I know some guys are running doublers in their monteros and I am wondering how difficult was it to make the np231 work for your sport. I'm considering doin a doubler when I do my SAS and the 231/231 or 231/D300 is what i'm thinking about running. Did you retain the stock transmission or did you go with the AW4 out of a jeep.


I'm going to be running a hp44 and a 9'' with 4.88's if not lower gears.

You have to use the AW4(called 30-43LE in the 97-99 Sports). The V4A51 and V5A51 from the 2000-04 Sports won't bolt to the jeep tailshaft housing. I swapped in the trans from the older Sport because mines an 01. To do that you'll need, (from a 97-99 Sport)the trans, flywheel with bolts + t/c bolts, pilot bushing, and starter, oh and the plate that goes between the motor and trans, I forget what that's called.
You need the tail housing, output sensor, AND sensor wheel off the output shaft, from the jeep. I think 97+ xj's had the short shaft 231, and the 6cyl's were 23 spline,thats the one you need. I went with a 300 behind the 231 because no chain, and twin stick control.

The D300's are hard to come by and pricey aren't they?

My 300 was $75 shipped from a junkyard. Found it on car-part.com. Then it got a rebuild kit for another $100. Another thing about the D300 is, the 4:1 gears are $600 compared to the $1000 set for the NP231.:smokin:

Would this setup work with the 5 speed tranny out of a 99-97 sport or does it have to be the automatic tranny out of the 97-99 sport?

Would this setup work with the 5 speed tranny out of a 99-97 sport or does it have to be the automatic tranny out of the 97-99 sport?

That'd be a question for "ES97Sport"(Search that user name on 4x4wire to see his setup). I think he bought, or made, an adapter to run the 231 behind the 5-speed.:homer:

ES97 has his own site too... http://www.4x4extremesports.com

IIRC, he had a coupling "tube" for the shafts made, and an adapter plate.

Would this setup work with the 5 speed tranny out of a 99-97 sport or does it have to be the automatic tranny out of the 97-99 sport?

Hi, Badmonty. Nope. The manual and automatic are totally different animals. You need an adapter between the factory transmission to transfer case housing along with a stub shaft to connect the transmission output shaft to the transfer case. There's nothing 'factory' that even comes close.

It's not complicated. The transmission and transfer case shifter actually sit in the stock 5 speed transfer case so basically all you need to do is replicate the section of the factory transfer case that houses the shifter(s). There are plenty of pictures on my site that show the adapter. Any competent machine shop could do the adapter in a week.

The stub shaft is more difficult but only because you need a shop with an EDM to do the splined input for the transmission output shaft. The shop that did mine does custom length and splined axle shafts by the hundreds and they also do mold work so it wasn't anything out of the ordinary for them. They already had the experience and all the tools.

There are two materials to do the adapter in. Either steel or aluminum. In retrospect I might have decided to do it out of steel. With aluminum it gets pretty bulky but it's a lot easier. The bolt circle for the NP impinges on the weld just enough around the tube so I have a persistent leak around one of the bolts. 1/4" tube versus 1/2" would have given plenty of clearance. All the welds have to be fluid tight - harder to accomplish with aluminum. Of course, all this could be fixed by sealing the interior of the adapter.:)

I've spoke to a couple coating and treating shops here in Denver and they suggested epoxy coating the inside or maybe something as simple as gas tank liner. I haven't gone there yet. My '97 is getting a new engine next winter so while the engine is going in I'll do something with the adapter. Let me know if you have any other questions.

Edward

Thanks for the great info. and I have been slowly reading through your site since I am in school right now and should be focusing on that but sometimes I can't help it :D. I'll probably have some more questions when it comes time to actually start the project but for now its just a plan on paper.

plenty of people in Arizona that can help you out with dubs and SAS
http://www.4x4wire.com/forums/postlist.php?Cat=0&Board=azcrawlercrew

PM "sneakyninja" on pirate if you don't want to join right away, but they seem to hang out over there more often

Badmonty, did i see you driving on university and lindsay around 2:05pm about a week ago? do you have a tan/gold sport? I was driving this http://pics.montypics.com/toasty/2010-03-08/1268066618_693447288_duwj7_o.jpg

Oh and I have the shiz to adapt jeep t-cases, I'm putting a doubler in my other montero and have aussie crawler gears in the pictured montero.

Yup thats me. I was going to work. When are you doin the doubler? I would love to come learn a few things!!

as soon as it comes in the mail, and i work up the motivation. I still need to pay Nathan for it, just waiting for him to get back with me on shipping cost. You'll have to come over sometime and let me check out your sport. I also sent you an email about wheeling next weekend.

I wish I was a little closer, I would come and help in a heartbeat. These doublers are a big leap forward for those who wish to build up their Mitsubishi's.

I wheeled with that doubler, when it was attached to Nathans 95.:homer:

Oh yeah it'll be getting put to good use! no worries there.

I'd be glad to come over and I would love to see the doubler when it comes in.

I just installed the aussie crawler gears yesterday, HOLY SHIT that is a big T-Case! Definately a 2 man job, hopefully i won't be doing that again for a while.

Did you end up finding a spare t case to swap in?

If so questions bout it for future reference, is it any noticable longer or way different mounts then the v5mt1 and t case? I ever find a 4d56 or better for my monte I'm thinking rebuilt 6g74+aw4+3.15 t case gears in my 91 MM

It's much much different than the V5MT1 t-case and yeah i bought a donor t-case to swap the gears into first. These trannies in the Monteros are AW3s and they are a little different than the jeep AW4, I'd stick with the Montero trans they are meant for the bigger truck

in your 91 montero you'd be better off using the auto that came in the gen 1's (aw2,km148) then mating it up to dana case,np231, or even an atlas. In a gen 1 its easy to swap over from 5spd to auto, and the gen 1 auto doesn't need to have the tail shaft changed to use the t\cases above its already 6 bolt circle pattern. If you need more if info i've done more than a couple 5spd to auto swaps in gen 1's and i run a dana case behind mine.

Badmonty, you coming wheeling with us this weekend? You'll get to se a bunch of fully locked and crawler geared monteros in action.

I dont know if I can. You going on saturday or sunday?

I'm personally going sunday, half the guys are going saturday morning and the rest of us are meeting up with them sunday. It turned into a two day deal.

I'll be there sunday come join us on the rocks man its gonna be a blast great weather good people badass wheeling.

I wish I could. I'll go next time. School's almost out!!:flipoff2:

From guys who have done a SAS. Would you recommend doing the doubler first and then the SAS? Or do it all at once? I don't know what I should start with.

what kinda of wheeling are you doing?

Mostly crawling, I live in AZ so all there is out here is dirt and rocks. I'm going to build my truck to crawl. I'm just not sure what to start with... Eventually I'm doing a SAS and a doubler but just wanted some input from guys who have done this before or have some experience with this and if they did one before the other or if it is better to do one before the other.

I guess i'm confused on whether or not the stock mitsu t-case case be used after a SAS? I'm pretty sure the answer is no and i would rather not have it in the first place, with a extremely low 1.9:1 ratio:shaking:.

The thing about the stock t-case is strength, the other thing is that the rest of your truck is geard lower than normal to make up the difference. So you still have close to the same overall crawl as a stock jeep or whatever. This makes montero's easy and cheaper to get a better low range, and if you buy crawler gears for your stock case you keep the extra strength of the mitsu case. Montero's were designed to haul ass offroad and take a serious beating, they aren't too hard to modify for rocks. You need to see some of our trucks and how they are setup and you'll get some idea. I know the sport is way different than the actual Montero but you'll still be able to do a lot of the same mods we do. Your truck is actually the SUV version of the mitsu pickup so you can get some of the cool parts from those things.

I did mine at the same time(sas+doubler). No sense in making a front driveshaft twice.

find a set of axles, then doubler to fit which side drop the axle is

From guys who have done a SAS. Would you recommend doing the doubler first and then the SAS? Or do it all at once? I don't know what I should start with.

Speaking from experience, if you can't afford to do them both at once it's probably a better plan to do the doubler first.

If you do the SAS first and set up your pinion angle for the short front drive shaft you'll need to tear the axle out, chop off the knuckles, etc. and set your pinion angle again. You will need to run a shallower (closer to horizontal) angle on the front pinion as you move the rear, front output yoke back (towards the rear axle).

Unless, of course, you run a split front drive shaft. Which is something to consider. It limits articulation somewhat (although not horribly if you're doing a radius arm setup and not leafs) but keeps the drive shaft off the rocks. I suggest doing some surfing on Pirate regarding this. Several people have figured out after the fact that bashing the crud out of your drive shaft was worse than loosing a couple inches of articulation.

I think I figured that a solid drive shaft would cut my clearance behind the front wheels from 24" to about 15". The clearance would steadily increase, of course the further back you go. The real problem is what the buggy guys on Pirate have found. The first time you come off a shelf square you're going to land directly on the drive shaft. And, no, putting a 1/4" wall drive shaft in is NOT the solution.

Raole Duke: Front AND rear twice. Extend the front and chop the rear. Been there. Sucks.

The stock 5-speed Mitsu t-case can not be used and I can't see any reason in attempting to use the auto t-case. Put a d300 in or NP242 if you want to keep AWD. Unless you want to screw around doing 'front digs' the NP series will do just fine. I run the NP231 for the reduction box and the NP231 with the Tera Low231 4:1 kit for the t-case. That will give you more gearing than God. So far in a vehicle that weighs in at about 6300 when 'wheeling I've managed to break EVERYTHING around that setup (including the transmission) but not the t-case and doubler.

BTW, the Mitsu t-cases are NOT any stronger internally than a 6-gear planetary NP231. I've broken three of the Mitsu t-cases. In fact, they're much more prone to problems because there's about a zillion more moving parts. They're big, heavy and expensive to fix. The only benifit over the NP231 is that the case is stronger. Which, of course, is pretty much academic. How many people bust the case on an NP231 'cause it ain't strong enough?

Get drive side drop axles unless you want to re-engineer your entire exhaust and fuel system for absolutely no reason.

Almost forgot. If you do the NP231/NP231 setup, make sure you get either the Tera Low231 for the t-case or build the t-case with the 6-gear planetary unit. You don't want to run 2.72 into a stock 3-gear unit.

Edward

The problem with the 231 is that the case splits in half. Thats why i'm hesitant to use one behind my doubler, I'm gonna use the mitsu case then later switch to a D300. I have never seen or heard of a mitsu case breaking (until today and maybe sport t-cases aren't as strong) but i've seen a graveyard of 231's that cracked open and most in the same spot. Who knows maybe the doubler will blow up my montero's t-case and i'll slap a 231 on and give it a shot. Not saying the 231's are bad but i don't think they are better than the mitsu case. They do have a lot more options and upgrades but so do dana 20's and 300's which are better tham both 231 and the mitsu cases and they're cheaper to build.

I read a few threads on the 231 range boxes splitting, and it seemed to me that guys that had supported the very rear of the doubler with a bushing that still allowed the whole thing to torque over freely with the motor, but supported the extra weight, weren't having that problem.

I'll be adding that bushing to mine before it leaves my garage again.

The problem with the 231 is that the case splits in half. Thats why i'm hesitant to use one behind my doubler, I'm gonna use the mitsu case then later switch to a D300. I have never seen or heard of a mitsu case breaking (until today and maybe sport t-cases aren't as strong) but i've seen a graveyard of 231's that cracked open and most in the same spot. Who knows maybe the doubler will blow up my montero's t-case and i'll slap a 231 on and give it a shot. Not saying the 231's are bad but i don't think they are better than the mitsu case. They do have a lot more options and upgrades but so do dana 20's and 300's which are better tham both 231 and the mitsu cases and they're cheaper to build.

First, there's no such thing as a 'Sport' t-case and a 'Montero' t-case. Most of the Mitsu t-cases were interchanged between the Raider, Montero, Montero Sport, the pickups, etc. over the years.

The 231 CASE is not as 'good' as the Mitsu's. If by 'good' you mean 'as heavily built'. The Mitsu cases, like the D300 have to be built heavier with more reinforcement because of the way the internal transfer case parts operate.

When drive force is applied to two meshed gears they try to force themselves apart from each other. Hence, the posts you'll read here about the D300 splitting the case apart. The Mitsu internals work off of one gear driving another gear - just like most t-cases, differentials, manual transmissions, etc.

The NP231 uses a planetary gear setup with a single main 'drive' shaft running the length of the transfer case. Multiple gears in a unit rotate around the drive (main) shaft. The force is evenly distributed outward from the shaft to all the planetary gears in the ring. Since the planetary unit does not make contact with anything else no force is transmitted to the case and no reinforcement is necessary.

That is why the case is made lighter (and out of aluminum) than a D300 or Mitsu case for example. So, you can't really discuss whether the Mitsu case is 'better' or 'worse' than a NP231 because the internal engineering follows two completely different paths. It's like arguing over whether a glow plug in a diesel engine is better than a spark plug in a gas engine.

NP cases do not just 'split in half' and finding a or several broken NP231s in a junkyard, even broke in the same way doesn't really mean anything unless you know what was going on when each broke.

Three problems have been identified with the NP231. The input, the planetary unit and proper mounting.

The input and planetary unit are documented everywhere and have been for years and they're really not specifically related to whether they're used as a reduction box. But, there's no secret on what the problems are there.

Raole is correct. The third is proper mounting - and I've been arguing this point for two and a half years.:shaking: You CAN NOT dangle a 80 lb+ t-case off the end of a NP231 doubler housing without supporting the t-case. The force generated by the leverage is insane and no case was ever designed for that.

My personal opinion is that it's ridiculous that transfer cases aren't supported independently in the first place from the factory. There are two documented instances of the factory cast aluminum transmission to t-case adapter on the Mitsu shearing and I've found several more mentions of that happening since last June. Even when a housing is 'designed' to entirely support the weight of a t-case they still fail.

'Proper' is the key word, too. Slapping a piece of 1/8" steel on a couple t-case bolts and then welding that to a cross bar is insane even if you sandwich a flexible mount in there somewhere. You never want to torque a cast aluminum housing (much) and you certainly never want to do it unevenly.

http://www.4x4extremesports.com/modifications/NP231_Transfer_Case_2008/SNC00002-1024-Transfer-Case-Conversion-Feb-2009.jpg

Ideally, you want to do something like what I did above. Keep your mounts on the same plane so you eliminate trying to bend the entire t-case, doubler, transmission, bell housing assembly into some strange pretzel shape when everything loads up, and distribute the load where it was built to be distributed. In the t-case to transmission mounting area itself.

BTW, the only reason people run 20s and 300s is because the front output is gear driven not chain so theoretically they're more durable with more HP/torque and gigantic tires. The latter is arguable in my opinion. Two of the shops I've been dealing with for more than a decade run NP231s with Terra kits on v8 competition vehicles with 40 and 44s and they've never busted a chain.

Something to consider, too, if you're dead set on using the Mitsu t-case behind a reduction box what are you going to do about a fixed yoke on the front and rear outputs? The Mitsu slip yokes absolutely will not take 5.2:1 reduction for very long. Even if you do the 'drill and bolt' thing the yoke cap area isn't strong enough to take that kind of abuse. The metal is just too soft.

Edward

Or just buy a 4 speed t case and don't worry about what the internet thinks about doublers and what T-case is behind them. These break rockwells :D
https://secure.advanceadapters.com/images/uploads/2009111008514129659_lrg.jpg

I'll see how the Mitsu case likes a doubler, 37's and huge rocks. If or when it breaks it will be Dana 20 or 300 time.

Absolutely! The Stak is another good one.

The 20s and 300s definitely work. There's no argument there. Just make sure you're mounting is good and everything should be happy.

The good part about all this is our Mitsu engines don't put our a ton of torque so even with 2.27 into the Mitsu case the multiplication is still not too crazy. I haven't been able to find the specs for any of the Mitsu cases for what the maximum theoretical input torque is. It'd be interesting to see that data.

Edward

I think it'll be interesting to push it to it's limit and i know just the place, when the time comes i'll give it hell.

Have you started your doubler sneaky? I'd be interested in seeing it!

Doubler won't be shipped until Nathan closes on his house and gets done moving. I'm trying to get the engine swap done in that time, I'd also like to have the 3 link and flat bed finished. That will likely be one of the last things that gets done but i will let you know when its going down. You can even come over and help put it in if you want, it's easier with a second person. :D

Sounds good. I'd even like to come over and see what you got goin on now. Sounds like a pretty sweet project.

And thanks Edward for the wealth of knowledge its been very helpful. Sounds like you've been around the block a time or two. :grinpimp:

And thanks Edward for the wealth of knowledge its been very helpful. Sounds like you've been around the block a time or two. :grinpimp:

Too many times.:rolleyes::)

Edward

Any word on the doubler Sneaky?

Just wating on a shipping price and then it's on it's way, Nathan sent me a message saying he's moved and it's in his garage.:D

Iv read this post now and will someone tell me what a 'Doubler" is?

Just wating on a shipping price and then it's on it's way, Nathan sent me a message saying he's moved and it's in his garage.:D

Nice! Let me know when it come it

Iv read this post now and will someone tell me what a 'Doubler" is?

Try using the search feature, noob.

Try using the search feature, noob.

I did, but nothing I read told me what it is, a lot of posts talk of having them though

I did, but nothing I read told me what it is, a lot of posts talk of having them though

Now its posted somewhere.:rolleyes:

The term 'doubler' is used to generically refer to gear reduction boxes that mount between the transmission and transfer case. Putting the transfer case in 4-low and enabling the gear reduction box 'doubles' the gear ratio of the transfer case. Hence the term 'Doubler'.

[t-case 4-low ratio] * [reduction box ratio] = final ratio

4.0:1 * 2.72:1 = 10.88:1

The term "Doubler" is a misnomer as technically the ratio isn't doubled. Typically reduction box gear ranges start in the low 2.xx:1 and go up from there. Not that anyone cares - it's close enough for government work.:D

Indecently, if you have to ask - you don't need one.

Edward

Thanks, your right though, I dont need one. There is not much in the UK that you can drive over that would warrant the need for such low gearing, unless you are in Challenge Events

The doubler project has started :D. D300 on its way!

I sent you a PM

The doubler project has started :D. D300 on its way!

:smokin: Will it be getting a rebuild? Mine looked a little rough on the inside when I got it, expected for 30 year old parts, so it got a rebuild.

We'll see, it comes in on tuesday but from the pictures it looks in pretty good condition on the inside.