Looking for a low range option

[JasonB]

I'm looking at options for a low range that would improve my crawl ratio significantly. Once I'm done working on my 9 inch rear I want to eventually start working on doing the AW4 to AX-15 conversion. That's the first step in lowering the ratio. Next is what transfer case setup to go with. I know I could put a Rubicon tcase in (NP241OR) which would give me a 4:1 and would cost in the range of $800-$1200. Another option is to get the Tera Lo kit which would also give me a 4:1 and be around $1200-$1400. I have a second Np231 lying around extra in which I could use it to make a doubler. The thing is is I'd love to have a doubler but A. I'm not experienced in building one and I haven't seen a lot of information or write-ups about doing this and B. Is this a good setup because I've heard that a 231 due to it being chain driven and not gears it would be prone to breaking? The little bit of information that I have found with jeep doublers is that most people use the Dana 300 from the cj's. I'm trying to keep it as cheap as I can plus like I stated before I already have this second 231 lying around. I know with the 231/300 combo I would have to do a flip kit on it since the 300 is passenger side drop so that would be another cost plus the cost of acquiring a 300 which is around $300. i know with just the 4:1 option that only lends me two options (1:1 and 4:1) but with the doubler I would have three options with the 231/231 (1:1, 2.72:1, 7.40:1)and five options with the 231/300 (basically same as the 231/231 setup but an added bonus of having front wheel and rear wheel dig). If I went with the ax-15 mated to the 231/231 doubler I could net about a 160:1 crawl which would be great. Any help or advice in this matter would be very appreciated. Thanks

[schardein]

I've had 4:1 Teralow gears in a Dana 300 in my CJ7 for about 10 years.  If you can rebuild a transfer case, you can install the gears.  I do a lot of four wheeling, and they have given me zero problems.  Recently disassembled the case to put in a new input shaft (Installing a Vortec 5.3, adding a clocking ring and clocking the case close to flat).  The gears look like new.

 

Can't help on the 231 questions as I don't have much experience working on them.  

 

Not sure of the benefit of a 160:1 crawl ratio.  My 67 CJ5 and my CJ7 both have a 75:1 low/low and I can't imagine needing twice that.  

[benjy_26]

Will you be doing a lot of highway driving?

 

If not, the Saginaw trannys are cheap and have a ridiculous 1st gear ratio.

[JasonB]

Not a lot of highway use but I did want to keep it either an AX-15 or NV3550. There's even a NSG370 6 spd for sale that I looked at but too much for my taste at $1500.

 

I just wish that someone would cater to Jeeps like Marlin Crawler caters to Toyotas with the doubler market.

[DirtyComanche]

This is all my opinion based on what I have broken personally, or seen break in person, or a trusted internet source has broken and documented.

 

I would not buy a Teralow kit for the NP231.  Yes, people have them and love them.  However, they're a total timebomb and their inability to cut the gears correctly means you have to limit input RPM severely in order to get any real life out of them.  This straight up does not work in certain situations, as with the 4:1 reduction you are lower than you already want to be some of the time, but high range would still be too high.  Specifically I am talking about mud, loose hills, and snow (may not apply to you).

 

The 231 is NOT up to the task of being the case behind a doubler.  It is a time bomb in this arrangement.  It will live longer with a HD SYE providing the front axle does not have a locker, but a failure is mostly inevitable.  If one wants to use an aluminum tcase behind the doubler, a GM or Dodge NP241 would be a decent option, as you get 6 pinion planetaries, a wider chain, stronger case halves, and 32 spline outputs on both ends.  One good thing about going this route is it does not weigh much more than a Np231 (231 is say 65lbs dry, 241 is about 80lbs dry IIRC).  The length disadvantage of this arrangement is largely irrelevant in a MJ, with the exception of the front driveshaft starting to be longer than what I find comfortable.  You will be hacking your floor pretty badly.

 

I have limited use for the D300.  The problem with it is that by the time you buy all the upgrades, you are approaching the price of buying a NEW Atlas.  However, you can find ones that are already built for pennies on the dollar.  The other thing that bothers me about them is if you run them flipped, which you will probably be doing, they tend to leak.  As in, I've never seen one that doesn't.  The seals for the shift rails were only meant to seal in a little splash oil, and seal out a little splash water and dirt.  If you don't care, then fine, for me it bothers me to the point that I couldn't do it.  As said, the Teralow gears for the D300 are fine, there is no limitations with using them.  The D300 is nice in that it is more compact than the other gear drive options, and does not weigh as much as them (85lbs dry in stock trim, it weighs more with HD outputs).

 

Personally I went with a NWF Ecobox (http://www.northwestfab.com/NWF-Eco-Box-Billet-Planetary-Doubler-Case_p_2403.html) and a Ford NP205.  This was because I had a broken NV241DLD to harvest the planetaries and ring gear from, and a couple useless NP231s with my needed 21 spline input gear.  This gave me a much stronger setup, which is also more compact than a standard NP231 doubler, and there was no requirement to weld a blockoff into the stock case and risk not having it seal properly.  I don't know if anyone is reliably building NP231 doubler kits anymore, everyone that used to do it was out of business when I went looking to buy one.  Also NWF is somewhat local to me and charged me in Canadian dollars and shipped it free (not value to you, but it costs me a lot to get stuff out of the US).  With the Ford NP205 I get 32 spline outputs on both ends, twinstick capabilities, I don't have to run it flipped, and it's super strong.  Unfortunately I wound up cheaping out when it came to driveshafts and bought 1310CV yokes for it, in the long run I'm guessing I will regret this move.  The penalty on this setup is it is very heavy, with the NP205 being about 140lbs dry and the doubler itself being about 50lbs, and it became fairly hard to package as I wanted to preserve ground clearance and wound up cutting my floor out badly, modifying my seats quite a bit, and it needs a second mount to help control the weight.  Oh, I also had to cut a massive hole in the tcase itself and weld a plate over it, since Ford has a very awkwardly placed mount boss 'thinger' on the top of the case.  And building the shifter setup took a fair amount of time and headscratching.

 

At the end of the day the Rubicon case seems like an easy and cost effective way to go.

[JasonB]

I'm thinking of just running the Rubicon case for now as I am not that savvy in just rigging something up and creating a doubler. And like you stated above, the market really isn't supportive of the Jeep doubler setup. It must be nice if your a Yota guy with all the aftermarket doubler support. (Kinda hating on the Yotas right now) lol. At least if I get an AX-15 mounted to a 4:1 Rubicon case I can select a higher gear if I need wheel speed and hit first or second if I'm in a situation where I need more control. And if I hit first gear with that setup and my diff gears being at 5.13 then that brings my crawl to a 79:1. I would prefer more selections but I'm not willing to shell out the big dough for the Atlas or Stak tcase. I have found a Rubicon case locally for around $1200. I've looked on eBay and it seems like that's where the price is typical for them to be had.

[DirtyComanche]

Rather irrelevant, but I don't think you can buy a Stak anymore.  They went broke, TrailworthyFab (IIRC, Dookey on Pirate) bought up the IP/rights to all their stuff, and since then he hasn't bothered to do anything with most of it.  Some people were pestering him to put stuff back into production, but he isn't interested at this point for whatever reason.

[JasonB]

Gotcha well either way they are way over my price range lol. Thanks for all the info. Seems like your a well informed individual. If you have any other suggestions just please don't hesitate.

[xjrev10]

Only thing I have to add is that the nv3550 has a lower first gear then the ax15. (Love mine)

 

A nsg370 takes some doing to install due to an integral bell housing and the crank sensor becomes a issue. I'm still waiting for a successful swap behind a renix. I know Pete Trasborg did one in his red MJ but I could never find the specific info about the crank sensor.

 

I'd also like to know where you are finding a rock trac for $1200!

[mnkyboy]

NWfab econobox will hook right up to a 231,TMI is also making a crawl box that will bolt up.

Mountain air offroad reverse engineered the Box4rocks so they are available as well,probably some other options too.

 

So there are doubler options for Jeeps.

[mnkyboy]

I have an AX15 hooked to a Behemoth crawl box hooked to an NP231 with 6 pinion planetary,wide chain,and Teraflex SYE. 7.4:1 is awesome especially since i have it all behind a 2.5l.

 

I can idle over almost anything.

 

[JasonB]

XJrev, man I can't tell all my secrets. Lol I think I can get the guy down even further than $1200. Cash talks!

 

Mnkyboy, dude that looks like a great setup but ouch at the floorboard. You had to fillet it. It would be nice to fix it up where u could just have an access hole for maintenance. Drill some holes and rig up clips and bolts. Just might work

[DirtyComanche]

NWfab econobox will hook right up to a 231,TMI is also making a crawl box that will bolt up.

Mountain air offroad reverse engineered the Box4rocks so they are available as well,probably some other options too.

 

So there are doubler options for Jeeps.

 

Who is TMI?

 

The umm, Mad Rooster? design has been cloned and made by various companies over the years.  The problem is all of them seem to go broke.  So one day you can order one, the next day you can't, the day after that you can get it somewhere else.

 

The EcoBox/BlackBox was really meant to be used with a NP205, it's honestly stupid overkill to bolt a NP231 to it.  Of course, they then offered their Titan setup for whatever reason, I'm guessing somebody with 1000HP and 40" tires managed to break a normal BlackBox.

 

Behemoth went out of business too, right?

[mnkyboy]

TMI is Total Metal Inovations.

 

The black box titan is meant for a 205,the eco box is nearly identical to my Behemoth.

And yes Behemoth fell off the face of the earth,mine would have been one of the last.

[mnkyboy]

XJrev, man I can't tell all my secrets. Lol I think I can get the guy down even further than $1200. Cash talks!

Mnkyboy, dude that looks like a great setup but ouch at the floorboard. You had to fillet it. It would be nice to fix it up where u could just have an access hole for maintenance. Drill some holes and rig up clips and bolts. Just might work

The floorboard is mostly due to the tummy tuck,the entire power train has been lifted,i have about 7" of lift but the belly clearance is just over 2 feet,nothing is lower than the frame rails.

 

The plan is to rebuild the floor with access panels.

[DirtyComanche]

The black box titan is meant for a 205,the eco box is nearly identical to my Behemoth.

 

I don't want to argue about it, but I've met the guys there and was buying NWF products when they designed the original BlackBox.  It was designed around being bolted to a NP205, it's internally nearly the same as a Behemoth, but the case was made stronger around where it bolts to the second tcase, and minimal material was removed to clear the NP205 shifters.  This was to avoid problems with having the case break from the weight of the NP205, even though they recommend you run an additional mount on it (you will break most aluminum transmission tailhousings hanging that much weight off them).  I never asked him specifically why they made the Titan, as in if guys were having failures, but it's obvious that it's marketed to the big $$/HP crowd.  The Titan has not been around for nearly as long as the BlackBox, which makes sense because the big $$/HP crowd is something that's relatively infant compared with tradition rockcrawling.

[Rockfrog]

I've often thought of using a black box (econo) and hanging a Ford NP208 off the rear on my XJ. That allows for addition of a Ford 205 at a later date should the need arise. Never had an issue with the 208 I abused in my Bronco. The 208 is far from perfect but should work for my uses.

 

Sent from my SGH-I337M using Tapatalk

[mnkyboy]

I have a Titan and 205 set up in the shop,until last weekend we had two eco black boxes and two Behemoths sitting there too.

The eco boxes didn't look any beefier than my Behemoth and it uses the exact same gear set.

 

Mine doesn't have the cut out for the 205 but Behemoth had a version that did,he also had the equivalent of the Titan that was about to release before he disappeared,we had one on order when Jacob quit responding.

 

Really you could put stock 231 guts in an eco box and have the same thing as a 231 doubler but with a stronger case.

[mnkyboy]

 

The black box titan is meant for a 205,the eco box is nearly identical to my Behemoth.

 

 

I don't want to argue about it, but I've met the guys there and was buying NWF products when they designed the original BlackBox.  It was designed around being bolted to a NP205, it's internally nearly the same as a Behemoth, but the case was made stronger around where it bolts to the second tcase, and minimal material was removed to clear the NP205 shifters.  This was to avoid problems with having the case break from the weight of the NP205, even though they recommend you run an additional mount on it (you will break most aluminum transmission tailhousings hanging that much weight off them).  I never asked him specifically why they made the Titan, as in if guys were having failures, but it's obvious that it's marketed to the big $$/HP crowd.  The Titan has not been around for nearly as long as the BlackBox, which makes sense because the big $$/HP crowd is something that's relatively infant compared with tradition rockcrawling.

I know a 205 will work with the standard box but the titan is the 205 specific box.

 

It is stronger than the regular box for high power but it is also around 3" shorter than the standard box which is huge when driveshaft length is a concern.

[DirtyComanche]

Image Not Found

 

Only picture I have that shows it, but the EcoBox has more material around where it bolts to the tcase, as they left the case at full diameter between the reliefs for the studs/nuts and the shift rail on the other side.

 

Has anyone broke a Behemoth?  No idea, don't really care either, since it's now obsolete anyways.

[mnkyboy]

I see,it's the clocking ring on mine,i could have got it without but i wasn't worried about it.

 

Either box has to be stronger than the mad rooster/box4 rocks ect.....and people rarely break those.

I've already decided that if my Behemoth gives me trouble it will be swapped for a black box.

 

 

For $729 the eco box kit is a good option for our Jeeps.

[DirtyComanche]

Yeah, I think the EcoBox is a good deal.  I think it's worth it in the long run to just spend a few more bucks rather than messing with the ones where you hack up a regular ol' tcase.

[mnkyboy]

That's how i ended up with the Behemoth,the hacked up 231 kits were around $500 and the Behemoth was like $635 shipped.

Stronger with almost limitless clocking configurations for barely more money.

 

Originally i wanted to put a D300 behind it but decided later to go with a built 231 since i already had it,with 231hd/241 guts it should be pretty tough as long as i don't break the 231 housing itself.

[JasonB]

Ok so ecobox is a good option. Where do I find this? How much does it usually run? And what are the details to installing it? Does it bolt onto my existing 231?

[DirtyComanche]

http://www.northwestfab.com/NWF-Eco-Box-Billet-Planetary-Doubler-Case_p_2403.html

 

I highly suggest phoning them and talking about you specific application, as they will point out whatever issues you might have.  And read the instruction manual before ordering so you know what you're getting into.  You need a 10+ ton press to assemble it (they say something like 30, you can get away with less).

 

One thing is they don't (or didn't) offer a 21 spline output.  This is okay because you don't want to run that, IMHO, but it means you can't bolt a pre-91 4.0L tcase to them.  So what you're going to wind up doing if you're in that situation is taking the input gear out of your 231, and using it as the input gear in the EcoBox.  Then if you buy it as a 23 spline output shaft you can bolt up any later NP231J out of an XJ.

 

The EcoBox is just a case that you can put the planetary set out of a NPwhatever aluminum tcase into.  It comes with whatever output shaft you need, the shift fork, and a stud/hardware kit and a few other things.  You will have to get a tcase to steal the planetary set out of, but you can use the one you have now if you pick up another to use as the 2nd tcase.  You will probably have to physically destroy the case half to do this, as not many people have the needed press too to get it out, YMMV.  You then need to press the ring gear you stole into the EcoBox, make sure you have the proper press tools when you do this as you do not want to damage it.  Then you drop your planetaries and input gear into it, then assemble the two halves of the EcoBox together, figure out your clocking, seal it up, install the input seal housing (also stolen from the donor tcase), and then you can then stick it onto your transmission, and bolt whatever tcase you want to use to the back of it.

 

As I said, I would avoid using a NP231 as the second tcase.  If you're gentle with it, it should be okay for at least a while though.  Also, they will recommend you use a 6 pinion/planet reduction set in the BlackBox, which I would agree with, however it's far more important that the second tcase has this. You will probably be okay just using a 3 pinion set in the EcoBox, especially if you only plan to use a NP231 behind it.

 

I didn't document assembling my EcoBox very much, as it was fairly straightforward.  But there is some threads on Pirate and other places that show it in reasonable detail.  Make sure you're up for it before you do it.  It isn't hard, but you do need a press.  Also you will have to build a shifter setup or buy one, so be prepared for that.  For my EcoBox I bought a blank shifter and boot from JB Custom Fab and welded it to the supplied fork adapter, it fits between my center console and the passenger seat tightly, and I had to bend it a bunch in my press to make it just right.  My NP205 twinstick setup (pictured in my prior post) is not really relevant to you, I believe you would just have to lengthen the one rod on your stock shifter setup to be able to shift the 2nd tcase.

 

I hope my post makes some sense, I'm supposed to be sleeping right now so I'm not firing on all cylinders.