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Converting a 2wd tranny into a 4wd tranny...

Discussion in 'The Garage' started by 90blzr, Dec 8, 2003.

  1. 90blzr

    90blzr 1/2 ton status

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    What is involved? Fairly straigt forward? My buddy needs a Th350 4wd. He cracked his and when putting it in reverse its like someone opens a valve and DUMPS tranny fluid everywhere. We fixed it for the meantime, he just doesnt put it in reverse /forums/images/graemlins/laugh.gif /forums/images/graemlins/rotfl.gif
    Anyways, he has two TH350's from a 2wd that are in great shape. Can we take his crackes one and the 2wd one and make a good 4wd one...or is it alot of BS or can it not be done at all?

    Thanks/forums/images/graemlins/thumb.gif
     
  2. mudhog

    mudhog THEGAME Staff Member Super Moderator

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    you need to change the output shaft from a long 2wheel drive one to the short 4x4 one
     
  3. 90blzr

    90blzr 1/2 ton status

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    what all is involved? I mean is it 'easily' done? Or do you need to disassemble the entire transmission? Or??
    thanks/forums/images/graemlins/thumb.gif
     
  4. nvrenuf

    nvrenuf NONE shall pass! Premium Member

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    You will have to disassemble the whole thing. /forums/images/graemlins/eek.gif
     
  5. 90blzr

    90blzr 1/2 ton status

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    So let me get this straight, basically what you are saying is....[darn] that, buy a 4wd version? /forums/images/graemlins/grin.gif /forums/images/graemlins/eek.gif /forums/images/graemlins/rotfl.gif
     
  6. nvrenuf

    nvrenuf NONE shall pass! Premium Member

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    It may not be that bad depending on what your buddy wants to do. Around here you can usually find a tranny shop running a deal on building 350's for about $175~$200 (for a carry in bench job). He might consider having the good case rebuilt and ask the guy to swap tailshaft's while he's in there. I know it's extra $$ but in the long run it might be cheaper than gambling on a used tranny. /forums/images/graemlins/thinking.gif
     
  7. 90blzr

    90blzr 1/2 ton status

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    yeah, he is just tight in cash right now and cant afford to have a tranny rebuilt.

    On converting the tranny over to 4wd...any special tools needed? I mean, is it DOABLE at home on the bench? The only reason we even talked about the conversion is because he has two trannies that he KNOWS are good, but they are 2wd trannies /forums/images/graemlins/frown.gifWe'll try anything once/forums/images/graemlins/thumb.gif Dont know until you try it right? /forums/images/graemlins/wink.gif /forums/images/graemlins/crazy.gif /forums/images/graemlins/tongue.gif
     
  8. fourwheelerjeff

    fourwheelerjeff 1/2 ton status Staff Member Moderator

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    well, depending on how much he needs the transfer case, i have seen a guy use a 2wd tranny and driveshaft until he could get his 4x4 tranny rebuilt, little bit different with a broken case, but he might be able to run it like that until he can either buy a case or change his cases around /forums/images/graemlins/thumb.gif
     
  9. 90blzr

    90blzr 1/2 ton status

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    /forums/images/graemlins/thinking.gif then he would just need a drive shaft I guess....what about the crossmemeber...woudl that be the same or different?
     
  10. Beast388

    Beast388 1/2 ton status

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    [ QUOTE ]
    ...any special tools needed? I mean, is it DOABLE at home on the bench?

    [/ QUOTE ]

    I did just what you are talking about.

    My orginal TH350 was fragged, I had chunks of the valvebody in the pan and throughout the tranny. So, of course, the tranny case was junk. I found a junk 2wd tranny for $20, stripped it down and cleaned it up. I then proceeded to put all of my 4wd TH350 parts as well as a rebuild & shift kits into the 2wd case. I've been running it behind my healthy 388 for about 5 years now.

    I used a Haynes GM Auto Tranny manual, a borrowed clutch-spring compressor(special tool-needed) and bought some little picks that resemble dentist's tools to do the job. /forums/images/graemlins/thumb.gif
     
  11. 90blzr

    90blzr 1/2 ton status

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    Thats what I wanted to hear/forums/images/graemlins/thumb.gif

    So there is a Haynes book just for the tranny? What parts did you replace etc? How much did you end up spending?
    Sounds like you kinda did the same thing as we are thinking!
    The 4wd tranny is slipping and all so its about done. So we would be bascially taking the internals from the 2wd and putting them witht he 4wd mainshaft. Everything else is the same except the mainshaft?

    How long did it take you? I have all of the 'dentist tools' and I am sure I can get that tool you are talking about. Pretty straight forward with some patience?

    Thanks man/forums/images/graemlins/thumb.gif
     
  12. R72K5

    R72K5 Banned

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    th350 cases are all same it doesnt matter 2wd or 4x4 except that some of the 78-up cases are K cases.

    parts will all swap between all the 69-up th350 cases, is a matter of doing the swapping, if you think you are mechanically inclined enough and have the necessary tools, then go for it, i would i fi had the tools and diagrams from repair book


    good luck
     
  13. 90blzr

    90blzr 1/2 ton status

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    I've done a couple 4spds from my elcamino before along time ago...and all we had was a diagram and we got through it. An auto has more to it that a bunch of gears on a shaft though /forums/images/graemlins/crazy.gif I didnt want to just jump in head first without askin around/forums/images/graemlins/thumb.gif
    I think we can do it if nothing else works out.

    Also, if we find a used TH350 for cheap, what should we look for? Anything besides color of fluid? When we drop the pan, how much 'residue' is 'normal' if any?
     
  14. Beast388

    Beast388 1/2 ton status

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    Yep, here is the Haynes Manual. I replaced everything that came in the rebuild kit, which I got from Napa.

    IIRC, the costs were as follows:
    Rebuild kit: $75
    Shift kit(Jegs): $45
    Used TH350: $20
    Fluid etc: $20

    So, about $160. I think it took about 16 hours to yank, rebuild, and reinstall the tranny. Bench pressing that NP205 was fun! /forums/images/graemlins/eek.gif /forums/images/graemlins/rotfl.gif
     
  15. Triaged

    Triaged 1/2 ton status

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    I rebuilt my th350 last winter. Make sure you have an area where you have a large bench to work on in a clean area. I did mine in the backyard with a sheet of plywood on some sawhorses. The output shaft is the last thing to come out of the case. I ordered a kit from summit...it didn't come with any of the thrust washers. Make sure the kit you get has them. Some of my hard parts were toast. I went to "Leon's Trans" near my house and got some replacements for like $30. Guys were cool to deal with. If you have any questions shoot me an email...I might be able to help (I have a manual if you want to borow it).
     
  16. R72K5

    R72K5 Banned

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    [ QUOTE ]


    Also, if we find a used TH350 for cheap, what should we look for? Anything besides color of fluid? When we drop the pan, how much 'residue' is 'normal' if any?

    [/ QUOTE ]

    yes try to find as internally clean of one as possible, dont want it if theres any metal pieces and/or alot of black goop junk, a little of it is normal though if high mileage taken care of, but not a bunch
     

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