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51 Buick std to auto trans conversion

Discussion in 'The Hokey Ass Message Board' started by DRD57, Jul 12, 2014.

  1. DRD57
    Joined: Mar 5, 2001
    Posts: 3,973

    DRD57
    Member

    What's the hot tip for changing a 51 Buick from a three on the tree to a modern(ish) automatic trans. I know these could be optioned with a Dynaflow but, those aren't very good.


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  2. AnimalAin
    Joined: Jul 20, 2002
    Posts: 3,417

    AnimalAin
    Member

    These guys don't give their stuff away, but seem to have a pretty good reputation.

    www.transmissionadapters.com/
     
  3. Hnstray
    Joined: Aug 23, 2009
    Posts: 12,047

    Hnstray
    ALLIANCE MEMBER
    from Quincy, IL

    Ditto on Bendtsens in Ham Lake, MN. They make quality parts. I have the Buick straight 8 to GM/Chev adapter and it allows installation of any stick or automatic setup with Chevrolet bolt pattern. You could use it for BOP pattern too, with minor mods, as the locating dowels are the same for Chev/BOP. www.transmissionadapters.com

    Of course, that only gets you halfway there. You have to replace the torque tube driveline/read end as well. The easiest adaptation is to use '60 to '72 Chev/GMC rear control arms (aka Truck Arms or Nascar arms) and make anchor brackets for the forward ends up in the front of the frame X member. There are numerous threads on that subject on the HAMB.

    You have a wide variety of rear axle assemblies that have a width would work, but you may want to choose something with a matching bolt pattern (5 on 5").
    GM pickups after '70, later GM big rear drive sedans/wagons, some '70s full size Ford........there are more.
     
    Last edited: Jul 13, 2014
  4. Rusty O'Toole
    Joined: Sep 17, 2006
    Posts: 9,578

    Rusty O'Toole
    Member

    Best, easiest, fastest and cheapest? Sell your car and buy one with an automatic. Or trade to someone who wants a standard. The standard models are rare, and more guys want them. You might even make a little boot on the deal.
     

  5. Rusty O'Toole
    Joined: Sep 17, 2006
    Posts: 9,578

    Rusty O'Toole
    Member

    Or take a driving lesson. Back in the day old ladies and grannies drove those. They are about the easiest manual trans car to drive. Very little shifting necessary, when you have a high torque straight eight. You can idle down to below 10 MPH in high gear and pull away without a buck.
     
  6. DRD57
    Joined: Mar 5, 2001
    Posts: 3,973

    DRD57
    Member

    It's not mine, it's a customer's car. I drive a manual trans car every day.

    If the customer wants an automatic, the customer gets an automatic.

    Thanks for the lead on the adapters.
     
  7. Hnstray
    Joined: Aug 23, 2009
    Posts: 12,047

    Hnstray
    ALLIANCE MEMBER
    from Quincy, IL

    buick%20rear%20end%20mount.jpg DSCF0043.jpg DSC04577.jpg DSCF0041.jpg

    Here are some photos of truck arm installs and one for a 4 bar setup.
    In most cases, you could use the original Buick springs, frame pockets and Panhard bar by using some of the brackets currently on the Buick axle housing.
    One caution....resist the temptation to use the original Buick diagonal braces. They are far too weak to use as torque arms as they do not carry those loads in the stock design, the torque tube does solely. The diagonals only serve to keep the rear axle housing 'square' with the torque tube.
     
  8. DRD57
    Joined: Mar 5, 2001
    Posts: 3,973

    DRD57
    Member

    Once I explained the scope of the project and how much needed to be changed besides the actual transmission, he decided he could live with the 3 speed manual. Only now he wants a floor shifter in place of the three-on-the-tree.

    Can one of the aftermarket floor shifters be made to work on this transmission?
     
  9. Hnstray
    Joined: Aug 23, 2009
    Posts: 12,047

    Hnstray
    ALLIANCE MEMBER
    from Quincy, IL

    Unfortunately, that transmission has what is commonly called a 'selector type' shift mechanism. One lever is used to shift all the gears, but, there is a small second lever whose movement determines which pair of gears the main lever engages.

    'Back in the day' floor shift conversions where made for these trannies, but to my knowledge, are not available for purchase new currently. Some folks have made their own and there are some threads here on the HAMB that have photos of those.

    The selector type trans was shared by Pontiac, Olds and Buick from about 1939 through '57 to '6o, depending on make.

    One thing you could consider. If you could obtain a '37/'38 floor shift Pontiac, Olds or Buick transmission, I believe it could be combined with parts from the '51 into a floor shift box that would bolt into the Buick with the only mod being a hole in the floor. The Pontiac/Olds trans are open driveline so the parts you most need from them is the main case and floor shift top cover, swapping in the the '51 Buick internal parts. It is possible that a Buick box would bolt in without exchanging parts.

    However, the customers car has a 5 bolt top cover trans, used with the smaller engines, and the replacement trans must be the same. The heavier duty 6 bolt top cover is very similar, but larger and is not interchangeable with the 5 bolt cover box. Hope this helps sort out the dilemma.

    Ray
     
    Last edited: Jul 29, 2014
  10. DRD57
    Joined: Mar 5, 2001
    Posts: 3,973

    DRD57
    Member

    Thanks for all the info.
    Still not sure which direction the customer wants to go with this.
     

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