Very nice write up, and pics. Its interesting to see some of the differences in the cases. Though, I am curious, why you didn't pick up new seals/bearings?? Have you considered replacing the chain as well?

 

Honestly, I'm curious as well. Seriously!

SWMBO calls me curious quite often. And special. Very special. I hear that one a lot!

 

So I really wanted to run the double row front input bearing, and I had a good one from our CRACKED case.

I also had 2 planetary assys in hand. One was the newer style for the double row but it was toasted from trying to be a roller bearing processor. The other was in nice condition but was the older style for the single row bearing.

At first I didn't realize there was any difference in the planetaries, but I must admit at some point in the back of my head i wondered what compensated for the different bearing thickness. Well, the input shaft/sun gear does, dummy!

It's also perhaps important to note that I had read somewhere (I kinda think it was cumminsforum.com) that you could simply upgrade to the double row bearing with nothing else. This isn't true.

This was the munched sun gear from our $500 "front input bearing processor. " It was the newer style to accept a double roller but I wasn't comfortable using it.

Newer double roller style left, older single roller right. The difference is .3125" or 5/16" because the single is 5/8" wide while the double is 15/16"

I'm stubborn, so let's swap on the 4-jaw, indicate it in to .001" TIR and turn back that shoulder (I went .310" based upon measuring existing parts)

Factory had a small radius groove right up against the shoulder, presumably for oiling, so I did one, too. I was too lazy to grind a true radius so I used a parting tool and just went shallow. I was concerned about creating a stress riser without a heavy radius, but whatever.....

Finally, I duplicated the flat at the oiling hole

My freshly modified shaft right, now ready for a double roller input bearing

If you don't do these mods or use the correct piece this snap ring groove will be buried within the bearing 5/16" back and your entire mainshaft will sit 5/16" too far to the rear -- not sure the case halves would even mate this way but I wasn't gonna find out

 

Here's what the thrust washer/shims look like within the planetary assy. You can see the left one had crushed, smeared and otherwise folded, spindled or mutilated many of its shims

 

Yay! We at least have proof of concept!

Again, I was used to BW 'cases (although I've also rebuilt a GM NP246, it was electric shift) where you can dummy shift it thru the ranges without the rear case half on. I tried that here and it will not work. You need that rear bearing support and rear snap ring in place (the latter is super important because it pulls the mainshaft back into proper position).

So you have to at least mock it up to this point then you can click it thru 2hi, 4hi, N and 4lo and check for proper function.

Now to take it back apart, double check everything (I keep hearing Eric O at SMA saying, "Don't forget that snap ring!!"), install the oil pump and seal up all case mating surfaces

Gotta be to this point to test shift

 

Oooo, you have some cool toys in your shop. Yep, I am jealous.

 

The external shift arms are very different from old style to new style

 

I was able to employ the same drunken kindergartener who stamped my OTC tool copy shown above to stamp my super high tech oilfield pipe seal installation tool for front input

You might be white trash if: You have a wheelbarrow full of NP241D parts to be stored in that old '76 Econoline out back....

 

Also installed the Sonnax transfer case "saver" in place of the factory rear snap ring

 

Got 'er stabbed back in. How I ever used to do this on my back I don’t know...