ST-300 Hop Up!

Discussion in ''Da Nailhead' started by Bigpig455, Nov 17, 2012.

  1. Bigpig455

    Bigpig455 Fastest of the slow....

    I'm working on the ST300 in my 65 Gran Sport and have a question..(Paging Tom T.....!)

    Making modifications to the high clutch feed shift pressure and shift RPM per the "Blueprinting Buicks For Action" article from '66 (?) Because I dont trust myself, anything I modify is an extra, and all the original parts will be preserved.

    I modified the governor to increase shift RPM -The article calls for removing one spring and drilling 4 1/4" holes (!) in each flyweight to arrive at a 5500 RPM shift point. I'm looking for maybe 5000 - 5200 RPM, so I drilled a single 5/16 hole in each weight and left both springs in. It's likely gonna be a trial and error process, so I'm starting slow.

    I found the high clutch feed hole in the valve body plate, and openened it up from .090 to .125, which should speed and firm up the shift (It's lazy right now, probably costing me a tenth)

    But now the question - talking to Tom, he said to pull the front pump pressure spring and either shim it or stretch it. I'd lean toward shimming it, but I cant tell if the snap ring retainer is accesable through the pan opening. Reading the manual, it looks like I'd have to pull the torque converter and them pull the pump out of the case to access it.

    Is it accessable through the bottom of the case? I havent dropped the pan yet so if it is, is it on the drivers side or passengers side of the valve body? You out there Tom?

    Thanks, and wish me luck!
  2. doc

    doc Well-Known Member

    Personally,,, I think your money and efforts would be better served by swapping in a sw pitch th 400..... unless that would throw you in a different class at the strip.....
  3. gsgtx

    gsgtx Silver Level contributor

    i know you want Tom to answer this. the first thing was to remove the spring and try it that will give you 400-500 rpm more,it would give you 4800-5000 shift. with the spring removed and now with your 5/16 holes i would guess you will be at about 5200. just the 5/16 holes will do very little. like to hear what Tom says about the front pump spring never heard or read anything about it.
  4. Bigpig455

    Bigpig455 Fastest of the slow....

    Doc -

    Actually I have the perfect ST-400 sitting on the floor, just waiting 'till I find that 67 shifter and rod. And I know it'll add weight, suck up HP and make traction more complicated with a lower 1st gear. But I like 400's as much as I like Q-Jets! Someday, I'm gonna make the swap.

    GTGSX - I'm interested in anyone's opinion or experience, and I know you've done alot of this before me. The reason I didnt remove the spring was Tom thought that that would have an effect on part throttle shift points too... ??? We'll see what he has to say..
  5. gsgtx

    gsgtx Silver Level contributor

    i know you can adjust part throttle shift points by the adjusting screw in the modulator were the vacum line is. it even moves the wide open shift point up or down a few rpms. yes were is Tom T. hope he is doing well.
  6. Bigpig455

    Bigpig455 Fastest of the slow....

    Been talking to him , he missed the flooding by 6 feet or so, but he's up on a hill where he lives and the water came highest it ever had over the last 100 years. His shop made out fine and he's good too.

    Unfortunately, the machinist working on his rockers wasnt so lucky..I guess they took on some water and that project has been set back some....
  7. doc

    doc Well-Known Member

    I am sorry,,, i guess I am missing something here,,,, i ran the sw pitch 2 speed and also the sw pitch th400. and did not experience any power loss at all.... in fact the intermediate gear made a big difference in the amount of power to the ground.... more not less... also the wheel spin was less.... and the th4 was tougher...
  8. Bigpig455

    Bigpig455 Fastest of the slow....

    I hope to tell you if I agree! Stick around!
  9. telriv

    telriv Well-Known Member

    From what I know/heard the TH400 uses 48HP from the flywheel to tailshaft because of the larger/more components. 10HP can be freed up by using a Torrington needle bearing in the rear of the case instead of the bushung. The 400 weighs more. Every 100lbs. is a tenth. The easiest part is the driveshaft. Would be a perfect time for an upgrade. When rebuilding an earlier 400 it would be wise to update the sprags & drums to the newer/stronger style. Don't forget Doc, Rhett is running street tires so the higher torque output with a lower 1st. gear, plus if the "Switch-Pitch" is used is going to give more traction problems than experienced now. Most that I know who have changed only picked up a tenth or so. As stated the 400 is MUCH stronger than the 300. As the HP goes up the reliability goes down. There are NO HP ungrades for a 300 except to use the best components available at the time of a rebuild. With the "Switch-Pitch" in the 300 it's almost like having a 4 speed with the convertor.
    The pump spring, if I remember correctly is located on the left side. You can see it with the pan removed. I know for sure about the 400. Look at a picture of a 300 & 400. I believe they are in the same location. I may be wrong as it's been alot of years.

    Tom T.
  10. Bigpig455

    Bigpig455 Fastest of the slow....

    I've got the pan down now, but couldnt get a good view while it was draining. I'll check tonight.

    So far the ST300 has actually been a pretty good tranny, and the fluid looked great for having had probably 500 passes or so on it...But like i said, I love the 400 and when I retire this car it's going in... and to Doc's point the intermediate gear in my other cars does make for a much stronger midrange. The shift in my car is so lazy and kills the run at about 6-7 seconds, between the RPM drop and the long/soft shift, it really doesnt get back into the groove until about 10-11 seconds. If the valve body and governer mods work like I hope, that should help quite a bit.

    Thanks to everyone.
  11. 300sbb_overkill

    300sbb_overkill WWG1WGA. MAGA

    Sounds like a shift kit might help as well,while the pan is off anyway.

    An old drag racer trick back in the day was to use type F ATF in their powerglides,T350,and T400 to make it shift harder. The idea behind that is that type F ATF has friction material suspended in the fluid to make the Ford clutches engage.And GM type clutches,has the friction material on the clutches,with fluid with no friction material in it (Dextron II). By changing to the type F fluid,a GM trans would shift harder with the extra friction material thats in the type F fluid.

    Doc,do you remember this trick from back in the day?

  12. Bigpig455

    Bigpig455 Fastest of the slow....

    They dont make a shift kit for the 300, what I'm doing is kinda the same thing though - new valve body plate, etc...

    I've never heard of using Ford ATF in a ST/TH transmission.... learn something new every day, although I'm gonna pass on that one..
  13. doc

    doc Well-Known Member

    No ,,Derek,,,, I dont think I have ever heard of that one and I go all the way back to the clutch/turbo set up's,,,,:bla: That's what ol Rhett actually needs,,, is a clutch/turbo set up.... put that tork to the ground,,, then he could put a set of 10 or 11 in. slicks on and hook up......
    I always just used dexron/mercon fluid... that covers all bases.....:Smarty:
  14. 300sbb_overkill

    300sbb_overkill WWG1WGA. MAGA

    Must of been a regional thing,I was going to try it on my 65,but I made the powerglide explode before I could.:Dou:

    And dexron/mercon didn't come out until 1980,before that it was dexron II,and before dexron II,GM transmissions called for type A transmission fluid until 1968.So if you were racing in the 60s,how could you have "just used dexron/mercon"?
    :Smarty: :bla: :spank: :Brow: :beer :TU:

    Would a powerglide shift kit work for a ST300? I know that a ST400 is very similar to a TH400 with basically the only difference between the 2 is the converter,and the solenoid that controls the converter. A TH400 can be converted to a ST400 by adding that solenoid,and a switch pitch converter,Poston used to sell every thing to do the conversion. Just wondering how similar the powerglide,and super turbine 300 are,both being 2 speeds,and interchangeability between the 2?:Do No:
  15. urbancowboy0307

    urbancowboy0307 Silver Level contributor

    Other than being 2-speed and an aluminum case I don't think they share much interchangability.
  16. DaWildcat

    DaWildcat Platinum Level Contributor

    X2. Totally different animals.

  17. doc

    doc Well-Known Member

    Yep,,, a 300 aint even close to a glide..... way more heavy duty.... and,,,,,

    as for the trans fluid.... I did use type f on ford products and type a on gm stuff... and when mercon/dexron came along I just used it.... So there ya go , pilgrim.... :Brow::Brow:
  18. 300sbb_overkill

    300sbb_overkill WWG1WGA. MAGA

  19. Bigpig455

    Bigpig455 Fastest of the slow....

    I'm under the impression the ST300 is more like a 2 speed TH350 than a powergilde, although I'm told a few parts do interchange.

    I looked up the instructions for the B&M shift kit for a TH350 and the valve body and hardware are totally different than the ST300, and the ST300 does not use check balls in the valve body. But they do call to get rid of the pump accumulator spring and open up the clutch feed paths in the valve body plate. The link is here: TH350 Shift Kit Instructions.htm

    Of note, B&M does call for F type trans fluid to be used after installation.
  20. 300sbb_overkill

    300sbb_overkill WWG1WGA. MAGA

    Must be why I heard about that way,way,way back in the day.The type F is suppose to make the clutches engage harder,coupled with the shift kit,I quess,back in the day was a long time ago. And type F fluid is made to handle more heat,maybe thats why they call for it also?

    Take a look at that ebay link I posted, they are selling a super turbine 300 3 speed manual. I thought all the 300s were 2 speeds?:Do No:

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