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V8 conversion question

Discussion in '40- & 55-Series Tech' started by isozelmonic, Sep 8, 2003.

  1. isozelmonic

    isozelmonic

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    Hello everybody

    When doing the v8 conversion to a chevy 350 and a sm420 transmission can you not go ahead and use the chevy transfer case that originally came with the truck you pulled the engine and transmission from. It seems like it would be easier. It would at least cut out the need to get an adapter for the transfer case that was on my fj40. Is this possible? Will save me any money any parts not needed?


    Thank you
     
  2. Gumby

    Gumby Supamod Staff Member s-Moderator

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    The cruiser rear end is offset to one side. You can change to a centered diff axle or use a Cruiser transfer
     
  3. zipp

    zipp

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    The sm420 that I bought was 2wd, so there wasn't a tcase attached to it. I personally don't even know what is available to bolt up to it. Anyways- I bought an adaptor, and kept my three speed tcase, mainly because I didn't want to mess with the offset diffs. But for the cost of an adaptor (mine was like $350 a couple years ago), I probably could have picked up a GM tcase and a centered rear output for not too much more. But then when you look into which rear axle to run, things to consider: you have to find a diff with the right gearing, 1/2ton axles have the same bolt pattern as cruisers, but the beefier 3/4ton axles have 8 lug wheels, you will need to run new brake lines with standard fittings, and adaptors where necessary, you will no longer have the parking brake on the rear of the tcase so you'll have to rig an e-brake up with the rear drums or something, and you'll need some driveshafts with the right flanges for the tcase and diff, and driveshaft length is an issue in the fj40's that don't have much room behind the tcase...

    Drawbacks from keeping the cruiser tcase are: aluminum housing, breakage-prone nose cone, adaptor clocking issues, grinding on the sm420 for the front output flange. Stuff like that.

    If you forsee yourself upgrading your axles in the future, then just get it over with, and do it now. Read plenty of articles in the tech section before you do anything else. But if you're going to be running 35's or smaller, the stock axles should be fine (assuming that you're not a maniac with the gas pedal). I am going to run my 3spd tcase until I have the time and money for a 203/205 doubler. Which will probably be a while, but I'm not worried about the case. Keep fluids in them, and they'll run forever.

    Anyways- hope that helps. Best of luck on the swap!
    Zipp.
     
  4. cruiserrg

    cruiserrg

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    I had to look for a bit, because my memory is fading, but the xfer usually found behind an SM420 is a Rockwell T221. Its a big heavy SOB with a dropped center rear output. Do a search on google to find a pic of one of these and you will decide not to run it.

    Plate adapters for the SM420 to a 3spd TLC case are relatively cheap and an easy swap unless you plan to run a factory PTO which won't work with a plat adapter.
     
  5. CruisinGA

    CruisinGA

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    [quote author=cruiserrg link=board=1;threadid=5078;start=msg39115#msg39115 date=1063063289]Plate adapters for the SM420 to a 3spd TLC case are relatively cheap and an easy swap unless you plan to run a factory PTO which won't work with a plat adapter.
    [/quote]
    Why doesn't a PTO winch work with a plate adapter? Is it because the t-case is rotated with the adapter plate?
     
  6. cruiserrg

    cruiserrg

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    [quote author=CruisinGA link=board=1;threadid=5078;start=msg39137#msg39137 date=1063066041]
    Why doesn't a PTO winch work with a plate adapter? Is it because the t-case is rotated with the adapter plate?
    [/quote]

    Because the output shaft of the SM420 does not extend far enough into the xfer to enven put a PTO gear inside. The AA for SM420 to Toy3sp xfer comes with a spud shaft that will allow use of the PTO, but is longer and more $
     
  7. CruisinGA

    CruisinGA

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    Damn. I knew the AA adapter would let it work, but waaay too much money. Guess I'll just have to get an 8274 then. ::) :D
     
  8. the shed guy

    the shed guy

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    centre to cruiser offset rear diff is not an issue, the tailshaft runs on an angle down, so across as well should not hurt it, thats what U joints are for.......
     
  9. hendo

    hendo

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    i have a 168 tooth fly wheel if you need one