Driveshaft lengths

Transmissions and Rear Ends

  1. slant6billy

    slant6billy Well-Known Member

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    My 2 door f body with a 904 & 8 1/4 is 49 inches. What is the length of the 727 car like a super coupe?
     
  2. Aspen500

    Aspen500 Well-Known Member

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    Not sure of the driveshaft length but the 727 is 4" longer than a 904. Bell block mating surface to the end of the extension housing is 904 31" and 727 35". Guess that would make the shaft 45", depending on where you are measuring (tube weld to weld, center of u-joint cups to center of u-joint cup, etc.)
     
  3. slant6billy

    slant6billy Well-Known Member

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    Center to center u joint is 49 on mine. I was wondering if someone has the 904 to 7 1/4 length shaft center to center U joint. I'm suspect to the length of mine being too long in the first place. Car was not an 8 1/4 car, but is now.
     
  4. Aspen500

    Aspen500 Well-Known Member

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    Doesn't the 8 1/4" need a shorter shaft than a 7 1/4"? One quick and dirty way to see if the shaft is too long, with the car supported on the suspension, unhook the shaft and push it all the way into the trans. See how much space there is between the u-joint and yoke. If you've got at least 1/2" or so, should be fine. Main thing is the front yoke never bottoms in the trans when the suspension travels.
     
  5. slant6billy

    slant6billy Well-Known Member

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    I should be ok. New Springs are 6 leaf and a slight taller shackle. I'm really curious what all the combo lengths are.
     
  6. BudW

    BudW Moderator Staff Member

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    An 8¼” driveshaft is 1.6” shorter than a 7¼” driveshaft is.
    Enough difference to cause troubles.

    I will try to find out the correct lengths, tomorrow.
    BudW
     
  7. slant6billy

    slant6billy Well-Known Member

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    thanks
     
  8. BudW

    BudW Moderator Staff Member

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    77 Prop Shaft.JPG
    From my '77 Parts Manual.

    H, N is Aspen Volare and F, G Lebaron Diplomat
    (R,W,X,S is B-body so pay no attention to last two lines)

    The only thing it doesn't mention is differential type - but a huge majority were 7¼” – so shouldn’t be too hard to figure out.

    The differences are:
    2 vs. 4-door (apx. 4” difference)
    7¼” vs. 8¼” (apx. 1.6” difference)
    727 vs. everything else (apx. 4.1-4.2” difference).

    All FMJ’s came with the small U-joints from factory (315G or 245/246).

    I see six different propeller shaft lengths:
    44.74” - obviously is 2-door, 727 and 8¼”
    48.60”
    48.89”
    50.45”
    52.70”
    54.45” – obviously is 4-door, 904 and 7¼”.

    BudW
     
  9. slant6billy

    slant6billy Well-Known Member

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    thanks brother.
    Yes, Gators E58 79 roadrunner with a 727 & 8 1/4 had just about a 45 inch shaft. My 904 with an 8 1/4 has a 48.89. To get my 8 3/4 swap to work, the A body 904- 8 1/4 2 door should fit
     
  10. BudW

    BudW Moderator Staff Member

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    Note: there is about 2.26" difference in propeller shaft length between 7¼” and 8¾”, as well as about 0.66” difference between 8¼” and 8¾” shafts. (The 8¾” propeller shafts would be shorter).
     
  11. Gator

    Gator Well-Known Member

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    Great information
     
  12. 79blueghost

    79blueghost Well-Known Member

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    904 yoke and 727 yokes are the same?
     
  13. volare 77

    volare 77 Well-Known Member

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    no 727 and 904 are different
     
  14. 79blueghost

    79blueghost Well-Known Member

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    Do you think the deconstructer has a driveshaft in 44inch length
     
    Last edited: Sep 19, 2018
  15. BudW

    BudW Moderator Staff Member

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    The A904/A998/A999/A500 and short tail A833 (A/F body) slip yoke is a lot smaller than the A727/A518 and long tail (all but A/F body) A833 yoke is.
    26 splines for the A904 vs. 30 splines for A727.
    The A904 yoke comes close to fitting inside of an A727 yoke (but not quite).

    Not only is the “slip” portion (or spline portion) of yoke different, but they also a big vs. small U-joint versions (2-1/8” (7260) vs. 2-5/8” (7290)) of both above mentioned slip yokes.
    All FMJ cars were built with the small U-joint (7260) and a few came an A727 (less than 1%).

    The A727 yoke is about 1/4” wider at splines and is about 1” longer – if comparing side by side.

    This picture I found online – but is not a very good picture. I have both versions in my garage . . . somewhere but it might take me a while to dig ‘em out.
    Yoke Difference.png
    Both of these yokes use the smaller (7260) U-joint.

    BudW
     
  16. 79blueghost

    79blueghost Well-Known Member

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    I've not been able to find one yet. Well I take that back I did find one for close to 200. Dollars.
     
  17. BudW

    BudW Moderator Staff Member

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    You have four choices:
    - http://www.manciniracing.com/driveshafts.html This site has a new propeller shaft (cut to length) shaft for about $300 (US) or already cut to fit, for about $60.00 more.

    - A local driveshaft shop can cut your original shaft down to size for about $100.00. A bit more if you want new U-joints installed (which is not a bad idea).

    - A local driveshaft shop can cut another shaft down (larger vehicles make for great donor vehicles, like pickups/vans), for about the same amount of $.

    - A local driveshaft shop can make you a brand-new shaft for maybe $50 to $100 less than the one link mentioned above.
    A person will just need to find a local driveshaft shop and call them for exact prices.


    Note: Chrysler has always called the shaft from transmission to rear of car a “propeller shaft” and the shafts from center of car to wheels a “drive shaft”.
    Almost everyone else calls the shaft going to rear a “driveshaft” shaft and shafts to wheels “axles”.
    If you go to a dealership and ask for a driveshaft, you will not be handed what you are expecting – just saying.
    BudW
     
  18. Oldiron440

    Oldiron440 Well-Known Member

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    I've always had very good luck with the local shop building or shortening driveshafts.
     
  19. BudW

    BudW Moderator Staff Member

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    Same here.
    BudW
     
  20. 79blueghost

    79blueghost Well-Known Member

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    This is my first time dealing with the propeller shaft . But a learning curve also.