1998 - 2007 GM NP8 NP246 Transfer Case Complete Tear Down & Disassembly (Chevy & GMC)
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- Опубліковано 31 лип 2024
- In this EPIC level of detail video we do a COMPLETE step by step tear down and disassembly of the New Process Gear 246 (aka NP246) transfer case as used by GM starting in 1998. This NP246 example is a first generation transfer case known as the Auto-Trak (or Auto-Trak I), or as regular production option (RPO) NP8. The NP246 transfer case is very similar to the NP236, and we will call out those differences between the NP236 and the NP246 as we go where we can, but we're focused on showing the NP246 disassembly here. These transfer cases were built by New Process Gear for both GM and Chrysler, later changing their name to New Venture Gear. After the name change, this model became the NV246 (or NVG246). The NV246 was also used on several Dodge and Jeep model trucks as a result of the Chrysler partnership, so this video will have some value there as well. However, we will be using the genuine GM factory service information for the steps involved, referencing any special tools required along the way.
This particular NP246 was not exhibiting any functional issues whatsoever, but did have a long term multi-year leak from the rubber plug for the spring clip access port on the top of the rear case half that warranted attention (leaks in this area are not uncommon). Upon opening up this 246 transfer case we find the unit still had fluid, though significant portions of this aged fluid had become more of a varnished hardened mud or goo from heat and age. Fortunately, this is the only problem with this NP246 transfer case so it was caught in time, and a full rebuild with all genuine GM parts will have it back into service quickly.
Link to rebuild video: • 1998 - 2007 GM NP8 NP2...
The eBay and Amazon search links below are paid links, for which I may be compensated and earn a commission, if you choose to buy the parts and tools shown in this video thru them:
Paint marker: ebay.us/yhT0AO and amzn.to/3msANz4
Blind hole puller kit: ebay.us/a6kEB1 and amzn.to/3xgtTlr
Wilde G409.NP wide opening snap ring pliers: ebay.us/HoJPiE and amzn.to/46KrVuC
Heat gun: ebay.us/nI5Fpj and amzn.to/3QcX1CI
Bushing driver / remover kit: ebay.us/mg3eDw and amzn.to/3mz6zKF
GM Transfer case unit repair manual (use 1999 and later only): ebay.us/BDBaJe
And if I've saved you some $$ here, consider some coins for the coffee tip-jar! ko-fi.com/drshock
1998 1999 2000 2001 2002 2003 2004 2005 2006 2007
Chapters:
0:00 - Disassembly overview
3:30 - Removing fill & drain plugs
5:14 - Removing the vent and encoder motor
7:24 - Removing speed sensors
9:13 - Removing the access plug and output shaft seal
11:04 - Removing the transfer case bolts
14:18 - Separating the case halves
16:56 - Removing the pump wear sleeve
17:25 - Removing the drive chain, sprockets, and pump assy
26:12 - Removing the rear output shaft assembly
27:00 - Removing the clutch lever and shift fork assembly (Part I)
29:32 - Removing the shift detent assembly
30:55 - Remove and disassembly the front output shaft assy and seal
40:00 - Removing the clutch lever and shift fork assembly (Part II)
42:20 - Removing the input shaft seal and planetary assembly
47:10 - Disassembly of the planetary assembly
49:00 - Removing the input bearing
50:12 - Removing control actuator assembly
51:34 - Removing the front case half ring gear retaining ring
52:31 - Removing the input gear pilot bearing
53:45 - Removing front case ring and front output shaft bearing
1:00:13 - Removing the control actuator bearing
1:02:00 - Removing the rear output shaft bushing
1:03:45 - Disassembling the rear output shaft assembly
1:21:01 - Removing the identification plate
1:21:24 - Cleaning and inspection tips
#drshock #np246 #obstruck #obstrucks
Disclaimer: DrShock, the alias for the human content creator for this UA-cam channel, is not responsible for any damages, injuries, losses, or liabilities associated with any repairs, upgrades, or maintenance performed on yours, or any other, vehicle whatsoever. No warranty, express or implied, is made as to the accuracy or completeness of any information provided within this channel. Viewing and using the “as-is" information of this channel is totally at your own risk. Always wear personal protection equipment and follow appropriate vehicle manufacturer service manual guidelines with original manufacturer parts only when performing any repairs, upgrades, or maintenance upon any vehicle. - Авто та транспорт
This was the most descriptive disassembly I have ever seen. It really took the fear out of the process.
Outstanding video. great audio and video. wonderful teardown. Thank you for taking the time. Excellent!
I'm about to tackle this project in my garage, transfer pump knocked a pin whole 🤕 Thank you for the Awesome tutorial for the DIYers!
How’d it go?
Thanks for your time and wonderful detail in your work
I think you done a great and thorough job going through the entire disassembly. Thanks alot, you saved me some time and broken parts, by showing the potential trouble areas. Thanks again.
One of the best how-to videos I've seen.
But what I learned is, by the time I buy the press/spacers/blind hole puller/total rebuild kit, I'm probably better off getting a reman. Now If I already had the tool investment (have somehow managed to get by without that stuff to this point,) it might be worth the time/effort to do the job myself.
Also, when you factor in in the "it jumped up and bit me in the ass" things, like the stripped/corroded allen head, combined with my general luck, which is usually around a 95 on the bad luck scale, I'm probably better off getting a reman! I'll have enough issues just with replacing that I'm sure. Plus will have to do the front shaft u-joints too while it's out...
Cannot overstate the value in this video though. Well done. You make what I'm sure is a tougher job than it looks in the video, look easy.
Good job. 👍
I refilled my 05 yukon t-case after 52 ounces leaked out. It holds 64 ounces total. I ran out of auto trak fluid after 26 ounces and made a mix of 50/50 Dex3 atf to 10w30 motor oil for the rest. So far so good. I understand any ATF is fine to use. I put a little oil to add to lubrication since it ran short for an unknown time period.
Just make sure it’s not synthetic ATF. The whole reason for the blue auto trak fluid is clutch material incompatibility with Dexron VI synthetics.
@DrShock why not synthetic? Is it too slick or something? That's what everyone was saying they substituted...some kind of synthetic ATF. I hope the oil I added makes up for whatever wear it maybe had from only having 10 to 12 ounces of AT2 in it for an unknown time period. I recently got this a few months ago. The 4x4 wasn't used by me except to test it twice.
Do you know if these NP246GM units spin the chain all the time even in 2wd, or does it disengage when it's not being used? My front shaft does not turn when in 2wd and rolling from what I can tell. The front driveshaft spins by hand when parked and off or on, in 2wd.
I don't know the specifics, just that GM issued a _do not use_ service bulletin around _not_ putting Dexron VI into these autotrak transfer cases. I showed this bulletin in part II of the reassembly video series.
Thanks!
I’m in the process of disassembling an np-246, can you please tell me what size Allen wrench fits the clutch lever pivot pin? I don’t have that size. I don’t want to go out and buy a whole set.
Thankyou soooo much for your help!! Im currently rebuilding my factory installed np246gm in my 2002 gmc sierra with pushbutton 4wd. I didnt find a wavy ring between my reluctor wheel and oil pump...do you know if this was optional on some models?
I go over in the rebuild portion of this series the differences in the earlier and later designs. I believe that wave plate was one of the ones I covered. The description will have links to that vid.
@@DrShock thanks for your response!! I will most definitely be following that video to complete my rebuild. Have also suscribed to your channel
Hi, i have a 97 c1500 rwd i replace the speed sensor on the transmission and works fine for one day then start doing same ABS ANTILOCK light come out and dont shift correct any other sensor you know I can check?
So is 3 speed sensor?on a c1500? 2 front 1 on the transmission?thanks for all the info on your video I hope U can help me with any advice for keep working on my c1500
Fantastic video. You gave me the confidence to tackle this job myself. What did you clean your internal parts with? I’ve heard mixed thoughts on using brake cleaner. You mentioned mineral spirits?
For jobs like this I use a parts washer basin, which uses a naptha based solvent (Crown PSC 1000) for the ferrous metal parts, mineral spirits also works. Non-ferrous metals, like the magnesium case, can be cleaned with engine degreaser or brake cleaner sprays. Non-metallic parts are hand cleaned with a water based degreaser like Simple Green, or similar. All internal parts should be spritzed with blue transfer case fluid to prevent flash rusting, or ease assembly in the case of non-metallic parts, after drying from cleaning.
Thank you so much. This is awesome. I appreciate you posting this. Where did you get the manual that you are using?
There's a link in the description where you might find the hardcopy TURM manual from GM. Alternatively you can print out the information, for a fee, from GM service information at www.acdelcotds.com
Does the fluid inside lubricates the output shaft splines?
No. The front output shaft splines to the front transaxle are statically lubricated, as are the rear output shaft splines to the driveshaft. Check out ua-cam.com/video/lg4hLNzNm2Y/v-deo.html around 22:54 and 32:21
Hello would you happen to have the brand or where you sourced the snap ring pliers that open up 1 1/2+ ?
I've added links in the video description to the tools used in the video.
@@DrShock Awesome, used your ebay link. thanks!
is this the same an an 263xhd transfor case for an 02 chevy 2500hd duramax 6.6
No, _not_ the same otherwise they wouldn't have different model numbers. ;-) For example the input shafts are different, the TCC module is different, the encoder motor is different, the wiring harness connections are different, the front case halves are different as well, etc, etc. But they are similar enough that there are a number of shared parts internally between them too.
Was feeling pretty confident about diy until the press and metric pressers were introduced.
What are the chances that automatic trans fluid was added at some point instead of the AutoTrax II fluid called for? Incompatibility of fluids may have been the cause of the caking inside the case.
Near zero. The owner has had the truck since 2001 and was quite positive it had *never* been changed. So it's likely the original fill from 1999.
The original factory fill for the NP246 in 1999 was Dexron III ATF. It was only later it was changed to Autotrak II fluid when Dexron VI ATF was found to be incompatible with the clutch material used.
My 97 uses ATF dexron 3
That _was_ the correct fluid when the vehicles were still relatively new. But GM superseded Dexron III decades ago, when they came out with Dexron VI which unlike with a transmission is incompatible with the clutch material in the auto shift type transfer cases this video covers.
GM came out with the blue Auto-track fluid for the auto shift types (e.g., NP246), and continues to make the red Dexron III additive package for manual shift types (e.g., NP241C) separately.
Cant thank you enough, just what i needed.
Are you planing to upload the assembling? If you do, there are torque numbers i would like to wait and see you do first. Thanks again.. EPIC
Thanks, yes I'll be doing the rebuild very shortly with all genuine GM parts and service manual torque values.
@@DrShock Awesome!!! Thanks
Anyone know what the install torque is on the two clutch pivot pins?
I'm sure I went over that during the reassembly video series that followed this one (link in the description).
@@DrShock no, you just winged it. I found it lol
No, unlikely _I_ would _wing_ a published torque value. ;-) It's on the service manual page at time index 48:16 on the reassembly video linked in this disassembly ones description.
@DrShock I'll look again but that's what i saw the first time. Thanks!
@@DrShock oh you're right. I think I got your video and another confused. It is 30 ft-lbs. I noticed you didn't put LockTite on the lower pin that oftentimes falls out. Wouldn't blue LockTite be a good idea? Also, I see there are two designs for the clutch fork, a 1st and 2nd design. How do I know which design I have? My Yukon is a 4x4 model, 2005 year. Thanks
how can I get a copy of the manual your using?
Links in the description.
@@DrShock yea my grandson showed me thx love the videos time to buy and put in the work
Cant find the manual man o man
Will you send me a copy of your instruction? I have a 1999 chevy suburban LT k1500.
There's a link in the video description to search for this, it's the GM transfer case unit repair manual for any given model year.
Speed sensors are all the same.
Worst tc design. Auto mode is another way for lazy people to drive. Never use the auto part in that unit and you'll have no problems. Mine is 25 years old with 200,000 mountain miles that carried 2000 lbs consistently. Beat on it hard, not one transfer case problem.