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Projects Pontiac 326 with Turbine 300 automatic, slips when warm.

Discussion in 'The Hokey Ass Message Board' started by kidcampbell71, Aug 17, 2020.

  1. Question. Recently rebuilt Turbine 300, by a professional transmission shop. Slips when warm.

    I'm a manual transmission owner. I know nothing of these things labeled as "auto-toe-matics". :D Even less .. if, in regards to a Turbine 300.

    Not that it matters, but 1965 Pontiac 326, coupled to same year transmission. Slips into gear, & shifts between fine, if manual shifting. Also operates fine when not manual shifted. No slipping when initially started.

    At operational temperatures .. it slips. Freewheels a bit, from "stand still go".

    Neighbor is not on forum. I realize we all like pictures. Car is back in "professional" transmission shop's attentions. 2 months now.

    Any information in regards to experience with these auto-toe-maticas ? Same symptoms found on later TH350/400's ?

    I didn't ask if fluid smelled burned. I will shortly. Car is not driven hard, just driven. Neighbor is a bit "civilized" --> original owner.

    Cutting up, downed trees in his yard at the moment. Can give y'all a picture of that .. maybe .. but if requested, be forewarned. I may have to model wife's bikini bottoms. o_O

    The forums I visited .. prior to this fine assembly of folks .. is devoid of enthusiasm & information for these transmissions .. seemingly. Most install TH400's instead.

    Guessing a $2000 rebuild of his, would suggest such a replacement is not in his purview. A little high, I know. Price wise. Maybe greenery wise, too. Ha !!

    Not mine, but the TH400 would have been my cheaper choice. Also of note, this may skirt really close to off topic.

    You may delete, this thread .. if so inclined.
     
    loudbang likes this.
  2. BJR
    Joined: Mar 11, 2005
    Posts: 6,706

    BJR
    Member

    You have my sympathies if your wife's bikini bottoms fit you.:eek:
     
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  3. Hnstray
    Joined: Aug 23, 2009
    Posts: 11,745

    Hnstray
    ALLIANCE MEMBER
    from Quincy, IL

    @kidcampbell71 ...those ST300’s have a variable pitch stator in the converter. Normally controlled by a long squarish switch between the carb linkage and back of manifold. I could imagine a problem 8n that sys5em, which could account for an appearance of ‘slipping’.

    Now, it may in fact be slipping. I am just pointing out there is a system related to that trans that someone not familiar with it could mistake one problem for another.

    By the way, Buick used that trans behind the 401 in ‘65 Gran Sports. Not a bad trans, per se.


    Ray
     
    kidcampbell71 likes this.
  4. @Hnstray .. have you owned one of these ? The fabled switch pitch, yes ?

    Interesting. I just now typed in Super Turbine 300 as you said, what a difference in search results.

    I had a '66 Olds Dynamic 88 for about 2 months in high school. 394 stocker. Guy I sold it to .. did some upgrades & had some sort of bypass switch to it, under dash.

    I had no idea this Lemans would have similar.

    So .. the reading says electrically controlled, then also states hydraulic into the converter. Sounds like a fun trouble shooting.

    Adjustments versus electrical controls to hydraulic.

    I of course know nothing other than you, and results found because of you. By all means keep going .. if my basic grasp is in left field.

    I'll keep looking, for sure. That's a great start. Thank you !!
     
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  5. Hnstray
    Joined: Aug 23, 2009
    Posts: 11,745

    Hnstray
    ALLIANCE MEMBER
    from Quincy, IL

    @kidcampbell71 .....A little OT, but, yes...I did have one, as a matter of fact. Back in 1970 I installed a Buick 225 V6 in a 1966 Datsun Pickup. Not a common vehicle or swap in those days, to say the least. Initially, I installed the GM 3 speed stick that came with the V6. A short time later, I decided the automatic would better serve my purposes and put in a ST300. A “Rich man’s Powerglide”:D

    It was used in Buicks from 225 V6 thru 401 V8. Similar for Pontiac and Olds applications. My next build was the same engine type, but by then the Turbo 350 was (I think) a significant improvement. In any case, in the Midwest in those days, this sort of thing was NOT common. My trucks surprised quite a few unsuspecting rubes! ;)

    Over a ten year period I built four such trucks, the last was a 1979 factory Buick Turbo V6/TH 350 in a new 1980 Datsun Pickup.

    Ray
     
    Last edited: Aug 17, 2020
    kidcampbell71 likes this.
  6. Should be pretty simple to troubleshoot that circuit if it has the switch-pitch. Switch open, no power to the trans and the converter should be in low stall mode. That's how it should work in most normal driving conditions.

    Switch closed, power to the transmission and the converter should go into high stall mode. This should occur when the throttle is about three quarters or more open. Check the operation like you'd stall test the converter. Hold the brake and slowly increase the throttle opening. When the switch closes you should hear and feel a noticeable increase in the stall speed.

    If the car is really sluggish moving away from a stop light but seems to drive normally after it's up to speed a bit, it may have a failed sprag in the torque converter. But if that's the case it will feel like you're dragging an anchor when you first start feeding it the gas. :mad:
     
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  7. Hnstray
    Joined: Aug 23, 2009
    Posts: 11,745

    Hnstray
    ALLIANCE MEMBER
    from Quincy, IL

    @ClayMart .....correct as far as you went, but it is also in low pitch at idle, to minimize creep.

    Becomes a default ‘passing gear’ at higher speeds because there is no intermediate gear, but the high stall boosts performance in that operating range.

    Ray
     
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  8. Aaron65
    Joined: Dec 29, 2005
    Posts: 285

    Aaron65
    Member
    from Michigan

    I believe that only Olds and Buick used the switch pitch converter, while Pontiac used a fixed converter on the ST300.
     
  9. Hnstray
    Joined: Aug 23, 2009
    Posts: 11,745

    Hnstray
    ALLIANCE MEMBER
    from Quincy, IL

    You may be correct. I only know Pontiac did use the ST300, have no direct experience to say it used the switch pitch feature. Always something to learn. Thanks for the comment.

    Ray
     
    kidcampbell71 likes this.
  10. Great information, so far .. guys.

    I found a factory ST300 service manual for Pontiacs, that should be here in a few days. A likely gift for neighbor Jim, after I read it, & make a copy.

    Wish the car was here to look at. Really clean example to HAMB build. :Do_O

    I have a nice RAIII 400 short block & some M/T Pontiac intakes that would make that car fun. Obviously not the focus here .. .. so I'll shut up.

    There really is not much info on these ST300's in Pontiacs pre-65.
     
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  11. Hnstray
    Joined: Aug 23, 2009
    Posts: 11,745

    Hnstray
    ALLIANCE MEMBER
    from Quincy, IL

    So far as I know (or remember/believe) they were introduced in 1964 for select models.

    Please report back on what you find out when you receive that manual ‘re Pontiac using, or not using, switch pitch converter.

    Ray
     
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  12. Unique Rustorations
    Joined: Nov 15, 2018
    Posts: 564

    Unique Rustorations
    Member

    Pontiac never used the switch pitch feature. It’s been discussed here before as well. Good luck with the trans repair. Randy


    Sent from my iPhone using H.A.M.B.
     
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  13. Aaron65
    Joined: Dec 29, 2005
    Posts: 285

    Aaron65
    Member
    from Michigan

    I just went and checked my Motor Manual from 1965...the transmission section mentions that Oldsmobile and Buick use a variable pitch torque converter, so I'd say we've gotten to the bottom of that one. I have a '65 Skylark with an ST300 switch-pitch. It's a neat idea, but a nice three-speed would have been a lot better. A few years ago, I disassembled the microswitch on the carburetor...American ingenuity at its best! Super cool stuff.

    Edit: I just noticed that Unique Rustorations mentioned the same thing ahead of me... :)
     
    kidcampbell71 likes this.
  14. So the switch was closed at idle and at roughly 2/3 or so to wide open throttle when working as designed. Didn't remember about it working at idle speed but that's a pretty ingenious way to reduce creeping at idle speeds.

    And somebody already answered my other question before I got around to asking it. I didn't think all ST300s had switch pitch. The only one I remember driving occasionally years ago was in a '65 or '66 Cutlass 4 door with a 330(?) and a QJet. With just the 2 speed ST300 the switch pitch made it much more fun to drive than you would have guessed.
     
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  15. Hnstray
    Joined: Aug 23, 2009
    Posts: 11,745

    Hnstray
    ALLIANCE MEMBER
    from Quincy, IL

    Beginning in 1964, Buick used the switch pitch ST300 with the 225 V6 and 300 V8 and in ‘65 used it with the 401 in the Gran Sport Skylark......

    Ray
     
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  16. Wrench97
    Joined: Jan 29, 2020
    Posts: 290

    Wrench97

    I had a few GTO's with the Super Turbine 300 usually slipping hot was caused by low oil line pressure, if the pump was worn and putting out low pressure a rebuild would last a couple months and start slipping again.................don't ask me how I know...............................
     
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  17. No S/P in Pontiacs Not it T400 either.

    A T350 is a direct bolt-in except for kick down cable.
     
    kidcampbell71 likes this.

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