Calculating weight loading....

[kogar]

I'm asking to see if there are any apps/spreadsheets out there that calculate the total load weight on a JLURD, and whether regearing (or larger axles) should be an option.

I have a stock '20 Rubi diesel, so I'm already tipping the scales hard. I will be adding an MC GC 3.5" lift, KMC 18" wheels with Falken Wildpeak 37s, steel front bumper and winch. On the spare, I plan to have 4 2gal diesel Rotopax mounted. I will also be adding MC steel underbody/DEF armor. Then there's the 5gal water can I carry, repair kit, bottle jack with lift extensions, plus a few other things.

Anyway, I can whip up a spreadsheet myself, but I'd rather not reinvent the wheel, so to speak, when it comes to calculating the total weight I am adding.

Oh, somewhat related: Currently, I'm planning on regearing to 4.56, but I'm a bit nervous because I see some folks saying the stock 3.77 works great, even on 37s. Assuming I'm ok with the cost to regear, is there any reason I shouldn't?

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[grimmjeeper]

The primary reason to regear is for a tire size change. Added weight only factors in to have you round up when you do the tire size calculation:

old axle gear * new tire size / old tire size = new axle gear, round up

That being said, 4.56 gears with 37" tires will be "more gear" than stock gears and tires. You will see higher RPMs on the freeway but you will have plenty of power to accelerate up to that speed. You won't have any problem with weight or tire size holding you back.

Still, the diesel makes tons of power off idle and is very capable of turning 37's even with extra weight while keeping the stock 3.73 gears. You could consider 4.10 gears but that is such a small change it just isn't worth it.

If it were me, I'd put on the 37s and load up the extra gear and drive it for a while. If you don't like it, upgrade the axle gears later.

 

[TheMike]

I was going to regear myself. But after having my Jeep as heavy as it ever will be, and doing a trip, I averaged 20.0 for over 600 miles. It’s not worth it to regear. I’m on 37’s.

 

[BadgerJL]

I'm actually in a very similar boat. '20 JLURD, 37" Nittos on 17" alloys, stubby steel front bumper with winch, steel rear bumper with tire carrier, MC skids and 3.5" lift, and LoD Signature sliders. I was concerned about weight so I took it to a scale and they measured 5500 (without me in it), well under the GVWR of 6100. It definitely accelerates a bit slower than stock and I need a little more pressure on the brake pedal but overall, it drives fine. You might consider 4.10 if you want to get it back to that stock feel but I agree with grimmjeeper. Drive it for a bit and see what you think before dropping the money on a regear.

 

[BuffaloBill]

I'm just now using mine for some longer drives after changing gears to 4.10. On last week's road trip north and back, averaged just under 27mpg for mostly 60mph travel.

This is with 315/70/17 and no lift. It wasn't bad with the stock 3.73, but enough different from stock (with 33" I mean) that I went ahead with the 4.10s. At this point I can't tell that I suffered any mpg loss. But it's possible as the Jeep gets more miles on it, that mpg is creeping upward because of that. It had about 5400 miles when I installed the 4.10. Now it has 7XXX miles on it. I appreciate, at 55/60mph, how it holds 8th gear, more of the time, relative to the 3.73 and 315/70/17s.

I would imagine if I had 37", it would have bothered me even more, making the change to deeper gears an easier decision. As I mentioned in earlier posts, I did the work myself so didn't spend that much. I would do it again with 35". But certainly, the engine has no problem moving the Jeep with the 3.73. I just like the transmission behavior better as it was stock. I'm now effectively, geared a bit deeper than stock, and that is to my liking, especially when towing.

 

[kogar]

Drive it for a bit and see what you think before dropping the money on a regear.

That's what I'm going to do. My go-to jeep shop...I spoke to the owner, who also owns a JLURD and regeared to 4.56. He suggested I drive my 37s with stock gearing first, then decide after a month or two.

 

[NCJL]

I tow at Max GCWR. Stock gears with 35” tires. I get 21 mpg towing. Up to 33 mpg not towing. Thinking 37” tires would not require a re gear.

 

[xtremejoe]

I agree with the folks that said drive without and see if you need it. In my case I did about 10,000 miles on it at 3.73 (half at the bigger tire size 37s). I live in a hilly area (California where your are crossing 7,000 overpasses or going into the Sierras). I also run a heavy overland setup. There was no way it was going to work. 4.10s maybe but why bother dropping almost 2k for that little change. I have no had 4.56 for almost a month and it drives way better.
I never go the MPG other folks have talked about...perhaps I drive a little too fast (notice significant mileage drops at 80 vs 60). I was less concerned about fuel economy and more about performance
Mike (posts above) runs a similar setup as me pushing 7k in weight at expedition level and somehow he makes his work. He also gets better MPG. So he either drives like Daisy or Alaskan fuel is better than the shit they probably deliver to California.
I did see another post where he added the Tuner/pedal monster and I was going to f/u with him on it as it still feels sluggish, but not sure I want the extra power on D44. If had done D60 for sure.
Net-Net I'm very happy with the change to 4.56 gearing...less about having to spend the money for something that is borderline requirement.

 

[xtremejoe]

I tow at Max GCWR. Stock gears with 35” tires. I get 21 mpg towing. Up to 33 mpg not towing. Thinking 37” tires would not require a re gear.

Sweet setup with the trailer. I had wanted to do similar setup with 35s and trailer, but then sold the TJ crawler and decided on 37s. Jury still out on whether it was the right move.

 

[NCJL]

Sweet setup with the trailer. I had wanted to do similar setup with 35s and trailer, but then sold the TJ crawler and decided on 37s. Jury still out on whether it was the right move.

Thanks. Hopefully your decision is better than mine. That trailer was a terrible decision!

https://www.jlwranglerforums.com/fo...xpedition-purchasing-experience-review.75590/

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