will a different converter have similar effect in a switch pitch trans?

Discussion in 'The "Juice Box"' started by Gran Sport66, Apr 18, 2005.

  1. Gran Sport66

    Gran Sport66 Well-Known Member

    I have the s/p trans on my car, but it's not got the electrical lines hooked up. I am working on that.
    I had it at a trans shop a week ago and had the pan dropped, and seems everything is OK, should be solid, no crap in the fluid, etc. Has a leak near the rear end-gonna have that taken care of soon.
    So, after looking at the innards with the pan removed, it seems to have a blue converter, and I guess I couldn't tell if it was original anyway just from lookin, but the guy at the shop said it had been rebuilt and the converter wasn't original. It is a BS trans.
    What kind of response will I get from this trans, with a regular converter? Will it be just like using the s/p? Not like the original?
    I do mean after having the throttle switch on the engine block fixed and working.
    Anyone have a s/p converter they don't need? Do you have to tear down the trans and do a rebuild to change the converter?
    Also, if I don't have the original linkage for the carb/switch on the current carb, can I get that stuff? Has anyone fabricated brackets/linkage for this purpose that works? (Of course you have, this is V8Buick!). :TU:

    Thanks
     
  2. quicksabre

    quicksabre Well-Known Member

    Blue converter... Sounds like AAMCO if it is sky blue. AAMCO would be lucky to rebuild one of those correctly, but it depends more on who they have doing their converters. The Kenne-Bell converters that I used to get were dark blue. Those take factory horsepower without incident, but have to be modified for high HP. Factory type converter will be 13" and take up pretty much the entire bellhousing. Just about any aftermarket converter is based on the ST300 type and is 12".
    No need to rebuild the trans if it is working properly and if the converter hasn't come apart internally.
    Many people just control the converter manually with a switch. All it takes is a switched 12V signal to the horizontal pin of the two pin connector on the left side of the trans. I would hook up such a switch and see if it works. Regardless of exactly what converter is installed, you'll know it if it truly changes stall. 12V applied = high stall. 0V = low stall. The factory 13" is very low stall in low stall mode, like less than 1000RPM. They just about kill the motor if you stop in low stall. Yet, they'll go up to around 2000, or slightly more, in high stall. And in my experience, a factory 12" without mods will be too high for a stock torquey big block, even in low stall.
    Hook up a switch and let us know what you find.
     
  3. quicksabre

    quicksabre Well-Known Member

    To add to your question, you can't put a non S/P converter with a S/P trans. You must use a S/P converter or convert the trans to take a regular converter. You might like the stall RPMS that it already has.
     
  4. Gran Sport66

    Gran Sport66 Well-Known Member

    When you say I might like what it already has, it does have-I would think likely a non-S/P converter, unless they knew what they were doing when they rebuilt it, or whatever. Wish I knew more for sure, but what you are saying is it must have been converted to a regular converter?
     
  5. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    No,
    A fixed pitch converter will not fit on a switch pitch trans. The input shaft and front pump is different. If you don't know the history of this trans, it may no longer be a switch pitch. Someone may have converted it to fixed pitch. Run a wire from a 12 volt source (fuse block, etc) Put a simple switch inline. Attach the wire to the horizontal connection at the trans. Start the car, put it in gear, and note the RPM's in gear. Then throw the switch. If the switch pitch is working, the RPM's will increase (high stall)
     
  6. Gran Sport66

    Gran Sport66 Well-Known Member

    I would love to be able to try this, but I don't have an rpm meter, or the means to do the test. I'm printing this though, cuz maybe I can borrow a gauge from Autozone

    Thanks, Larry
     
  7. nailheadina67

    nailheadina67 Official Nailheader

    I would just simply try connecting 12 volts to the pin with the motor not running and listen for the solenoid to click. I would suppose that if they used the SP pump and a non-SP input shaft with a non-SP converter it might still click though. I will say this.....if it is a SP converter, and you don't have it connected, it is in low stall and the idle will be very raspy as the car will tend to "creep" and be hard to hold back with the brakes even with a low idle speed. :bglasses:
     
  8. speed70

    speed70 Henderson Driveline, Grafton OH

    S/p

    Are all the ST-300 2 speed trannys up to 19?? S/P ? Single prong connector is for kickdown no? Or did they use the vacuum modulator for up/down shifts?
     
  9. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    You don't need a tach, you'll be able to feel, and hear the engine speed increase as the converter goes to high stall. Not sure if all ST300's were SP, but if it has a 2 prong connector, it should be. In the 70's, that second prong was used for a smog switch signal on the THM 400's. Like Joe said you can apply 12 volts to the horizontal contact, and listen for a click, but I like my way better, because you'll actually feel the converter get looser.
     
  10. Sportwagon400

    Sportwagon400 Well-Known Member

    As far as I know only 64-67 ST300 were SP trans my 68GS350 has a ST300 and no SP my 67 Skylark 340 has a ST300 and SP so thats how i came up with that info

    Ken

    hope it is correct
     

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