[FC] Question about Powerglides

[James Davis]

Yes. The powerglides are quite different from the Hydromatics, 
Turbohydromatics (TH350/Th400) as well as the Turboglides in there 
operation.   In the Corvair Powerglide, a valve connected to the TV lever 
determines the maximum pressure available to the transmission clutches and 
band piston.  The modulator simply limits maximum available pressure to the 
clutches based on the engine vacuum.  You can disconnect and plug the 
vacuum line to the modulator and it will not change the shift points (up or 
down).  You do risk breaking the "E" clip with the vacuum line connected 
because of the harshness of the shifts.  When the drive clutch starts to 
slip from  wear, the old get home trick is to disconnect the modulator line 
(applying full pressure to the clutch disk).  This allows the car or FC to 
be driven home without the clutch pack slipping (for a short while).
Jim Davis

   At 11:02 PM 8/18/2004, you wrote:
>On a TH350 or TH400 the modulator changes the shift points as well as the
>firmness.  Are you saying that the PG modulator works differently?
>
>Joel in Keller, TX (DFW area)
>'66 Corsa w/air
>'63 Greenbrier 4spd
>'63 Greenbrier 8dr 4spd "Bob"
>'63 900 Convertible 4spd
>'67 Monza 4spd Posi
>15 others
>
>
>-----Original Message-----
>From: corvanatics-admin@corvair.org [mailto:corvanatics-admin@corvair.org]
>On Behalf Of James Davis
>Sent: Wednesday, August 18, 2004 10:29 AM
>To: corvanatics@corvair.org
>Subject: Re: [FC] Question about Powerslides.I NEEE
>
>Bob there is only one modulator for the Corvair powerglide.  It controls
>the harshness of the shifts (controls the pressure of fluid to the
>clutches).  The governor in concert with the springs in the valve body and
>the speed of the rear pump control the upshift/downshift points.  For the
>140, GM wanted to raise the shift point points to higher rpms.  They went
>from 4,400 rpm to 5,200 rpm at full throttle with a proportional increase
>in partial throttle shift points.  They did this by changing the governor
>weights (lighter than stock) and the valve body springs and piston
>diameters (stronger and bigger).  There were no changes to the transfer
>plate and the gears, clutches, and case.  The 67-69 powerglides have a
>different TV lever on the case but the internals are the same.  The
>61-63's  are very different and should not be used with a 164 cuin engine
>(although some parts of the transmission are the same).  Other than the
>shift points and the TV lever, all 64 to 69 powerglides parts are exactly
>the same and interchangeable. In fact, any TV lever can be used on any
>powerglide if the TV rod that goes with that TV lever is used on the
>transmission/engine installation.   It is just that the 64-66 TV rod won't
>work with a 67-69 lever and vice versa.
>Jim Davis
>
>
>
>At 08:17 AM 8/18/2004, you wrote:
> >The 140 automatic has a different valve body and modulator, but the
> >differences are small.  The modulator is also slightly different.  It has
>to
> >do with the shift points.  Either can be used interchangeably and you can
>mix
> >and match with no detrimental effect.  Paul in CT
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