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NP231 doubler / crawlbox

JMT

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Sounds like another perfect option for the TJ.

Actually what I would like is the Dana 300 widened out another inch with a new 4-1 gear set built to be left hand drop. That is a case that makes sense for a normal TJ.
Me too. Exactly what I’d want. I’d have to go with a simple 300 if I ever have any problems with the TeraLow.

4:1 preferable over 2.72:1, but I prefer both options, which is why a 4-speed Atlas seems ideal. Just $$$ and BIG. 😕
 

freedom_in_4low

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That could very well be. Throwing the rubicrawler in there increases the input torque to the tcase by a factor of 2.72. So on the stock I6 it goes from 260 pound feet to 707 - and that’s just in 4th gear. First is much worse. That’s crazy when you think about it.

Edit - Throw it in first at 2.84:1 and all the sudden you are throwing 2,008 pound feet at the case.

while it seems unlikely (to me) that someone would be at full throttle, 3000rpm in 1st gear and low range, it certainly illustrates the point of how easy it could be to destroy downstream components by not being mindful of what you're doing. And with the torque multiplication you get from the torque converter, it could indeed be quite high just off idle.

Throw the crawler AND the transfer case into low, and then through a 4.88 or better R&P, and it's not hard to imagine destroying the strongest of hubs and axle shafts.
 
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Gollywomper

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I am somewhat surprised nobody has made a gear driven case with the 231 width specs.
Did the chain driven cases get wider due to auto transmissions or did autos get wider due to the extra room given from the chain driven cases. Lol
 
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LincolnJr

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The problem is 10.88 isn't as good as 7.4-1
Why is this, and is it the same for manuals and autos? Not sure if the different gear options make a difference. And am I off my rocker here? On paper I could build a 231/231 doubler for less than finding or building a single 4:1 tcase, but is that more trouble than it's worth?
 

freedom_in_4low

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I am somewhat surprised nobody has made a gear driven case with the 231 width specs.

It's a very niche market, so it doesn't surprise me at all

Did the chain driven cases get wider due to auto transmissions or did autos get wider due to the extra room given from the chain driven cases. Lol

now that is a very interesting question. My bet is that transmissions got wider and necessitated wider cases, but i can easily see the opposite happening as well.
 

Apparition

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Why is this, and is it the same for manuals and autos? Not sure if the different gear options make a difference. And am I off my rocker here? On paper I could build a 231/231 doubler for less than finding or building a single 4:1 tcase, but is that more trouble than it's worth?
I can do the 7.4:1 and it's stupid low, I can't come up with a reason I'd want to be lower.
 

freedom_in_4low

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Why is this, and is it the same for manuals and autos? Not sure if the different gear options make a difference. And am I off my rocker here? On paper I could build a 231/231 doubler for less than finding or building a single 4:1 tcase, but is that more trouble than it's worth?

a 231/231 would be a mile long...useless for a TJ wheelbase. Might work on an LJ.
 

Gollywomper

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I can do the 7.4:1 and it's stupid low, I can't come up with a reason I'd want to be lower.
We were thinking we would want the 4-1 in the rear box. However after driving the compound low at 7-1 I am glad I didn’t spend the extra for the low gear set. 7-1 is very low and will be used somewhat rarely. But it is nice to have the option without giving up the 2.72 stock gears.
 

Mike_H

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We were thinking we would want the 4-1 in the rear box. However after driving the compound low at 7-1 I am glad I didn’t spend the extra for the low gear set. 7-1 is very low and will be used somewhat rarely. But it is nice to have the option without giving up the 2.72 stock gears.
4:1 is really low. I can't image needing 7:1, but over not wheeled out west either
 

mrblaine

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Would’t engaging the rubicrawler slow the input shaft on the tcase?
I made some phone calls to find out what exactly was going on. Turns out, being lazy bites you on the ass. The ones who fucked these up had a habit of running down the trail in 2hi, get to a tougher spot, shift the Rubi-crawler into low. So not only were they not using the t-case, they were making the rear axle do a lot more of the work. Had they grabbed 4hi at the same time, I suspect not making the rear push the fronts over stuff quite as much would have made the 231 last much longer. Torque did not, not RPM.
 

Gollywomper

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That's true. In low, the math on my rig puts about 50,000 ft pounds to the axle shafts.
1642181822003.jpeg
 

NashvilleTJ

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Rubicrawler w/231 TC 7.4:1 total crawl ratio 107:1. And yes I forgot to turn on the lockers at the bottom. @AussieNick was copilot

View attachment 302519
That's awesome, Ryan. One of my proudest moments wheelin' occurred on Hell's Gate from that exact perspective. At TJ Fest last year, I came up there with a bunch of folks who had never wheeled it before, and some were quite nervous about doing it. Since I was one of the first up, I started spotting. So with a big crowd of folks behind me at the top, I spotted 10 or 12 rigs up there.

After the last rig came up, the crowd started walking back to where the rigs were parked. Just then a woman came up to me and said "I know this is called Hell's Gate, but I thing god sent you here to keep us all safe."

True story. Still makes me smile when I think about it.
 

Wildman

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I'm watching this thread as an affordable 3-speed tcase would be tits. Most of the time the 231's 2.7:1 is perfect and a 4:1 would be too low, but I would like lower on the rocks. So far I get by working the clutch but that isn't ideal. I suppose for the price of a double I can buy a lot of clutches... and advil

I have a STaK's 3 speed t-case and I LOVE it even if OTHERS think it isn't a good choice.

Yep they had issues with them popping out of gear and some spit oil. I burned up two cases because they'd told me I could flat tow it but for some reason it didn't oil the bearings. And yes I had it in gear like like recommened.

I had both versions of their shifters and like the first better for shifting but it was a PITA to adjust.

This was the first version.

IMG00829[1].jpg


This was the second version.

IMGP0235[1].jpg



IMGP0889.JPG


And YEP it's BIG as heck and weighs 150lbs but I'm not as worried about weight as some.

IMGP0169[1].jpg


Nope I don't have a flat skid but I only need a 1-1.5" drop skid to clear it.

IMGP0213[1].jpg



I have the 3.05 & 5.44 ratios and like them both. I run it in 3.05 most of the time but when I need to go slow I can use the 5.44.
The Hero box that is a 3speed is expensive. When I bought the STaK's it was $3K.

Yep it isn't for everyone but I like it.
 

Apparition

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That's awesome, Ryan. One of my proudest moments wheelin' occurred on Hell's Gate from that exact perspective. At TJ Fest last year, I came up there with a bunch of folks who had never wheeled it before, and some were quite nervous about doing it. Since I was one of the first up, I started spotting. So with a big crowd of folks behind me at the top, I spotted 10 or 12 rigs up there.

After the last rig came up, the crowd started walking back to where the rigs were parked. Just then a woman came up to me and said "I know this is called Hell's Gate, but I thing god sent you here to keep us all safe."

True story. That still makes me smile when I think about it.
Interesting you mention that, I've never had a spotter up it.

I remember one of the guys last year didn't do it the first day we did Hell's but we went back which is when this video was shot. He said it's one of the things that was on his bucket list and I believe he went up before this video, there was no stopping him it was a man on a mission, not even a slight hesitation. I was impressed.