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  1. #1
    Super Swamper
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    Updating the Burb...

    Well I finally got all the sub-assemblies rounded up for the upcoming SAS on my 99 Burb K2500.

    Axles!

    Front is a Ford Dana 44 high pinion. It has a Yukon grizzly diff, 4.10s, Warn lockouts, and of course...some 8-lug THORparts ABS compatible hubs and H3 4-piston calipers. This will be crossover steered so it has flat-tops.

    Rear is a 2006 14-bolt full floater. It has a stock Gov Loc diff, 4.10s, and fresh brakes. Both have Powerslot rotors, EBC greenies, and Krylon Edition calipers.




    Because the truck came with the optional NP246 (AutoTrac) t-case, it needs to be replaced to work with a live front axle. So I scored an NP241 to replace it. This is the large 32-spline unit and I was fortunate enough to get the manual floor shifter, linkage, and driveshaft with it. Sweet!...no crawling around in bone yards.




    I should be kicking off the t-case swap soon. Stay tuned.

  2. The Following 4 Users Say Thank You to 4speedfunk For This Useful Post:

    3Hummers (01-05-2018), cgalpha08 (01-07-2018), Enter Hummer (01-05-2018), Woodtick (01-05-2018)

  3. #2
    a.k.a. "The Jackal"

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    Sweet! This should be exciting
    Squeaky3: 06 H3 ALPHA D70 front/Eaton HO72 rear 5.13 gears, custom crossmember for long arms, lockers, 4:1 T-case, v8 swap, hybrid cage, Warn 12k Custom bumpers....do it all vehicle

    "H3 front axles are like drunk cheerleaders....just use em until they get mouthy...then toss em and get another." -anonymous


  4. #3
    Super Swamper
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    Okay. A long but productive day yesterday. I got the old case out. I scraped the old gasket off the adapter. And called it a day. I actually got my hand stuck for some time...trapped under the truck and out of reach from the cell phone. That sucked. I eventually bent the heat shield away from my hand, and levered the trans over about 2" to allow me to get it free with all fingers still attached. Very sore today.

    If you are planning to yank a t-case from a full size GM...you must have a stubby 15mm gear wrench. Preferably one with a flexy head on it. This tool was invaluable, and I was throwing everything I had at it. Because my truck is 100% bone stock, I had to fight the stock y-pipe, cat converters, and heat shields. These are items that seem to be missing from all the online blogs I read about this swap. I think most full size guys are running 8+ inches of lift and their trucks are stripped of most non-essential items. So, the info you get is not really accurate for stock trucks like mine. There was a lot more to it, than I first thought. I am trying hard to keep this a "factory" looking SAS.

    Driveshafts came out first. Here you can see the difference between the NP246 front shaft (top) and the NP241 front shaft (bottom). The NP246 shaft uses an oddball male splined end, (much like a CV shaft on an H3). Because this is intended to be used with the stock (fixed diff) IFS, this shaft cannot be used with the (live axle) SAS. Of course it must be installed all the time, as fluid would quickly exit the t-case without it. The NP241 uses a traditional flanged connection at the t-case. It has a slip collar mid-shaft to compensate for the travel that a live front axle will have. Additionally, because the flange is sealed...you have the option to run the truck without a front shaft at all. I may do this temporarily as I get deeper into the swap...
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    Here's a couple shots of the two transfer cases. The 4-mode, electronically shifted, auto-trac NP246 (left) and the old-school 3-mode, manually shifted, NP241 (right). The NP246 is widely known for several design flaws, and they rarely last 150k miles without problems. This case uses a clutch pack for the auto-trac mode...it works much like a motorcycle clutch. It has a series of plates and friction discs stacked in a basket, and it will break free at a specific load so the truck does not bind when turning. All fine & dandy until it gets worn or the fluid gets filthy. The other issue with the 246 is that the internal fluid pump can rub thru the magnesium case, thus emptying it (mine did this). Many owners prefer to back-date their 246 trucks to the 241 and its a common swap (for both IFS and SAS trucks)...
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    Here's the front view NP241 (left) and NP246 (right). These both use 6-bolt attachment. If you are familiar with the H3, the BW4493/4494 transfer case uses a 5-bolt attachment. Its important to note that you can easily convert a 4L60E or 4L80E trans to either style as the tailshaft adapter is a separate piece. My K2500 Burb has a 4L80E trans, so I am working with 32-spline inputs. If you have a K1500 truck you would be using the same stuff, except with a 4L60 trans and the smaller 27-spline input. Both the 241 and 246 came in either spline count, depending on the chassis. I cannot say for sure on the 246 but, the 241 can be easily converted by changing the input shaft. The 241 uses an ALUMINUM case, not magnesium. Both are chain driven. Both have similar low ranges (2.72:1 I think)...
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    Next task will be the wiring. Or should I say...the LACK of wiring. And also installation of the mechanical shift lever.
    Last edited by 4speedfunk; 01-11-2018 at 08:56 AM.

  5. #4
    El Diablo
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    Quote Originally Posted by 4speedfunk View Post
    O
    If you are planning to yank a t-case from a full size GM...you must have a stubby 15mm gear wrench. Preferably one with a flexy head on it.
    I keep one of these in the H3 - it's helpful on the H3 too!

    Cool progress on the 'Burb, looking forward to more updates.

  6. #5
    Super Swamper
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    Nice work so far, keep them posts coming!
    2009 Hummer H3T Alpha
    4 Rancho Lift, 37x12.5x17 BFG A/Ts, Method "The Standard" rims, Magnuson Supercharger, Magnaflow exhaust, 50" LED light bar, Thor Parts rear bumper w/ swing out for full-sized spare, Hidden 9,500 lb Superwinch, Custom Sliders, Custom aluminum bed rack & matching roof rack

    www.ministryofadventure.ca

  7. #6
    Baja
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    That's going to be awesome. So which is easier, H3 or Suburban? I'd guess the Suburban will require a lot less custom stuff since it's been done before?

  8. #7
    Super Swamper
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    Updating the Burb...

    New t-case is in...shifter works well. Im fighting some VSS issues right now. I either have something wired up wrong or the VSS that came on the 241 was bad.

    On the SAS...
    The big decision is whether to go LEAF or COIL? I have some F-250 Super Duty front leafs, and a kit is only $400 or so. This is a very common swap but, usually with 8+ inches of lift. It might be hard to do with minimal lift. Plus...leafs on a full size have a pretty horrible ride. The full size crowd is really into 40 swampers and ridiculous lifts, so its hard to find any info on a mild SAS build.

    Obviously I have unlimited 3-link parts, and I am considering using the same basic H3 brackets to create a 3-link for the Burb. I have some big coils and all the stuff to do it. It would be one-off and probably take more time but, it might be a better riding, lower sitting rig when done. I figured I would get the IFS chopped off first and then slide the D44 in place and see what my options are for the suspension. My goal is for a practical street build, and not any sort of flexy crawler rig.
    Last edited by 4speedfunk; 01-12-2018 at 07:20 AM.

  9. #8
    Super Swamper
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    UPDATE:

    It was a bad VSS on the NP241. This critter here...
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    So I got a new one ($94...OUCH!) and popped it in. Bang...speedo is back...trans shifts normally...ABS light is off.

    Now I will move on to the other wiring issues that are involved when swapping an electronically shifted NP246 for a manually shifted NP241. The truck currently has a "Service 4WD" light on the dash, and it is my understanding that this will go away when I pull the TCCM from the truck. However, I will still have couple issues to fix.

    The first known issue is that there is a low-range shift map built into the trans software on this truck. This is true for both electronic and manual t-cases, and it is basically a map that tells the transmission "Hey, I'm in low range...so all my shift points and speedo need re-calibrated to suit". This map is normally activated via the TCCM but, after removing it...I will need to tap the correct wire and add a switched ground circuit to toggle this map on & off. Without it, the tranny will not shift out of first gear when the t-case is in low-range. This can be done with either a manual switch, or I can connect it to the indicator circuit on the 241, so it happens automatically when I shift to low-range.

    The second issue has to do with the CAD (center axle disconnect) on the front axle. This is the typical solenoid dohinky that most modern 4x4's use to engage/disengage the front axle. Normally this would be controlled by the TCCM but, as stated above the brain box will be gone. So I will need to find the correct wire and put this on a manual switch as well. OR...I can also connect it to the indicator so the front axle gets engaged in either 4HI or 4LO. This is only needed if I were planning to keep the IFS. My new solid axle (Dana 44) has Warn manual locking hubs, so I may just pass on rigging up this system. I am going to try and get everything working properly. If it gets really complicated....I will just ignore the issues until the old-school axle is installed. At that point...it will basically work like a 1968 Burb.

  10. #9
    Baja

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    Visit Schwarttzy.com for more parts and info on the H3 Hummer.

  11. #10
    Mud Terrain
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    Very nice and you better keep the Alcoa wheels on it!
    Sent on a rotary device ,with a really long cord.

  12. #11
    Super Swamper
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    Updating the Burb...

    The Alcoas are out. I am going with H2 wheels (17) or possibly some vintage steelies with 70s GMC hubcaps.

  13. #12
    Super Swamper
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    Updating the Burb...

    Its been a little over a year since my last post on this thread. The Burb has been doing lots of highway miles between Indy and DC...mostly without drama. However last month, the left rear axle seal started puking oil. Rather than fix the ole semi-float drum brake axle, I decided to go ahead and do the upgrade I have been planning.

    The new axle came from a 2005 GMC 2500HD. It has the same 4.10 gears with the same Gov-Lok diff but, its a real 14-bolt, full float with factory discs (not sure what the old axle was...it had 14 cover bolts but it was not diamond shaped like the real 14-bolts are). Doesnt matter anyway...its bound for the scrap yard.

    Pics...



  14. #13
    Super Swamper
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    Updating the Burb...

    I bought this axle two years ago, and did a mild rebuild on it. The rotors, pads, hard brake lines, and e-brake shoes were all junk. The cover and backing plates were crumbling into rust. So I replaced everything except the bearings & gears. Since both the Burb and the donor truck were 2500 chassiss, I thought this was going to be a direct bolt-in but things got interesting.
    The new 2005 axle had spring perches about an inch wider, which required some creative manipulation with a ratchet strap. The perches were also taller...requiring new u-bolts as well. Then I discovered it takes a 1410 series u-joint (instead of a 1350)...so off went the shaft for some mods.
    The e-brake system is completely different and fortunately I got the cables with he axle when I bought it. I am currently fiddling with that, and trying a custom cable clamp idea.
    I am voluntarily replacing the master cylinder with a 2001-up version that is made for disc brake trucks. My hope is that this will work better than my original drum brake MC.

    Original MC...

    New MC...
    Last edited by 4speedfunk; 03-19-2019 at 06:13 AM.

  15. #14
    Super Swamper
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    As a side note...ignore the rusty ole shocks. I have new ones but, I am saving them for when I do the front SAS. This rear axle swap is just to get me going until I can pull the Burb in for major surgery.

  16. #15
    El Diablo
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    Bet those new brakes will feel great on the road.


 

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