65 barracuda driveshaft length / transmission question

Early A-Body Discussions

  1. Scott Bowers

    Scott Bowers Member

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    Hey folks!

    I am restoring a 65 barracuda, V8 auto. Originally the driveshaft had a flange connection to the transmission instead of a U joint.

    Well, to make things complicated I do not have the original transmission, but I do have a later model 1978 904 auto transmission. I should also mention I have upgraded the rear end to a 8.25in A body.

    Once I get the transmission in, I obviously will measure the driveshaft length, but I am wondering if anyone has done this combo before and has any advice on if there is an existing driveshaft length I can grab from a junkyard? Or is it likely I will need a custom length?

    Also, has anyone ever put a 904 1978 trans in a early A-body? Any gotchas?

    Thanks!
     
  2. JDMopar

    JDMopar Well-Known Member

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    I can't help any with your driveshaft length question, but wanted to ask what engine you're putting in? If you have the 65 model 273, the register on the front of your 78 model 904 torque converter won't fit into the back of the crankshaft in the 273. The later cranks had bigger holes in the back of them.
    The 904 you plan to use will bolt into the car just fine. You can use an aftermarket floor shifter, or find an automatic on the column, steering column from a 66 Valiant or Dart. Bonus if it's a V8 parts car with all of the linkage!
     
  3. Scott Bowers

    Scott Bowers Member

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    I do have a 65 date coded 273. The guy I got the engine from said it was out of a B body. Sorry what do you mean about the register? I was able to bolt the engine to the trans/torque converter/flexplate together. Maybe I am missing something? Or maybe the previous guy modified the 273?
     
  4. JDMopar

    JDMopar Well-Known Member

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    Previous guy may have either changed the crank or had the register in the back of the crank bored out. If your motor and transmission is out of the car, take your torque converter out of your transmission and fit the center hub into the hole in the back of your crank. It should fit very closely with little slack around it. I think I worded it wrong before. The register is the hole in the back of the crank, and the hub is the round part that sticks out from the face of the converter. The register in 273 cranks were smaller in the "I think" 64-67 cranks. Therefore, the converter hub was smaller also to center the converter with the crank. There is an adapter made to use the early converter in a later crank, but if you want to use a later converter in the early crank, you have to have the register turned larger on the 273 crank, or have a special converter made with the smaller size hub, or swap cranks to a later crank with the larger register. Building the 273 for my 65 Barracuda, I had planned to use a 998 lockup transmission, so I used a later 318 crank in my 273. The old guy at the transmission shop that built my 998 transmission actually made me call my machinist and put him on speaker phone so he could measure my crank register before the transmission guy ordered my new converter. He'd been down that road before...lol. Hope this helped some.
     
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    • Scott Bowers

      Scott Bowers Member

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      Gotcha. Thanks for this info! I am new at this so every little tip like this helps me out a lot. I am pretty sure the previous engine owner did a crank swap if that is the case.
       
    • cudamark

      cudamark Well-Known Member

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      As mentioned, you'll need to do something about shifting the transmission. Also, a later speedometer cable is needed.....66-early '68 model will work with your '65 speedo head. '66 works the best since it has the correct firewall grommet and is the correct length. As for driveshaft, I don't know what the correct length will be with your particular combo, but, once you get the drivetrain installed and weight on the rear end, you can measure what you need. Slide the yoke into the transmission, all the way. Pull it back out about 1 1/2". Measure center to center of where the u-joints will be. Assuming your yoke and pinion flange have the same u-joint size, (probably the 7260 2 1/8" joint) just get a driveshaft with the correct length if you're lucky. If you can't find one the correct length, get one a lot longer and have a driveshaft shop shorten and balance it. If you need to shorten one, get a driveshaft that has at least one end that isn't tapered. If you get one that needs to be cut right where the tube necks down, that won't work. Having one with the same size tube from end to end is the best type to use. It gives the driveshaft shop more options.
       
    • 65 Cuda 340

      65 Cuda 340 FABO Gold Member FABO Gold Member

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      I'm running a stock, uncut Duster 340 driveshaft in my 65 Barracuda with later 4-speed and 8 3/4 rear. Even though the early A body wheelbase is two inches shorter than the later (Plymouth) A bodies, the distance from the trans cross member to the rear axle is the same. Just to complicate things, though, remember that while most A body Plymouths are 108 inch wheelbase and most A body Darts are 111 inch wheelbase, Demons/Dart Sports are 108, and Dart-based Plymouth Scamps are 111.

      7 1/4, 8 1/4 and 8 3/4 all take different driveshaft lengths.

      If I remember right, 3 and 4 speed manuals and 904 automatics are the same length (may have different yokes for different transmission output shaft diameters, but those are easily swapped), while 727s are longer.

      Thus, you have to find a donor car with the correct trans and rear end.

      SO - in your case, a driveshaft from a later 108 inch A body with 904 trans and 8 1/4 rear should bolt in.

      Not sure how hard it might be to find what you need in the junkyard these days; the alternative would be to measure and have a new one made.
       
    • JDMopar

      JDMopar Well-Known Member

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      Not arguing, but trying to learn....I have always heard that 8 1/4 and 8 3/4 were same length from axle centerline to u joint centerline? I may have heard bad info!
       
    • 65 Cuda 340

      65 Cuda 340 FABO Gold Member FABO Gold Member

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      Okay, I was thinking they were different lengths, but my guess is that I was wrong and you are right.
       
    • RAT ROD AL

      RAT ROD AL I know just enough to be dangerous FABO Gold Member

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      I have a drive shaft out of a 65 Barracuda, that had a 67 V8 and 904 ( slip yoke ) with a 7 1/4 rear. If you think this will work for your app PM me. I can measure it for length !
       
    • wheelsport

      wheelsport Well-Known Member

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      Hi Scott,

      I suggest that you convert your drive shft to a slip yoke similar to 4X4 transfer cases. When the yoke on my shaft wore out, I converted to the slip yoke. With a slip yoke the driveshaft length won't be that criticle and be much smoother. I found all the necessary parts on Amazon for a very reasonable cost. I got the part numbers from someone's post on this forum. With all wheels on blocks or on the floor, measure the length, with the tranny installed, between the differential yoke and the tranny coupler yoke. Find a shaft and take it to a driveshaft shop along with the below list of parts and your measurment.

      spicer 5-153x U joint: $16.99, Spicer 2-2-349 flange yoke: $67.98, Spicer 2-40-1711 tube shaft: $56.92, Spicer 2-3-8001kx slip yoke assembly: $69.68.
       
    • cudamark

      cudamark Well-Known Member

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      From the OP's description, he already has a slip yoke transmission.
       
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