[Mmusicman]

Well, well... it's finally my turn to do this upgrade!

I keep finding myself working on job-sites pulling heavy loads off-road desperately needing 4-LO range gearing and full time 4x4 operation. The 4.3 in the single high range AWD with taller tires and stock gears just isn't working well for me at all... it generates a lot of sudden heat... it struggles badly and is severely under-powered... and it REALLY puts a strain on the trans too. The AWD system has reliability and operational issues too, issues with sticking or failing encoder motors (99-up), issues with clutch-packs and wear, but most importantly lacks a very needed low-range gear.

I considered both the NP233 vs the 236 transfer cases... but since I do not live in snow country, I do not need the benefit of the auto AWD, or the complexities of the 236 installation. The simple drop-in NP233C was chosen!

I have also chosen to go with the "manual" shift conversion vs the electronic push-button shift, for both simplicity, dependability, and reliability.

I'm re-posting a couple of posts (from a couple different threads) so I have it all here in my build thread. This was the start topic...
NP233 vs NP236: https://www.astrosafari.com/viewtopic.p ... 9&t=135734

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July 5, 2018:

UPDATE: My "new" 233 unit arrived today! :mrgreen:
Actual unit weighs only 68lbs... much lighter than I expected.

I purchased the unit though Ebay, $175 (including shipping)
This unit is from an 03 Blazer. I confirmed it has 32-spline output.

I've read there may be some case indexing issues old vs new.. I'l let you know how this one does.

The unit is light enough it can be lifted and carried with one hand.
I turned everything by hand and verified the 4x4 Hi/Lo selector is working.

The new basic gasket/seal kit arrived today as well... $12 on Amazon.

Now to fabricate my manual shifter.

I'm learning toward possibly something similar to this that "LiftedAWDAstro" did on the other site... but perhaps either a little shorter, or further back.
I will experiment with leverage lengths and angles once the cable is in place.
I have a box that sits in the center between the seats, so this really won't be visible.

Looks like I may go with this Lokar S-7100 cable kit ($50 from Summit) connected to a simple shifter mounted to the side of the driver seat facing forward. I think I'd prefer the shifter close as possible to the seat vs cutting open the floor.

This cable kit appears to have everything I'll need (except actual shifter lever)

But I'll probably take a visit to the junk yard just to see my other options.
I'm pretty excited about taking this to the next level!

See more at NP233 vs NP236: https://www.astrosafari.com/viewtopic.p ... 9&t=135734
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July 7, 2018:

The new unit is here.. I'm just shopping for my best linkage solution. Still undecided on the Jeep Liberty shifter (found a nice one in JY yesterday).. or making my own (shifter mounted on the side of the seat base). The Liberty shifter will be the simpler and cheaper choice, and comes complete with everything I'll need. I'm probably going to go back and pull it Monday, regardless. The cable though the floor to a simple seat mounted shifter is my preferred choice. But once I cut the big opening in the floor, the choice will be made.

 

[Mmusicman]

July 9, 2018:

Today, I went to the junk yard and pulled a complete transfer case shifter assembly from an 04 Jeep Liberty. They consistently go for $100 used on Ebay... I got mine for $16! The only challenge was pulling it in the hottest part of the day in the middle of July in South Florida. The job took me about a half hour.

The shifter is in excellent condition!

 

[Mmusicman]

July 23, 2018:

Started working on my NP233 manual transfer case conversion.
Drilled the initial pilot hole (will be tapped and threaded)

Started working on the shifter linkage... to see if it will work.
Despite picking up a nice 4x4 floor shifter, this will mount to the side of seat.
Checking angles, forces, cable throw positions and lengths.
This is a rough mock up made of simple parts, and it worked great.

Here is the critical bracket I made from some stock I had...

Crude, but works!

These are all very preliminary photos.. I'll have better as I progress.
Gear-shift ball from Grainger arrives tomorrow.

 

[Mmusicman]

July 25, 2018:

Mmusicman, can't wait to see the build thread. My NP233 is being delivered tomorrow!

AWESOME! Welcome!

My primary focus is pulling this job off, with least amount of expense, yet perfectly functional, simple and reliable. Even though I have access to welding equipment.. I'm doing this job totally "weld free", using simple basic off-the-shelf stuff available from Home Depot or any hardware store.

The manual shifter is key to this job. Purchasing one for almost $300 is completely ridiculous and out of the question... and it puts the shifter in an awkward terrible place.

The Liberty floor shifter is an awesome solution. I pulled one in great condition from the JY for $16... in case I decide later to use it. I think it will take up more floor space than I'd like, so I'm going to try the side seat option first.

My goal as of now, is to mount the shifter to the side of the seat, with the arm in a safe place, out of the way, tight and close, sitting low and facing forward. When you need 4x4, you simple reach down and pull up. I intend to mount the arm's pivot point probably near the top back of the seat base, kind of behind the seat belt... with the shifter ball even with, or just past the front of the seat base. We'll see.

I discovered shifters however, can be quite expensive, as well as shifter balls. I saw prices ranging from $50-$100 or more. I knew I needed more of a simple "lever".. like something you'd see on a machine, but something that still looks nice, with a nice shifter ball. I could see in my mind what I wanted, but couldn't quite find it. I did eventually located a shifter lever knob assembly from MSC, but with shipping was still slightly out of budget. But the more research I did, the more I figured out exactly what I wanted, and didn't want.

So I made my own from a 12" piece of 3/8" threaded rod, a piece of 3/8" ID steel tubing, a coupler and an eyebolt.. all less than $10 worth of parts from Home Depot! The arm is strong and functional. The shifter ball (I just picked up yesterday) is Davies high-gloss phenolic 2" ball knob... I paid a whopping $5 for it, and it looks and feels great. Looks like a pool table 8 ball. Total homemade shifter arm and ball... about $20

Where did you get that cable from, and what does the other end look like?

Matt, the cable is a Lokar S-7100 cable kit ($50 from Summit)

Here's the other end..

Some of my initial indecision was based on functionality. The detented shift on the 233 is quite firm, and I wanted to be sure everything would shift smoothly and accurately. Since the cable has exactly 3" of throw.. I needed to be sure the pivot points of BOTH the linkage on the TC, and the linkage point on the shifter arm all give exactly 3" of useful maximum throw.

The shorter the arm, the less throw, and harder to shift.
Here are the 3 linkage arms:
Left: Liberty NP231, middle: Mine, right: Lokar kit

I'm not sure why the Liberty shifter on the NP231 case is somewhat smoother than the 233 case, but no matter... a little more leverage and it's resolved.

I've set up a crude mock test setup in my shop, to see it all work. The way I've designed the shifter arm, the linkage point can still be moved for perfect positioning and throw. The closer the cable is to the pivot point, the further throw the arm will have. I'll determine throw when I mount the arm on the side of the seat. I still need to tap the shaft and mount the linkage to the TC, before I can finish the final positioning of the arm (off the TC case) that holds the cable in place. I want it in perfect alignment so the pull is smooth and straight.

Here's my mockup setup (as of this moment)
UP=4L > MID=4H > DOWN=2H.

Sadly, you used to be able to click on the photo to enlarge them if you liked.
Now if I place a large photo, it won't display correctly.

Next step.. tap the shaft and mount the linkage arm.
Final step.. position cable arm on TC

I still have to change the seals, and I think that's about it.

I'll post all the specifics, measurements, parts and part numbers, and better photos in my build thread, to hopefully help the next guy. So far, nothing too hard... it's all pretty basic and obvious.

Some additional discussion here: https://www.astrosafari.com/viewtopic.p ... tart=14736

 

[Mmusicman]

July 30, 2018:

Today I did a "preliminary test fit" of my new NP233 manual "make-shift shifter" (no pun intended). :mrgreen:

I think I'll make the arm a little bit shorter, and I'm considering the ball-size a little bit smaller... but otherwise it looks and feels about right. No interference or issues in my preliminary test fit. I'm just doing a little fine-tuning, but still need to route the cable though the floor. I will be installing everything this weekend.

 

[TurnNburn]

Thanks for documenting your progress, per usual, and as always, nice pictures. Have you come up with a brilliant solution for engaging a 4 LO switch for the ECU to know to ignore the speed differences yet?

:weld:

 

[Mmusicman]

Thanks for the nice compliment. No I haven't. I'm primarily focused on the mechanical installation right now. I will address the ECU issue sometime later... if I even find it to be an issue. And even then, most likely (knowing me).. I'll probably just do the easy route and install a toggle switch under the dash (for the rare occasion I would even need it). I just don't really see it as a concern right now.

Tomorrow I will post the final pictures of the TC preparation.. it is complete.
It all goes in this weekend.

 

[TurnNburn]

Yeah I hear you there. It will still engage 4lo without grounding that pin, but wont shift out of first. So its still good for getting unstuck, but not as good for "long" distance 4lo usage in sand or snow.

Even with the deep snow we get, I very rarely use that toggle switch(the simple ground switch), but its nice to have when you need it.

That little sensor looking thing with the 3 plastic nipples on the t case above where the shift motor used to be is where the 4lo "sensor" (its actually a switch) is. Obviously without the rest of the vacuum system to utilize it, it isn't useful. But perhaps you can find some other kind of sensor with the same dimensions that can replace that thing and use as the switch. I never looked into it, but at least if you are interested you have somewhere to look.

Or I have seen micro switches installed where the shift arm can/will touch it in 4lo. But they are small and delicate and as long as they are exposed, they are prone to debris getting lodged in them and corrosion(especially if you live in a salt state). A momentary on switch might be more robust, but likely still prone to failure from things noted above.

 

[akforceten]

nice work! I have never had to use the 4LO just 4hi when running over the mountain pass here and in the deep snow.

 

[Astro Pop]

Awsome write up. Can't wait for the rest of it.I'll be following along about 2 weeks behind you only on a '96. Journeys off road says I'll need two new driveshafts also.

 

[akforceten]

Journeys off-road says I'll need two new driveshafts also.

yes when I did mine I had to change both drivelines on my 95 safari

 

[WimpTech]

GREAT write up Musicman, I like all the details. I might have to follow you on this one, my TCase is still sitting in the garage for over a year now.

 

[TurnNburn]

Journeys off-road says I'll need two new driveshafts also.

yes when I did mine I had to change both drivelines on my 95 safari

They don't need to be "new", you just need the driveshafts from a 2000+ astro/safari.

 

[nico541]

Great Pics/write up!

GREAT write up Musicman, I like all the details. I might have to follow you on this one, my TCase is still sitting in the garage for over a year now.

Haha I hear ya man. I've had mine sitting in the garage on the to do pile for the past year or 2.

Journeys off-road says I'll need two new driveshafts also.

yes when I did mine I had to change both drivelines on my 95 safari

They don't need to be "new", you just need the driveshafts from a 2000+ astro/safari.

Whuuuut? Your saying I can't reuse the driveshafts on my 98? :crying:

I thought it was 98 and up.

 

[TurnNburn]

Maybe 99 and up? There has been discussion in other threads on this. I guess the age thing isn't as important in this situation. It all depends on which t case you have now. IF you have the Borg Warner t case (the old style) then you WILL need the newer drive shafts. IF you have the NP136 (new style with the shift motor) already, then the 233 will bolt right in and you WONT need drive shafts.

 

[nico541]

Yep looks like the cutoff is 99, Dangit! Aw well, thanks for the clarification.

 

[markmitch]

My concern would be bumping the shifter while driving -like if you were to reach for something and engage the 4x4 while moving ? Just a thought. Great write up and pics.

 

[TurnNburn]

The lever is easy to move, but not THAT easy. In the 15k miles we have put on our van with the lever right there I have not once engaged 4x4 on accident. My handle is a little bit more hidden and low profile though.

 

[Mmusicman]

My concern would be bumping the shifter while driving -like if you were to reach for something and engage the 4x4 while moving ? Just a thought. Great write up and pics.

It's too firm to move by accident.
I also intentionally put mine in a safe position.
Even if you engage 4HI while in motion, nothing is going to happen. It's also not likely you can even get it into 4LO intentionally, let alone by accident.

Great write up and pics.

Thanks (to you and the others) .. more coming..

GREAT write up Musicman, I like all the details. I might have to follow you on this one, my TCase is still sitting in the garage for over a year now.

Thanks! AND what are you waiting for???

It will be my intent to show how easy this will be. I'm intentionally doing mine with easily available hardware, without welding, and without any real fabricating or cutting, other than making a little bracket! Of course, if you like you can buy an expensive kit too... with a bulky shifter sticking up though your floor. It would be nice if you could just buy the little bracket though.

I've actually completed the preparations.. now I just need to put it in.
(and post some more specific details and photos)

 

[Zebediah III]

I really appreciate what you are contributing for us.

I want to do this with my V8 '05. I hate the Mushy AWD in it. I have most of the parts, and you are providing the inspiration and technical info, so I think I'm not putting it off much longer.

Big Bravo Zulo and a Hoooo -Aaaah to you !!!!!