Rebuilding an NP202

[Gunfighter97]

Now that the majority of the case is painted and shinny new, its making my old hardware look pretty tired. Usually the bolts and nuts are painted over, but frankly I hate painted hardware as it flakes off the minute I need to take it apart again. While I could strip and blacken each bolt head, washer, and nut individually, the reallity is it just takes waaaaaay toooo looong (as anal retentive as I am, I'm not crazy). Nothing else I could do to the bolts would be very corrosion resistant in their environment under the truck. I bit the bullet and ordered up a new set of nuts and bolts; while I was at it I upgraded to Nord lock two piece washers. The three roll pins for the idler shaft and shifter bars I'm replacing with the same size in stainless. All of this hardware I sourced from McMaster Carr, who made it verry easy to find everything with a cell phone app I would HIGHLY recomend. For about $150 I have enough spares to heavily carry over into my T98 rebuild with maybe $30 in suplement parts. I selected the zink-alluminum coating for superior corrosion resistance to the brass colored coating (quoted as 8x the corosion resistance). In addition to that, all of it was grade 8 over the stock grade 5. Big Ed, whom some of you may know on the forums has given me a couple good pointers on a failsafe for the four large mount bolts. I'm planning to safety wire them in place in addition to the nord lock washers. This will ensure that even in the event of a nuclear blast, those bolts WILL NOT VIBRATE OUT!!! EVER!!!
Here is the case mock up assembled:

Coming up in no particularly clear time frame or order are the crossmember, mounting solutions, learning to safety wire and a how to on building a lateral support thats actually good (I'm looking at you PO!) Stay tuned for the continuation of a large messy project I hoped to have done by now

For real though, at the end of the day, I cant really complain about the results ive gotten. i could go back and do it faster... Anybody know if IH made a time machine??? I assume not given lack of parts availability... Or are those parts not... Yea no...

 

[Gunfighter97]

The cross member and mounting can be an issue on these rigs for several reasons.
-The first is a problem these units always had, wich can best be described as "rocking" on the frame mounts fore and aft. Picture a drag car pulling a wheelie, the torque wind up on the pinion in the rear axle drives the ring gear down in the front, rotating the wheels and sending the car forward, but also providing a lifting effect wich raises the front of the car. I'm no scientist but I'd imagine its at least partly an effect of the pinion gear "climbing" the front of the ring gear. In the case of our old pickups, most of the time they aren't doing sub 10 second runs, but rather winding up extreme torque at low speeds in low gears climbing over rocks. This rocks the case forward by lifting the rear of the case. Another thing can be the rig coming down on or over a rock. In any combination of cases, this resulted in the rear mount bolt holes at either end of the member of my rig to be indented downwards. In addition, the two main bolt holes that mount the case to the member have stress cracks around where the spacers were welded in.

-The next problem is more apparent upon removal in that the mount bushings are fossilized 50 year old rubber. Untill recently the only known replacement kits have been ones that require mods, and use ridged poly rather than rubber wich absorbs vibration better. Also: $$$. Fortunately with some help on Binder Planet and a bit of effort I managed to research my way into a LORD CORP part #, emailed them, and received a new current part # of the still produced bushing (still original spec). These are now available right here on IHPA: https://www.ihpartsamerica.com/store/SL163387R1.html
-The last main problem is linked to the first in that we still have the fore aft flex to deal with. This can be accomplished with a lateral brace, wich we'll deal with here later once the unit is back mounted in the vehicle.

Now, my crossmember, mounts, and brackets. These carried the same gunk as the case, wire wheeling and putty knife to remove the majority and I tried something new here. Evapo-rust. Five gallons worth. For a skin safe, biodegradable rust remover it works very well. It doesnt remove paint, however it loosens up surface material enough to scrape off easily. Here is one mount after an overnight soak:

On repairing the member, there are numerous ways to flatten out the dimples, heating and hammering with plates, heating and clamping with plates, I just happened to have a good friend with a home made three hundred ton press this took all of five minutes.

Next up the main crack was a three branch, wich i drilled through at all three ends and where they met. I opened it up with a cut off wheel to find the crack went impressively deep though not completely through and then filled in with weld wich still needs to be ground flat. While cleaning up the part to weld and also for a ground contact I found several other 1/4 inch cracks, so I decided to proceed further after derust to better search. Here it is after the first round and wire brushing some remaining paint and debris free:

Once these are fully repaired and clean they will get paint in black to match the pto port cover. I have a replacement yoke to paint and then I will begin working toward cleaning the internal parts and begin reassembly.
Later on, we will lay out a blueprint for a lateral brace that will use one additional OEM bushing, allowing the same plane of flex as the other bushings while preventing fore/aft rock. In addition, since my parking brake linkage is kinda mangled, I will be incorporating that in the design of the braces crossmember.
*edit: upon further development the parking brake design has been changed entirely, stay tuned. . .

 

[Gunfighter97]

And the process trudges forth! The cracks, while not a mirrored pattern on both sides, are infact pass through cracks, just at angles. I repaired the cracks via a cut off wheel, making a V groove over the cracks on one side about 60% of the way through. Next I set up to weld and preheated the part with a MAP torch, till it was hot enough to sizzle off a drop of water applied by a finger on contact. Once it reached that point I would weld a section and then let it cool before cleaning away the slag and repeating. Once one side was finished I ground the other side about 75% through, and then welded with the same pre heat method. Here it is after. All the welding was done:

Note in above, part of the weld is ground flat, I ended up having to grind out and reweld most of the original since I was running out of shielding gas while I did it, and as I cleaned up where I left off, I kept finding porosity.

Once the welding was done, I heated with the map torch as previously described and held it at that sizzle temperature for about ten minutes. This was just to help ensure uniform hardness around the repair area, and not a full annealing. Lastly, I ground off the top welds flat with a flapper disc, and shaved down the under side welds with a dremel tool, to provide a more uniform surface for paint.

Now with this and the mounting brackets in the painting process, final assembly of the gearing starts after a very thorough cleaning of the internal parts. I began by checking the specs, first of all, is the snap ring that hold together the idler shift gear assembly.

The shop manual lays out specs for various internal parts, I simply used a set of Lyman callipers to measure thickness of these various parts. Spec for the snap ring is to select maximum size that fits the groove. There are three sizes listed, and by measuring the groove, I found my size, wich conveniently, was what I already had. No change required. In addition, all my spacers and thrust washers were also in spec. To begin assembly its important to apply oil to the parts to prevent scoring and corrosion as well if you don't plan to reinstall or fill oil right away. I simply took a clean tub from my favorite cheese dip and filled it with the 90wt oil I will use in it. As I assembled I simply finger painted on generous amounts to all surfaces. Note, this process took several days, and to prevent accumulation of dust, I wrapped all components with shop towels as I cleaned, oiled and built the subassemblies.
First up as seen above, the idler shift gear assembly is put together with it's very stubborn snap ring. I then installed the main bearings into the main housing, first by coating with oil then starting them in their bores by tapping with a plastic mallet. Once started the two front bearings actually pressed in almost fully by hand.

Now with the retainers loosely installed, feeler gauges can be used to determine what gasket thicknesses are needed to fit the retainers properly. At this point, I took an additional step to stupid proof wich holes were blind and wich were pass through, in addition to double checking that the threads were completely clean and ready for sealant.

Coming up next, reassembly part 2, stay tuned for more!

 

[Gunfighter97]

Part 2, subassemblies.
The first hunk I put together was the rear output assembly, which is much simpler now that I have a needle bearing that isn't falling into a hundred pieces.
The needle bearing unit is pressed into the rear output bearing housing as shown here (wood slat used for padding not shown):

Once the end of the bearing is pressed flush, the rear output shaft can be stood pointing up by the large integral gear, and following coating with oil, the housing can be slid on to it followed by the speedo drive gear, and the drive gear spacer. Next comes the main bearing, wich I tapped into place with a plastic mallet:

Now the retainer can be installed, wich in talking with a member of Binder Planet who was likewise in the midst of a rebuild, we noticed that this is definitely not the original retainer, wich accounts for a couple of things in my truck. This retainer is actually from the newer NP205, a noteworthy detail for later on.

In the above pic, the "brake drum flange spacer" is shown on top of the bearing. This flipped on the light that something was up with the retainer and other things surrounding this area under my truck. From here, the yoke can be added and the retaining washer and nut installed by hand. This ensures the unit stays in one piece during installation and can be easily removed later along with the retainer to add the gasket and main seal.

Lastly. Thread the speedo drive in finger tight. You'll take it out again later.
Now we dive into the rollers. The rollers come packed in the kit in odd numbers within plastic packets and not in the totals you need. Here I took the time to sort all my original rollers, count them, ensure I had all of them (old and new) and understand where they live in the machine. This lead to the prevention of much panic later on, as I found there were extra rollers in the kit. Here the parts manual became invaluable, as it actually numbers the various rollers.
For installing rollers within their bores, the manual calls for use of Lubriplate no. 110 grease and a technique I've always known as gunsmith's glue. Essentially, use the grease as glue to hold rollers and spacers in place.
I'll be the first to admit I'm no chemist of oils. I only know that certain chemicals cant be present in these old gear boxes otherwise yellow metals go bye-bye. Lubriplate no. 110 is difficult to find, however I tracked it down to avoid a chemical goof. Its a calcium based grease, and during assembly I noticed that it near instantaneously disperses on contact with the 90wt oil which I found interesting to watch. Again, I'm no chemist, I'm just adding this for the record.
Here you can see the first row of rollers in the idler shift gear bore:

Next comes the spacer, i simply stuck it to one side of the bore, followed by the last row of rollers:

Lastly, the thrust bearings can be stuck on the front and rear face with a few dollops of grease; likewise their races:

In part 3, we'll add this to the case and assemble the input cluster, stand by!

 

[Gunfighter97]

Installation of the idler assembly looks easy in these pictures. It is not. You will knock loose the thrust bearings and races as manny, if not more times than I did, and have to start over. It takes two people and probably an hour of tedious frustration, and in my case took three people as I was also trying to document the process. After about an hour and at least four dozen attempts, I got it aligned perfectly enough to slip between thrust surfaces without disturbing the bearings or races. Fortunately the rollers stayed put through all this. The assembly goes in like so, and must be perfectly lined up front to back to slip into place:

In the above picture, follow my index finger to the left inside face of the housing. That protrusion has a face, that the thrust bearings race sits against. On the opposite wall is the same thing. Front to back, this assembly has maybe ten thousandths of play for you to slip it in. This is the hardest part of the entire process, but once this is done, its all easy. Here you can see a shot of the bore as I got it aligned:

Here is where your helper comes in, in inserting the idler shaft into the case half way. At this point, I coated the press fit area at the head of the pin in back, and the hole in the front of the case with gasket/thread sealer, to prevent any seeping of oil. I did goof in that I forgot to clock the retainer pin's bore in a manner that allows easy removal. Whenever I need to remove this next (hopefully not for another fifty years) The pin will stop half way out, and I'll have to cut it off and then drive the rest out. Not a huge deal to me, I'm sure in fifty years I'll be cursing my past self

Lastly for this component is the separate idler shifter assembly. I oiled up the shift bar, slid the seal on, and put it in up to the bore for the poppet spring and ball.

This can just barely be depressed by hand as you push the shift bar into place. Also be careful, "You'll shoot your eye out kid!"

Then the shift fork is prepared with its roll pin:

And is slipped into the shift gears groove, and rocked into place.

For a pin driver, I used the same method as I did to remove it, a socket extension holding my roll pin punch through the pto port. This completes the idler gear shift system. Part 4 for the input cluster coming soon!

 

[Gunfighter97]

Part 4, input cluster sub assembly.
To start off, everything gets oil (through the whole process this is true except for the rollers and grease surfaces)
The sliding clutch washer slips on the shaft first. This provides the input drive gear a place to stop against as shown here:

Then the first row of rollers are added to the gear, followed by the spacer ring, then the second row of rollers.

I found it easiest to set the gear on edge, like a wheel with a rag to prevent it rolling away and pass the shaft through being careful not to disturb the rollers.

With this portion complete the washer will hold the gear in place with the yoke end pointed upwards. The pto drive can be added, the spring washer is first added along with the brass thrust washer, take note to clock the tab for the washer into its hole in the pto gear.

Once assembled, hold the gears in place on the open end of the shaft and add the input shaft clutch gear:

Since I wouldn't need this portion for a little while, I added the drive yoke, retaining nut and washer to keep everything together. I also wrapped it in rags to keep dust off.
The next sub assembly I did was the rear bearing retainer for the forward output shaft. Unfortunately I didn't get a picture, its not too complicated however, you simply press the needle bearing cup into the large round plate that is the front output's rear retainer.
Stand by for part 5!

 

[Gunfighter97]

Part 5, front output assembly, and input cluster installation (or vise versa )
I installed the input cluster next, if I had it to do again, I would put the front output in first, just because the case became top heavy and a bit tippy on my home made stand. The front output is very simple, so if you are following along, skip down this post to that, then do the input. (Note, one advantage of doing it the way I did, is that if you drop something into the case and have meatier arms than me (everybody) its much easier to get to without the front input installed. I could reach under the idler gear because I'm scrawny lol)
Input cluster:
Quite easy, since we already assembled it, take the yoke off, and simply pass it through the rear opening in the case, and pull the shaft through the bearing from the front OR push the SHAFT ONLY at the rear (DO NOT PUSH THE GEARS! Your rollers will disperse if you do).

Next add the yoke, washer, and nut to retain the assembly together.

Now the two speed shift components are added, first drop the interlock pin into its bore. It should sit between the shift bars. The idler shift bar will need to be in one of its two positions in order to allow the interlock pin to move out of the way of the two speed shifter bar. The clutch gear can be removed and fitted to the fork, wich should be prepared with the pin started in advance, then added to the case. It takes some finger gymnastics and weird angles to get it to slip in.

Once here, its pretty easy to align to drive the pin. I used the same method as the other shift fork. Move the shaft flush with the rear of the case, move the yoke all the way rearward, then drive the pin.

Front Output:

Very simple, first add your gasket sealer to the rear bearing retainer and add the gasket to it. Add the front bearing retainer and two nuts to retain it, then oil up the front output and slip it into place. Add the yoke and hardware to keep it in place in the meantime. (You will have to align gear teeth manually, take care as the edges of my gear teeth were sharp) next paint the other side of the gasket with your sealer, then align the bearing in the retainer with the respective surface on the back of the output shaft. Make note of what holes are and aren't blind here. Once clocked the retainer may require seating with a rubber mallet, make sure to hit it in the center over the back of the bearing cup.

Now add your hardware, I put thread sealant on all the bolts, but took particular care for the open hole bolts to ensure they would seal. The others it just acts as a sort of thread adhesive. I tightened them down snug with a rachet, alternating like installing a wheel. No torque spec is given for these bolts in the manual, and I didn't make note of what I set them to, but I want to say I went around once at 30 ft-lbs then again at 35. I used the same torque setting for all the retainer bolts/nuts and where the rear output mounts to the case.
Next up, part 6, we install the rear output assembly and the last of the rollers. Just keep rollin you're almost done with the complicated part!

 

[Gunfighter97]

Installing the rear output isn't hard, I do want to note a few things before proceeding.
-due to my aforementioned hint at something to do with the main seals, none of the retainers have been gasketed or torqued down yet.
-in addition, the rear retainer present on my unit is worth noting for a couple reasons. Firstly, it was the odd man out for seals even though they all leaked. In fact, upon removal of the gasket, I found a gasket stain from another retainer that didn't match up with the current one. A little research later I found that the cast aluminum retainer was used to an extent on the np202 but is fairly common if not standard on the 205. At this point I'm not sure how I hadn't noticed yet, but a look in my parts manual showed a retainer that mounts a large hand drum brake. Suddenly a bunch of things began to make sense. The strangely long front e-brake cable. The odd placement of the mount for the cable near the t-case. The shoddy placement of the newer style linkage that goes between the front cable and the V shaped cable connected to the rear drums on newer axles. . . like my 1973 axles. . . Here was where it finally clicked that I likely originally had a t-case mounted e-brake.
-last note is following the previous one, I have been researching a disc brake conversion for this truck, and previously wasn't considering doing the rear for how big of a pain the parking brake seems to be. . . well, time to find a t-case mounted e-brake.

Mounting the rear output assembly isn't hard, the bore inside of the large gear contains the final set of rollers, wich are glued in place with our Lubriplate grease.

Next I used the large opening to carefully look around and make sure there was no debris present inside the case, and then coated the end of the shaft with the 90wt.

Next the gasket is painted onto the output housing with sealant, then the other face is painted and the unit carefully slid into place. It helps to have someone look through the pto port to stop you if you aren't aligned. This prevents you from having to reinstall the rollers repeatedly. Lastly, the threads are sealed, and all bolts torqued.

Next we will address the seals and front retainers.

If we have a look at our oem seal above we notice its a two in one deal. The inner side is a normal seal, wich keeps the oil in. On the outside face we have a ring of compressed felt which helps keep dirt away from the seal, in addition it will absorb the small amounts of oil that do make it past the seal. With the help of patrick r of Binder Planet, I was able to copy what he had done to recreate these seals. A second set of the seals provided in the kit is purchased, and the rubber portion removed with a sharp blade such as a box cutter or exacto knife.

This leaves an empty meatal housing, for wich we then fabricate a felt doughnut for.

This felt ring is then glued within the seal body, and pressed into the retainer after the seal. The seal is simply pushed fully down into the retainer. It is important here that when the felt portion is installed, the larger opening in the seal body faces outward in order to clear the small lip at the back of the oil slinger on the yokes. These seal assemblies stack a bit thicker than the oem and stick out a bit, wich is fine, as long as the large opening of the felt seal housing faces outward.

Once these are seated fully, the front retainers gasket thickness is determined as described in the service manual, and the gaskets are sealed to the retainer, housing, and the nuts are torqued. The rear retainer we will leave mocked up for now. Stand by for more. . .

 

[Gunfighter97]

With the rear assembly mocked up, we will move to a couple other remaining details. First up, the seals of the the shift bars are pressed in.

I found that a 3/4 inch pvc fitting was a. . . fitting tool.
Next I figured there would be a leak present at the end of the splined shaft and yoke under the washer. So I made some thin gasket washers to seal those.

Lastly I installed the pto port cover with the gasket with no sealant and hand tight. Just in case I need to get in there again. In addition I allocated all the hardware necessary for completion to ensure I have everything I need.
One thing I would do differently in this process, is at this point I would remove the yokes and polish the seal surfaces. I did this later, it would've been easier at this point.
Lastly, we'll dive into the parking brake. This kit by TSM is designed for the NP205, but having that retainer, it makes a bolt on fit very easy. Here is the assembly mocked up for the first time.

Now, several issues arose here, the installation of the rotor requires removal of the oil slinger, not a big deal, the yoke presses right out, however it ruined my paint in the process.
Next up we'll detail the installation and adapting this guy to the np202.

 

[Gunfighter97]

So, first impressions of the kit are pretty good, its good quality, has good paint, and is very user serviceable. Mocking it up to the np202 yoke revealed about 1/8" of visible runout or wobble in the rotor. Being I had a true square surface at the round end of the yoke, I clamped it up in my bench top mill and did an experiment. I faced off the ends of the flange where the U-bolts pass through.

Then I mounted the rotor to the front; go figure, no more runout. The areas where the nuts/lock washers go on the back of the yoke is a cast surface on my oem parts. I'm thinking the yokes of the np205 are machined, so naturally I need to machine them evenly. Should be easy. I already trued the four prongs, so setting on those surfaces and milling four notches at the same height will make it run true mounted where its supposed to be. Unfortunately my little mill didn't have enough reach. I was able to call in a favor to a friend who has a full size Bridge Port mill. He did it in less than ten minutes in exchange for a bit of yard work. Gotta love the good ol barter system.
Now the rotor has a flat even place to sit, and I got the runout to within 4 thousandths. A bit of runout isn't a bad thing here, but a full 1/8" would be straight up dangerous.

Now that runout wasn't an issue I did a large scale mockup of the t-case with the e-brake caliper and all three drivelines.

Here I discovered that the fancy u-joint caps in the kit don't clear the yoke on my rebuilt drivelines. With the standard U-bolt, the nut is fully threaded on all four corners without a washer, so I will torque these with red thread lock.

At this point I added the shift linkage

And lastly set up the caliper and got it oriented the way I want it, and roughly tuned in. After all seemed good, I repainted the yoke.

 

[Gunfighter97]

Once almost everything was sorted with the brake, I bolted on the mounting brackets. Here I used a special cap/washer thingy for safety wire to help ensure the four main bolts wouldn't ever come out.

Once torqued to spec with thread sealer, the safety wire went in, with an unknown number of attempts and six or seven feet of wasted wire. . . hey, I know how to safety wire now

With this portion installed the crossmember is mounted, and the top two bolts torqued and sealed along with the safety wire. In addition, the bracket is bolted to the crossmember as well. Here is where I wished I had been more picky in my black paint, it didn't perform well in large surfaces and flaked around the bolt when torqued. . . guess I'll take it back off whenever I do the frame some day

From here, all that was left was the flange nuts, rear retainer gasket and finalizing the brake mounting. I waited to seal the rear retainer gasket because I wanted to replace three of my bolts with longer ones to account for the e-brake bracket. Once that was all glued together, I torqued the flange nuts by locking the t-case with the e-brake adjusters. I slathered sealant on the back of the nut and the threads, and used new washers which I also backed with sealant. I sanded the back of the washer till the cotter pin hole would half align when torqued dry. Then added the sealant for perfect alignment. After that the cotter pins went in, followed by drain plugs. I left the pto port gasket for dead last just to be able to get anything dropped in there back out if necessary.

This chunk will go on a palate for now full of oil as I am planning a move. Other than installation, that's this beast wrapped. . . . wait, WHAT? I FINISHED SOMETHING?