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Technical What are the ins and outs of transmission adapter plates?

Discussion in 'The Hokey Ass Message Board' started by NAES, Aug 26, 2019.

  1. NAES
    Joined: Dec 24, 2008
    Posts: 434


    So I've been tinkering with this '55 Caddy for a while now and it's becoming more and more obvious (to me) that an overdrive transmission would be a better way to go than having the original one rebuilt. I like to cruise low and slow except when I'm on these SoCal freeways. I need to be able to hit 75 comfortably without the engine winding up.

    I have a 700R that would be a great candidate but of course need to adapt that to the 331 that's in there. There's a kit from Wilcap to the tune of $570 plus a new starter which seems a little steep for a hunk of aluminum and a flywheel. Yes they did the R&D so they can ask whatever they want for it but really, how hard is it? Seeing as though I own an milling machine and a lathe, I should be able to make something for my needs for little more than materials cost. My time in the shop is free so I don't count that necessarily.

    If you guys could kinda give me a walkthrough on this I would greatly appreciate it. It would be cool to send some chips flying and make something super useful.

    Thanks all, NAES
  2. Mr48chev
    Joined: Dec 28, 2007
    Posts: 25,373


    I'm seeing three pieces plus the flexplate bolts when I look at the kit.
    I think the issue isn't that you have the equipment and can use it well. The actual issue is do you have the designing experience and layout experience or skill? It's going to be a lot more involved than holding a piece of cardstock from dollar tree up to the block and tracing out the pattern and then holding it to the trans and tracing out the pattern and whittling it out.
    Even if you get that part done there the spacer between the crank and the flex plate, Making a flexplate and welding a ring gear on it or engineering the whole setup to work with a starter of your choice.
    Self satisfaction aside I think I'd use that time to either do a project for someone who will pay enough to pay for a good part of that kit or make something that I could sell to pay for it.
    Hats off to you if you are up to accomplishing it though.
    j-jock, Texas Webb and Hnstray like this.
  3. Hnstray
    Joined: Aug 23, 2009
    Posts: 10,586

    from Quincy, IL

    @Mr48chev .......very well stated. The precision required in laying out all dimensions in, out, up, down and no small thing, and is crucial for longevity of components.

  4. Oldioron
    Joined: Dec 12, 2018
    Posts: 841


    Isn't it more of a CAD drawing than anything then CNC.???
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  5. jimmy six
    Joined: Mar 21, 2006
    Posts: 4,544

    jimmy six

    NAES..If $570 is to expensive I'm certain that you won"t be looking at a Bendstens at $1500.... I think you'd better get ready for the real world...
    Hnstray and warbird1 like this.
  6. $570 is a steal. Just order the Wilcap and move on with your life.

    The last 2 Ford FE to AOD conversions I have done required custom built torque convertors that were north of $1000 ea. Then you tack on the adaptor, starter, drive shaft mods, and transmission upgrades to handle a healthy FE, and the wallet gets thin real quick.

    Also, Have you priced out Alumium Tooling plate lately? An 18" x 18" x 1" thick chunk of 6061-T6 will probably run you around $450 anyways, unless you have a line on some good scrap.
    Last edited: Aug 27, 2019
    Hnstray and Crazy Steve like this.
  7. My experience is it's always cheaper to buy stuff like this over building it. I'm not adverse to building my own parts if I can't find what I need but it's rarely a big money-saver.

    And raw material costs have gone up sharply lately...
    Hnstray likes this.
  8. irishsteve
    Joined: Jan 10, 2017
    Posts: 350


    I think you would be ahead time,and money to buy a Gear Vendors overdrive unit.Their web site shows their unit on old Caddys,and other big cars from the 30"s up.
  9. DDDenny
    Joined: Feb 6, 2015
    Posts: 12,034

    from oregon

    If you got the "goods" to machine it (accurately) yourself, go for it.
    For those ordering a new one from vendors like Wilcap, Advance, Hot Heads etc. know EXACTLY what you have and what you need, lots of variables to be considered.
    Also, don't be shy about asking them questions, much easier now than later.
    Hnstray likes this.

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