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Matthew Jeschke
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The most important part, painting is complete haha
Pulling off the Perfect NP246 Transfer Case Rebuild
- Thread starter Matthew Jeschke
- Start date
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rockola1971
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Old or new stack? Give numbers of both new and old stack.
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Matthew Jeschke
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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
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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)
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Matthew Jeschke
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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.
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.
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Matthew Jeschke
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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
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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.
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Matthew Jeschke
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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?
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Matthew Jeschke
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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.
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Matthew Jeschke
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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.
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.
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Matthew Jeschke
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I did a final sanity check on the clutches. The new clutch stack is within 5 thousands of old one so I think good enough. I'm assembling and is very easy to put it all together but ran into a hiccup.
The snap ring for the gear selector is no good. It barely hangs on the shaft. I'd replaced that bearing in the case and now I think I need a new snap ring there.
Video of what I'm talking about HERE
Anybody know where I can get the gear selector snap ring?
The snap ring for the gear selector is no good. It barely hangs on the shaft. I'd replaced that bearing in the case and now I think I need a new snap ring there.
Video of what I'm talking about HERE
Anybody know where I can get the gear selector snap ring?
rockola1971
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.005" difference. Id call that good and send it!
Gear selector seal lip should face out like you have it.
Snap ring is in the groove like it should be BUT snapring appears to be too thin. They can be found individually at home depot, lowes, menards and the like. Mic the groove diameter and thickness on the shift shaft.
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Matthew Jeschke
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Ooops haha I just ordered from merchant automotive. Your suggestion would have been more affordable. It was only $3.99 however shipping was $16 so I threw magnetic train and fill caps.
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Matthew Jeschke
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I need part numbers for the input shaft snap ring (that goes on hub for gear hub / input side)... And the output shaft.
I'm nearly completely done but those two snap rings are loosey goosey.
UPDATE:
I found the part number it's GM 682653. Looks like both the planetary snap ring and front ouput are same size and that part number comes with 10 snap rings.
I'm nearly completely done but those two snap rings are loosey goosey.
UPDATE:
I found the part number it's GM 682653. Looks like both the planetary snap ring and front ouput are same size and that part number comes with 10 snap rings.
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rockola1971
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Since its been so long since you presoaked those auto clutches, I would add some AutoTrac fluid and spin the unit over by hand wetting those new clutches thoroughly BEFORE you install the TCASE and put it under power.
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Matthew Jeschke
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My slow a$$ is finally getting the TX case put in. Learning LOTS about messing up encoder motors! Took encoder apart as was clocked wrong *sigh*
Long story short, I'm 9/10ths installed.
I noticed, probably should have made note earlier too, that the front output is TIGHT. Specifically when in 2 high I can turn the front output independently with a lever while rear tires are locked and front driveshaft is off. I keep second guessing those clutches as I didn't use the tool tool. I think I'm fine... But just a sanity check here.
Also worth noting, they were presoaked... and right now I only have 1 quart of tx fluid in there. I need to pickup the second one. I assume once they get a little fluid between them they spin a little easier?
Thanks!
Long story short, I'm 9/10ths installed.
I noticed, probably should have made note earlier too, that the front output is TIGHT. Specifically when in 2 high I can turn the front output independently with a lever while rear tires are locked and front driveshaft is off. I keep second guessing those clutches as I didn't use the tool tool. I think I'm fine... But just a sanity check here.
Also worth noting, they were presoaked... and right now I only have 1 quart of tx fluid in there. I need to pickup the second one. I assume once they get a little fluid between them they spin a little easier?
Thanks!
rockola1971
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Fill her up once install is done. Keep in 2wd and drive around like that for 10miles or so and that will get the clutches thoroughly soaked then 4wd should be good to go.
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Matthew Jeschke
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haha, thanks for the tip... I cycled all the modes, then each one a little blip of the throttle. Drove one mile. It works like a CHAMP!
I'll put it in 2hi and drive about 10 miles. I do notice the motor is under a bigger load. I'm assuming that 4wd is partly engaged. However, tires don't bind when I turn which is good.
Build was SUPER easy. You were correct. I just had to find time to get to it. I built it up once... Then RTV'd it only to find I forgot a snap ring! I tore it completely down and reassembled it again in like 30 minutes.
The only blooper (separate post) was a efd up the encoder motor. Had to take it apart, pull the motor, and spin the shaft to get it back to neutral position. PITA I was almost done swapping the case after 9 hours of work... Only to have that encoder motor give me crap and it take another 9 hours to figure out.
Few notes. At 250,000ish miles the TX case looked like NEW inside. It was MINT, clutches were in spec, only issue was the pump rub. Had I not done this rebuilt, it's for SURE it would have rubbed through the case. A person maybe just as well to just put in a case saver and throw it back together. Otherwise wasn't too expensive to buy the rebuild kit. Chain IMO is a waste of money. The factory one was in perfect shape, no slop at all... only slop was a little from the carrier bearings on the shafts. Once I put new bearings the chain had no slop at all. I saw a few people on YouTube checking chain slop w/o supporting both sides of the shafts in the case. You cannot do that... It'll look loose that way. Once the case halves were temporarily put on it had no slop in the chain. The light noise when you spin the shafts is the apply hub (I think that's what it's called) touching the shift fork. It's normal and not the chain. The upgraded Raybestoz GPZ clutches were cheaper than the factory ones (I didn't want Chinese spec stuff they were not much more than those though). Hardest part was just getting the case out off the truck. I don't know why anybody would not try rebuilding one of these on their own. Was SUPER easy, just be careful you pull the encoder motor in NEUTRAL (or 2hi?). To put in neutral, push 2hi and 4lo buttons w/ trans in neutral for 10 seconds. Then pull the encoder motor and next the tx case. I pulled the encoder motor because I was worried about smacking it on the ground / breaking it otherwise.
Thanks for all the help! Stoked to have a good as new (better than new?) transfer case. Has upgraded clutches, case saver, and all new perishable parts replaced...
I'll put it in 2hi and drive about 10 miles. I do notice the motor is under a bigger load. I'm assuming that 4wd is partly engaged. However, tires don't bind when I turn which is good.
Build was SUPER easy. You were correct. I just had to find time to get to it. I built it up once... Then RTV'd it only to find I forgot a snap ring! I tore it completely down and reassembled it again in like 30 minutes.
The only blooper (separate post) was a efd up the encoder motor. Had to take it apart, pull the motor, and spin the shaft to get it back to neutral position. PITA I was almost done swapping the case after 9 hours of work... Only to have that encoder motor give me crap and it take another 9 hours to figure out.
Few notes. At 250,000ish miles the TX case looked like NEW inside. It was MINT, clutches were in spec, only issue was the pump rub. Had I not done this rebuilt, it's for SURE it would have rubbed through the case. A person maybe just as well to just put in a case saver and throw it back together. Otherwise wasn't too expensive to buy the rebuild kit. Chain IMO is a waste of money. The factory one was in perfect shape, no slop at all... only slop was a little from the carrier bearings on the shafts. Once I put new bearings the chain had no slop at all. I saw a few people on YouTube checking chain slop w/o supporting both sides of the shafts in the case. You cannot do that... It'll look loose that way. Once the case halves were temporarily put on it had no slop in the chain. The light noise when you spin the shafts is the apply hub (I think that's what it's called) touching the shift fork. It's normal and not the chain. The upgraded Raybestoz GPZ clutches were cheaper than the factory ones (I didn't want Chinese spec stuff they were not much more than those though). Hardest part was just getting the case out off the truck. I don't know why anybody would not try rebuilding one of these on their own. Was SUPER easy, just be careful you pull the encoder motor in NEUTRAL (or 2hi?). To put in neutral, push 2hi and 4lo buttons w/ trans in neutral for 10 seconds. Then pull the encoder motor and next the tx case. I pulled the encoder motor because I was worried about smacking it on the ground / breaking it otherwise.
Thanks for all the help! Stoked to have a good as new (better than new?) transfer case. Has upgraded clutches, case saver, and all new perishable parts replaced...
rockola1971
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Tcases are indeed stupid easy to rebuild. They arent anywhere near as involved as rebuilding a tranny or an engine. Definitely not rocket science especially with all the youtube videos available on how to.
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Matthew Jeschke
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And your help! Everybody wants to use that dumb tool for a gazillion dollars to spec the clutch stack spacer. I'd have been sunk if you'd not have pointed out to just measure them by hand. Maybe the only time your really need that tool is if you have a new clutch drum?
