Easy manual shift NP-231C T-case swap How-to
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Gavio thanks for documenting this. I just got a JY in OR to pull the TC + the entire linkage + indicator for me for a VERY good price. I had some ideas for making a 233C work, but frankly figuring out the linkage had my head spinning with limited fab or welding skills... and I got the whole package for a lot cheaper than the Journey's kit!!
Are there any electrical connections on the transfer case itself like the NP233? Do those steps still apply? I'd assume there is a speedo sensor, but I don't know nothing about nothing in this world.
EDIT: I figured this out by looking at pictures of the NP231C online! Same speedo sensor and pigtail as the NP233 it looks like. I just wanted to make sure I had this straight!
Are there any electrical connections on the transfer case itself like the NP233? Do those steps still apply? I'd assume there is a speedo sensor, but I don't know nothing about nothing in this world.
EDIT: I figured this out by looking at pictures of the NP231C online! Same speedo sensor and pigtail as the NP233 it looks like. I just wanted to make sure I had this straight!
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I'm intersted in following your lead by installing the 231-C transfer case. When searching on car-part.com, I'm given the choices in the attached photo. Can you help me out and let me know what option is the 231-C? I'm intersted in the GT4(3:73) gear ratio. I need to be sure I get this write. My nearest junkyard wants $300 for a front axle assembly.
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I'm planning to change my gear ratio from 3.42 to 3.73 at the same time I convert to 4X4. Seems like it would be less hassle if I could get the TC and front assembly from the same donor. Wishful thinking?
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No way to know without calling the yard directly since GT4 with 4x4 could either be a electronic or floor shifted unit.
Your best bet will be calling yards with the floor shifted transfer case and see if they have a compatible differential. I'm not sure what year blazers have the same diffs as the Astro anyways.
Honestly... I'd guess like 50% of the parts on car-part.com are already pulled and sitting on a shelf anyways so you may have better luck just calling a yard with lots of stock and seeing if they can put together a diff and TC for you.
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Your best bet will be calling yards with the floor shifted transfer case and see if they have a compatible differential. I'm not sure what year blazers have the same diffs as the Astro anyways.
Honestly... I'd guess like 50% of the parts on car-part.com are already pulled and sitting on a shelf anyways so you may have better luck just calling a yard with lots of stock and seeing if they can put together a diff and TC for you.
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Somehow I missed that there were new posts on this thread...... Cool that some peeps are interested in this swap.....
Winnie, it sounds you got it dialed in..... Yeah, the case itself is identical to the well-documented 233 swap in its installation details....
Forest, Similar to what Winnie said, I would add that the case and linkage are the harder parts to come up with, so find those first, get the diff you need from any gen2 Blazer that has it, then put it together and BAM, good to go.....
I look forward to seeing y'all's finished installs....
Winnie, it sounds you got it dialed in..... Yeah, the case itself is identical to the well-documented 233 swap in its installation details....
Forest, Similar to what Winnie said, I would add that the case and linkage are the harder parts to come up with, so find those first, get the diff you need from any gen2 Blazer that has it, then put it together and BAM, good to go.....
I look forward to seeing y'all's finished installs....
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Gavio -
Only things missing were some sort of retainers on both sides of the shift cable. Gavio- could you send some photos of the shifter side and Tcase side if you have them? Or is there a part I can just buy that'll slide into the shifter cable eyes?
Is this the right sort of thing? Seems like the attachment nipple on the shifter and the tcase lever are the same, so I imagine the same part should work for both?
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Only things missing were some sort of retainers on both sides of the shift cable. Gavio- could you send some photos of the shifter side and Tcase side if you have them? Or is there a part I can just buy that'll slide into the shifter cable eyes?
Is this the right sort of thing? Seems like the attachment nipple on the shifter and the tcase lever are the same, so I imagine the same part should work for both?
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Yup, that's the right sort of thing...... I don't have a good picture of the original.....
Mine was intact when I got it, but the one on the shifter end broke after installing/removing it multiple times and I lost the cap part..... I found another shift cable end on a Jeep that threaded right onto the cable but fits sloppy on the pin, so my handle has a bit of play in it when I go to engage the 4WD..... It doesn't keep it from working, and the cable is so stiff that it can't actually slip completely off the pin, so all is well..... Still someday I'd like to find the right one so it goes back to being really solid like it was at first......
That said, you can use it without that grommet thingee on the shifter end at all, it will just be sloppy...... It's probably much more important on the t-case end..... Somebody on the S-10 forum might have found a replacement as I suspect they all break at some point......
Mine was intact when I got it, but the one on the shifter end broke after installing/removing it multiple times and I lost the cap part..... I found another shift cable end on a Jeep that threaded right onto the cable but fits sloppy on the pin, so my handle has a bit of play in it when I go to engage the 4WD..... It doesn't keep it from working, and the cable is so stiff that it can't actually slip completely off the pin, so all is well..... Still someday I'd like to find the right one so it goes back to being really solid like it was at first......
That said, you can use it without that grommet thingee on the shifter end at all, it will just be sloppy...... It's probably much more important on the t-case end..... Somebody on the S-10 forum might have found a replacement as I suspect they all break at some point......
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Turns out that one I found in OR was from a vehicle with lots of water damage, so I ended up just getting a refund. I was, however, lucky enough to find a manual shifted Blazer at my local Pick N' Pull -- pulling the linkage without dropping the TCase was a bit of a pain, but now I'm good to go. I should have snipped off the pigtail while I was there too. Oh well, I think I can source that from whoever supplies the tcase.AstroWill said:
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Gavio -- if you want to "tighten" up your shift, I can verify that that the bushing I linked previously works just fine. You'll need to cut some of the shoulder off to install it into the shift cable, which might be a total PITA with the cable already installed... but maybe not.
Same part number worked on both sides:
Omix-Ada 18680.19
https://www.amazon.com/Omix-Ada-18680-1 ... B00390NYQ0
Which looks identical to Crown Automotive 53004810...
https://www.amazon.com/Crown-Automotive ... B009X1UYT4
Which also looks identical to those you can find in your Dorman help section at the LAPS, save for color.
Anyways -- some sort of grommet like this will definitely bring back that "tightness" in your shift. The inner part of the grommet fits the TC level nipple and shifter nipple perfectly.
Same part number worked on both sides:
Omix-Ada 18680.19
https://www.amazon.com/Omix-Ada-18680-1 ... B00390NYQ0
Which looks identical to Crown Automotive 53004810...
https://www.amazon.com/Crown-Automotive ... B009X1UYT4
Which also looks identical to those you can find in your Dorman help section at the LAPS, save for color.
Anyways -- some sort of grommet like this will definitely bring back that "tightness" in your shift. The inner part of the grommet fits the TC level nipple and shifter nipple perfectly.
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Also, been thinking about how to mount the indicator.
Seems there are four options that make sense:
1 - where Gavio mounted it
2 - in the little wallet pocket above the cup holders (my satellite radio is there)
3 - on the dash like a gauge pod
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4- knee panel
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I think the dash pod style or where Gavio put it is my favorite. Although the dash pod shouldn't be too hard given that I have the console cover from the Blazer.
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Seems there are four options that make sense:
1 - where Gavio mounted it
2 - in the little wallet pocket above the cup holders (my satellite radio is there)
3 - on the dash like a gauge pod
4- knee panel
I think the dash pod style or where Gavio put it is my favorite. Although the dash pod shouldn't be too hard given that I have the console cover from the Blazer.
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Mounting it like a Guage pod will be easier by a fair bit than putting it in the spot where I did it.... I like it in the dash, very factory looking, but a bunch of really fiddly work cutting it apart and reassembling it....
Have you considered cutting the console down and reassembling it as a mini console between the seats?
Have you considered cutting the console down and reassembling it as a mini console between the seats?
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So I went looking at Hotwire's build last night, and I found some really cool stuff that might make this T-Case Swap even more streamlined with the right parts and a bit of work on the interior of the case.
This one [email protected]: I think the Jeep Liberty (KJ) cable shifter might be the best application for our vans for an easy, streamlined installation, especially with the 231, which was already intended to be controlled by a cable shifter.
![s-l1600.jpg]()
The key being, this shifter is meant to sit flat and the "meat" of the shift cable protrudes out of the bottom of the shifter. I think with this sort of installation, one could have a VERY clean and easy installation -- i.e. cut a square hole in the floor and bolt it down. Taboot, the shifter boot snaps directly into the mounting bracket for the shifter.
![s-l1600 (1).jpg]()
Doesn't come with the cool 4LO ground but Hotwire came up with an INCREDIBLE mod for making that easy that I missed previously (I love that guy's thread). It involves cracking the case and doing some work, but it is super cool and smart! I don't think I'm qualified to crack the case and do the mods Hotwire did, but it is definitely the slickest solution to the 4LO PCM wiring. https://www.astrosafari.com/viewtopic.p ... d#p1026002
There are a couple Jeep KJs at my local yard, so I'll see if I can pull one of these shifters to get it in hand and compare it to the Blazer 231 shifter to see if it works together.
It isn't set-up for the 231, so you'd likely still need the transfer-case side bracket for the Blazer.
I think if I could get the 4LO ground to automatically trigger via the Hotwire mod and use the KJ shifter, this would be the sort of "clean" install I love.
You'd lose the indicator lighting -- but frankly (and in my opinion) it might be more trouble than it is worth.
This one [email protected]: I think the Jeep Liberty (KJ) cable shifter might be the best application for our vans for an easy, streamlined installation, especially with the 231, which was already intended to be controlled by a cable shifter.
The key being, this shifter is meant to sit flat and the "meat" of the shift cable protrudes out of the bottom of the shifter. I think with this sort of installation, one could have a VERY clean and easy installation -- i.e. cut a square hole in the floor and bolt it down. Taboot, the shifter boot snaps directly into the mounting bracket for the shifter.
Doesn't come with the cool 4LO ground but Hotwire came up with an INCREDIBLE mod for making that easy that I missed previously (I love that guy's thread). It involves cracking the case and doing some work, but it is super cool and smart! I don't think I'm qualified to crack the case and do the mods Hotwire did, but it is definitely the slickest solution to the 4LO PCM wiring. https://www.astrosafari.com/viewtopic.p ... d#p1026002
There are a couple Jeep KJs at my local yard, so I'll see if I can pull one of these shifters to get it in hand and compare it to the Blazer 231 shifter to see if it works together.
It isn't set-up for the 231, so you'd likely still need the transfer-case side bracket for the Blazer.
I think if I could get the 4LO ground to automatically trigger via the Hotwire mod and use the KJ shifter, this would be the sort of "clean" install I love.
You'd lose the indicator lighting -- but frankly (and in my opinion) it might be more trouble than it is worth.
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