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Customs 301 Poly Transmission- Swap or Keep?

Discussion in 'The Hokey Ass Message Board' started by 46Mopar!, Aug 3, 2020.

  1. 46Mopar!
    Joined: May 20, 2009
    Posts: 10

    46Mopar!
    Member

    I have a 301 poly engine that is from a 1955 Chrysler Windsor. What transmission can be easily swapped to be able to run at today’s highway speeds? I believe this is the transmission that doesn’t have a park as the park brake was used when wanting to park the vehicle. Didn’t find hardly any info on swapping this transmission so was hoping someone on here has maybe had experience with these or knows of a swap. I was planning on putting this into a 1946 Plymouth Special Deluxe 4 door. Thanks in advance.


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  2. KenC
    Joined: Sep 14, 2006
    Posts: 1,137

    KenC
    Member

    I think you may have a Powerflite. First full auto from Mopar. two speeds and reverse. High gear is 1:1 like almost all 2 and 3 speeds of the day. No problem running highway speeds at all. Very durable trans with a good converter that provides a lot of torque multiplication down low. Sort of hides the lack of more gears. Kind of heavy and bulky but a solid transmission. Unless upgrading to an OD, there's really no good reason not to use it.

    You're right, no park, but not necessary as long as you keep the parking brake in good shape. Your plymouth has a similar brake on its' manual trans. Powerflite is internal expanding shoes and the Plymouth is external band.

    The block bolt pattern is the same as early hemis so adapters are available to later transmissions.
     
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  3. 46Mopar!
    Joined: May 20, 2009
    Posts: 10

    46Mopar!
    Member

    Thanks for the info [emoji41]


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  4. Hnstray
    Joined: Aug 23, 2009
    Posts: 12,357

    Hnstray
    Member
    from Quincy, IL

    Yep, as @KenC says...it’s a Powerflite. I agree with his comments. However, to answer your original question, should you decide on a replacement, I offer the following. Except for the ‘51/‘53 Chrysler Hemi, all other V8 Dodge, DeSoto and Chrysler V8 engine thru, I believe , ‘61 models, share the same bell housing bolt pattern and crankshaft flange dimensions. There are several suppliers of trans adapter kits for both MOPAR and GM automatics. @73RR , here on the HAMB is one such vendor.

    By the way, I have a ‘55 Windsor.......

    Ray
     
    Last edited: Aug 3, 2020
  5. 46Mopar!
    Joined: May 20, 2009
    Posts: 10

    46Mopar!
    Member

    Hnstray
    Ray - thanks for all the info! I think I’m gonna keep the Powerflite. I don’t plan on racing...just want to be able to keep up with traffic. Thanks again!


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  6. Bbdakota
    Joined: Oct 23, 2019
    Posts: 83

    Bbdakota
    Member

    I have a powerflite behind my 315 poly. To make it more hwy friendly, I changed my rearend with 3.08 gears.
     
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  7. 73RR
    Joined: Jan 29, 2007
    Posts: 7,342

    73RR
    Member

    Yup, good trans. Change the fluid on a regular interval and keep the internals adjusted and you should be fine.
    The 'little' 301 is a bit light on torque but in a 46 sedan some 3.0-3.3 rear gears should do what you want. Check out the Explorer 8.8 units; they are usually cheap and very stout.

    .
     
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  8. 46Mopar!
    Joined: May 20, 2009
    Posts: 10

    46Mopar!
    Member

    Thank you everyone for all great info!


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