Building up an NP-231, few questions about parts to do so

Well, possibly stepping up a few extra modifications to the Jeep... The plan has always been get the Jeep done, then when the transmission goes (presently had the Peugeot-10), replace it and the t-case with an ax-15 and a newer NP-231. At the same time though, I am going to be adding upgraded upper control arms, and "Superizing" the 231. I was going to wait until I finished the XJ to even begin to look into this stuff, but I found a very good deal on the tranny t-case combo that I can't pass up, and am getting it tomorrow. I still plan to wait until the present one goes to replace it, but if I can get this stuff in the 231 sooner, then I will just swap it out when I complete the 231 build up.

The plan is to add these upgrades:

- Slip Yoke Eliminator
- HD chain and sprockets
- 6 planetary gears out of a NP 241
- The proper gear for the speedometer to register for 33's and 4.10's
- CV driveshaft for the SYE
- Maybe the low range kit if there is enough money left after the above

I figure I may as well do everything I can to the t-case while it is open, and get it all done at once to save the time of having to do it again in the future.


What I am looking for here is this, I know I can get the planetary gears out of an Np 241. I am wondering what model and year vehicles have these that I should be looking for in the scrapyard? Are there any junkyard parts that may have the hd chain and sprockets I could use for this build up? I know the low range kit I will have to buy, which is part of the reason I am hoping to be able to do the rest of the upgrades cheap enough so I can afford the low range kit. Also aware of having to get the speedometer gear new.

One more question, for the cv shaft, is there any vehicle I could look for in a scrapyard that may have something I could use for my build up? The rig it would be going in is an 88 XJ, 4.5" lift, with a 8.8 in the rear. Or would the driveshaft be something I would have to measure for after putting in the SYE?

Thanks for any help you may be able to provide.

Paint

who sells a 4:1 kit for the 231? thought that was only available for the Dana 300 and the np207?

Tera-Flex is the only company I have seen that makes one. Something like $240ish with shipping which is why I might not do it. If I can do the rest of those modifications cheap enough, then I figure I may as well do it, do every upgrade to the thing I can while I have it all torn down lol.

Paint

Samsoffroad.com has 4:1 kit for 975.00&2low kit for 242.00

Passing on the 4:1 kit, outside budget too much lol. Was planning on that 2:1 though, meaning that is the final option for me with this build, IF there is enough money left after the rest of the parts... Thanks again,

Paint

Well, bought the Slip Yoke Eliminator, and the HD Chain and Sprockets. Picking up a 241 locally for the Planetary Assembly, and have since decided to pass on the 2wd low kit from Tera Flex. Just too expensive and doesn't really offer me any advantage I couldn't get from using the correct locker.

Onto the new issue though...

I also got a front driveshaft from a ZJ a friend has for parts. It appears to be the same length as my XJ front driveshaft. The issue I am having is, everyone I have talked to said that I would have to shorten a front XJ driveshaft for use with the rear axle. Measuring from the Ford 8.8 to the back of my t-case, it seems to be too short. And that is not taking into account the SYE (which should increase that length measurement). Possibly a stupid question, but would this just mean I need to lengthen the shaft? Or will the measurements change enough when I do the SYE that I will still need to shorten the DS?

Thanks again to all who have helped out.

Paint

The SYE will make the distance from the t-case to the rearend yoke longer.

You will need to pick up a 241 from the correct years to match the build date of the 231. The planetary gear cut changed at some point. Early 90's I believe. I had to deal with that when I started my doubler build.

Personally I have never seen the planetaries shot in a NP231 and I run a stroker and have 10+ years on mine with 35's. Thought about doing this, but it never seemed worth the hassle.

The wide chain is nice, but if you check/replace the chain every few years it should be fine. Chains sometimes stretch over a long period of extreme use, but rarely break. The chain is only under tension when you are actually in 4wd.

As for the Terra2Lo kit, if you have a lunchbox up front, it is REALLY nice. It is one of the nicest upgrades. It really comes in handy on slickrock or on tight switchbacks.

nwautoxer said:

You will need to pick up a 241 from the correct years to match the build date of the 231. The planetary gear cut changed at some point. Early 90's I believe. I had to deal with that when I started my doubler build.

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I am aware of this, the guy I am getting it from had the 241 for the same modification, he just never did it. Should be the correct part. Guess I will find out lol.

old_man said:

Personally I have never seen the planetaries shot in a NP231 and I run a stroker and have 10+ years on mine with 35's. Thought about doing this, but it never seemed worth the hassle.

The wide chain is nice, but if you check/replace the chain every few years it should be fine. Chains sometimes stretch over a long period of extreme use, but rarely break. The chain is only under tension when you are actually in 4wd.

As for the Terra2Lo kit, if you have a lunchbox up front, it is REALLY nice. It is one of the nicest upgrades. It really comes in handy on slickrock or on tight switchbacks.

Click to expand...

I have no doubt they would be good for quite some time, but if I am in there for all the other stuff, and for the price of the planetary assembly I figure I may as well upgrade everything I can while in there. Can't hurt anything so... That and if for whatever reason I part out the XJ in the future (I honestly don't see that happening lol) It will add quite a bit of extra value to the t-case lol.

I have decided not to go with the Terra2low kit. Too much for me at this time, and not enough benefit for my needs to make it worthwhile at this time. Also, presently I am not locked up front. Would like to, but a locker is outside my budget. When I do eventually get one though I will probably reconsider the low kit. Only other thing, no plans for rocks ever...

Thanks again to all,

Paint