Transfer Case Indecision (A copy from my build thread)

[DirtyComanche]

Figured I'd post in tech too because I'd like more opinions... My XJ has 1-tons, 37s (planned), double beadlocks (planned), a 4.0L (as long as I stick with it), probably going to go AX-15, and will weigh some serious numbers... Oh, and I consider component failure to be basically unacceptable.

 

So...

 

I'm pretty undecided on my transfercase... I was just going to run the NP241DLD and call it good. Strength wouldn't be an issue, and I located a flange to do a hack'n'tap style SYE on the rear for cheap. The only issue is I really don't like the 2.72:1 low. I had figured I could fight it with the AW4, just run a big trans cooler.

 

Right now I'm leaning away from the AW4 and keeping the AX-15... There is no way I will live with the AX-15/NP241 setup unless I run something silly like 7.17s in the axles (which I won't do for other reasons). This requires a doubler, or something else. My first instinct was I probably could run the box4rocks 231 doubler with the 241 behind it. Strength wise, I don't think I'd have any real issues. Driveshafts would be a different matter. The front would be grossly too long. This would require a 2-piece shaft with a carrier/hanger/midship bearing. Given that I'm unwilling to run 1310 ujoints, this leaves me with a sneaking suspicion that I'd have a very costly front driveshaft as I don't think the junkyard would yield many usable parts.

 

From there I figured 'A D300 as the second case would be easy! :brows: ' As I looked into that, I started to get :( Both outputs on a D300 are 27 spline - unacceptable stock NP231 junk basically. So, they'd have to be changed. After that the common failure point appears to be the gears, and they like to go badly when they do. The option is to run the lowmax 4:1 gears, which are pricey. And then I started looking at case failures... Stak makes a better case, but you might as well have bought a real stak at that point. My conclusion is that the D300 was engineered to be a damn fine 1/4 - ton tcase, and that's it. My likely final weight is simply going to be too much for it to jive with my requirements for reliability.

 

So, I could buy a stak or an atlas. Maybe by christmas time I'll have saved up enough 'fun money' for that. Probably not.

 

The last option I could think of is the one I've always written off. The bloody old NP205. Basically indestructible, at least that I can tell. I will have to look into the failure points of them, but I'm certain they've all happened behind big blocks and been in 8000lb trucks. I could either run the NP231 box4rocks into it, or a NP241 box4rocks... I'm leaning towards the 241. I think I should track down a passenger drop case for that (earlier dodge, maybe some others?) as there might be interference potential with the front output on the NP205 otherwise. As I gather, it would probably make the most sense (and be the strongest) to track down a short chevy 32-spline NP205 input gear so I could use a 32 spline output on the doubler. I'd install this in a ford NP205 with the round pattern as they have 32 spline front outputs, and 32 spline rear without a slip yoke (haven't checked that for sure). A major issue is the one shift rail won't work; the case has to be drilled for it to come out of the back. Beyond that I can grind them to be twinstick. Also, it weighs a lot, so I absolutely need an extra mount on it, which will require some more research. My last concern is sizing of the NP205 and how well it will fit (seat interference might be the problem, my floor certainly isn't).

 

I'd have a 5.33:1 with the 241/205 setup.

 

I would like input as to of the technical accuracy of what I've said, and what people think beyond that. Is there other options I've missed? Etcetera...

[Pete M]

Just to clarify, the Rubicon 4:1 231 t-case is too weak? Too expensive? Both?

[jpnjim]

I went through a similar thought process with my build.

 

FWIW, you didn't have to describe your XJ :nuts:

 

I think EVERYONE has seen that build already. :cheers:

 

When I was reading the thread on here & Pirate, I was thinking this thing needs an Atlas. :thumbsup:

 

 

 

 

If you are going to go 205 (will it fit?), a 203/205 doubler might be a better choice (& stronger).

Plus there's more choices of where to get one.

 

The 203 weighs more, but if you're going 205 anyway, what's a few more lbs?

 

 

 

 

After obsessing about this stuff for way too long, my general opinion:

 

Dana 300/Stak RAC:

D300 for low bucks (esp if 2.6:1 is enough).

STaK D300 Replace-a-case if an Atlas/Stack mini would be a tight fit.

Other than that, it's not worth it for the couple hundred bucks you might save (even though that RAC case IS beautiful :banana: ).

 

 

Atlas/STaK mini

I like the STaK 3spd gearing best, but (again, IMO) the 4spd Atlas is a better fit for an XJ, to get the ft driveshaft length up a little.

 

I bought a regular Atlas on 'Christmas special' last year ($2k for any ratio + HD ft output + oil kit), and feel I'm going to have to limit axle droop on the drivers side, to keep from maxing out the ft driveshaft angle.

It's not installed yet, but I had a flipped D300 in there (= same length ft shaft), and was easily maxing out the double cardan at full droop.

 

I'm still considering putting in a box-4-rocks too, but that's way more gearing than I need (Atlas is 5:1 w/NV3550 & 4.56's).

 

 

So, after all that, I guess my opinion is do a 4spd Atlas, or a 203/205 doubler if you have room (Dodge 203 will bolt to the AX15).

[jpdocdave]

i've been through this all to, in my yj i'm going w/ np 203/d300 doubler. i say 203/205 doubler is your best bet. the reason i didn't do that one is for the clearance, cuz its bigger and hangs lower, and the weight/ length.

 

i'd rather build one of these, than buy an atlas or whatever.

 

if you going through all that and talk about failure, why run either of those transmissions? i'm running the sm465 6.55:1 first gear and indestructible. there's quite a few better trans options to consider if you wanna build this strong.

 

edit: i bought my sm465 w/ the 203 already on it for $20 :clapping: :yes:

[dunl]

Hey Dirty...there's an Atlas for sale on the Calgary Jeep site....

 

http://forum.calgaryjeep.com/index.php?topic=13546.0

 

I know where you are, but consider that they are hard to find up here, and you wouldn't have to worry about cross-border shipping.

[DirtyComanche]

Hey Dirty...there's an Atlas for sale on the Calgary Jeep site....

 

http://forum.calgaryjeep.com/index.php?topic=13546.0

 

I know where you are, but consider that they are hard to find up here, and you wouldn't have to worry about cross-border shipping.

 

 

If I'm reading it right, it isn't worth it. Wrong drop, wrong input, flanges have to be changed, and it's only 3:1. If I was going to be happy with that, 2.72:1 would be close enough. I passed up another one for $2K that was 3:1. I'd still have to run a doubler in front of it, IMHO.

 

There's also a stak 3-speed mini for sale in Calgary, same deal, totally unused (in shipping crate). Too much money for now... Same goes for spending $2k on an atlas, really.

 

Oh, BTW, I was in Calgary for most of the weekend. Went to pick up some parts (work related) and wound up sitting around due to shipping related issues. Now I'm in beautiful La Ronge, Saskatchewan, hoping that the locals don't steal my truck.

[DirtyComanche]

Just to clarify, the Rubicon 4:1 231 t-case is too weak? Too expensive? Both?

 

 

Bad bang for the buck, at least around here. I haven't been able to get a price on one even. I'm figuring it would probably be $1200 min. Beyond that, it seems a little funky to me, needs flange conversions (I think), and can't be twin-sticked. Which isn't a requirement, but if you're going to spend the money... Also, I'm not sure on the 4:1 doing what I want, totally. I'd have to bother to do a little math, but I think I'd like a lower low, and a mid-range gear.

[DirtyComanche]

i've been through this all to, in my yj i'm going w/ np 203/d300 doubler. i say 203/205 doubler is your best bet. the reason i didn't do that one is for the clearance, cuz its bigger and hangs lower, and the weight/ length.

 

i'd rather build one of these, than buy an atlas or whatever.

 

if you going through all that and talk about failure, why run either of those transmissions? i'm running the sm465 6.55:1 first gear and indestructible. there's quite a few better trans options to consider if you wanna build this strong.

 

edit: i bought my sm465 w/ the 203 already on it for $20 :clapping: :yes:

 

 

I shy away from the 203/205 setup because it isn't low enough, or so I think, again I should do some math. They're both 2:1. The 3:1 gears for the 205 are quite expensive (since they come with a new case), and I'm not sure if the 203 gears are still available. I'll say it again, I'm a little strapped for cash, as I have to budget at least $3K for rims/tires :ack:

 

Also, I wanted to maintain the street manners of this... Somewhat. SM465s are great. I just hate shifting them. Also, a lack of overdrive is a bit disconcerting. The alternative is to leave my rather high ratio gears in the axles (I have a set of 4.10s that are okay enough to run), and say screw the OD. That might work, other than it will leave some fairly wicked gear splits. I'd probably have to, again, do some math before I figured if that was a good idea. Cheap, yes, but I don't know about adapters. Or how well it will fit, but I don't recall it as being a terribly large trans (mainly height is the issue, not that I can't work around anything). I wonder what the combined weight of a SM465/203/205 setup is...

 

Also, I think an AX-15 shouldn't ever fail behind a 4.0L if it good shape, and some level of common sense is used while driving. I could be wrong. I may look into the costs associated with a rebuild, since mine probably isn't 'in good shape' :rotf: .

[DirtyComanche]

Atlas/STaK mini

I like the STaK 3spd gearing best, but (again, IMO) the 4spd Atlas is a better fit for an XJ, to get the ft driveshaft length up a little.

 

 

I don't have too many worries about the length of my front shaft. I think as I had left it my front axle is at least 4" forward over stock, and it will have minimal static angles due to the height of the rig. The main issue with it actually might be if it clears the LCA backets on the frame. If anything, having it shorter with a tcase that keeps it tighter to the transmission might be better. Other than that might result in some interesting compound angles, not the end of the world for a front shaft. It's all rather academic without parts to see what fits best.

[reson46]

Just to clarify, the Rubicon 4:1 231 t-case is too weak? Too expensive? Both?

 

Do the JK Rubicons use a 4:1 231? I'm pretty sure the TJ Rubicon used the 241, but I don't have as much experience with the JK Rubicon.

 

i've been through this all to, in my yj i'm going w/ np 203/d300 doubler. i say 203/205 doubler is your best bet. the reason i didn't do that one is for the clearance, cuz its bigger and hangs lower, and the weight/ length.

 

i'd rather build one of these, than buy an atlas or whatever.

 

if you going through all that and talk about failure, why run either of those transmissions? i'm running the sm465 6.55:1 first gear and indestructible. there's quite a few better trans options to consider if you wanna build this strong.

 

edit: i bought my sm465 w/ the 203 already on it for $20 :clapping: :yes:

 

 

I shy away from the 203/205 setup because it isn't low enough, or so I think, again I should do some math. They're both 2:1. The 3:1 gears for the 205 are quite expensive (since they come with a new case), and I'm not sure if the 203 gears are still available. I'll say it again, I'm a little strapped for cash, as I have to budget at least $3K for rims/tires :ack:

 

I'm also not a big fan of the 203/205 doublers. Strong, yes, but with a combined low range of only around 4:1! Not worth it.

 

I ran a 4.3 Atlas in my XJ for years. So far, for a single low range set up, that is what I have been happiest with. I liked it a lot better than the 2.72 of the 231. But, I still ran into situations where I wanted either a lower gear or a higher gear.

 

Willy

[jpdocdave]

i've been through this all to, in my yj i'm going w/ np 203/d300 doubler. i say 203/205 doubler is your best bet. the reason i didn't do that one is for the clearance, cuz its bigger and hangs lower, and the weight/ length.

 

i'd rather build one of these, than buy an atlas or whatever.

 

if you going through all that and talk about failure, why run either of those transmissions? i'm running the sm465 6.55:1 first gear and indestructible. there's quite a few better trans options to consider if you wanna build this strong.

 

edit: i bought my sm465 w/ the 203 already on it for $20 :clapping: :yes:

 

 

I wonder what the combined weight of a SM465/203/205 setup is...

.

 

umm, heavy, my trans w/ just the range box hooked to it now is too heavy to lift, i have to scoot it around the floor, and the d300 i'm putting on it is over 100 lbs, definately a heavy driveline.

[DirtyComanche]

Just to clarify, the Rubicon 4:1 231 t-case is too weak? Too expensive? Both?

 

Do the JK Rubicons use a 4:1 231? I'm pretty sure the TJ Rubicon used the 241, but I don't have as much experience with the JK Rubicon.

 

 

 

It's a 241J, aka NV241OR. Same case. I knew what Pete meant.