Help with Chevy T-case

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bradbury

Senior Member
Jun 25, 2008
264
28
28
Riverside
Hey guys. So I have a 2004 Chevy Silverado 2500 HD with the NP263 HD transfer case. Back in the beginning of summer the transfer case experience pump rub and wore a hole in the rear section of the housing so I replaced the entire rear section of the housing and put all new bearings and seals in the T case. Now it is starting to make noise randomly and will no longer go into four-wheel-drive high or low. Anybody on here happen to know how to work on these or know somebody who does? The remanufactured replacements are around 1100 bucks and being Christmas time can’t really afford to replace it at the moment.



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04yfzkid

I are smarts
Mar 21, 2007
33,433
305
83
Flagstaff, AZ
I doubt it's any help but my t-case struggles to go into 4 low. It goes in about once every 40 tries. When it doesn't go into 4 low, I can hear the motor trying but making grinding noises before it gives up. 4 hi now only likes to go in at a stop or if I am moving I have to throw it in neutral before I switch in or out. Everyone I've talked to says it's the shift encoder motor. I'm still not sure if the previous owner did the preventive pump rub kit, or magically this truck has gone 310k miles without having that issue.
 

Bertismyname

member
Oct 1, 2018
888
298
63
San Diego
They aren't too difficult to rebuild. A few basic hand tools is about all that is needed. Sounds like you may have a bent or broken shift fork. It might be worth opening it and taking a look. Post pictures if you do.
 

bradbury

Senior Member
Jun 25, 2008
264
28
28
Riverside
I have opened it up when replacing the tail housing and put new seals and bearings. Everything seamed to be in good shape. I thought it may be the encoder and bought a new one and it still wouldn’t work. I took the encoder off and tried shifting into 4wd with a wrench on the key that the encoder shift but it still wouldn’t work. Guess I’ll pull it out and look again but was hoping to find someone with experience since it’s a pain in the ass to pull in and out. Only picture I took.



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Bertismyname

member
Oct 1, 2018
888
298
63
San Diego
I would take a close look at the shift fork and shift rail. Since has a motor and not a manual shift the shifting mechanism should be buttery smooth.
 

84projectford

Senior Member
Sep 8, 2010
922
364
63
Phoenix Az
You didn’t get down in there deep enough. Check EVERY bearing for any kind of notchy or bad feeling after you clean the oil out of it.

The shift forks on that year wear the pads out in the collar. Once they wear out, the fork will half ass engaging 4 low and cause bad noises. Merchant automotive sells the updated fork/pads and collar to stop the issue or i think rock auto has the old style still. The 4wd shift fork also wears out so inspect it well as well. Chains don’t really stretch in these. Parts are not cheap for these t-cases. Your still going to spend and pretty penny fixing it
 
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bradbury

Senior Member
Jun 25, 2008
264
28
28
Riverside
You didn’t get down in there deep enough. Check EVERY bearing for any kind of notchy or bad feeling after you clean the oil out of it.

The shift forks on that year wear the pads out in the collar. Once they wear out, the fork will half ass engaging 4 low and cause bad noises. Merchant automotive sells the updated fork/pads and collar to stop the issue or i think rock auto has the old style still. The 4wd shift fork also wears out so inspect it well as well. Chains don’t really stretch in these. Parts are not cheap for these t-cases. Your still going to spend and pretty penny fixing it
I did tear down the entire thing to a bare case but that was the only pic I took. I replaced every bearing, seal, spacer and sleeve. I also replaced the rubber on the shift forks with new ones that came in my kit but maybe the entire fork needs to be replaced? I’m going to tear it down again this Saturday and see if I can spot the problem but now that I know I can shift it with a wrench that should help.


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84projectford

Senior Member
Sep 8, 2010
922
364
63
Phoenix Az
I did tear down the entire thing to a bare case but that was the only pic I took. I replaced every bearing, seal, spacer and sleeve. I also replaced the rubber on the shift forks with new ones that came in my kit but maybe the entire fork needs to be replaced? I’m going to tear it down again this Saturday and see if I can spot the problem but now that I know I can shift it with a wrench that should help.


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unless its an updated case from 2006 or 2007 (not likely since the back was still magnisium, updated cases got aluminum), you cant replace the feet on the fork. they are injection molded into the fork and when they have worn out enough, they take the fork with it. you may have been looking at the big mode fork for 4wd/2wd. the smaller fork next to the planets with a smaller collar is what the main issue stems from.

yes, just shift it back and forth with the wrench. its not unheard of for the encoder motor to go bad but 9/10 times is internal t-case issues.

Post pics up if you are unsure. ive rebuilt a few of these and there aint shit out there as far as specs on how to rebuild them. i tried and even pulled some strings with guys i know at GM. New Process wouldnt give shit out. Probably why GM went to BW in 07.5 trucks
 

bradbury

Senior Member
Jun 25, 2008
264
28
28
Riverside
Okay got it. I ordered new mode fork and hi/lo fork just encase I need them when I open it back up. I thought it was the encoder so I took it off and tested with a wrench but could not get it to shift at all. Im assuming I messed something up during installation that has now worn out. Defiantly agree that there is minimum info out there on these and seem to be the most expensive Np to replace.
 

Bertismyname

member
Oct 1, 2018
888
298
63
San Diego
The encoder motor gears are small and weak. Any binding will take them out. The factory motor on my trail blazer failed. Bought a replacement. Installed the new motor. It was bad out of the box.( bad gears, shitty rebuild) swapped factory gear set into replacement motor works great. And mine is constantly shifting since the trailblazer s.s. is all wheel drive.


It's a simple enough task to build / cannibalize a manual shift lever onto these transfer cases. If I had the time I would build a kit to ditch the encoder motor.

In your case. Pun intended. I might look at swapping in an older lever shifted case. I've thought about doing it to the trailblazer so I can do smokey burn outs with the wife's truck. It's already had a cam swap and d.o.d. delete done and I have h.p. tuners.
 

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