Th350 to th400 driveshaft changes please help

Discussion in 'Transmission & Driveline Topics' started by sliceoflife81, Jan 1, 2017.

  1. sliceoflife81

    sliceoflife81 Member

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    Nov 20, 2014
    bell,ca
    Hey guys I have a 81 Berlinetta Camaro with a 3.8 v6 th350 to 10 bolt 8.5 rear end and I'm swapping in a 468 with a th400 and I need help with a driveshaft

    I don't know much about driveshafts or how to measure the stock engine and tranny are still in the car

    Is there a way I can find a longer shaft and just send to cut it when the swap is done??
     
  2. Fbird

    Fbird Veteran Member Lifetime Gold Member

    2,125
    18
    Feb 12, 2011
    atlanta, ga
    depends on which th400 your going with... Ususally a (short shaft) most common is used. This will TYPICALLY require a 3/4" shorter driveshaft. NOW..... typical, most common, usually .... all means....Until you have YOUR exact pieces... nobody knows.
    Motor mounts, tailshaft length, drivshaft yoke, pinion housing.... all make things change.
    As for how to measure.... install the transmission yoke ALL THE WAY IN THE TRANNY... and measure from rear edge of hole (u-joint hole) to rear edge of u-joint hole on rearend ...THEN subtract 1/2" as the driveshaft needs room to slide in and out of tranny. (is preferred that rear suspension be AT RIDE HIEGHT...ie drive on lift, or jackstands under rearend so suspension is loaded)
     
  3. sliceoflife81

    sliceoflife81 Member

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    0
    Nov 20, 2014
    bell,ca
    Oh OK sounds easy enough to measure how about hooking up the 468 to the th350 I heard that a th350 set up to a v6 can't bolt up to a v8 engine is that true?
    Cus if I could I can just swap the motor and drive it until I buy everything for the th400 setup
     
  4. Hey G

    Hey G Veteran Member

    516
    5
    Mar 18, 2012
    SC
    Don't forget about the output shaft on the TH400 is usually larger. They typically are 32 spline output shaft so the end of the drive shaft would need to be changed. Something like this will work. Hope this helps.

    [​IMG]

    G
     
  5. sliceoflife81

    sliceoflife81 Member

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    Nov 20, 2014
    bell,ca

    So I would be able to use a driveshafts that came on a truck or car with a th400 to 10 bolt rear as long as it is long enough? Or it will just be easier to do it that way?
     
  6. Hey G

    Hey G Veteran Member

    516
    5
    Mar 18, 2012
    SC
    With a 400, the shaft length will need to be about 48-48.5. However, you will need to measure your car from the end of the output shaft the center line of the u-joint cap on the diff and speak with driveshaft shop to make sure you have the right length. You could use a shaft out of a truck or car if the u-joint size is the same as the camaro. The camaros usually have a smaller yoke on the diff. Also, they do sell combination u-joints (or cross-over u-joint, by Moog) with multiple sizes on one joint, and this allows you to mismatch a diff with driveshaft...I did this with my car.

    Also, some good info here: http://www.nastyz28.com/2gcog/rearaxle.html

    G
     
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  7. sliceoflife81

    sliceoflife81 Member

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    Nov 20, 2014
    bell,ca
    Thank you so much bud
     
  8. Fbird

    Fbird Veteran Member Lifetime Gold Member

    2,125
    18
    Feb 12, 2011
    atlanta, ga
    yes your 468 will bolt up to ALMOST any chevy transmission .... 200r4, 700,325c,350,400.

    The ONLY v-6 tranny that poses a problem was the POS 60 deg 2.8 l {which never got a th350 anyway)

    OBVIOUSLY we are talking about an IRON 454 thats been punched out? not some LS configured thing right?
     
  9. sliceoflife81

    sliceoflife81 Member

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    0
    Nov 20, 2014
    bell,ca

    Yeah lol its a Gen v 454 bored out
    So I can just bolt it up to that just changing the torque converter huh?
     
  10. Fbird

    Fbird Veteran Member Lifetime Gold Member

    2,125
    18
    Feb 12, 2011
    atlanta, ga
    350 and 400 use the same convertor .... you probably will NOT want the v-6 th350 convertor behind a big block... do to TORQUE handling abilities... but physically.. the same.
     

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