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Technical Is This a Switch Pitch TH400?

Discussion in 'The Hokey Ass Message Board' started by kentuckyscum, Jul 28, 2018.

  1. kentuckyscum
    Joined: Dec 11, 2009
    Posts: 107

    kentuckyscum
    Member
    from kentucky

    Found in a '66 Delta 88. Engine is gone so I could get the stuff easily. The lower terminal on the accelerator linkage switch says BAT. The two connector wire goes to the trans. Tag says "OB 66 225412." Maybe you need more info than that. If it is a switch pitch, I need the converter, the pump and what else? It would be going on a later Chevy case. Thanks. 254 (360x640).jpg 251 (640x360).jpg
     
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  2. squirrel
    Joined: Sep 23, 2004
    Posts: 47,441

    squirrel
    Member

    probably. The input shaft is different, and there is an orifice in the case that you need to duplicate in the Chevy case. Also, what year Chevy case are you planning to use? after a while, they quit casting in the passages...late 70s maybe...
     
  3. kentuckyscum
    Joined: Dec 11, 2009
    Posts: 107

    kentuckyscum
    Member
    from kentucky

    The only good case I have is a '74.
     
  4. squirrel
    Joined: Sep 23, 2004
    Posts: 47,441

    squirrel
    Member

    that should work. Look for the passage in the front of the case, where the pump feeds to the case...here's a chevy case with a jet used for the orifice. The later cases do not have any metal where that jet is located.



    [​IMG]
     
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  5. greybeard360
    Joined: Feb 28, 2008
    Posts: 1,558

    greybeard360
    Member

    You probably need the correct valve body also and whatever the electrical connection is in the case.
     
  6. squirrel
    Joined: Sep 23, 2004
    Posts: 47,441

    squirrel
    Member

    there's nothing in the valve body that has to do with the switch pitch...
     
  7. kentuckyscum
    Joined: Dec 11, 2009
    Posts: 107

    kentuckyscum
    Member
    from kentucky

    Thanks for the info. I used to know this stuff pretty well 15 plus years ago when I was sort of actively looking for one of these cars, but it never happened and it all kind of slipped my mind. So looking at this Olds was a "you've got to be kidding me" moment. The Ron Sessions book talks about this in some detail, but he doesn't cover drilling the orifice to do the conversion. Anywhere I can read up on that or is it not really that complicated?
     
  8. squirrel
    Joined: Sep 23, 2004
    Posts: 47,441

    squirrel
    Member

    I think the orifice is .030" or thereabouts. There is a little cup plug with a hole in it, in the Olds case. You can measure the diameter using a needle and a caliper, or try different small numbered drills. If you can remove the cup plug without damaging it, that would be the thing to do...it's kind of tricky!

    The converter, pump assembly, input shaft (including forward drum, usually), are different. There is that wire, that goes from the solenoid on the pump, to the electrical connector in the case, and it's retained by a valve body bolt or two, also. The orifice is the tricky part, of all of it.
     
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  9. greybeard360
    Joined: Feb 28, 2008
    Posts: 1,558

    greybeard360
    Member

    I couldn't remember where the solenoid was... First thought was valve body but it's been a few years.
     
  10. squirrel
    Joined: Sep 23, 2004
    Posts: 47,441

    squirrel
    Member

    it's screwed to the pump. Makes it fun to snake the wire around, especially when it's 50 years old and brittle
     
  11. Hnstray
    Joined: Aug 23, 2009
    Posts: 11,745

    Hnstray
    ALLIANCE MEMBER
    from Quincy, IL

    Could you please tell me what “Ron Sessions book” you are referring to? I have a couple of switch pitch Buick trans and a Chevy TH-400 core. Would like to know more about their potential for conversion.

    Ray
     
  12. squirrel
    Joined: Sep 23, 2004
    Posts: 47,441

    squirrel
    Member

    He wrote a book on the TH400 several years ago.

    how to work with and modify the turbo hydra-matic 400 transmission

    is the official title, although it should have some capital letters.
     
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  13. squirrel
    Joined: Sep 23, 2004
    Posts: 47,441

    squirrel
    Member

    btw the book seems to be out of print, and used ones are kind of hard to find.
     
  14. Hnstray
    Joined: Aug 23, 2009
    Posts: 11,745

    Hnstray
    ALLIANCE MEMBER
    from Quincy, IL

    Oh well.....but I do appreciate the reply...at least I know what watch for......
    Thank you.

    Ray
     
  15. kentuckyscum
    Joined: Dec 11, 2009
    Posts: 107

    kentuckyscum
    Member
    from kentucky

    The book doesn't really talk about converting a Chevy to SP, just mostly about the theory and differences and why it's such a sweet deal. Also he has some dated photos of Kenne Bell conversion stuff that I assume is no longer available. They even made an adapter plate to use a BOP case on a Chevy. I think the main value of the book is that it is great for people like me, who are really good at a lot of things, but not auto transmissions. He does all the theory, then says if you don't care/know that stuff, just follow these instructions. I was easily able to convert a Monte Carlo trans for use in an early square body 4wd that way. But the asking price on
    these books now is a joke.

    I was able to find some of the material I had collected years ago. It does mention the orifice, which I had forgotten. Here's the list of stuff that has been pretty well covered here:

    Converter
    Pump
    Solenoid on the back of the pump
    Input shaft (or shaft/forward clutch)
    2 wire case fitting for wiring.

    The stuff I have also mentions that the input shaft has a steel sealing ring down near the drum that must be there. And I guess it's assumed that you need the wiring from the solenoid to the wire fitting on the case. And the orifice has to be dealt with.

    That it?
     
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  16. squirrel
    Joined: Sep 23, 2004
    Posts: 47,441

    squirrel
    Member

    yup, I forgot the sealing ring, that's the reason you need the different input shaft. You can re use the old one, they are cast iron and last a long time. Years ago, I bought some new ones, when ATP still listed the part number.
     
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  17. Mike VV
    Joined: Sep 28, 2010
    Posts: 2,184

    Mike VV
    Member
    from SoCal

    Contact John.
    He is one of the foremost guys on the T-400 and its variations, and what can be done with them. He's been modifying them since the late 70's, working with GM on their future modifications, etc.
    Back a...few...years, John built me a Switch Pitch out of a standard T-400 for my 409 powered, 61 Impala. Never hurt it in 5 years of street driving and some drag racing.

    http://www.kilgoretrans.com/

    Mike
     
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  18. gimpyshotrods
    Joined: May 20, 2009
    Posts: 17,899

    gimpyshotrods
    ALLIANCE MEMBER

    Ray, they are all over on Amazon.com, but they start at about $60.
     
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  19. kentuckyscum
    Joined: Dec 11, 2009
    Posts: 107

    kentuckyscum
    Member
    from kentucky

    Ok, I got everything.

    The wire going to the solenoid had some damage. The pan on this one was a little different with a filter canister to the side rather than the flat filter with a tube, like I was used to. The pan seemed to be shallower as a result, and the wire had apparently been pinched between the pan and a couple of the valve body bolts. I will either have to splice and repair the wire or replace it, the question being how does shrink tubing or normal wire insulation hold up in Dexron. I don't know if it requires something special. I took the downshift solenoid as well, although I'm sure I can just use what I have.

    The pump has two extra bolts (?). It came right off. I had in my mind I was looking for some kind of cast iron washer on the input shaft. No idea why I thought that since nobody said it was a washer. I finally did figure out where the RING is, I'm pretty sure. I'm pointing to it in one of the pictures.

    I did manage to get the restrictor plug with the orifice out. Don't want to say how--it was a tragedy. I did damage it a bit, not sure if it is usable. In some of the material I have a guy said you could use the metal end of a glass tube fuse for the plug and drill the .030 orifice, and he seemed serious. Now I see why. Pretty clever. The carb jet idea that was posted still seems the cleanest solution.

    Another problem I was having was visualizing where the orifice plug was supposed to go. Again, while nobody ever said it, I had for some reason decided it had to be drilled. Not so. I pulled the pump off a 400 with a cracked case and looked. The hole is there already. Just need to put the restriction in it. Duh. I have a picture of it with the fuse stuck in it. You can also notice the shaft doesn't have the sealing ring.

    Two questions: What do I do with the wire? And, a 50+ year old converter? I have no problem trying it out--the trans seemed to be in good condition with bright red fluid--but what if it has issues? For fun I looked up buying a converter for a 1966 Delta 88 with a 430/2bbl (found the carb in the trunk) and the Autozone website at least basically asked me what I was smoking.
     

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  20. squirrel
    Joined: Sep 23, 2004
    Posts: 47,441

    squirrel
    Member

    I had seen the fuse trick, and forgot about it...should work! and be pretty easy to do.

    I have cut off the original wire, near the solenoid, and used a crimp connector to attach a replacement wire.

    Yes, it's a sealing ring on the input shaft, just like the other sealing rings for the clutch drums, only smaller.

    The trick is to get a 12" converter for a Super Turbine 300 transmission, such as from a Buick Special, it will give about 500 higher stall than the 13" 400 converter. And you can get these converters rebuilt with more stall, although they all seem to come out different--some just raise the stall speed 500 rpm, others by quite a bit more. The converter in my Chevy II gets about 1500-2000 in low, and about 3000 in high stall. Pretty wild.
     
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  21. kentuckyscum
    Joined: Dec 11, 2009
    Posts: 107

    kentuckyscum
    Member
    from kentucky

    That is pretty wild! I had actually read about the Super Turbine 300 in "the book" and learned to identify them since this junkyard I was in had an early Riv. But it had some other trans I couldn't identify.....there's an old school place near me that may have something I could use. The problem is that it's so overgrown you don't dare try to pick parts there in any season but winter. Snakes, poison ivy, etc.

    This should give me a good start. I will probably start with something low buck/low stakes because this is new to me and I want to see how it goes.
     
  22. Terry T Petty
    Joined: Dec 3, 2019
    Posts: 2

    Terry T Petty

    Hi-I just signed up with H.A.M.B. I'd like to know what size does the orfice need to be?
     
  23. squirrel
    Joined: Sep 23, 2004
    Posts: 47,441

    squirrel
    Member

    .030" seems to be what they started with, and works well.
     
  24. Lobucrod
    Joined: Mar 22, 2006
    Posts: 4,122

    Lobucrod
    Alliance Vendor
    from Texas

    I'm running two switch pitch 400's. One is a converted Chevy 400 in my 38 Coupe behind a 409. I have a toggle switch on the dash to switch it. Switch it to high stall and leave it there at the drag strip. Low stall for the street.
    The other one is in my 1950 Chevy Sedan Delivery behind a 401 Nailhead. I'm using the factory Buick switch that works off of the accelerator linkage. It will go into high stall at anything over about 50% throttle. Love them both.
     
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  25. 500caddy
    Joined: Feb 8, 2019
    Posts: 90

    500caddy

    I put one in my 53 gasser I put a push button switch by the gear shift if you use a toggle switch have it wired to the key ,if you forget to turn it off you will burn out the solenoid


    Sent from my iPhone using The H.A.M.B. mobile app
     
  26. Kato Kings
    Joined: Aug 22, 2006
    Posts: 682

    Kato Kings
    Member
    from Minnesota

    If anyone is need of the stock buick switch that operates off the carb accelerator linkage I have a few. PM me.
     

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