Greatly appreciate you for sharing this detailed explanation overhaul on this np246, I'm in the final stages of wrapping mine up , I must have viewed this 50 times then skipping here and there making sure I didn't miss anything. 🍻
Thank you for this very detailed video. It helped me a lot with my MP3023 transfer case. Some of these are similar, especially the planetary gear. For example, I didn't know how to replace the shaft seal on the input shaft without destroying it. But with your video I was finally able to do the steps in reverse order. Thank you Sir
This is a fantastic reference video for assembling a 246. There are two measurements of the special tools that are a must for accurate reassembly that i cannot find here. first the range selector shaft bearing and seal assembly tool seems to have a boss that would recess the bearing below the surface of the mounting flange into the counterbore that the bearing on the shift motor sets into. i have measured the height of the flange on the drive socket in the shift motor and it seems to be around 2 millimeters above the surface of the shift motor. i suspect the boss on the bearing insertion tool is 2+ millimeters to provide clearance between the drive socket and the range selector shaft bearing. also the special tool that drives the front output shaft seal in place has a groove that establishes the planes that the two parts of the seal. a quick measurement of the depth of that groove would complete the video. Again this is a fantastic video for anyone assembling a 246. I was a machinist by trade and now have a machine shop in my garage just for building and rebuilding my own toys. i have built all of the special tools for this install.
I wanted to thank you for your wonderful video content you’re so thorough it is really giving me the confidence to take on my transfer case overhaul myself. When you were putting the case on for the final time I couldn’t help notice that the updated antirattle clip was missing from the pump.
Thanks, that's the whole reason I take the time to share them. Your clip observation is just another example of how much these rebuilds can be very model year unique when done _by the book_ as I've shown here. This 1999 one intended for pairing with the 6.5L diesel V8 would not have all of the same parts originally, as well as several other differences, from 1998 and then later years. I did another video last week that really homes in on how these units varied from each other every single year.
Dr Shock I Loved your video rebuilding the np246 transfer case! I own a 05 silverado that I just replaced my encoder motor but currently now have an issue with the functionality of my transfer case 4wd hi. For some reason I believe the dorman encoder motor may have been shipped to me in a different phase other than neutral? My 4wd functions however I have cannot put my transfer case in 4hi from 2hi, indicating that the clock synchronization problem I believe now? This problem is what prompted me to see how a NV/NP246 transfer case goes together! Thank you so much for sharing your expertise regarding these transfer cases!!! I’m sure many like myself have learned something and found this process interesting!!!
Had the same problem with my 04 the encoder motor comes clocked wrong from the factory on certain brands. Good friend of mine that is a mechanic helped me figure that one out.
Great video!! I"m a pretty confident mechanic and this is my lively hood. One question if we don't have the $600+ measuring tool for the clutch pack shim what would be the alternative for this?
I'm not aware of any alternative aftermarket type tool for this one. Though some folks who have a machinist background may have fab'd their own versions on their lathe. What I suggest to most of us folks who don't have a lathe, is buy the Kent-Moore tool used on eBay (search links in the video description), and then resell it when you're done.
Could you tell me what position, N, 4H or 4L the transfer case is in at the end of this video with the shaft pointing up and down? I went to change my shift motor and when taking it off the shaft seemed to have sprung a bit and I could not get the replacement motor onto the shaft. Thank you.
This unit was disassembled with the encoder motor in the default 2H position (the normal driving mode). When reassembling you will want to return it to this, or whatever position you started in if different. I showed how you can use a wrench to manually reposition the selector shaft to line up with the encoder motor, whose position will reflect where you started. You know you have it when the encoder motor will simply slide back over the shaft (the motor and shaft are keyed to each other) with its mounting bolt holes in alignment.
@@DrShock Thank you for your reply. I understand this, my truck would not shift out of 4Hi. The only way to drive it without binding was to pull the ATC fuse which would disengage the front axle. It was then that I decided to change the shift motor. When doing so I heard a noise like a spring releasing as I removed the old motor. The shaft had turned slightly and now I cannot lineup the replacement. I wonder if the transfer case is damaged internally, not allowing the shaft to properly align with shift motor. Or could I be 180 degrees out. I'll look in your video to where you are shifting the case manually. But I don't think there is a full half turn throughout the different modes. Any thoughts? Again, Thank you
I can't say I'm any sort of expert with these older transfer cases. I've rebuilt a few and am comfortable with that process, but not familiar with recognizing all of their various failure patterns. Typically, you should be able to manually cycle the selector lever just like the encoder motor would. So if you cannot get the selector to realign with the encoder motor, I would suspect either a problem with the encoder motor resting position itself, or the internal clutch mechanism for the selector inside the transfer case. Would have to open up the transfer case to confirm the latter. What's happening operationally as you cycle those selector shaft positions is tension on that clutch pack mechanism is changing. Functioning very similar to an automatic transmission clutch, just instead of hydraulic pressure it's mechanical thru the fork that the encoder motor is actuating via the selector shaft.
Outstanding! Also, your bushing/bearing seal driver kit, does it allow you to stack the 50mm and 48mm or whichever combination you choose? I`ll answer my own question, Yes! Read the tool description on the website LOL! THANKS!
I just got through taking apart my 246, and the fork pivot pins have stripped the threads in the housing. Have you used a product like loctite form a thread for this application, or do you have any recommendations to fix these threads? Thanks!
There's significant force applied here, I would just replace the case half with one from an LKQ salvage yard donor. But if you just wanted a temporary repair, something like _Alvin Lab-metal_ would be worth a look.
The new and "improved" oil pump anti rattle/rub clip (29:07) would be better replaced by the Merchant Automotive pump plate. The improved clip is known to fail also.
I was thinking the same thing no matter what a whole plate that protects the whole pump rather than a singular piece on one side just seems like a no brainier to me only part of the video I where I was like umm I think I'm still going to do the plate
For the speedometer check the speed sensor installation, and the correct sensor for this model is being used, and wiring integrity. Could also be that you do not have the sensor pickup aligned with the reluctor wheel inside the case. The lack of shifting is perhaps that the clutches were not properly done. Either way you're going to have to go back inside to find out. This model transfer case _must_ be filled with blue fluid, GM Autotrak-II transfer case fluid. And the clutch pack _must_ be properly shimmed using the special tools and procedure I went over in this video series, otherwise it will not shift properly at all. It's design is more similar to a transmission than a traditional transfer case.
@@DrShock we try speed sensor , after test drive i feel some sounds my transfer case then i see light on servics 4x4 odometer. Tomorrow we rebuild again. I am from Azerbaijan, Baku.
I know your question is from two months ago, but I spent about $350 on eBay for the tool set. I do plan to re-sell it on eBay for a considerably lower price once I've used it. Let me know if you're interested.
There isn't a free one as GMs legal department will shut that down. You can buy it used (links in the description), or subscribe at www.acdelcotds.com for the electronic version.
The non-preload clutch started around or after 2003. AFAIK both types do have to be shimmed. And while both determine which shim to use by using the J-44295 tool set, I believe there is a difference in setting up the tool used to measure this between the two designs. What I showed is the tool setup _only_ for the earlier design. I'm not familiar with the setup used on the later design though. Best advice would be to consult the service manual for your model year truck to be sure.
Wrong correction from 1999-2001 r the same 246 transfer case the shift motor is a different gear the 199-2001 has two plugs on that shift motor on the side thats a different gear the 2004 and i no 2005 r the same but i do t no how far they go up to b the same everyone of these 246 transfer case housing rubs a hole n the housing after that rattle clip breaks
Greatly appreciate you for sharing this detailed explanation overhaul on this np246, I'm in the final stages of wrapping mine up , I must have viewed this 50 times then skipping here and there making sure I didn't miss anything. 🍻
Thank you for this very detailed video. It helped me a lot with my MP3023 transfer case. Some of these are similar, especially the planetary gear. For example, I didn't know how to replace the shaft seal on the input shaft without destroying it. But with your video I was finally able to do the steps in reverse order. Thank you Sir
Excellent work, felt like I was in shop class
This is a fantastic reference video for assembling a 246. There are two measurements of the special tools that are a must for accurate reassembly that i cannot find here. first the range selector shaft bearing and seal assembly tool seems to have a boss that would recess the bearing below the surface of the mounting flange into the counterbore that the bearing on the shift motor sets into. i have measured the height of the flange on the drive socket in the shift motor and it seems to be around 2 millimeters above the surface of the shift motor. i suspect the boss on the bearing insertion tool is 2+ millimeters to provide clearance between the drive socket and the range selector shaft bearing. also the special tool that drives the front output shaft seal in place has a groove that establishes the planes that the two parts of the seal. a quick measurement of the depth of that groove would complete the video. Again this is a fantastic video for anyone assembling a 246. I was a machinist by trade and now have a machine shop in my garage just for building and rebuilding my own toys. i have built all of the special tools for this install.
Nicely done. Best video I seen on UA-cam. Thanks a lot.
I wanted to thank you for your wonderful video content you’re so thorough it is really giving me the confidence to take on my transfer case overhaul myself. When you were putting the case on for the final time I couldn’t help notice that the updated antirattle clip was missing from the pump.
Thanks, that's the whole reason I take the time to share them. Your clip observation is just another example of how much these rebuilds can be very model year unique when done _by the book_ as I've shown here. This 1999 one intended for pairing with the 6.5L diesel V8 would not have all of the same parts originally, as well as several other differences, from 1998 and then later years. I did another video last week that really homes in on how these units varied from each other every single year.
Dr Shock I Loved your video rebuilding the np246 transfer case! I own a 05 silverado that I just replaced my encoder motor but currently now have an issue with the functionality of my transfer case 4wd hi. For some reason I believe the dorman encoder motor may have been shipped to me in a different phase other than neutral? My 4wd functions however I have cannot put my transfer case in 4hi from 2hi, indicating that the clock synchronization problem I believe now? This problem is what prompted me to see how a NV/NP246 transfer case goes together! Thank you so much for sharing your expertise regarding these transfer cases!!! I’m sure many like myself have learned something and found this process interesting!!!
Had the same problem with my 04 the encoder motor comes clocked wrong from the factory on certain brands. Good friend of mine that is a mechanic helped me figure that one out.
Does the preload clutch pack have to measured for a shim with the clutch setup tool like the Nobel reload does?
Thanks for the help!
Thanks this helped out a lot. If you don’t mind where do I fine the paperwork at
Should be a link in the description where you might find an used service manual set.
Great video!! I"m a pretty confident mechanic and this is my lively hood. One question if we don't have the $600+ measuring tool for the clutch pack shim what would be the alternative for this?
I'm not aware of any alternative aftermarket type tool for this one. Though some folks who have a machinist background may have fab'd their own versions on their lathe. What I suggest to most of us folks who don't have a lathe, is buy the Kent-Moore tool used on eBay (search links in the video description), and then resell it when you're done.
Thanks for video.
Could you tell me what position, N, 4H or 4L the transfer case is in at the end of this
video with the shaft pointing up and down? I went to change my shift motor and when
taking it off the shaft seemed to have sprung a bit and I could not get the replacement motor onto the shaft. Thank you.
This unit was disassembled with the encoder motor in the default 2H position (the normal driving mode). When reassembling you will want to return it to this, or whatever position you started in if different. I showed how you can use a wrench to manually reposition the selector shaft to line up with the encoder motor, whose position will reflect where you started. You know you have it when the encoder motor will simply slide back over the shaft (the motor and shaft are keyed to each other) with its mounting bolt holes in alignment.
@@DrShock Thank you for your reply.
I understand this, my truck would not shift
out of 4Hi. The only way to drive it without binding was to pull the ATC fuse which would disengage the front axle. It was then that I decided to change the shift
motor. When doing so I heard a noise like a spring releasing as I removed the old motor. The shaft had turned slightly and now I cannot lineup the replacement.
I wonder if the transfer case is damaged internally, not allowing the shaft to properly align with shift motor. Or could I be 180 degrees out. I'll look in your video to where you are shifting the case manually. But I don't think there is a full half turn throughout the different modes.
Any thoughts? Again, Thank you
I can't say I'm any sort of expert with these older transfer cases. I've rebuilt a few and am comfortable with that process, but not familiar with recognizing all of their various failure patterns. Typically, you should be able to manually cycle the selector lever just like the encoder motor would. So if you cannot get the selector to realign with the encoder motor, I would suspect either a problem with the encoder motor resting position itself, or the internal clutch mechanism for the selector inside the transfer case. Would have to open up the transfer case to confirm the latter.
What's happening operationally as you cycle those selector shaft positions is tension on that clutch pack mechanism is changing. Functioning very similar to an automatic transmission clutch, just instead of hydraulic pressure it's mechanical thru the fork that the encoder motor is actuating via the selector shaft.
Thank you sir very informative
Outstanding! Also, your bushing/bearing seal driver kit, does it allow you to stack the 50mm and 48mm or whichever combination you choose? I`ll answer my own question, Yes! Read the tool description on the website LOL! THANKS!
I just got through taking apart my 246, and the fork pivot pins have stripped the threads in the housing. Have you used a product like loctite form a thread for this application, or do you have any recommendations to fix these threads? Thanks!
There's significant force applied here, I would just replace the case half with one from an LKQ salvage yard donor. But if you just wanted a temporary repair, something like _Alvin Lab-metal_ would be worth a look.
@@DrShock i will look into finding a salvage unit to rebuild, thank you!
The new and "improved" oil pump anti rattle/rub clip (29:07) would be better replaced by the Merchant Automotive pump plate. The improved clip is known to fail also.
I was thinking the same thing no matter what a whole plate that protects the whole pump rather than a singular piece on one side just seems like a no brainier to me only part of the video I where I was like umm I think I'm still going to do the plate
Great work have fun doing it all over again in 10 years lol
With OEM parts, more like 20 years. ;-)
@@DrShock yeah yeah ok mr 4th Gen ya got me there. Us 5th gens would have to di it again in 10 years lol
After rebuild transfer case my car does not change shifts, and speedomeger dont work my car is Chevy Tahoe 2000 . May be we did mistake anythink?
For the speedometer check the speed sensor installation, and the correct sensor for this model is being used, and wiring integrity. Could also be that you do not have the sensor pickup aligned with the reluctor wheel inside the case. The lack of shifting is perhaps that the clutches were not properly done. Either way you're going to have to go back inside to find out.
This model transfer case _must_ be filled with blue fluid, GM Autotrak-II transfer case fluid. And the clutch pack _must_ be properly shimmed using the special tools and procedure I went over in this video series, otherwise it will not shift properly at all. It's design is more similar to a transmission than a traditional transfer case.
@@DrShock we try speed sensor , after test drive i feel some sounds my transfer case then i see light on servics 4x4 odometer. Tomorrow we rebuild again. I am from Azerbaijan, Baku.
Hi, how much is the three piece clutch pack measuring tool?
There's links in the video description where you can find the parts, and this tool, online.
I know your question is from two months ago, but I spent about $350 on eBay for the tool set. I do plan to re-sell it on eBay for a considerably lower price once I've used it. Let me know if you're interested.
Where can I get the manual?
Should be a search link in the videos description text.
👍👍👍👍👍👍👍👍
It looks like the 12547475 ring is discontinued by GM, where were you able to source one?
Yes I was, NOS. You may have to look aftermarket if you cannot find it from one of the discontinued GM parts vendors on eBay or Amazon.
How i get pdf manual? Can you share pls?
There isn't a free one as GMs legal department will shut that down. You can buy it used (links in the description), or subscribe at www.acdelcotds.com for the electronic version.
I would like to note that you cannot do this job with normal snap ring pliers, you need special snap ring pliers.
Did I miss something. I didn't see how the planetary gear set go back in the case??? I thought you were going STEP-BY-STEP!! Otherwise great video.
Did you check part I? ua-cam.com/video/11dcXWnipkY/v-deo.html
I mean non preload cultch.
The non-preload clutch started around or after 2003. AFAIK both types do have to be shimmed. And while both determine which shim to use by using the J-44295 tool set, I believe there is a difference in setting up the tool used to measure this between the two designs. What I showed is the tool setup _only_ for the earlier design. I'm not familiar with the setup used on the later design though. Best advice would be to consult the service manual for your model year truck to be sure.
Wrong correction from 1999-2001 r the same 246 transfer case the shift motor is a different gear the 199-2001 has two plugs on that shift motor on the side thats a different gear the 2004 and i no 2005 r the same but i do t no how far they go up to b the same everyone of these 246 transfer case housing rubs a hole n the housing after that rattle clip breaks