Pulling off the Perfect NP246 Transfer Case Rebuild

[Matthew Jeschke]

The most important part, painting is complete haha

 

[rockola1971]

Clutch hub and drum was immaculate. Some wobble in the needle bearing though at neck of drum. no abnormal wear on the shaft or anywhere. Maybe is typical.

I measured the clutch pack including the apply plate and spacer. Measured in three places was and pretty uniform. When measuring I held clutch pack with one hand in a fist to squeeze it together, while I measured with dial caliper next to my hand. I measured all the clutches and steels as well. They were pretty uniform. Rough dimensions below:

Ten clutches ~ 0.086" each
Nine steels ~ 0.067" each
One spacer = 0.071"
One pressure Plate = 0.252"

Stack up ~ 1.803"

Old or new stack? Give numbers of both new and old stack.

 

[Matthew Jeschke]

Old or new stack? Give numbers of both new and old stack.

It is the old stack. Not sure where to buy the new clutches.

Do you just use any clutches & steelsthat fit? I see some kits on ebay.

 

[rockola1971]

It is the old stack. Not sure where to buy the new clutches.

Do you just use any clutches & steelsthat fit? I see some kits on ebay.

You can get anything you need for a 246 at Allstategear out of San Antonio, Texas.
Check your apply plate for warp. If in doubt....replace it. This is one of the key parts that keep your clutch pack uniformly applied when in AUTO4wd. Reuse a worn apply plate and it will cause premature clutch wear. Check inner drum hub for scoring and burrs on notches. 99.9% of the time the inner hub can be cleaned up with a file. Seldomly do they need replaced on Tcase that did not grenade itself.

https://www.allstategear.com/NP246-Clutch-s/2473.htm (clutches, steels, apply plate)

https://www.allstategear.com/NP246-Transfer-Case-Parts-s/1553.htm (all 246 parts)

 

[Matthew Jeschke]

Saving notes here... Apply plate looks perfect. When I built my 4L60E they were all chewed up in core I rebuilt haha. The one in my build here looks like a new one.

Apply Plate Thickness 0.252" Measured in three locations w/in 0.0002"
Selective Spacer: 0.071" Measured in three places w/in 0.0002"

Everything else looks brand spanking new... Drum, hub, gears, etc looks spotless. Only thing is the the clutch steels. They are a bit warn, although no heat marks. I think want to replace them in the least. I'd imagine you always replace clutches with steels.

Partly what's throwing me for a curve is the factory service manual has two different style clutches. My tx case has the newer style GM part #89059648 Cheapest I can find these though is $12 each at rock auto (Picture below).

I ended up buying ten Raybestos GPZ115 518 clutches spec'd for a 47RE Overdrive pack. It appears to be the same. I will validate when I they arrive.

The dimensions were the same... I was a bit leery of purchasing no-name clutches. I used this material / brand clutch for 4th gear in my transmission.

 

[Matthew Jeschke]

Curious how you replaced the front output needle bearing assembly. The one that's captured in the rear part of the case. I'm looking for some tricks to avoid the sucky job that awaits haha

 

[rockola1971]

Are you talking about the need bearing at 6:53 mark? I use a seal remover tool and a sharp chisel if the bearing doesnt want to get outta there.

 

[Matthew Jeschke]

Yeah that's the bearing. I just ordered a bearing removal tool kit (tired of renting them) It has a BUNCH of different stackable sizes. I also ordered a blind hole puller w/ slide hammer and screw jack. Cost a $100 for generic stuff. I don't own a press, but damn I'd like one. Not sure, maybe this is the project that finally motivates me to not be so damn cheap. I'd LOVE to find a smaller press that takes up less room though. Have you ever seen one?

 

[Matthew Jeschke]

Eager to finish this project up. Parts laying all over my workbench. However, waiting for stuff to arrive in the mail. I have two of these transfer cases. Going to see how this one goes and will rebuild the other and sell it if goes well.

 

[Matthew Jeschke]

I FINALLY got around to soaking the new clutches and measuring them. I think my new clutch pack and steels is virtually identical height to old one... at least w/in 5 thousands worst case...

However, one spot I measure on new clutch pack is thinner. another 3 thousands thinner. Not sure if that makes any difference?

New clutch pack measured in three spots (three times each)
4.798, 4.795, & 4.798 - not sure why one reading was 3 thousands less

Old clutch stack up measurements from my notes.
4.8030, 4.8035, 4.8029

I also noticed the inside radius of the shim was higher than outside. I oriented shim in same way it was on original clutch pack. I was compressing that quite a bit when I measured the new clutch pack (used a bar clamp to compress clutch pack) The original clutch pack measurements were taken by hand w/o compressing that inner radius so clutch packs are honestly probably identical.