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4;56 gears and 35 tires not going to work for me

Discussion in 'The Garage' started by 4x4k20, Nov 9, 2002.

  1. 4x4k20

    4x4k20 1/2 ton status

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    i just swapped the rear 4;56s out of my m1008 and put them in my 79 k20 replaceing the 3;73s it had i put the 3;73s in the m1008 it does good . but the 4;56s i put in my 79 are too much for it i drove it today it runs down the road at really high rpms i have a turbo 400 with 35 tires it acts like you have it in second gear the whole time i like the power it has but i am going to need to do something different i have a 383 stroker engine that has about 300 hp it only runs on premium fuel so i was thinking about all i could do to help my situation is find me a overdrive 700 i want to keep my 203 case so i need some suggestions from you guys on which way i need to go
     
  2. BLUESMAN

    BLUESMAN 1/2 ton status

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    How about the perfect time to get larger tires....cheaper than a trans swap,though you might need more lift.You're gonna spend some $$$ on a beefed up 700 trans.Just an idea!! /forums/images/graemlins/smile.gif
     
  3. carolina custom

    carolina custom 1/2 ton status

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    When I first put the 4.56s in my k20 I had 35"s and a 6.5 diesel & th400. 3100rpm was 70mph. That not to bad with your 5000-6000rpm 383 . I switched to 37"s and 70mph is 2950-3000rpm.

    Marc
     
  4. 4x4k20

    4x4k20 1/2 ton status

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    yea i have thinking about going to a 6 inch lift and 36s but i dont think they will make much difference and besides that my ass has gotten too old to jump in and out the truck now even with the 4 inch lift i have now i have trouble getting in and out of it
     
  5. Chris_T

    Chris_T 1/2 ton status

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    I love my 700 with 4.56 and 35's. In fact the OD makes me wish I had gone a little deeper, say 4.88s, so I'm sure you'd find it a good fix
     
  6. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    I have 4.56's and 36's (measure about 34.5" now) with a SM 465 and I'll never get a speeding ticket on the freeway. I do manage to keep up with most of the traffic though. 70 is about 2900 RPM, but I have no slip through a convertor like you would have with the TH400. Trim the fenders and throw some 38's on it...

    Rene
     
  7. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    It can be done. Two ways to do it. THere is a spacer that will let you bolt the TH350 version 203 up. Problem might be where the shifter ends up. The 700 is 2 inches longer than a TH350. The spacer will add about another 2 inches I have been told.
    The other option iI have been told about is a output shaft that will let the TH350 203 bolt up with the stock adaptor..
    Now this is with a 203 for a TH350. I know the adaptor is different on the 400 so I'm not sure what your going to have to do on that, You could probably sell that TH400 203 for a good chunk of change. Probably enough to cover a TH350 203, the shaft replacement, and maybe even the retube of the driveshafts.
    Steven watson at ORD I have been told can get the shaft for the 700 for replacing a TH350. He might also have something like that for the 400.
     
  8. Swanson52

    Swanson52 1/2 ton status

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    4L80E. /forums/images/graemlins/thumb.gif
     
  9. 4x4k20

    4x4k20 1/2 ton status

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    grim you have gotten me lost here with the talk of the turbo 350 / i have a turbo 400 with the 203 case what i was thinking of doing is finding me a 700r4 to replace the 400 that i have now i know i havent seen anybody else do this but i am sure it can be done so if you know where i can find out any info on this let me know i want to keep my 203 if i can and not have to get any driveshaft work done
     
  10. supersize75

    supersize75 1/2 ton status

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    /forums/images/graemlins/deal.gifI'm not just talkin,

    I gust got 38 inch tsl's and my 3.73 gears aint gonna work either! So here goes, swap me gears I'll pay shipping and we call it even, not kidding! So PM me if this is something you would consider or not,or I could throw in some money too! /forums/images/graemlins/grin.gif

    thanks in advance, Shawn
     
  11. 4x4k20

    4x4k20 1/2 ton status

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    you would have to throw in alot of extra money because this gear swap has already cost me 2000 i still have to put the dana 60 in the front and i am going to do it even though i aint real happy with the 4;56s i could go back with my 3;73s but i am in way to deep now and i have always thought about going with an 700 but i have heard alot bad things about them but it looks like thats the way i should go
     
  12. fourwheelerjeff

    fourwheelerjeff 1/2 ton status Staff Member Moderator

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    want some 4.10's for them 4.56's??
     
  13. Diesel Dan

    Diesel Dan 1/2 ton status

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    </font><blockquote><font class="small">In reply to:</font><hr />
    though i aint real happy with the 4;56s

    [/ QUOTE ]
    I have some 3.07 Danas we could trade /forums/images/graemlins/grin.gif.
     
  14. HarryH3

    HarryH3 1 ton status Author

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    I hope Z3PR sees this thread. I was just telling him that I have a 400, 4.10's and 35's and that I wouldn't want to go any lower on the ratio because of highway revs... /forums/images/graemlins/frown.gif 37's or 38's would be better with 4.56's and no overdrive. /forums/images/graemlins/cool.gif
     
  15. zakk

    zakk 1/2 ton status

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    weird...i have 4.10's and 39.5's and i am spinning about 2900rpm at 75 or so.
     
  16. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    Yeah I know it can be done with the TH350 version 203. The 700r4 has the same bolt pattern as a TH350 where the adptor bolts up. The problem is shaft lenght. The shaft can be replaced with one that will alow it to bolt up just like factory.

    The TH400 version 203 uses a 32 spline input. (203 for TH350 and 700 would be 27). The input has a larger bearing so you can't go back to the 27 spline input like the 700r4 would use. THe adaptor to the transmission also has the wrong bolt pattern.

    I think at this point you might want to hit the ORD forum or call Steven at ORD and explain the problem. He should be able to give you all the options.

    I think though the cheapest route would be to get a TH350 version of the NP203 (dime a dozen ($50 is normal price). Then replace the output shaft of the 700 R4. That will get you hooked up. Then sell your TH400 vesion 203. You could probably sell your 203 for a pretty good amount since it is so rare. You could easily get $250 for your 203.
     
  17. trailblazer87

    trailblazer87 1/2 ton status

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    Hey swanson, there is one sitting is a 2000 1-ton 2 wheel drive in Mojave CA right now. Guy wants $750 for it. /forums/images/graemlins/deal.gif
    I was thinking about buying it and having it converted to manual shift 6 speed /forums/images/graemlins/eek.gif
     
  18. trailblazer87

    trailblazer87 1/2 ton status

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    You can just go to a cable shifter. No need to run a hard linkage. The 700R4 would take the same one as a B&amp;M streetfighter. You could even go with a floor shifter then /forums/images/graemlins/cool.gif
     
  19. Tweetysuarus

    Tweetysuarus 1/2 ton status

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    Kinda like this:
    [​IMG]
    [​IMG]
    Bill
     
  20. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    Why do you wish you went deeper? Is it because pulling a hill the tranny wants to hunt between 3rd and 4th? I have a 700/35's/4.56's and that is what my blazer does. Makes me think I should have choose 4.88's instead.
     

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