246 tcase questions

[Matthew Jeschke]

Makes since... I cannot find that same info anywhere else. Would be really nice if it did take the same fluid... I think maybe they looked up the non auto 4wd case.

Curious as though what is it that precludes the np246 from using dexron 6? I am rebuilding one and if possible would like to make it use dexron 6 so I don't need to keep a special fluid on hand.

 

[Fless]

If you're interested in reading about how it works, as well as some diag info, here are links to some articles:

Theory of operation (Pete Huscher):
https://atracom.blob.core.windows.net/gears/2006/2006-07/2006_07_10.pdf

Diag (note that our trucks use a 5volt reference, not the 8v in the article):
https://atracom.blob.core.windows.net/gears/2006/2006-08/2006_08_08.pdf

 

[Matthew Jeschke]

@Fless WOW that's cool. I'm reading those

 

[rockola1971]

Makes since... I cannot find that same info anywhere else. Would be really nice if it did take the same fluid... I think maybe they looked up the non auto 4wd case.

Curious as though what is it that precludes the np246 from using dexron 6? I am rebuilding one and if possible would like to make it use dexron 6 so I don't need to keep a special fluid on hand.

The unit using standard Dexron fluid do not have clutches in them for the Auto 4wd since they do not have Auto 4wd function. Not a common animal out there but they are out there. Both of my 2003 LT's have the Auto 4wd. The non Auto 4wd probably are in the base model Tahoe, Yukon, K1500, Sierra, etc.

 

[Matthew Jeschke]

I kind of wondered. They must need the special fluid so the clutches slip a bit and allow for less friction / heat. I read those articles and it is a PWM function that applies and releases clutches quickly. I think in automatic transmission there is very little slip in clutches like that. They either lock up or release. Is my theory... must be a slip additive in the autotrack fluid?

 

[rockola1971]

I kind of wondered. They must need the special fluid so the clutches slip a bit and allow for less friction / heat. I read those articles and it is a PWM function that applies and releases clutches quickly. I think in automatic transmission there is very little slip in clutches like that. They either lock up or release. Is my theory... must be a slip additive in the autotrack fluid?

I believe its a friction modifier.

 

[Matthew Jeschke]

I need to spec out rebuild parts and or just buy a kit. Any suggestions?

- Case saver
- Case vent elbow
- Not sure if clutches wear out? They are cheap though
- The clutch fork plastic lip deal (I want one that goes over whole end of fork)
- Shaft seals
- Shaft bearings? There is ZERO perceivable play in the input and output shafts.
- Chain? I assume some slack is normal not sure what spec is though to check if I need a new one
- Planetary gear set - Considering buying the 6 pinion. Isn't too expensive.
- Rebuild / gears for encoder motor?

 

[rockola1971]

I need to spec out rebuild parts and or just buy a kit. Any suggestions?

- Case saver
- Case vent elbow
- Not sure if clutches wear out? They are cheap though
- The clutch fork plastic lip deal (I want one that goes over whole end of fork)
- Shaft seals
- Shaft bearings? There is ZERO perceivable play in the input and output shafts.
- Chain? I assume some slack is normal not sure what spec is though to check if I need a new one
- Planetary gear set - Considering buying the 6 pinion. Isn't too expensive.
- Rebuild / gears for encoder motor?

NP246 Transfer Case Parts - GM Transfer Case Rebuild Parts

Allstate Gear carries parts for New Process 246 transfer cases used in both GM and Dodge trucks built in the 2000s. We also have individual Dodge and GM 246 transfer case parts, so you can fix small problems without doing a complete rebuild

www.allstategear.com

Im guessing the Tcase is all original and was in a 2001? Replace all bearings, seals, Auto clutches, chain, fork lip and any hard parts that fail inspection. Makes no sense to replace a little of this and that for something like a bearing or chain to fail and destroy your Tcase. Do it once and be done for a long time. I always replace the Auto clutches on a Tcase that is well used. Be sure to soak all the clutches in autotrac fluid overnight before assembly!
Harbor Freight has cheap bearing and seal drivers. You will also need a set of internal/external snapring pliers with extended reach(nose). Thats about it for "special tools".
You run into any questions feel free to ask us anytime. There are tons of youtube videos on the 246 case disassembly/reassembly and most of them are pretty good. Dont let the Tcase intimidate you. There really is not alot to them. They sure arent anything to the level of a transmission and not near as many parts.
Just take your time and dont be in a hurry.

 

[Matthew Jeschke]

Just finished 4L60E build Transfer case and steering gear box are last things not rebuild on my truck. I wouldn't mind to upgrade it a bit on way too... I'm thinking of that 6 pinion planetary. Truck is used quite a bit off road on moderate trails, no rock crawling stuff though.

I'll just do a complete rebuild. You know of a kit or brands I should steer clear of?

I noticed non GM / OEM chains are MUCH cheaper.