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Anybody Run A Np208

Discussion in 'The Garage' started by 4wheelin4Jesus, Aug 16, 2005.

  1. 4wheelin4Jesus

    4wheelin4Jesus 1/2 ton status

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    Hi,
    I was looking at upgrading from an np203 transfercase. I noticed that the np205 can be modified in many ways. But, it is pretty hard to come by. I have a th400, and was looking at the np208. Can anyone tell me if this is a good upgrade? Also, can you tell me the pros and cons of it, and if you like it? Im looking at making my rig into a rockcrawler/mudder.
    thanks.
     
  2. sled_dog

    sled_dog 1 ton status

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    Pros:
    - Good ratio for a stock case (2.61:1 vs. 2:1 of a 203)

    Cons:
    - Thin aluminum case isn't strong
    - Chain drive still, so limited torque input.
    - No SYE kits for them, and factory(Dodge) parts to do it are hard to find.
    - No upgrades for them at all actually, that I know of.


    Better option? 241.

    Pros:
    - 241 has a better ratio yet (2.72:1)
    - SYE kits are available, as well as electronic and cable driven speedo setups.
    - can upgrade to 241HD parts for better strength

    Cons:
    - still thin aluminum case
    - hard to find in a 32 spline input version(either from an SM465 or TH400)
    - still chain drive

    I'm running a 241 myself, I did in my Suburban with no complaints, but that was just a very very light trail machine/dd.
     
  3. sweetk30

    sweetk30 professional hooker Premium Member

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    dont forget if you swap from 203/205 to a 208-up you need to change the tail shaft in the tranny.:rolleyes:
     
  4. 4wheelin4Jesus

    4wheelin4Jesus 1/2 ton status

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    thank you for your reply. Can you tell me anything about the 205's? Ive heard that they are pretty much bullet proof.
     
  5. sweetk30

    sweetk30 professional hooker Premium Member

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    205 = cast iron and steel gears . no chain and aluminum for seal holders. :D :wink1: :p:
     
  6. clarkjw24

    clarkjw24 1/2 ton status GMOTM Winner

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    So are you saying that you've got a TH400/NP203 combo in your truck now?
     
  7. 4wheelin4Jesus

    4wheelin4Jesus 1/2 ton status

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    nope, i have a th350/np203 combo. Im rebuilding a th400, and wanted to upgrade from the np203.
     
  8. clarkjw24

    clarkjw24 1/2 ton status GMOTM Winner

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    Ok then. I was gonna say if you did you should be thinking doubler for what you're wanting to do. Your right, a np205 is hard to come by around here. To find a TH400 version will be even harder. I'm running Th350/NP205s. I've got 3 of these combos but they were not easy to find. Finding the adaptor alone for the TH400 version will be a pricey event (I had one but sold it on evil bay, it brought $200). I was able to get just the 400 input for a 205 incase I go doubler one day. I love my 205s. I've sold every NP208 I've had (5 in the last 2 years) for around $100. They're ok and easy to come by but I've seen 1st hand how the alumnium cast will bust. I just got a SM465/NP205 that will be replacing the auto setup.
     
  9. Kiwi John

    Kiwi John 1/2 ton status

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    Hi Sleddy. As a foreigner i'm a little out-of-the-loop on some of the terminology you guys use.
    I'm having trouble with my 208 (Had a thread running last week) and just wondered what you mean by a 'SYE' ?
    I am unlikely to upgrade in any way as there is no easy access to parts for the necessary modifications here.
    Is there any logic to the numbering v the relative strength or rating of these transfer boxes? (i.e. 203, 205, 208, 241... )
     
  10. clarkjw24

    clarkjw24 1/2 ton status GMOTM Winner

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    SYE=slip yoke elimator. So you'll have a fixed yoke at the rear of the tcase.

    The numbering is cronological order in which they were "design" and built in production vehicles.
     
  11. Kiwi John

    Kiwi John 1/2 ton status

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    Sye

    Thanks John. I guess there is a lot of 'previous' in the forums on this concept if you have an abbreviation for it so i'll have a search. But if you eliminate the slipping yoke... how does the driveshaft handle the axle movements?

    So i understand that the numbering bears no relation to 'strength' ?

    BTW Congrats on being rig of the month.
     
  12. stallion85

    stallion85 1/2 ton status

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    The driveshaft will have a slip in the center of it like your front drive shaft ;)
     
  13. jekbrown

    jekbrown I am CK5 Premium Member GMOTM Winner Author

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    if you're willing to swap in a ford front axle (hp D60?!) then get a np208 from an old bronco. These cases not only had a fixed rear yoke but were "clocked" from the factory for a nearly flat belly. Not bad, only real downside is that its driver's side drop.

    j
     
  14. clarkjw24

    clarkjw24 1/2 ton status GMOTM Winner

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    Slip yoke tcases work like this. There is a female input about a 9"(i'm guessing but its close) shaft that slides into the rear of the tcase and has a ujoint and yoke on the other end. So you have about 5" of play "slip" in your drive shaft. Then your main shaft has a ujoint and yoke at both ends.
    The fixed yoke is similar to your front shaft. These are "fixed" at both ends (tcase and axle) and your slip is in the middle. The fixed term means that the ujoint or one end is bolted with ujoint straps, ubolts, or flanged. You can have these made with more slip "travel" and reduces the chances of pulling the driveshaft apart while flexing the suspension. I think all chevy NP203s and some NP205s came factory with fixed out put shafts. Your NP208 has a slip yoke out put.

    I wish I had some pics for you. Maybe someone will post some. Or maybe you could look around at highangledriveline.com and it will make more sense.
     
  15. Kiwi John

    Kiwi John 1/2 ton status

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    Apparently my PO replaced the front driveshaft with one from a Range Rover so I'm not really sure what is supposed to be going on with regard to the slips.
    Thanks anyway. I'll look it up.
     
  16. RootBreaker

    RootBreaker 3/4 ton status Premium Member

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    I havent posted in the for sale yet.. but I got a NP208, SMC465 mated to a NP205 all for sale..... Sub-Zero doesnt want the smc/205 combo...(already paid me) anyone wanna buy it? :crazy:
     
  17. Kiwi John

    Kiwi John 1/2 ton status

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    :confused: :confused: :confused:

    WTF does this all mean? Can somebody do subtitles???

    "There is a female input about a 9"(i'm guessing but its close) shaft that slides into the rear of the tcase and has a ujoint and yoke on the other end. So you have about 5" of play "slip" in your drive shaft. "

    clarkejw24, Does the slipping occur by this female part sliding thru the oil seal on splines?

    I'll have to get under my truck and have a look at the weekend.

    4wheelin4jesus: I really don't mean to hijack your thread buddy, just that i'm desperate for all info on this type of thing. Appreciate all your input fellas.
     
  18. clarkjw24

    clarkjw24 1/2 ton status GMOTM Winner

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    Yep. Thats right.
     
  19. Kiwi John

    Kiwi John 1/2 ton status

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    Got it. I understand. It would explain why a sliding joint in the middle is preferable. the slip-yoke must put a strain on the rear of the transfer case. The engineering to convert to this SYE setup must be complicated tho?
     
  20. sled_dog

    sled_dog 1 ton status

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    Couple advantages with a Fixed Yoke.

    -Bearing right at the end of the shaft(well as close as it can be), so good support and strength there.
    -Output is shorter, allowing for a longer driveshaft and shallower angles on the rear u joints.
    -Fixed yoke style slip joint in shaft. Slip yokes don't allow for a lot of suspension travel and on some of our rigs, thats an issue.
    -Oil Retention. If you break your rear driveshaft with a slip yoke, you have to stuff something into the output or else it will piss trans fluid out of the open hole. With a fixed yoke, there is a seal and yoke, so no leaking will occur if you don't have a rear driveshaft installed.
     

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