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Getting Ready To Upgrade My NP231 And Need Some Advise

Ice_Man

NAXJA Forum User
Location
Western, MA
I have the NP231 out of a 2000 XJ, 4.0L, automatic transmission, part time 4x4. I currently have plans and have purchased a slip yolk eliminator kit (full kit, not hack and tap). My question is; if I purchased 1-1/4" chain upgrade along with the 6 gear planetary pinion set from this guy ( http://www.ebay.com/itm/310373471642?item=310373471642&viewitem=&vxp=mtr ), will this entire setup all be compatible (SYE/ 1-1/4” Chain and Gears/ 6 Planetary Pinion set)? I have never rebuilt or done an SYE on a transfer case before, so I would like to do it right the first time. Is there any thing else I should consider? Should I pick up a NP231 rebuild kit with new bearings? Are there any other heavy duty upgrades I could do while I have it out? How about 4:1 ratio? Thank you in advance for your help.
 
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If you have the coin do it. Some things can get expensive. Yes the planetary and wide chain kit will work. Just make sure you get the wide chain kit with the wider gears and not just the chain. And yes get a rebuild kit. New bearings, seals, and the shifter fork pads are always a great idea you have the case already opened. For the little amount of money why not. As far as the 4.1 kit.... This is a preference thing. The 4.1 kit is expensive as hell. iMHO if you're going to do a 6planetary, a widened chain and a4.1 kit you might as well go and get a rubicon 241 transfer case. In stock form it is everything the 231 inspires to be. Just a stronger t case all the way around and comes stock with the 4.1. I have seen them go from around 700 to 1300 depending on the seller. Most of the time it's around 900 from what I've seen. The 231 is plenty strong and reliable and with a see it's even stronger. I personally would go the 241 route over the built up 231. If you want to get even better buy an atlas.
 
$ is an issue so I guess Ill scratch the 4:1 idea, and as for the 241, thats a little pricy for my right now. It sounds like just the SYE, Wide Chain/Gear, 6 Planetary, and a rebuild kit for me. Do I have any other options or is that pretty much it?
 
As long as you stay away from the 4:1 kit, it is less expensive to rebuilt the 231. What I would not do is buy a used chain set off of Ebay...

I looked into doing the full retrofit (4:1, chain and SYE) on my 231 back in 2000 (this was on the 97 I had) and cost wise, for less than $200.00 more, I could have the 241OR from http://www.jbconversions.com/ they are a tad more spendy these days...

Do yourself a major favour and use new parts for the chain and sprokets.
 
What size tires and gearing do you run on your axles?

The 6 gear planetary and wide chain kit almost seem like a waste in a stockish XJ.
 
Another vote to stay away from used internals for NP231 overhauls. You've really got no way of knowing what shape the chain is in.

Wow. Prices have gone up a bunch. 10 years ago, I picked up an HD NP231J transfer case from JB Conversions for under $700, complete with an SYE.
 
Another vote to stay away from used internals for NP231 overhauls. You've really got no way of knowing what shape the chain is in.

Wow. Prices have gone up a bunch. 10 years ago, I picked up an HD NP231J transfer case from JB Conversions for under $700, complete with an SYE.


Yah, and I paid $1300 for a 241OR that was ready to bolt in. JB Conversions installed the correct U-Joint flanges and had it clocked correctly. It just bolted in. Even the linkage was easy to connect. This is back in either '01 or '02. The box is $1900 now... But, If I had a spare $1900 laying around, I would do it again. The 4:1 makes a huge difference.

But back on topic, avoid used internals. If you are going to go used, find a complete case from a Red Letter Member. I got the one I am running in my 98 from a Member out of Fort Collins for less than what the AA SYE on it would have cost me new. The Member is an upstanding sort of fellow and I have had zero issues. It just works as it should.
 
I wouldn't worry about buying used parts, there is very little that can go wrong with the sprockets that wouldn't have destroyed the aluminum case first, and a new chain from O'Reilly is only about $70(Cloyes p/n 10-022). So for $160 you have the same thing JB Conversions would sell you for $425. Take the money you just saved, buy your SYE, add another $30-40 to what you have left and buy your 6 pinion planetary from ebay, and you are done.

$875 to buy your wide chain, 6 pinion, and SYE new from JB Conversions, VS $380 for a used wide chain conversion, 6 pinion, and a new SYE.... $460 if you throw in a new chain. I don't know about most of you guys, but an extra $400 would be very useful when you want better shocks, tires, wheels, control arms, etc.


As far as used parts go, think about the odds: How many people actually use the 4wd on their vehicle more than a couple of times a year? Probably only in snowy conditions. A very small percentage actually take their vehicles offroad, and even then a very small percentage of them submit them to the kind of abuse that we would, that would cause the kind of stress to damage the sprockets. If you think about it like that, the chances of getting new parts with a factory defect aren't much better.
 
Im running 33"s with about 5"s of lift and stock gearing (power-trac in the rear). I have plans for an ARB in the front. I would like to stay away from used internals however I don't have the $ for a 241 right now and figured for under $200 I could improve the durability of my 231 for now and if blows up, it would give me a reason to get the 241 with the 4:1. Im overhauling it now because ill have it out for the SYE install and id like a little peace of mind. This XJ is built as an overland expedition rig and just as any other, reliability is important, especially since I mostly wheel solo. Thanks guys.
 
Im running 33"s with about 5"s of lift and stock gearing (power-trac in the rear). I have plans for an ARB in the front. I would like to stay away from used internals however I don't have the $ for a 241 right now and figured for under $200 I could improve the durability of my 231 for now and if blows up, it would give me a reason to get the 241 with the 4:1. Im overhauling it now because ill have it out for the SYE install and id like a little peace of mind. This XJ is built as an overland expedition rig and just as any other, reliability is important, especially since I mostly wheel solo. Thanks guys.

I've never seen/heard of someone blowing up a 3 pinion planetary so I wouldn't bother with the 6 pinion.

With 33s as an overland expedition rig, I wouldn't even bother with the wide chain kit.
 
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