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700/208.........400/208 questions

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Bubba Ray Boudreaux, Jun 21, 2003.

  1. Bubba Ray Boudreaux

    Bubba Ray Boudreaux 1 ton status

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    Just some exploratory work here folks......

    What do y'all think I can get out of a 700/208 combo? The 700 has at least 100K miles and has been in the truck at least 11 years that I know of. No known problems. The 208 has worked, does have a leak, but may be from the slip yoke.
    ??????????????

    As for the 400/208 combo, does a 208 from a 700 mate up to it with the appropriate adapter, or does something need to be changed on the TC?
     
  2. Seventy4Blazer

    Seventy4Blazer 3/4 ton status

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    ill give the th700 and 208 a nice kick out the door for ya.

    and since your mall cruiser is trying to be on the skinny side then i understand why you want to use the 208.
    to put a 208 behing a 400 im not sure what you have to do. the 208 should bolt right up to a TH350. but the spline count for a 700r and a th400 are different.
    Grant
     
  3. Bubba Ray Boudreaux

    Bubba Ray Boudreaux 1 ton status

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    [ QUOTE ]
    ill give the th700 and 208 a nice kick out the door for ya.

    [/ QUOTE ]
    No bad attitudes accepted here /forums/images/graemlins/rotfl.gif



    [/ QUOTE ]and since your mall cruiser is trying to be on the skinny side then i understand why you want to use the 208.
    to put a 208 behing a 400 im not sure what you have to do. the 208 should bolt right up to a TH350. but the spline count for a 700r and a th400 are different.
    Grant


    [/ QUOTE ]

    Right now I'm just kind of checking options.

    I've got a 208 fixed output to put in and I was thinking this morning that maybe I would sell off the whole setup in the K5 to help $$$$ for a new 700. Just curious on the 400, if it's gonna be a hassle, then I would drop it like a lead weight.

    The K5 is getting ready to get parked after BF due to a new addition to the family (Toy 4x4) and it's time to give it some intense therapy.

    /forums/images/graemlins/rotfl.gif /forums/images/graemlins/rotfl.gif
     
  4. imiceman44

    imiceman44 1 ton status

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    Hey mista
    You know the th400 has 32 spline output, the 700 has 27.
    The only way you will be able to mate a 700 version 208 is by replacing the main input shaft from a 400 version.
    That would mean a tear down.
    On the other hand you could also replace the main output shaft on the th400 from a 375 which is a cross th400 internals and 350 output.
    If that helps.
    And if you want a home for the 208 you can use it on the sheep to have more traction

    /forums/images/graemlins/rotfl.gif /forums/images/graemlins/rotfl.gif /forums/images/graemlins/rotfl.gif
     
  5. Bubba Ray Boudreaux

    Bubba Ray Boudreaux 1 ton status

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    [ QUOTE ]
    You know the th400 has 32 spline output, the 700 has 27.

    [/ QUOTE ]

    Nope, didn't know that before /forums/images/graemlins/grin.gif

    [ QUOTE ]
    And if you want a home for the 208 you can use it on the sheep to have more traction

    [/ QUOTE ]

    Don't need no stinking traction /forums/images/graemlins/thumb.gif

    By the way, is the 4L80 same spline count as the 400?
     
  6. imiceman44

    imiceman44 1 ton status

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    [ QUOTE ]
    By the way, is the 4L80 same spline count as the 400?


    [/ QUOTE ]

    Yep /forums/images/graemlins/thumb.gif
     
  7. the professor

    the professor 1/2 ton status

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    Minor point here... a 375 is a FWD TH350.. used in Eldo's and Rivs..
    --
    A 4L80e has the same spline count as a TH400, and the same tail shaft bolt pattern, but the case hole is a different size, so you need the NP adapter for a 4l80e...also ALL 4L80's are "electronic" transmissions, requiring a computer to tell them when to shift....
    --
    There are so many high performance parts available to rebuild a TH700, and increase the strength AND at a reasonable price, I would NOT use a TH400 for a replacement.. KDS http://www.kdsperformance.com/kdsperformance/
    and BOWTIE
    http://www.700r4.com./

    Remember, not only is the 400 a 3speed with NO overdrive.. It also has a 2.48:1 first gear vs. the 3.00:1 in the 700.. and lastly the TH400 draws about 35 more hp thatn a 700 just to operate it..old technology...

    The very fact that your trans lasted as long as it has, shows that a properly built and adjusted ..particularly the TV cable, that a TH700r4 is an excellent trans..

    I just destroyed my TH400 behind a mildly modified 454 in my K20, and am presently building a 700/208 to replace the 400/205 /forums/images/graemlins/cool.gif /forums/images/graemlins/truck.gif
     
  8. zcarczar

    zcarczar 1/2 ton status

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    Why not ditch the 208 and go with a 241? The 241 is the superior case in my opinion and its been known to hold up in high torque applications. /forums/images/graemlins/thinking.gif
     
  9. imiceman44

    imiceman44 1 ton status

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    [ QUOTE ]
    Minor point here... a 375 is a FWD TH350.. used in Eldo's and Rivs..
    --
    A 4L80e has the same spline count as a TH400, and the same tail shaft bolt pattern, but the case hole is a different size, so you need the NP adapter for a 4l80e...also ALL 4L80's are "electronic" transmissions, requiring a computer to tell them when to shift....
    --
    There are so many high performance parts available to rebuild a TH700, and increase the strength AND at a reasonable price, I would NOT use a TH400 for a replacement.. KDS http://www.kdsperformance.com/kdsperformance/
    and BOWTIE
    http://www.700r4.com./

    Remember, not only is the 400 a 3speed with NO overdrive.. It also has a 2.48:1 first gear vs. the 3.00:1 in the 700.. and lastly the TH400 draws about 35 more hp thatn a 700 just to operate it..old technology...

    The very fact that your trans lasted as long as it has, shows that a properly built and adjusted ..particularly the TV cable, that a TH700r4 is an excellent trans..

    I just destroyed my TH400 behind a mildly modified 454 in my K20, and am presently building a 700/208 to replace the 400/205 /forums/images/graemlins/cool.gif /forums/images/graemlins/truck.gif

    [/ QUOTE ]

    I trust your knowledge in trannies from previous posts.
    Any plans for the th400/205 that you are replacing?
    /forums/images/graemlins/thumb.gif
     
  10. 83ZZ502_Jimmy

    83ZZ502_Jimmy 1/2 ton status

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    If you get a complete 400/208 combo with adapter, it will bolt right in with no driveshaft mods at all. There is a tall and short adapter foot, though... The tall(earlier) requires the "flat" crossmember. The short (later) uses a crossmember that has a hump in the middle. My 83 was the tall, the 87 and 88 are short adapters.

    I have done this swap twice and it is really pretty easy.

    John
     
  11. Bubba Ray Boudreaux

    Bubba Ray Boudreaux 1 ton status

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    [ QUOTE ]
    also ALL 4L80's are "electronic" transmissions, requiring a computer to tell them when to shift....

    [/ QUOTE ]

    Negative Ghostrider............
    4L80 non electronic
     
  12. 83ZZ502_Jimmy

    83ZZ502_Jimmy 1/2 ton status

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    [ QUOTE ]
    [ QUOTE ]
    also ALL 4L80's are "electronic" transmissions, requiring a computer to tell them when to shift....

    [/ QUOTE ]

    Negative Ghostrider............
    4L80 non electronic

    [/ QUOTE ]

    Yes but thats the same guys that make the 700R4 Raptor aka "Craptor"

    After all the bad things I've heard about them on this site and others, I dont think I'd be getting that from those guys.

    John
     
  13. doctor4x4

    doctor4x4 1/2 ton status

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    wow Great post guys and info
    yea i allmost bought into the Raptor - Craptor - Scamtor
    hype but thanks to CK5 reporting i didnt
    P.S. Hey Professor
    iam also interested in your old outdated P..O S. 400 - 205 how much ??$$
    :-) /forums/images/graemlins/rotfl.gif
     
  14. Lance

    Lance 1/2 ton status

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    I am curious how they made the 4L80 non-electronic. I did a lot of research on this swap when I burnt my original tranny. Very interesting. Anybody have any ideas?

    I bought the BTO stage III tranny, awesome setup. Bigger pump, kevlar bands, hardened sun-shell, etc. and still very streetable. Warranty activation isn't a joke, but well worth it. Took it for it's first test drive and all I can say is WOW!! My first impressions are it has some very crisp (bordering on the edge of too crisp) up-shifts, but all in all an excellent driving transmission.

    Just an FYI, the 350 and 700r have the same bolt pattern and t-case adapter but the ouput shafts on 700's are longer than those found on 350's. (I am sure there may be exceptions to this but in general this is true.) So if you do find a t-case from a 350 you'll have to get the tailshaft from the same and swap it into the 700 or get a spacer of some sort.

    As for a t-case get the 241, almost identical to the 208 but it's lighter weight, has better oiling abilities and a slightly deeper lo-range. Upgrade to a 1.5 inch chain and a fixed output, clock it parallel to the frame rails and call it good.

    Lance
     

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