bar eliminates lateral movement of the axle and will help eliminate sway induced by the towed vehicle. The setup of the front axle of the towed vehicle is critical as well. It should be relatively free from lateral movement and the steering should have an acceptable amount self centering built in through proper caster and tow-in adjustments. Fortunately these characteristics also make for a good on-road driver. For my CJ, I built my SOA with adequate caster. I adapted a telescoping track bar for a YJ to the CJ and ensured tight steering gear with an AGR box and a decent steering box brace. If you have to use a bungee cord to get the steering wheel to self center, then you shouldn't be flat towing your POS.
 

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Bonus Features:

The towing vehicle has a few additional features that help immensely and make it acceptable for flat towing in my opinion. First it has ABS which is essentially standard these days. But it also has VDC or vehicle dynamic control. It will cut the throttle and apply the brakes individually to reduce the chances of an oversteer induces skid. This is very handy in keeping the CJ from pushing the Xterra side to side. A flat towed vehicle will tend to push the rear of the towing vehicle to the outside of a turn when the turn is started. In finishing the turn, it will tend to push the rear of the towed vehicle in the direction of the turn until the towing vehicle pulls it strait again. The issue is the delay in the towed vehicle's steering responding to the change in direction of the towing vehicle. This force, if sudden and high enough can break free the rear tires of the towing vehicle. This tendency is very noticeable in sharp turns, such as a tight cloverleaf. The VDC keep this in check within limits, of course. There is no overcoming physics if one is simply going too fast for the turn.

Lastly the Xterra has what Nissan calls ABLS or an Active Brake Limited Slip. This applies individual brakes to keep the open diff from spinning a tire when starting out. With a flat tow setup, there is essentially no additional weight over the rear tires from the towed vehicle, so it is easy to loose traction when starting out, especially on a slick surface. The ABLS helps in 2wd. My Xterra has 4wd with 4 wheel ABLS and a rear electric locker if things get really tough.
 

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Discussion Starter #4 (Edited)
The Towing Gear:



The main piece of towing gear is the draw bar. It attaches the towing vehicle to the towed vehicle. Mine is a simple folding bar meant for a Jeep. There are very complicated bars that ease hitching the vehicles together and eliminate bind at extreme angles, but mine is good enough. I did modify it a bit though. First is I moved the mounting point from the Jeep's bumper to the shackles by replacing my front shackles with Currie tow shackles. This moved the mounting point down by about 6. Secondly, I shortened the overall length of the drawbar to reduce the amount of leverage the Jeep has on the towing vehicle. The overall length of the bar is about 6 shorter than it was before. I kept it long enough so the Jeep's bumper won't hit the Xterra's bumper in a tight turn.



Next is the hitch and ball mount. I chose an adjustable height ball mount. It is critically important that the draw bar be level when towing. My SOA'd CJ on 35's is a good bit taller than the Xterra, so a mount that could be adjusted upwards was important. I also use a locking hitch pin that eliminates rattles in the receiver. The Class III receiver on the Xterra is rather shallow and the ball mount is excessively long, so I trimmed about two inches off the receiver end of the ball mount and moved the hitch pin hole accordingly (insert sexual innuendo here). This reduced the distance between the hitch ball and rear axle of the Xterra, thus reducing the leverage the Jeep has on the Xterra.



I use high quality break away cables instead of tow chains. They are d-ringed to the front bumper’s shackle mounts and clipped to the receiver hitch. I like the spiral feature which makes them compact for storage and keeps them off the ground.



The wiring is a molded 7 pin connector and cable.



It's routed under the Jeep's grille where it splits. One harness powers the rear taillights. Another harness grounds the two vehicles together and provides a fused charge line for the CJ's battery. I zip tied a carabineer to the cable that I attach to the Jeep to serve as a strain relief.

 

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Discussion Starter #5 (Edited)
The Braking System:

The braking system is a self contained proportional braking system from Roadmaster.



Roadmaster Evenbrake

The visible nest of wiring is for the tow system. There are power wires for the brake system and its transmitter. Another cable ties the two together. A third cable ties into the vehicle's brake switch. A fourth cable powers the rear lights.

It uses a compressed air cylinder and a compressor to apply the towed vehicles brakes through the brake pedal. It's wirelessly linked to the towing vehicle. In the towing vehicle is the head unit which contains accelerometers. The head unit senses deceleration and commands a proportional braking response from the towed vehicle. The head unit is in two-way communication with the braking unit so you get messages when the brakes are applied and it informs you of malfunctions.



There is also a break away function that applies full brakes should the Jeep break away from the hitch and cables. This is required by law in most states.



In order for the system to work well, I made a few modifications to the Jeep's braking system. First I added a power brake booster and MC. It was long overdue and required for use with this setup. Manual brakes are overpowered by this braking system. I also added an adjustable proportioning valve to the rear brakes to eliminate premature rear brake lockup. I went through the brakes at the same time and replaced all the shoes, pads, disks and drums. I bled and flushed the entire system at the same time.
 

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How it works:

It actually works quite well. The Xterra has plenty of power. With the combined weight of the Jeep and Xterra, the combo ends up with a weight to power ratio of 29.1 lb/hp. It has 27.1 lbs of weight for each lb-ft of torque. For comparison, a 2007 6.0 Silverado HD has 28.6 lb/hp and 27.1 lbs/lb-ft towing my CJ on a 1500lb trailer. The largest difference is that the Nissan 4.0 has its peak torque much higher in the power band so it has to be revved more. So my setup can more than keep up in traffic. For reference, the Jeep by itself has a weight to power ratio of 28.7 lbs/hp, the Xterra by itself is 16.6 lbs/hp.

I've tested the setup with an empty Jeep and empty Xterra. The Jeep does try to influence the Xterra, especially in turns, but the Xterra's VDC keeps things in check if I push it too much. IMHO the setup handles better than the similarly heavy U-haul trailer I pulled cross country last year. There is absolutely no sway induced by the Jeep. It handles better than it used to flat towing the CJ behind my old ½ ton Chevy P/U, but not quite as good as the 4wd Suburban I used to tow with. With my normal gear loaded into the Xterra, and more weight over the rear axle, it should only get better.

The brakes are the biggest difference. With the brake system set on its strongest and most responsive setting, The Jeep will lock up all fours in a panic stop. I also discovered I still have a little too much rear brake bias in the CJ as the back tends to step out in a panic stop. But it's nothing the turn of the portioning knob won't fix. Sensitivity and force of the braking system are adjustable. At its highest sensitivity, the Jeep will brake slightly while the Xterra is engine braking down an incline. So some care has to be used in selecting the proper settings to keep the Jeep's brakes from overheating. The braking system does warn if the towed vehicles brakes have been applied too long. The only thing I can fault on this system is a lack of a way to manually apply the brakes to the towed vehicle.
 

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My Opinion:

Overall it is a good setup with the safety of a well maintained tag along trailer. It's just easier to store and weighs less.

A couple of other notes on flat towing:

1. It isn't cheap. My setup cost the equivalent of a steel tandem axle trailer.
2. You can't back up with the two vehicles connected. So you have to plan parking carefully, or unhitch the two vehicles.
3. A CJ has a tight foot well for this type of setup. The braking unit barely fits. Fortunately, the linkage I have between the brake pedal and brake booster is adjustable. I ended up shorting up the linkage enough to provide the required room for the unit. This adjustment required me to readjust the brake light switch. Otherwise the brake lights remain on all the time. The braking system relies on input from the brake switch to function properly as well.
4. A draw bar hooked to Currie's tow shackles will not serve as a ground path between the two vehicles. The spring bushings act as isolators. A separate ground wire is needed.


Well that's it. It's probably more than you cared to know about how I flat tow. And no, you can't have those ten minutes of your life back either.

-Old Army
 

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Discussion Starter #9
This was written for Pirate. If its not absolutely complete with disclaimers, some fool will start flaming you.

I've been on that board since the late 90's and I'm still a newbee.

-Old Army
 

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Thanks for the follow up post. Very well done! Ten minutes well spent.
 

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Nice right up!

I'm getting ready to rig my X to be flat towed behind my 33' Itasca motorhome.

How do you like the even brake supplemental braking? I'm undecided between the even brake and the $200 cheaper brake buddy. I'm just not sure how important "proportional" braking really is. I've towed my Scion behind the motorhome without supplemental braking without any problems. But, the 2000# scion is quite a bit lighter than the X.

Rob
 

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I nominate this post for best topic of the year! Well, it is kind of self serving since I too have a CJ-7 that I hope to flat tow with my X. Old Army, I commend you on a terrific write up. Great detailed pictures and written explanations! :cheers:
 
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