NP273 Rebuild and Duramax Swap

I'm pretty happy about how the reluctor wheel and clamp worked out. It centers quite well and spins true!

The clamp is a Dayton 1L710. I bought two just in case.

I spaced it apart so it was round and then opened it up to 2.100" and then made a .250" shoulder with a diameter of 2.198. It clamps down nicely on the output shaft and holds the wheel very securely. I'm on the fence about having a clamp on each side of the wheel.

Do yall think I need a second one? It couldn't hurt....right?

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The drill, tap, and clocking ring showed up today! I got the ring from WFO and it comes with bolts and studs, but you'll have to get new bolts for a 273 as they're metric. 10mm x 1.5 x 25mm.

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Almost there! Made a bung for the VSS and milled a flat spot to weld it on to.

I will note that the VSS is a weird ass thread. They're supposed to be M22x1.5, but it's more like M21.5x1.5. The major diameter of the threads only measure .846....which matches nothing....so I bored it and thread it on a lathe.

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Turns out that I made the bung too long, but I got it squared away today. Left about .010 clearance. Should work nicely!

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I dropped off the tail housing and bung to be welded. I should have it back tomorrow. I also crawled under the truck to take some measurements and gander at a few things.

The new rear driveshaft will be 72" long from the output flange to the center of the u joint at the pinion. I know this because I measured from the back of the transmission and I know that the NP273 with the clocking ring is 22.75" long. I have also seen plenty of guys use a stock CCSB F250 rear shaft...guess what, it's also 72" long. I'll measure for the front shaft after the case is installed.

I also looked at the clearance between the current transfer case and the ABS module. From what I've heard, there will only be about a 1/2" between the 273 and the module, so I'm going to move it upward on the frame 1" and see how that does. I could also shorten the mount feet on the bracket. I refuse to move the module and have to bleed it though. I just don't want to do it!

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A guy at work welds on the side and I got him to dab a little bit on the bung to hold it in place. Doesn't need much because it won't have any stresses on it. I'll fill around the back side with ultra gray RTV for safe measure.

I also had to face the second clamp to clear the bearing surface of the output shaft since it wound up being farther back than I had planned, but it works now. I'll refine that some on my next one.

Now all I have to do is get some free time this weekend or one afternoon next week to bolt up the clocking ring, install the pump, put the tone ring back on, and bolt up/seal the tail housing. I'm in the home stretch!

Soon after, it'll be time for the swap and some driveshafts! :D

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Not the most work I've put in at one time, but it's the one that's made the most visual progress!

The pump is in, the tone ring is clamped back on with some loctite, the tailhousing is bolted on, VSS is in, the output flanges are bolted on, and the clocking ring is installed. Good stuff.

The next step is probably moving the ABS module and swapping the cases. I'm fairly sure I'm going to chance it and order a new rear driveshaft before the swap. I've confirmed the needed length a few time and the fact that people have used stock Ford shafts makes me feel pretty confident. I also need to set the cases side by side and make sure I have the studs in the right place on the clocking ring.

Oh, and the last picture just shows the positions of the shift lever in case anyone was wondering.

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I decided to only run one clamp on the reluctor wheel and it turned out, I didn't need drill and tap....so not counting those two things, I'm only in this thing for 710 bucks. Not bad, right?

That number also includes the shipping costs for the stuff I ordered.
 
I ordered a new rear driveshaft this morning. It was only slightly painful, but I'm excited to get the shaft, for once :D

Possibly this weekend I'll get the clocking ring studs in their final resting place, pick up some transmission fluid for the case, and move the ABS module up. The only thing left after that is to actually do the swap.

I think I'm going to roll with just two shift motor bolts unless I decide that I REALLY need to drill and tap the third one. I feel like it'll probably be fine.

Stay tuned for more soon!
 
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Shit is about to get real! My new rear shaft showed up today. I'll be glad when I don't have to buy any more driveshafts. They're not cheap! This one was 500 bucks and 74 for shipping. It's 72" long, 1410 joints, and the Ford flange at the transfer case end.

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Now I just need to move the ABS module, swap the transfer case, and get bolts for the driveshaft flange at the transfer case. Then I can measure for a front shaft and wrap it all up.

I'll be glad to make back a good portion of my money by selling the stock transfer case and shafts too.
 
Picked up some driveshaft bolts from Advance earlier. Luckily Doorman has a kit in the help section. They're 12x1.75x30mm, grade 12.9, and a 12 point head, just like factory Ford bolts.

I also grabbed three quarts of Valvoline full synthetic transfer case fluid. I was planning to just run ATF of some sort, but after reading up on it there was a lot of conflicting information and a Motorcraft XL12 lube listed, but several places just suggested using the Valvoline stuff. It's easy enough to find at any local parts store, meets/exceeds the Ford specs, and it isn't outrageously expensive or anything...I think 11 bucks a quart? Not too bad since you only need two and you don't change it all that often anyway.

Hopefully I'll be getting around to doing the swap one of these weekends soon!
 
Croatan_Kid said:
Picked up some driveshaft bolts from Advance earlier. Luckily Doorman has a kit in the help section. They're 12x1.75x30mm, grade 12.9, and a 12 point head, just like factory Ford bolts.

I also grabbed three quarts of Valvoline full synthetic transfer case fluid. I was planning to just run ATF of some sort, but after reading up on it there was a lot of conflicting information and a Motorcraft XL12 lube listed, but several places just suggested using the Valvoline stuff. It's easy enough to find at any local parts store, meets/exceeds the Ford specs, and it isn't outrageously expensive or anything...I think 11 bucks a quart? Not too bad since you only need two and you don't change it all that often anyway.

Hopefully I'll be getting around to doing the swap one of these weekends soon!
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I’ve been following along on your 273 build and was wondering if you might be able to help with the trouble I’m having with mine. When I manually shift mine I’m only getting one 4wd range. Not sure which one I’d have to look this afternoon and compare to your picture where you wrote on the side of your where each range is. Mine just feels like it’s in neutral in two of the detents. I’ve got one 4wd then 2Hi and neutral and then nothing??? I pulled it back apart and made sure I had the kodiak 273 shift cam and it’s the correct one
 
Check it out and let me know.
 
Croatan_Kid said:
Check it out and let me know.
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When I turn the cam all the way clockwise and compare it to your picture where you wrote the ranges down with a sharpie I have 4lo and when I start turning back counter clockwise and shifting manually I get 2hi the next one I get neutral and then neutral again??? These are loud clicks into each position. Not sure where I screwed up.
 
I noticed that sometimes it won't go in to 2wd when it's dry, sitting on a table, and kinda leaned to one side. It'll kinda hang out and act like it's still in neutral.
 
Croatan_Kid said:
I noticed that sometimes it won't go in to 2wd when it's dry, sitting on a table, and kinda leaned to one side. It'll kinda hang out and act like it's still in neutral.
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I flipped mine over every which way to see if it would make a difference and was about to call it a night when I propped it up perfectly flat and it finally started to work right. Mine is still sitting on the table with no fluid like you described. Thanks for the help.
 
I had noticed the same thing...thought I had filled it full of neutrals like a bone stock 4L60E behind a boosted 5.3 :D
 
For anybody waiting on me to finish this, don't worry! It won't be much longer. If I don't have to work this weekend, I might go ahead and do it. I want to get it done before my stock case gets the pump rub and I can't sell it. Plus, I have a really expensive driveshaft sitting in my shop that needs to be put to use.

I'm just trying to get my hands on a driveshaft for the front now and I should be just about ready to roll.
 
It finally happened and it works perfectly!

I unbolted the ABS module, popped it out of its bracket, and zip tied it to the top of the frame for the time being. I will probably either modify a bracket or get the kit to move it back 12 inches.

It shifts perfectly and the rear drive shaft is very smooth. Zero vibrations!

I did only bolt the encoder motor on with the bottom two bolts. I knew this was an issue ahead of time and I'm alright with it. If there are any issues with it in the future, I'll either make bushings to fill the gap around the bolts or I may possibly drill/tap the third hole. I'll report back with any issues.

I DID have to slot one of the holes in the transfer case adapter since the spacing is different from one case to the next, but not the end of the world!

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Hard to say...I'd guess it depends on how much they want to do themselves. I could probably do any stage of completion. I feel like the main things are the tone ring and output housing to make the VSS work. Everything else is pretty simple and mostly just rebuilding the case.
 
Yep. Fixed flanges on both outputs now.

I think a full case price would depend on what it needs internally. Apparently the main shafts changed in the later cases to improve oiling and keep them from wearing shift fork pads or something like that.

I want to say the ones you can buy from Transfer Case Express are like 1500 bucks, plus shipping, PLUS they want your old case as a core! I plan to sell my NV263XHD and stock driveshafts to cover a good portion of the cost.

I think I'm around 750 in the case, 500 ish for a rear shaft, and about 120 for a stock front Super Duty shaft that I'll cut down.
 
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