Teach me about the TS400 switch pitch/'67 LeSabre400

Discussion in 'Wet behind the ears??' started by LeSabre400Coach, Sep 27, 2020.

  1. Just got this beautiful car but it's a little hermaphrodite to me. The more I learn the more I love it! I have the TS400 transmission and the last owner didn't reconnect the switch pitch when he installed a Holley carb. I have fabricated a new linkage out of some old aluminum angle I had laying around the garage and I'm not trying to learn how to adjust it properly. The problem I'm currently having is it doesn't kick down into a passing gear unless I manually do so on the column and I'm not exactly sure where the shift points are supposed to be or how to properly adjust the switch pitch arm. Any info and or feedback would be greatly appreciated. Thank you in advance!

    Attached Files:

  2. Roberta

    Roberta Buick Berta

    Might want to read the shop manual, so you can learn how it is supposed to work before you ask for a bunch of opinions, that may or may not help.
    LeSabre400Coach likes this.
  3. Great resource!! Thank you!!
  4. philbquick

    philbquick Founders Club Member

    There's 2 functions involved with those switches. 1) switch pitch is controlled by the micro switch at the top of the vertical throttle linkage arm near the firewall. The pivot hole where it connects to the rod that goes forward is oval so when there is no pressure on the gas pedal the switch is closed. Once pressure is applied to the gas pedal, and before the throttle plate moves, the switch opens and the stator goes to low stall. If it's working properly you should almost be able to take your foot off the brake at stop lights. Also, if it's working properly, you can change the idle with pressure on the gas pedal. With you foot off the pedal listen to the idle, then put slight pressure (without moving the throttle plate) on the pedal and you will hear the idle decrease, almost like letting the clutch out on a standard shift car. Here's another feature, there is a 1.5 second delay when it changes from high stall to low stall, so, if you want to get off the line fast keep your foot off the pedal and the tromp it, and it will get off the line in high stall (and probably bark the tires). If anyone has been monkying around with the linkage this is probably not working. Without the engine running, push back on the vertical throttle linkage at the firewall and you should hear the micro switch click, if not, it's not working. The 2nd function is passing gear that is very straight forward, when the throttle goes open the switch closes and it down shifts. There should be 12v on one if the wires when the ignition is on.

    Enjoy your Buick!
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  5. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    I would first verify that you actually still have a switch pitch. Many of them were converted back to fixed pitch when the transmission was rebuilt. If you don't know the entire history of the car, this is a possibility. Just because it has 2 electrical contacts on the transmission, and the right ID code, does not mean it still has the switch pitch internals.

    One way to find out is to wire a simple toggle or momentary switch to 12 volts, and to the stator contact on the transmission. That would be the horizontal contact. Apply 12 volts to that contact and you get high stall. With the car fully warm and idling IN GEAR, flip the switch. There should be a noticeable increase in engine RPM.

    You can purchase an electrical control box for the switch pitch. The box has 3 timers and a vacuum switch.
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  6. buicksWILD

    buicksWILD Well-Known Member

    Good info here.
  7. Trans has never been rebuilt. Only has 32k and switch pitch is functioning. Just don't know how to adjust it properly and it does not kick down into passing gear unless done manually.
  8. Yes! Lots of good info. Keep it coming guys. I'm a sponge right now.
  9. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    OK, there are 2 spade connections at the transmission. They look like this,
    The vertical one is for the kick down, the horizontal one is for the switch pitch. If the transmission is not kicking down, then you first need to troubleshoot the solenoid and wiring. First, run a wire from the battery positive long enough to reach the transmission connections. Touch the vertical connection and listen for a click emanating from the pan. The solenoid will click every time you touch that vertical connector. If you do not hear a click, there is a problem with the solenoid or wiring inside the pan. You will need to drop the pan. The solenoid is easy to change if that is the problem. It is held on with 2 bolts at the corner of the valve body.

    If you hear the click, move on to the external wiring. A multi meter or test light is all you need. Check for voltage at the transmission kick down wire at the transmission. Have someone floor the gas pedal engine off, key in the run position. No voltage at the transmission? Go to the throttle switch. Again check for voltage at the switch, throttle closed and wide open.
    LeSabre400Coach likes this.
  10. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

  11. Quick Buick

    Quick Buick Arlington Wa

    That Homemade linkage will not work..Plus the adapter plate.... Two Totally wrong Geometryies ... Find the factory carb that come on that 430/ST400 trans...
    Last edited: Sep 29, 2020
  12. Thank you so much... Between the shop manual and your guidance I've got it straightened out!!! There were multiple little "Stoopid" things that needed to be worked out. First was the detent solenoid not being reconnected by previous owner when he installed the Edelbrock... I referenced my temporary solution previously. Next kink I found in the manual that was shared above. At some point, I'm assuming when the carb was replaced, someone reassembled the micro switch incorrectly. The business and spacers we're not put back properly never allowing the switch to pivot on the throttle arm properly. So even tho the switch itself is operational the spacing and leverage were it off wack preventing it from functioning properly. Thirdly, I was not happy with the electrical connections on trans casing. Even tho I was getting power to the trans it was not a "clean" solid connection and I'm confident it would short itself out from time to time so I cleaned that up and made sure it was connected securely. So far so good!!! Thank you guys so much for all of the input.

    I still plan to replace the detent solenoid as the years have gotten the best of mine and the rubber boot has deteriorated to the point it has mostly cracked and flaked off through the course of my troubleshooting and experimenting. Again! Thank you all so much for the input and knowledge. I'm sure I'll look to y'all for more knowledge in the future and do my best to return the favor when the opportunity arises.
  13. Actually, my bootleg linkage works great. The main problem was distance between the detent arm and the throttle arm on the carb. But the length of travel is fairly close to that of the factory carb.

    That being said, I do have the original carb still in the Edelbrock box in the trunk where the last owner left it. I will eventually rebuild it and put it back on but in the mean time the Edelbrock is doing it's job and it runs great, trans is functioning properly and my old man always said "If it works leave alone bonehead!"
    buicksWILD likes this.

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