Crawl ratio

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Phils67
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Re: Crawl ratio

Postby Phils67 » Wed Jun 20, 2018 4:27 am

Then i am sold. Ill stick with my plans of going 3.73s giving me the 48ish crawl ratio
1967 J2000/ 4.0MPI/T18/D20/35s

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Lumpskie
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Re: Crawl ratio

Postby Lumpskie » Wed Jun 20, 2018 4:58 am

Just a thought... Another thing you could always do is add a hand throttle to the mix.
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derf
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Re: Crawl ratio

Postby derf » Tue Jun 26, 2018 3:11 pm

One idea for over-thinkers is to modify the transfer case. You can get a 3.15:1 low range gear kit like this one: https://teraflex.com/shop_items/low20-g ... -automatic

Combine something like that with a more highway friendly gear ratio in the axles and you get a better range of performance. You get lower RPMs driving down the highway but then when you shift into low range, you get good crawling.

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Phils67
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Re: Crawl ratio

Postby Phils67 » Tue Jun 26, 2018 4:18 pm

I like the way you think. Its a future possibility...
1967 J2000/ 4.0MPI/T18/D20/35s

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tedlovesjeeps71
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Re: Crawl ratio

Postby tedlovesjeeps71 » Tue Jun 26, 2018 5:02 pm

Crawl box...

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Phils67
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Re: Crawl ratio

Postby Phils67 » Tue Jun 26, 2018 5:04 pm

tedlovesjeeps71 wrote:Crawl box...

....go on...?
1967 J2000/ 4.0MPI/T18/D20/35s

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tedlovesjeeps71
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Re: Crawl ratio

Postby tedlovesjeeps71 » Tue Jun 26, 2018 6:11 pm

Phils67 wrote:
tedlovesjeeps71 wrote:Crawl box...

....go on...?

I run a northwest fabworks crawl box in my scrambler. It allows me to use the regular gears/t-case hi-low, or put the crawl box in low and the other stuff in whatever. Gives me a wider range of gearing options for different situations. Sometimes low/low is too low. If you do the transfer case reduction swap you may find hi is too high and the new low is too low. I like options.

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Gives me options.

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will e
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Re: Crawl ratio

Postby will e » Tue Jun 26, 2018 9:28 pm

That's a cool setup. Mine is similar. I went with the Atlas 4 speed. The transfer case is 2:1 and with a twin stick. In between the transmission and the transfer case is a 2.72 to 1 planetary gear. So I can go 1:1 1:2 1:2.72 or 1:5.44.

When deciding what to do with my rig I looked at this option or going with a 4 speed automatic. The costs were similar. With the 4 speed I could go lower axle gearing and make up the difference with the overdrive. With the Atlas I could go with taller axles gears (4.54 and 37" tires) and stick with the 3 speed 727. Since my rig isn't a daily driver I decided the flexibility of the Atlas was more favorable compared to a 4 speed auto transmission.

It all just depends on what you are doing with the rig.
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tedlovesjeeps71
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Re: Crawl ratio

Postby tedlovesjeeps71 » Tue Jun 26, 2018 9:53 pm

Yeah, the 4 sp atlas is a good setup. I couldn't afford it and stumbled on someone selling the BB. When my T5 grenades I knew it was time to step up. The NV4500 has plenty of 1st gear grunt (similar to the OPs t18) and the BB allows me to double that. I was able to keep my diff gears at 4:10 with 35s, keep the use of 5th gear, run 80mph and when I get to the trails I can choose a gear for the obstacles at hand.

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Phils67
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Re: Crawl ratio

Postby Phils67 » Wed Jun 27, 2018 4:02 am

Thats pretty cool but would it work with a Dana 20 that has a "texas" bolt pattern?
1967 J2000/ 4.0MPI/T18/D20/35s

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derf
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Re: Crawl ratio

Postby derf » Wed Jun 27, 2018 6:44 am

I have the 4 speed Atlas in my JK. But I went with the 2.72/4.3/11.7 combo. I do most of my wheeling in 4.3 low. But when I need it for a very technical crawl, I shift into super-low (238:1 final combined). It gives me a ton of control and finesse.

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derf
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Re: Crawl ratio

Postby derf » Wed Jun 27, 2018 7:23 am

Phils67 wrote:Thats pretty cool but would it work with a Dana 20 that has a "texas" bolt pattern?


Probably not. There is very little these days that isn't focused around the Jeep Dana300/NP2xx bolt pattern. Parts like that for the older transfer cases are getting harder to come by. You can still rebuild them easily enough but significant modifications like a crawl box just aren't out there.


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