231 TC upgrades

StG58

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I ran across some interesting upgrade possibilities for the NV/NP231 transfer case while out browsing the interwebs. Totally academic for me at this point, but thought I would share.

I appears that you can upgrade to a wider chain in the 231 by installing a chain and both sprockets from a Dodge Durango 231HD. Any year appears to work.

To go from three to six planetary gears, you can use the planetary gears and carrier from a 241C transfer case out of a Chevrolet / GMC.

Then there are the various slip yoke eliminator kits, some of higher quality than others. Whose would you choose?

Any other hot tips and trick out there?

Now, I don't hear of many transfer cases in Jeeps grenadeing, but it is a good topic for discussion anyway.

We can do all sorts of magical upgrades to our Dana 30 / 35 axles to make them live longer and work better off road, and it appears that we can do the same with our 231 transfer cases.
 
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One of the best things I ever did to my past 231s was the Tera flex low range kit.
I know of three (Advanced Adapters tech rep can add more) 241 s that have exploded. Mine was one and the total repair bill was a tad over 5k with me doing all the work.
 
One of the best things I ever did to my past 231s was the Tera flex low range kit.
I know of three (Advanced Adapters tech rep can add more) 241 s that have exploded. Mine was one and the total repair bill was a tad over 5k with me doing all the work.

OUCH! 5 grand to fix a 231!? It only cost me a grand to do the NV246 transfer case in the 3/4 ton Suburban, including all the upgrades. And that was a specialty NV246 they only made for two years! What happened? What all was involved with the Tera Flex low range kit? Curious minds want to know...
 
It was/is the 241 that has the problem of the internal oil supply tube coming off.
This is what caused me to put the Atlas in. However, the collateral damage was extensive as if a bomb exploded next to the floor board. Not to the mention the damage both drive shafts did before they exited the vehicle.
This happened while being towed in Mississippi. Left me with a 4880 pound bike rack for the remainder of our cross county trip!
 
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I remember that from another thread now... That was a Rubi transfer case, wasn't it? Too lazy today to go look that up. There's a pretty easy fix for that if I remember correctly. As long as you do it BEFORE the TC blows up!
 
One of the best things I ever did to my past 231s was the Tera flex low range kit.
I know of three (Advanced Adapters tech rep can add more) 241 s that have exploded. Mine was one and the total repair bill was a tad over 5k with me doing all the work.
Stinger, when you do a low range kit, dosen't it take it to a 4 to 1 ratio? So what does it do to your 2 high driving gears? is it also lower too?
 
I remember that from another thread now... That was a Rubi transfer case, wasn't it? Too lazy today to go look that up. There's a pretty easy fix for that if I remember correctly. As long as you do it BEFORE the TC blows up!
Exactly correct.
Stinger, when you do a low range kit, dosen't it take it to a 4 to 1 ratio? So what does it do to your 2 high driving gears? is it also lower too?
I don't remember exactly. It has. Been many years since I have had a 231. But, IIRC it dropped the low range to at or around the 4:1 ratio. It did not effect the high range at all. Again IIRC there was a caution about running in 4x4 low and max speed because the new gears would turn at such a high rpm. It was nothing that the average wheeler would ever have to worry about. Maybe the guy who had the mod and was running in 4x4 on snowy roads on the way to work. Best check their web sight. I like their kit for this mod, but really don't care for any of their other stuff.
 
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Almost ready to install my Advanced Adapters transfer case cable linkage to get rid of the corroded , binding mechanical shift linkage.
 
Exactly correct.

I don't remember exactly. It has. Been many years since I have had a 231. But, IIRC it dropped the low range to at or around the 4:1 ratio. It did not effect the high range at all. Again IIRC there was a caution about running in 4x4 low and max speed because the new gears would turn at such a high rpm. It was nothing that the average wheeler expulsion ever have to worry about. Maybe the guy who had the mod and was running in 4x4 on snowy roads on the way to work. Best check their web sight. I like their kit for this mod, but really don't care for any of their other stuff.
Is IIRC a company ? Are you referring to irock? Sorry for the newbie questions just dont know all the mfgs.
 
Is IIRC a company ? Are you referring to irock? Sorry for the newbie questions just dont know all the mfgs.
If I Recall Correctly is what IIRC stands for and he is very likely referring to the 4-1 Tera Low conversion which replaces the front half of a 231. It has a smaller planetary gear set so you have to be careful how fast you spin it due to over revving the planet gears and burning them up. The 241 Rubi case has a monstrous planetary so it doesn't have the same issue.

There are only 2 good things about the Tera part. You don't have to replace drive shafts, change the linkage, do any fab work, or do a speedo correction conversion generally and it is a very easy swap. The biggest thing wrong with it is it is made by Tera and has quality control issues. I've got a brand new one in the garage I bought because the case was leaking fluid through the casting due to a porosity issue. I bought it cheap because I can repair it.
 
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What Blaine said.

When my 241 blew up the only thing left was that "monstrous planetary" gear hanging on the back of the transmission. Gut wrenching sight!
 
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thanks for the info. prob not going to do it. but really like the idea of very very slow rolling. i have 4.10 gears and a 5 speed , low gear is pretty good but could be a little slower.
 
With the Terra low range kit ya pays your money and takes your chances. Mine worked okay, but I won't buy an thing else from them.
 
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