1964 ST-400 Valve Body diagram?

Discussion in ''Da Nailhead' started by Superstingray77, Jan 7, 2020.

  1. The background info:

    I have a built up 64' Riviera with a fairly fresh stock ST-400. The trans was rebuilt by someone locally by the previous owner.

    Engine Spec:

    The engine is a built up fairly hot cammed 434 Nailhead with Headers/Mandrel bent 2.5" pipes, Doc Mod and ported intake, cleaned up heads, new valves, pistons, rods, etc and I have installed a 2000 RPM Hughes Converter which works awesome.


    1. Its leaked fluid since day 1 when parked from the pan rails. (resolved)
    2. The electric kick-down never worked, yes it has power and you can hear the solenoid click inside the trans. (resolved)
    3. Manual 1-2 Shifts are terrible. Slow and sliiiiiiiiiddddeee into 2nd under heavy throttle.
      The 64' shift quadrant and the "trick" and if you shift from L to D then back to L to manually hold 1st and shift and hold 2nd it takes about an hour to slide into 2nd gear.
    4. An automatic up shift from 1-2 if left in Drive is crisp and firm and fine for normal driving but could use improvement under 3/4 to Full power.
    Current State:
    After installing the converter it was time to sort out the rest of the BS with the trans.
    1. I fixed the bent trans pan rails that were causing the leaks.
    2. I pulled the valve body and realized they completely OMITTED the separator plate gaskets (Likely because they are damn hard to find for this one year only trans) and they cleaned it up using an 80-100 grit roto-disc which left it fairly scratched up. It is flat as is the valve body and case. So were relying completely on 57 year old cast iron, steel, aluminum to remain fully sealed...... Not a fan of this approach but... OK...(not really)
    3. The electric solenoid was a cheap **** replacement that was broken at the 2 of the 3 spot welds. The spring was laying in the bottom of the pan. Installed a new Borg Warner quality kick-down solenoid.
    4. Pulled the metal filter and pickup tube and found 2/3 of one O-ring hanging in the pump housing. Found the missing 1/3 laying in the back of the pan. They installed it using 2 O-rings and the lower one was damaged. The upper (closest to the pump) was in tact and prevented the pump from ingesting the bits of the torn ring.
    The Dilemma:
    I have built dozens of automatics of all flavors over the last 30+ years. So I have a very solid understanding of them.
    There are literally ZERO shift kits or documentation available for this ONE YEAR ONLY trans.
    The only thing in common with the >65 up units is the valve body bolt pattern and general location of the valves within the body. The case and valve body for this year are NOTHING like a 65-up. Thus cannot be interchanged.

    The Questions:
    1. Does anyone here have experience modifying the 64' ST-400 valve body, accumulators, separator plate etc.
    2. Does anyone have a Valve Body channel map indicating what fluid flow is taking place in each of the VB passages? (I have it for the >65 up) The 64' Buick manual shows the valve locations and exploded view of their assembly into the body and there are photos of each valves operation but they failed to tie all that together with an actual VB diagram.
    3. I attempted to change the 1-2 Accumulator Valve spring in the valve body (not the servos) by using a lighter & shorter spring on the OUTSIDE portion of the valve as on the 65-up this is supposed to firm up the 1-2 shift. (The 64 uses the adjustable type 1-2 Accumulator Valve) It did not work. The trans instead behaves as if the modulator vacuum line is missing. It shifts around 4000 RPM at light throttle into 2nd etc. So I am pulling the pan and going back to the stock spring tonight.
    The Goal??
    1. Clean crisp shifts that execute quickly.
  2. Bens99gtp

    Bens99gtp Well-Known Member

    I would give chris at ck performance a call, he can be hard to get so be patient, but he know these things better than just about anyone I have ever spoken too
  3. Thanks I will do that. I have actually read some stuff off his website and it was good info. In the meantime hopefully someone may have more info to share. :)
    Last edited: Jan 7, 2020
  4. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    Our NE club transmission specialist is Mark Deconti. He is DCM422 on V8 but he doesn't come here very often. His e mail is dcm422@aol.com Try e mailing him and put "transmission valve body question" in the subject line so he doesn't mistake it for spam. He is the most knowledgeable guy I know about the THM 400.

    PGSS likes this.
  5. wkillgs

    wkillgs Gold Level Contributor

    Tom Telesco posted this way back in 2005 and I had it saved. Words of wisdom from our Nailhead Guru!:
    >>> a shift kit is really not needed. You locate the 1-2 & 2-3 fluid
    transfer holes in the separator plate & enlarge them to .125" (1/8th.)
    This helps fill the clutch packs faster along with a faster/firmer shift.
    Then locate the servo in the valve body & stretch the spring about 1 inch.
    This applies more pressure. Or you could remove the spring altogether &
    install the piston up side down. Then remove the spring in the front pump
    & install a 1/8th. inch washer. This will again increase the pump
    I did this on my '64 Riv. back in '65.
    Tom T
  6. Bigpig455

    Bigpig455 Fastest of the slow....

    An oversimplified answer is find a 65/66 ST and Convertor. they can be built to behave like the TH400 we all know and love, with the added benefit of a SP convertor.
    PGSS likes this.
  7. Bigpig455- You are correct. If I were to stay with the 3spd TH400 that would be the way to go.

    The long term plan (winter 2020) will be to swap in a built 4L80E and controller. I want overdrive, and with lockup I can run a decent stall speed and still have direct lock as needed. This trans has maybe 15k on the rebuild and the stall converter is only 2 weeks old. The 2k stall works great for the street and cruises nicely. For all out racing I suppose I could have gone with a 3k stall but with single wheel peel and 3.07 gears the torque I already have will destroy tires from 25 miles an hour even in 2nd gear. Here in Austin TX / and Texas in general the open freeways and toll roads are posted 75-80 MPH legal speed limits. Even cruising at the speed limit in the slow lane people blow by you like your standing still. I drive the car to work on nice days and to shows etc that are 100-300 miles away one way. The OD and lockup should get my cruise RPM down to 2100 @ 80 with present gearing and 29" tall tire.

    I plan to go through the rear end next as both axle seals are leaking and I have decel whine. So its either find a 3.07 posi carrier and gears, or build a 9" Ford rear for it and set it up with rear disc brakes etc. I hate to remove the original rear end but it would be nice to have one I can find parts for.
  8. wkillgs- thanks for the info :)
    This is exactly what my plan is. I was hoping for a fluid flow diagram as I wanted to be certain I have "reverse engineered" properly and found the correct holes to enlarge before I pull that drill trigger.
    He mentions "find the servo" I presume hes talking about the front band apply servo and spring. I think deleting the spring and flipping the piston over = hammers the intermediate sprag much harder than it is designed to take. Unless the trans is upgraded with a 34 element sprag perhaps.

    I have created some very detailed diagrams and documentation for modifying this 1964 ST-400 (ONE YEAR ONLY) trans.
    I took photos of the case passages, separator plate and valve body and overlaid them using Photoshop to create a "see through" layering of all the passages. I then spent a few hours using all available material to determine what function every passage, port, valve etc performs.
    I plan to finish it up this week and put it all into a write-up in case anyone needs it.

    1. I have modified my separator plate and now have crisp quick shifts on the 1-2 and 2-3.

    2. I set this up so that it drives nearly stock like under light throttle but the speed and firmness of the shift increase at a very comfortable but quick and solid rate directly proportionate to throttle/engine power. Which is how a good street/strip trans should shift. Its not harsh tire chirping for no reason etc.

    3. Torque Converter is a Hughes 2000 RPM Stall which is PERFECT. (Part # GM20-400BP)
    This unit works great with my fairly choppy idling cam and the engines brutal torque curve. One of the worst things one could do is use "too loose" of a converter and waste all the torque these engines make from 1200-2500 RPM. I cruise this car around quite a bit even in Austins brutal rush hour traffic and it feels nearly stock until you start to lean into the pedal. There is no noticeably "wasted" RPM while cruising. The idle is not loaded up and trying to pulse, and pull away from lights @800 RPM in Drive. If you want to rip the tires off it does it nearly at will. Especially in low gear below 40 MPH. I need a posi carrier badly....

    4. I did stretch the 1-2 accumulator/servo piston 1" as Telriv suggested. Id feel better if I could find a proper spring to refit it with as this one will likely try to shrink itself back to its former size over time and heat cycles. None of the spares I had from shift kits appeared correct nor had the appropriate tension when I measured them using my valve spring pressure tester :).

    5. This weekend I will work on governor tuning now that I have the valve body sorted out.

    Curious if anyone knows (like Tom-T etc) at what RPM these cars shifted at WOT from the factory. Id like my WOT shifts to be around 5200. It pulls strong until 5600, however if I need it up there for some reason I can just do it using the L position on the shifter.
  10. Nev

    Nev Member

    This is very cool. I have a '64 and the trans will need work soon. Is there a chance I could get some guidance/diagrams from you? Happy to reimburse you for your efforts. I am in Australia.
    322bnh likes this.
  11. I will be glad to help. No $$ required here as this forum is to help each other out. I am going to finish up my documentation this weekend (hopefully). I am an engineer for a large software / cloud computing company, as such I am trapped in training sessions all this week. I will post it all up and PM you once I have it together.
    322bnh likes this.
  12. Nev

    Nev Member

    Extra cool. No rush here as I have to build the engine first.

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