NP203 removal and rebuild

[Chris64]

Mine looks more like it's a part similar to this, which with 51 years of dirt and grime looked like it was part of the trans.

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[Chris64]

dust cover aside - I have a short break before the weather turns dark on me.

I'm cracking the last bolt and it started draining red fluid, which I assume is tranny fluid. I didn't expect that, I assumed these would be sealed from each other. I'm letting it drain now but wanted to check in with the square-body-idpedia to see if this is going to be another task for me to deal with. It wasn't leaking tranny fluid on the ground before so if it is leaking into the union space with the transfer case, it seems to be sealing it there.

 

[Chris64]

OK - update -It was just residual oil from the transfer case. well, it's officially out and I still have all my digits. Putting it back in will be fun.

As a bonus, I leveled it up in the stand to roll it all the way around my house. Unknowingly to me it started pouring out a 150' line of tranny fluid on our backyard concrete. yay. So there I am pressure washing our concrete right before a storm in the dark. Fun.

Now I have a project to work in in the rain though! I can't wait. What do people recommend for degreasing this thing?

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[Chris64]

I needed to order a socket for the rear (1 5/16) so in the mean time, I'm just pre-cleaning the transfer case before I crack it open. Do these normally get painted or just bare metal? It looks like some of it was painted the same green as the truck but I'm not sure if that's original - probably not.

BUT, it appears the trans (AT350) is leaking a little fluid on the output. It seems like it might be coming from the little hole that's submerged. I didn't see it coming from anywhere else. I soaked up all the fluid and it refilled in just a few minutes.

Thoughts on this?

This wasn't where I was having a leak. My leak was on the opposite side coming from the speedometer output.

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[Chris64]

Looking around online, I need to replace the seal, which looks real simple on the 2wd's they show. Not the same for 4wd. Can this be repaired in place?

 

[bucket]

Looking around online, I need to replace the seal, which looks real simple on the 2wd's they show. Not the same for 4wd. Can this be repaired in place?

What kind of fluid came out of the t-case? Was it over filled? That tail shaft area of the trans should have some ATF in there. Iirc, there's a seal on the t-case input shaft.

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That's a nifty little jack too. Although, constructing some kind of makeshift base is well worth it, imho. Makes things a lot more secure and safe. I'd hate to have a heavy a$$ 203 fall on my face, lol.

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Also, I don't believe the cast aluminum inspection cover with the support rods came along until '81 or so.

 

[Old Guy Bill]

You definitely don't want it smashing a finger... don't ask how I know.

 

[Chris64]

What kind of fluid came out of the t-case? Was it over filled? That tail shaft area of the trans should have some ATF in there. Iirc, there's a seal on the t-case input shaft.

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That's a nifty little jack too. Although, constructing some kind of makeshift base is well worth it, imho. Makes things a lot more secure and safe. I'd hate to have a heavy a$$ 203 fall on my face, lol.

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Also, I don't believe the cast aluminum inspection cover with the support rods came along until '81 or so.

It was tranny fluid I believe. If it's meant to be there - then I'm good. The more I look online the more unsure I am - but that part wasn't leaking so do I care? .

I love the wooden cradle. 100% I'm doing that to get it back in there. I don't know what this weighs but it's way more than I can lift if even it wasn't the most awkward shape ever invented.

 

[Chris64]

on this topic - and while I'm awaiting my UPS guy to show up - I removed the shifter assembly.

Small back story: I had to shift this into low to get the truck into my backyard with the QuadraJet that could only run at an idle - so I could idle it up a hill into my yard. It wouldn't go back into normal high range. after a bunch of monkeying with it - it did. I read somewhere that the problem is almost always the linkage. The NP203 has two knobs on the case (Knob 1: H,N,L. Knob 2: front/rear lock). This shifter assembly takes a single knob and converts it to two knobs.

I guess they can get gummy or whatever. I'd like to clean it out and give it an inspection. The problem; it's riveted shut. I did find this video from a 1973 (mine is 1974) where it's bolted together.

Is it reasonable to say that this can this be drilled out and I can just make it serviceable?

Here's the video I was talking about:

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[bucket]

Iirc, the 203 is supposed to be filled with 30w oil. If it was overfilled past the fill plug, the seal is probably leaking and ATF has been getting pushed into the t-case.

A good cleaning and lubing of the shifter can help a lot.

There's also this thread here on refurbishing the shifter:

https://www.gmsquarebody.com/threads/np203-shifter-w-rebuild-how-to.43883/

 

[Chris64]

All this research has me wondering if going to a dual shifter might be better. By the time I re-engineer this stock shifter to be serviceable (which is really less than perfect solution IMO) I could just fabricate a new dual shifter and never wonder if both levers are doing the right thing.

It'd be nice if I could get another one of those Hurst shift arms though. I just think it looks cool.

Like this:

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[Chris64]

update - taking the first part off which is the rear output, which also has the leaky speedo output. Then answer - no o-ring on the speedo . I could've resolved this without removing it.

Oh well. I'll keep taking it apart and replace a couple gaskets and seals because I'm there but I may just call this and inspection and spit shine. Modifying the shifter sounds way more fun.

Right now fighting the rear seal. If I can get the bearing out it would be easier but the clip that holds it in is no joke. I bet there's a trick or a tool for this.

 

[Turbo4whl]

So a couple interesting facts about the New Process Gear 203 transfer case. Depending on which year owner's manual you look at, 10W30 or 10W40 engine oil was the original fluid. Engine oil, for the proper lubrication for the chain.

The 203 was the first transfer case to be chain driven for light duty trucks. But a problem that was not addressed, the chain would stretch over time. So aftermarket, at the time, offered a kit to install a tensioner for the chain. If you are lucky, your 203 had this installed. I don't think anyone is making such a kit now.

The other common aftermarket up-fit was the shifter. As you know, Hurst was contacted to make the single stick shifter for this, also first ever, full time transfer case. Aftermarket jumped in with several different shifter alternatives. This was because the first fuel shortage hit and fuel prices went to the sky. Many believed removing the best feature of he new 203 (full time) would save gas.

Hurst in my opinion never realized that the 4WD crowd would be driving through creeks or plowing snow and road salt. Their unsealed shifter would loose it's grease and rust up. The last useless fact, New Process Gear, a division of Chrysler Corporation, designed the 203 to be featured in their new Plymouth Trail Duster and Dodge Ramcharger for 1974. GM bought them and offered them a year earlier, 1973.

Now a question, GM only offered a stick shift a few years starting in 1974, then only automatics. I own one of these rare birds in my '74. Who knows why they stopped offering a stick shift? Points can be awarded for the correct answer!

 

[Strick]

GM offered manual (stick) shift throughout the entire run of Squares. I have a 76 SM465/NP205 K15 & 78 K25 with the same setup.
Heck, 25 years ago I had a K10 with the overdrive 4-speed/NP208.
I'm not understanding your question right or something...

Half-Stumped

 

[bucket]

GM offered manual (stick) shift throughout the entire run of Squares. I have a 76 SM465/NP205 K15 & 78 K25 with the same setup.
Heck, 25 years ago I had a K10 with the overdrive 4-speed/NP208.
I'm not understanding your question right or something...

Half-Stumped

The 464/203 combo. Extremely uncommon. I thought it was '74-only, but really not sure.


@Turbo4whl I always wondered why it was only briefly available. I ASSumed that maybe it had something to do with some kind of backlash in the driveline while going around a turn or something. But that's just a wild ass guess.