Good luck on your trip. I am jealous.
Still a long way to the beginning of my expedition but already got the JK and starting to prepare it, hope will have something to show by the end of next week.
I the meantime, I have updated my blog with some nice pictures of my visits to DeLand, if you guys care to see the link is HERE
For those willing to join part of the way, check my route HERE and don't hesitate on email me! I will be writing an 170 pages book of this trip and everybody joining will be sure mentioned!!
So... We are now in Cancun and the odometer just turned 21,000 miles, the actual overall weight of the JK is 6,820 pounds (us included) and it the lowest weight we reached so far (7,480 being the highest).
Suspension is a 9th degree from AEV and stock Rubicon tires. We have gone through asphalt, dirt, snow, sand, mud (not much) and some pretty rough unpaved terrain on Baja and inland Mexico. No problem so far. On highways we maintain average speed of 70+ mph (top speed of 106.875 mph on two GPSs)
Mileage is low, I will publish the results shortly.
As mentioned there is more to this than just adding a few things and calling it good.
If you could get your hand on the data, I think getting your hands on the specifications for the modifications that went into the J8 chassis would be worth an in depth look, specifically the modifications to the frame. I would be very interested to know what they changed, added, etc.
There is also the T1 military long wheelbase TJ program. It had a coil rear suspension AND a much larger payload capacity. I think it was something like 2000lbs.
My feelings with the JK chassis is that the major stumbling block for long term high weight use would be the rear axle and rear suspension. I have heard of a decent number of people that are bending the axle flanges in heavily used heavy weight JK 4-doors with larger tires. I don't know how much of this is tire or weight? Spring rate can be increased easy enough. Control arms and mounts could be a factor at some point. I always wondered why they went with leaf springs on the J8?
Tom Sheppard goes into this issue fairly in depth in his books. A summary of what I remember, lighter is better, always. He promotes the trailer thing a little bit. Also, keeping the weight forward and as low as possible. A vehicle that is heavier on the rear axle than the front generally performs poorly and/or works much harder.
I have a set of heavy duty JK springs I am going to be posting up for sale, they are off a 2012 4-door hardtop Rubicon with tow package, let me know if you can use them.
I would like the see what they did on the T1 military version of the TJ. I'm pretty sure it had a 2000lb payload and coil springs.
I did a little more digging into this.......
From what I can gather the J8 frame is hydroformed of thicker material than the stock JK frame even though the dimensions are much the same. There are also added reinforcements in key areas, mainly the front control arms attachment points. There are added brackets for the rear leaf springs on the rear section of the frame. The ends of the frame where the J8 bumpers bolt on are also beefed up to allow lifting of the entire vehicle by the bumpers.
The J8 was ran over the same durability course as a JK........the J8 lasted 3 times longer than a stock JK as far as useful life.
There are a LOT of differences between them, not just cosmetic things....
If it can tow 3500 lbs, + 1200lbs of gear then that pretty much sorts out any worries about engine, tranny, cooling and brakes right?
So what's that leave? Suspension, frame, axles? The AEV suspension is designed to carry a heavier load. I mean all these aftermarket bumpers, armor, winches, etc people put on there don't seem to be a concern and they would easily add hundreds of pounds, on top of what you were carrying inside before, no?
Could always swap in bigger axles if you're really worried about it.. The frame looks pretty robust, but the info above about the J8 is intriguing...
Being able to carry the weight around for a few miles on the highway is TOTALLY different than being able to carry that weight over rough terrain for extended periods of time......
Interestingly the J8 still uses a semi-float ( C-clip! ) 35-spline rear axle, I think it was originally from the SRT-10 program?
JK's have been known to bend the rear axle flanges.
It's not so much just 'bigger' axles really, but axles that are factory rated for more load. I think the axles off something like a Dodge 2500 Powerwagon would be just about perfect. Dynatrac offers a full float rear axle for the JK with the factory style ABS sensors.