gonzo 6.2

iTrader: (8)

Who remembers those from the late 60s,not sure which GM the factory put them in but they came in front of a THM 400,I want to say is was a Pontiac model.Seems like it was a good concept,can it be brought back and improved.If I remember right,with a flick of a switch the TC vaines would change pitch thus having a higher stall.

jimmyblue

iTrader: (11)

I had a ST400 out of a '68 Wildcat, was gonna put it
behind the 455 for my Skylark (RIP). From what I can
gather you would get the stall speed difference, but
not very efficient and heavy as hell. The ST400 had one
solenoid valve inside that directed the juice differently
and any TH400 can be modified that way if you get the
parts. But I'm pretty sure you'd rather have a 4L80E
and a lockup, high stall converter instead.

gonzo 6.2

iTrader: (8)

You would certainly want the late model trans,If someone could build a effecient dual
purpose converter that would be slick.

chris718

we build many here with the super turbine 300 11 inch cores and are currently working on one with our converter supplier pro torque.they actually work quite well with a transmission brake as well.the problem is the buick cases were cast with a port for the vp pump and although it was never a chevy option the early cases did have the signal passage.these cases are quickly becoming extinct.in these situations one must install a cup plug orifice in the case or use a modified vp oil pump that pulls and orifices signal oil from the pump cover.the technology is great and we are looking forward to producing smaller diameter converters by manufacturing the parts needed by pro torque on our new in house haas 5 axis cnc machine.if anyone would like additional info on the vp feel free to email me.

jimmyblue

iTrader: (11)

The ST400 was "switch pitch" while the ST300 was a true
(continuously) variable pitch. I don't know what the largest
motor the ST300 was put behind. The ST400 backed up a
430 motor that had about 445lb-ft of (rated) torque, a 10:1
CR and unfortunately did not like a diet of unleaded low octane
gas, plain water coolant and creosote for oil (by the look of
things when I pulled it). I think the Dynaflow trans was behind
6s and maybe the earlier Buick small blocks, 330CI or so.
Swapping the ST400 in is something the GS enthusiasts do,
as a minor heresy (in comparison to, say, an overdrive A4).

2002_Z28_Six_Speed

iTrader: (19)

SWITCH PITCH! I don't suggest it. Hard to find someone that will work on the trans. They aren't very reliable in my experience. Tried this setup to no avail. Not even a diff TC solved the issue.

chris718

the system works with the right parts.maybe john kilgore will join this discussion.he is very knowledgable on this set up.

Gearhead1

Check this out. http://www.paeenterprises.com/paeframe.html
Go to the bottom of the page and click on online shopping, then choose switch pitch converters. It's a pretty cool (old) concept.

2002_Z28_Six_Speed

iTrader: (19)

Considering that man could probably own us in every aspect of tranmission building maybe he knows of something that builders usually miss that causes the setup not to work right.

SmokingWS6

iTrader: (1)

my guess is they'd be very heavy and horribly inefficient at any pitch compared to a fixed stall

Yank

iTrader: (181)

we have been making a 10" switch pitch converter for about 16 years for the Gm race teams that run Pikes Peak with the th400 trans it works well on the low stall till about 8000 ft up then they go to the high stall for the run to the top.
It likes a low power engine as the efficiency is low in high stall about 84%
the switch pitch lowers the STR from 2.46 to 1.45 allowing the converter to flare up faster
the pump flow is unchanged as the pump blade angles do not change
all it is doing is a lower STR and restricted oil flow to the converter body
in the high stall mode they build alot I mean alot of heat and a huge cooler is needed, with over 3400 stall

gonzo 6.2

iTrader: (8)

Do you think someday our vehicals will have something simuliar to this concept/function and regulated by throttle position,that would be cool.

john kilgore

the reason for the vp in the early gm cars was that the stator in that tc made so much torque the car was hard to stop. plus the 400 trans was developed by buick and the dyna flow had a varible stator that was controlled by throttle opening

2002_Z28_Six_Speed

iTrader: (19)

Actually, my guess is that they will move to a computer controlled wet clutch to replace the automatic's TC, but not anytime soon. I am guessing that a clutch system could be made for less due to the high cost of toolings to make torque converter pumps, ect. Die and stamping machines cost millions and millions!

Maybe the system would allow the engine to rev down when coasting saving on gas. Less heat production?

Nothing wrong with the current auto though.

BlackHawk T/A

iTrader: (3)

Actually my 99 Grand Prix GT did that, if you are cruising at any speed and let off, the car will drop to idle and just roll like its in Neutral until you push the gas again and you could feel it grab again and the RPMs come back up to normal. It was a really cool feature, and something I noticed immediately that the TA didn't have.

FirstYrLS1Z

iTrader: (4)

My 1965 Buick Skylark Gran Sport(401 cu.in,325 hp @ 4200,445 ft.lbs.@ 2800)had one.Buicks' version of the 2 speed Powerglide.A 'micro' switch on the throttle carburator linkage controlled the 'variable pitch' aspect.Full throttle activated the switch which in turn changed the 'stall'.I put a switch on the dash so I could control the stall.I was able to choose which 'stall condition' worked best for 'launch' depending upon existing traction conditions,and for top speed runs,I could switch to the 'other stall' when I ran out of RPM and it felt sort of like an upshift to get higher MPH.Longevity and durability were good as the original OEM torque convertor was still in it at 205,000 miles,and that with a 445 ft lb motor