drive shaft length

Discussion in 'U-shift em' started by GSX-PKV, Jul 6, 2016.

  1. GSX-PKV

    GSX-PKV registered user

    I'm restoring my 70 GSX with a correct M21 transmission. I want to order a new driveshaft from the Parts Place that is listed as being "55 1/2" long with a u joint which measures 3 1/4" to cap" according to the description on their website. My question is: the car originally had a 10 bolt rear but 40 years ago a previous owner installed a 12 bolt. I wonder if having a 12 bolt vs a 10 bolt effects the length of the driveshaft? Thanks and I appreciate any info. Paul
     
  2. sean Buick 76

    sean Buick 76 Buick Nut

    best bet is to measure... the engine and trans mounts could easily be moved from stock location...
     
  3. flynbuick

    flynbuick Guest

    Have one made and measure for it PER THE SHOP'S INSTRUCTIONS. Try locally first.
     
  4. knucklebusted

    knucklebusted Well-Known Member

    Did you have a working driveshaft in it before? Is so, what was the trans/rear combo then?

    I can tell you that when i went from a Chevy 12 bolt to a 8.5 Buick 10 bolt, the drive shaft for the 12 bolt was too long by about 3/4" to 1". If you don't have a working setup now, the only safe thing to do is measure.
     
  5. GSX-PKV

    GSX-PKV registered user

    Thanks guys. We'll measure after installing the trans and have a driveshaft made then.
     
  6. dl7265

    dl7265 No car then Mopar

    Paul, the yoke is prob diff length. But the shaft according to the manual is 56" measured from center to center of the u joint. PS why not restore your original ?is it bent ?


    DL
     
  7. GSX-PKV

    GSX-PKV registered user

    Don, I broke the original driveshaft at Union Grove drag strip with 10" slicks on the car back in '92 :0 A prior owner took out the original M21 and replaced it with a Turbo 400. When I bought the car in '89 I returned it to being a 4 speed but chose a Super T 10 because I wanted to race the car a lot and was told that the Super T 10 would be better for that. Now, I'm replacing that with a date code correct M21 so the car will be more correct.
     

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