NV246 / NP246 transfer case **high level discussion**

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Thread: NV246 / NP246 transfer case **high level discussion**

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    NV246 / NP246 transfer case **high level discussion**

    How many changes were made to this case throughout its application. I am speaking specifically about the NP8, M30 RPO code model.

    From what I gather there were 4.
    An early rare version in 98, 99-02, 03-05, 05 and up.

    Suspected changes range from clutch packs to clutch return springs, different bearing sizes, and the discontinued use of viscous coupling. The internet is a deep confusing place, but more helpful than most dealerships.

    What are the differences?
    When were they applied and how can one tell?
    What changes would have to be made to put an 01 case into an 05 vehicle and vice versa?
    How can there be so many versions, but a one size fits all rebuild kit?

    I need a new transfer case, but if there is one that no longer spins the driveshaft while in 2wd (apparently this happened sometime in 05), I want to go that route.

    Any and all information is gratefully received and can hopefully clarify some of the myths out there.

    http://www.chevyavalanchefanclub.com...opic=41895.new
    https://www.gminsidenews.com/forums/f...-t-case-23897/
    Last edited by Farlsincharge; 12-31-2013 at 01:01 PM.

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    Re: NV246 / NP246 transfer case **high level discussion**

    There are many differences, if you're gonna rebuild this unit yourself you will need the Kent Moore tools to set the clutch clearance. This is a must or you're wasting your time and money. The unit needs many up dates to make it last, so if you' re gonna install used don't be surprised if it does't last. In my shop we don't install used unless the customer supplies it. When a 246 is in 2wd the front drive shaft is free and not driven. The 2001 unit would free wheel the front drive just like any other 246, in that respect they're all the same. As far as the internals go there are 2 chains, 2 different front case halves along with 3 input shaft, also different bearings go with each shaft. The shift cam is different for 03 and up. Also these were installed in full sized dodge rams and dakotas so you will have changes there. For GM there was 3 different encoder motors.

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    Re: NV246 / NP246 transfer case **high level discussion**

    Thank you for your reply. I understand that the driveshaft is not driven, but it spins all the same. Some people claim theirs doesn't.
    It seems there is an updated clutch return spring that could be responsible for that.
    The 99-02 also had a preloaded clutch whereas the newer ones don't, correct?

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    Re: NV246 / NP246 transfer case **high level discussion**

    So what change was made in 05 that stopped the front driveshaft from spinning all the time?

    Is it the upgraded clutch return spring, or an encoder motor or what?
    Last edited by Farlsincharge; 01-06-2014 at 11:38 PM.

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    Re: NV246 / NP246 transfer case **high level discussion**

    Quote Originally Posted by Farlsincharge View Post
    So what change was made in 05 that stopped the front driveshaft from spinning all the time?

    Is it the upgraded clutch return spring, or an encoder motor or what?
    Maybe the difference is in the front differential?
    Did some use CAD and others did not?

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    Re: NV246 / NP246 transfer case **high level discussion**

    I have a question on these 246 cases, I have a bad GM 1999 246 case with a new encoder motor slot type, I picked up a 2004 246 case with no encoder motor but use's the spline gear encoder motor question is can I change out the cam inside the 2004 case that the encoder motor turns with my 1999 cam and use the 2004 case with my slotted encoder motor ? And put this newer case in my 1999 chevy Tahoe ?

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    Re: NV246 / NP246 transfer case **high level discussion**

    Old thread, but you seem to be the guy to ask. I have the "rare" 1998 np246with the NP8 RPO code. Is there any differences in the rear cases? The prior owner replaced the transmission, but left a transmission mount loose, which I believe caused stress on the rear tail shaft bushing/housing. I have a lot of play in the tail shaft and if makes it feel like an universal joint is bad at about 65 mph. It really vibrates bad. I can not find the exact replacement rear housing, usually only 99-00. Will one of those housings fit my 98 suburban. 4L60e transmission, Np8 NP246 transfer
    Last edited by Ntimed8r; 08-24-2017 at 08:02 PM.

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    Re: NV246 / NP246 transfer case **high level discussion**

    Replace the rear bushing and seal, very common repair. The rear case half on all NVG246 unit are the same but for this repair save your money and just do the bushing and seal.

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    Re: NV246 / NP246 transfer case **high level discussion**

    Quote Originally Posted by TheBUC View Post
    Replace the rear bushing and seal, very common repair. The rear case half on all NVG246 unit are the same but for this repair save your money and just do the bushing and seal.
    Old post and thought I'd ask instead of creating a new one.

    Are you referring to the bushings in the tailshaft and the tailshaft output (rear trans/transfer case seal)?

    I've went through the drivetrain rear axle and t-fer case output to front axle u-joints , balanced and remedied it for awhile but after a couple years it vibrates while driving at 72-85 (80MPH interstate speed here in South Dakota) and seems familiar with what I had before with the u joints when they went out few years ago.

    I did get the driveshafts balanced after replacing the u joints as this is always highly recommended as I learned when working on Semi Trucks in the 90's and doing automotive work the last 10yrs. Easier to show why it needs done than explain though based on GM's u-joint plastic injection molding process. Scary to say the least.

    Also I have the NP-246 with the RPO Code NP8 . I have a 04 with 4.8 L engine with the auto 4wd option but after doing the pump rub leak fix and having my local trans shop check other components after pump replacement with the Merchant Automotive machined pump by me they did the clutch pack as said not to use the auto clutch anymore which makes sense so I just punch the button based on the surface.

    There's one other thing that's been a irritant this winter when in 4 hi which is it seems that compared to previous winters when running 4 Hi that the howling noise coming from the front differential. Is there anything specific that I should look for ujoint the front diff? I'm basing that it's the front axle off of it only making noise when it's engaged so this seems logical. IS there anything common with these that I should be looking at? I have replaced the front diff fluid every 50k miles and check it regularly. It has just under 126k miles which I think is low mileage for the year model of 2004.

    Any and all help is much appreciated as I will probably have to inspect it soon. Maybe draining it, checking the oil for any metal is a start. I have multiple inspection cameras that have lights I can peek in the diff with and hopefully get a better picture of what's going on vs having to crack it open. That would be good if I could rule things out that way. We'll have to see as I feel opening it up will probably have to happen this spring/summer.

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