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TH400 Switch pitch

Discussion in 'The Hokey Ass Message Board' started by tommyd, Feb 25, 2012.

  1. Deuce Roadster
    Joined: Sep 8, 2002
    Posts: 9,519

    Deuce Roadster
    Member Emeritus

    Actually, you also have to drill one small passage in the Chevy 400 parts.

    I have a small fabricated electrical throttle activated switch on my SBC ... to make the switch pitch work.

    [​IMG]
     
  2. squirrel
    Joined: Sep 23, 2004
    Posts: 51,168

    squirrel
    Member

    depends on what year your Chevy case is, they did away with the drilled hole in the late 70s, then a few years later they got rid of the casting so it won't work at all. So if you have an earlier Chevy case, go for it. I have a few of them, they're fun
     
  3. cortcomp
    Joined: Dec 26, 2008
    Posts: 20

    cortcomp
    Member


    I know this is an old thread, i found it digging around for some SP400 parts.

    That statement is not true, i have an 80K all original except paint and wheels 2bbl 389 4 door 66 catalina, that has the switch pitch 400 trans. It has the heal detent pan, switch setup near the carb, 2 prongs side case, etc. Nothing has been cut, hacked, switched around or swapped on this car...i am the third owner and you can tell that the harness is part of the car. I can take pictures later of the linkage, pan, etc if someone thinks i am mistaken (which i mean i guess i could be.)

    Being as i have a 66 cat, i check them out on ebay/craigslist frequently and lots of people post pics of their undersides...i have clued in a couple 66 cat owners that they have a SP trans and asked them to send me pics of their throttle linkage, and it matches what i have and also appears factory.

    The reason i'm jumping in this old thread is that i've been googling around for that throttle switch setup...i'd like to yank the 389 complete down to every bracket and bolt and mothball it and save it. I have a 428 that i want to put trips on and drop in it's place, and i want to adapt another of those linkage/switch setups to the trips if i can find one, instead of taking the one of the 389. I want the 389 to just be on it's storage stands complete, carb, dist and all, linkage springs, etc, ready to go back in.

    Pontiac linkage looks different than the buick setups i've seen googling around today.
     
  4. john W.
    Joined: May 16, 2017
    Posts: 126

    john W.
    Member

    Internals Screen Shot 2022-01-27 at 2.46.58 PM.png
     
    Elcohaulic likes this.
  5. cfmvw
    Joined: Aug 24, 2015
    Posts: 928

    cfmvw
    Member

    Had one behind a 455 Pontiac in a '72 Lemans. I wired it to activate with the brake pedal, and also had a toggle switch on the shifter (Hurst dual gate from a 1968 GTO) to operate it manually. It was a lot of fun!
     
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  6. gimpyshotrods
    Joined: May 20, 2009
    Posts: 20,193

    gimpyshotrods
    ALLIANCE MEMBER

    Switch pitch converters have just about vanished, and the remainder of the support parts are getting very thin on the ground.

    I have a TH425 switch pitch, and a TH425 fixed pitch transmission sitting in the shop right now, and have the ability to build either one, but I'm having trouble finding any support parts for the switch pitch one.

    I will likely have to pass on it.
     
    Elcohaulic likes this.
  7. squirrel
    Joined: Sep 23, 2004
    Posts: 51,168

    squirrel
    Member

    What parts are you referring to? I had a converter rebuilt by Hughes a few years ago, no problem. The solenoids have not been available forever new, but used ones work...the brittle wire insulation can be a problem. The sealing ring on the input shaft is hard to find, I bought a few NOS ones years ago, haven't had to use them yet, I don't think.

    With the non-SP converters available today, there really isn't much reason to use a switch pitch, except for special applications. Like building a sort of period car using a 55 year old 12" converter that you want to drive a lot, and run low 10s with.
     
    David Gersic likes this.
  8. gimpyshotrods
    Joined: May 20, 2009
    Posts: 20,193

    gimpyshotrods
    ALLIANCE MEMBER

    Every single solenoid that I have been able to get my hands on is dead. Everyone that I buy online is dead. Everyone that I find in person that I check first, is dead.

    I have an SP TH425 that is now the mock-up transmission, because I can't find anybody who wants to rebuild the torque converter on it now, or a solenoid to put in it.
     
  9. squirrel
    Joined: Sep 23, 2004
    Posts: 51,168

    squirrel
    Member

    bummer.

    I guess I better not get rid of any solenoids, then....

    (but I'll look and see how many I have, I know I have one complete transmission, and maybe another pump and some other stuff)
     
  10. jaracer
    Joined: Oct 4, 2008
    Posts: 1,537

    jaracer
    Member

    There is a guy who builds an electronic controller for the convertor. It controls the convertor based on manifold vacuum and brake input. It works quite well. All you need to add is a switch to give a full throttle downshift. I've got one of his controllers on my Model A (Buick nailhead). I'll look up his information tomorrow.
     
    rod1 likes this.
  11. jaracer
    Joined: Oct 4, 2008
    Posts: 1,537

    jaracer
    Member

    His name is Bruce and can be reached at bcroe@juno.com.
     
  12. David Gersic
    Joined: Feb 15, 2015
    Posts: 2,516

    David Gersic
    Member
    from DeKalb, IL

    If the solenoid core is still ok, could you rewind it with new wire.
     
  13. gimpyshotrods
    Joined: May 20, 2009
    Posts: 20,193

    gimpyshotrods
    ALLIANCE MEMBER

    I have already given up on it. It is now a parts donor.
     
    David Gersic likes this.

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