------------------------------
Date: Wed, 21 May 1997 13:05:19 -0700
From: Tom Anhalt
Subject: Stall speeds..."Switch Pitch" TCs...TH400s
Since the wife has commandeered the Cherokee for daily use, I've been
using my '65 Buick more often. This has given me a little more
incentive to spend time wrenching on it instead of the FSJ. I've
learned a couple things so far that I think would be of interest to us
FSJ types anyway. Please bear with me through the long
explaination...I'll eventually get to the point.
I just acquired a factory service manual for the Buick and in reading up on
the SuperTurbine 300 2-speed Auto tranny, I've learned that it has a feature
called a "switch pitch" torque converter. Basically, the angle of the
stator blades in the torque converter are adjustable and the energization of
a solenoid will "switch the pitch". What this means is that during most
driving situations, the converter acts like a low stall speed converter and
thus generally as a fluid coupling. But, when the situation demands it,
like when you floor the accelerator, the tranny detent switch also energizes
the stator solenoid. This causes the converter to act like a high stall
speed unit with the attendant "torque multiplication". Kind of neat. There
is also a switch that energize the solenoid when the throttle is closed.
This decreases the tendency for the car to want to creep forward when you're
stopped and holding the brake. I quickly determined that my switch for this
condition wasn't working. Well this all sounds kind of cool....but you're
probably still asking what this all has to do with FSJs...well, just keep
yer pants on. We'll get to that in a bit.
It seems that the Buick performance (read "dragstrip") crowd has really
taken to this feature. In looking through a Buick catalog I have, they are
selling these "switch pitch" torque converters with a low stall of 1400 rpm
and a high stall of 4000. Apparently, these guys will wire the solenoid to
the brake pedal to activate the high stall at the start line, and then have
it switch to low stall once they've launched. Pretty trick.
Finally...Here's the part about FSJs. These guys like this feature so
much, they also sell retrofit kits for TH400 transmissions!!!! Think
about it...you could have your tranny set up so that when you're
climbing a steep, gnarly hill you're using the high stall setting and
therefore getting the "torque multiplication" ....and then when you want
some downhill compression braking, you flip a switch, and presto!...a low
stall converter goes into effect. And it's a much lower stall speed than
the stock converters are. One side benefit is that you'll be able to use it
on the street to surprise some Mustang or Camaro or something.
So...What do you guys think? Is this something you could take advantage of?
Tom Anhalt
'81 Cherokee Laredo
------------------------------
------------------------------
Date: Wed, 21 May 1997 14:31:59 -0700
From: Tom Anhalt
Subject: Re: Stall speeds..."Switch Pitch" TCs...TH400s
SuperKen wrote:
**
** well i hate to break ur bubble, but the AT in ur 65 IS a th400.
** super turbine is a selling name. the 'switch pitch' convertor
** was used in cads and BOP HD cars from 65-67. it came i two
** flavors, 13" or 12". i have the 12" in my Super. but i dont
** have the switch that is on the carb, i have my switch on the
** dash. its ez to convert a normal th400 to this feature. u need
** the SP convertor, switch, front pump, and solinoid!!
**
I don't think it's a TH400. I thought the TH400 is a 3 speed
transmission. This is a 2-speed (SuperTurbine 300. There was also a
SuperTurbine 400). Plus, in a Chilton's manual that I have it lists the
TH350 and TH400 being used in later years and it has seperate section of the
manual for them.
** if u say that that buick cat has these in it, i want to no
** where i can get a copy of that cat!!!
**
The company is called Poston Enterprises. I don't have the address or
phone # handy right now. I'll post it later tonight.
** the cad switch was on the carb itself and came on at idle
** and when the throttle valves passed 40degrees. on the BOP
** cars, it was similar except it went into hi stall when u
** pressed on the brake!!
**
The switches on my Special are on the throttle linkage. One is built
into the switch that also controls the downshift detent and the other is at
a pivot point and is supposed to be closed when the throttle is closed (i.e.
idle). I think having it wired into the brake light would be the way to do
it for drag racing. That way you could rev the engine up in high stall mode
while doing a brake stand and then let'er rip. When it's hooked up to the
throttle, as soon as you give it gas it will switch out of high stall. It
would be neat to have an overide switch on the dash like you have, or maybe
two switches. Just think, you could have a switch that would take it out of
automatic mode (i.e. using the linkage/brake switches) and into manual mode
and then you could have another switch that would select low or high stall.
Tom Anhalt
'81 Cherokee Laredo
------------------------------
------------------------------
Date: Wed, 21 May 1997 15:20:19 -0700
From: SuperKen **---.net**
Subject: Re: Stall speeds..."Switch Pitch" TCs...TH400s
Tom Anhalt wrote:
**
** I don't think it's a TH400. I thought the TH400 is a 3 speed
** transmission. This is a 2-speed (SuperTurbine 300. There was also a
** SuperTurbine 400). Plus, in a Chilton's manual that I have it lists the
** TH350 and TH400 being used in later years and it has seperate section of
** the manual for them.
u r correct, the super turbine 300 is a 2spd. the superturbine 400 and
the th400
aer the same.
**
** The company is called Poston Enterprises. I don't have the address or
** phone # handy right now. I'll post it later tonight.
kool
**
**
** The switches on my Special are on the throttle linkage. One is built into
** the switch that also controls the downshift detent and the other is at a
** pivot point and is supposed to be closed when the throttle is closed (i.e.
** idle). I think having it wired into the brake light would be the way to
** do it for drag racing. That way you could rev the engine up in high stall
** mode while doing a brake stand and then let'er rip. When it's hooked up to
** the throttle, as soon as you give it gas it will switch out of high stall.
** It would be neat to have an overide switch on the dash like you have, or
** maybe two switches. Just think, you could have a switch that would take
** it out of automatic mode (i.e. using the linkage/brake switches) and into
** manual mode and then you could have another switch that would select low
** or high stall.
all u have to do to obtain manual control over
the stator solinoid, is to run the wire from the driv side
of the case that operates the solinoid, i cant remember which, to
a switch on the dash. connect the other half of the switch to
12v, and boom, u can leave it in hi or lo, depending on ur mood!!
but if u want OEM operation, i cant believe that those at that buick cat
cant lead u to find another detent/stator swithc replacment!!
i dont have an overricde switch, i have no automatic features. i wired
the connection form the trany directly to the dash.
**
** Tom Anhalt
** '81 Cherokee Laredo
**
** ---------------------------------------------------
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