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Unread 09-24-2008, 12:24 PM   #1
sprowley
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1997 TJ Wrangler 
 
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NP231 Tera Low 4:1 conversion OR Atlas II

Which one? There's an obvious price difference, but I want to do this right.

So, do you have one? Tried the other? Opinions?

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Unread 09-24-2008, 12:34 PM   #2
jeepster93
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I have a tera low 4 to 1.
LOVE IT!
One of the best mods I have done.

Got it cheap(relatively speaking), got a second.(it had been drilled-clocked- improperly, they re drilled it and sold it at half price).




Just remember that both multiply torque output. Both will absolutely trash a stock drivetrain.
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Unread 09-24-2008, 01:02 PM   #3
sprowley
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Awesome to hear, thanks!

I have decided to go for 33" GY Silent Armors for the winter, which will be a few inches larger than what it currently has. I also have decided that I very much like my stock 3.07 gears (gas mileage is great - up to 21mpg with 4.0 combined city/highway) but 33's make low range not so awesome when I'm pullin hummers out of snow banks in a few months
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Unread 09-06-2009, 01:22 AM   #4
Joe Dillard
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There came a point where I needed deeper gears for offroad, and axle gears were not going to do the trick in my case - so a tcase upgrade is where I decided to focus.

I went the Atlas route & chose a 5.0 reduction for several reasons.

Pretty easy to install
Major gains in strength across the board
Optional flat clocked no charge
Longer rear drive shaft
Excellent gear reduction (5.0)
Superior reliability
Easy to maintain
Sold my SYE equipped NP231 to offset cost
Twin stick is standard
Very easy to operate
2wd low is standard
Value is high
Resale is high
Ability to do front digs
Built to my specs

Both tcase upgrades are good choices.
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Unread 09-06-2009, 05:50 AM   #5
JeeperDon
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Or, plan C: Get a junk yard Rubicon 241OR. It bolts right in, has SYE and 4:1, and can be had for 1/3 the price of an Atlas.
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Unread 09-06-2009, 09:52 AM   #6
KMA Krawler
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What junkyards do you know that have 241OR's?
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Unread 09-06-2009, 10:20 AM   #7
RockWoRM
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If you're not ever going bigger than 33's, then the 4-1 is good option if ya can get a good deal for one. The one thing I do not like about the 4-1 is the fact they (Tera) do not recomend using 3rd and 4th gears very much, due to the fact it turns the planetaries too fast. This is a pain for me b/c I'm always in a spot where I need those mid range gears on the trail.
I got mine as a second at a good price, but still had to pay a shop to install it since I do not trust my gear skills. Not to mention the fact I already had $$$ invested in the HD SYE.
If I could start over from scratch, I go with the Altal 5.0 for all the reasons Joe mentioned. My gears are set up exactly like Joes, including tires, and I would love to have that extra 17# of low ratio. Not to mention I"ve seen Joes rig in action and know the difference of his low range to mine. In your case, it may not be needed.
If you could find that salvage yard 241 for 1/3 price, I'd prolly go for it, too. Perhaps Don can send ya one!



WRM
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Unread 09-06-2009, 10:34 AM   #8
moonshinefuel
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Sprowley, you mentioned you want to do whats right. Get an Atlas. Go right around everything else. Go for the gold standard if you can. There is not a person in this forum who is going to say that was the wrong thing to do.
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Unread 09-08-2009, 09:20 AM   #9
Digger 5
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Quote:
Originally Posted by sprowley View Post
I have decided to go for 33" GY Silent Armors for the winter, which will be a few inches larger than what it currently has. I also have decided that I very much like my stock 3.07 gears (gas mileage is great - up to 21mpg with 4.0 combined city/highway) but 33's make low range not so awesome when I'm pullin hummers out of snow banks in a few months
I think you'll find that when you change your tire size you're going to lose substantial MPG. 3.07 gears will be too high to really use 5th gear much, if at all.
Obviously, the Atlas is a great t-case. If money isn't a huge issue then go for it. If you're on a budget, the Rubi case is probably a better option if you can find one. As others have mentioned, the Tera kit has a few drawbacks.
It all depends in how you wheel. Personally, I can't imagine not having a twin stick so an Atlas or a STaK RAC would be my best options(for a LH drop t-case).
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Unread 09-08-2009, 08:15 PM   #10
leftlanetruckin
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i had an atlas in the yj.
i just ordered the teralow for $920 shipped.
my t/case already had the sye installed when i bought it. joe did forget that he got a killer deal on his atlas, so that is to be considered too!
i paid @$1950 shipped for the atlas i had in the yj, which was a very good price. currently you are going to spend @$2500 plus the driveshaft etc work.
i went with the teralow so i can do the following:
not have to mess with my crossmember, which is also the mounts for my long arms.
no driveshaft work needed.
no speedo work needed.
no shifters to install on an xj (PIA).
i never once used front low with my atlas, although it was nice to be able to put it in rear low and knock the front end out. with selectable lockers, this is a minor point for me though (not to mention jk rubi 44's and chromo axles/cts u joints i now have).
ultimately if money was no object? i would have another atlas in a heartbeat.
in the real world of a crappy economy, mortgage, family to support etc, the teralow got my vote.
another option is a klune underdrive, it gives you a 4 speed t/case with lower gearing than the atlas if needed, as well as your exiting ratios and the ability to run it in 4:1 on the rear end only. i happen to have one for sale
hope this helps.

martin
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Unread 09-08-2009, 08:38 PM   #11
doug_1994
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Quote:
Originally Posted by KMA Krawler View Post
What junkyards do you know that have 241OR's?


Car-Part.com--Used Auto Parts Market


I found about ten.


I you really want gears, put two t-cases in! HA!
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Unread 09-14-2009, 05:46 PM   #12
moonshinefuel
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Kind of reviving this thread..but.. I did find one that just came online today on craigslist Los Angeles. 241J with 4:1 ratio, claims very very low mileage. He didn't list a price so I called them, was told $900.00 an hour ago. That's about a third of the price of an Atlas. Still available. Transfer Case 241J for Jeep TJ
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