<VV> Powerglide questions

Brent Covey brentcovey at hotmail.com
Tue Apr 18 05:59:32 EDT 2006


Hi Ken-

Low and reverse in Powerglide are both 1.82:1 ratio- This means most
Corvairs have over 50MPH availible in 'Reverse' range.

At 'stall" the torque converter is about 2.5:1 multiplication if its working
properly, so effectively the maximum reduction from a Powerglide would be
4.55 to 1- first gear in a 4 speed manual is between 3.65:1 and 3.11:1 by
contrast.

With a 3.55:1 axle, the engine torque (about 125 ft/lbs in lates- less at
the speed the converter stalls which is about 1700 rpm) is multiplied by
16.15 for almost 2000 ft/lbs at the rear wheels at full throttle in Low
range if the car can be loaded to max the converter out at stall. A manual
trans car has about 1300 availible at the same engine speed but actually
much less when you come right down to it unless you store energy in the
flywheel and dump the clutch at high RPM. This is why trailers are easier to
tow with automatic cars, its much easier to get heavy things rolling from a
stop with an automatic.

The Powerglide will not work 'reverse rotation' because the low band only
would operate well one direction, and the pumps are hard to change to work
the other way. There would be ways to modify this but they dont look too
rewarding.

HOWEVER, if you'd like to have a complete Powerglide transaxle with Corvair
differential that works the other direction, GM made a few that had reverse
rotation differentials with special pinion shafts for Powerglides- the
pinion gear moves to the front of the shaft and this turns the wheels the
other direction. About 1989 a bunch of thse shafts were around suddenly, the
Monza GT showcar used a system like this. The ring and pinion need to be
reverse rotation to put the quiet part on the drive side of the tooth,
although it would function with a stock gearset.

If you would like to drive the Powerglide from the front end, this is also
possible using the adapatations from the 1961-1963 Pontiac Tempest.

Last of all, 'Turbo Hydramatic 350' was designed to work in the Corvair but
GM doesnt appear to have built any for us, so that would be a nice big
adaptation. The parts are laid out in a  manner to permit both drive and
output shafts to exit at the rear of the transmission. I am sure Corvair
would have got the THM 350 transmission if they continued building Corvairs
after '69.

Brent Covey
Vancouver BC


> What is the gear ratio of low and reverse for the powerglide? High would
be
> 1:1 I believe. Also, has anyone tried a reverse rotation powerglide?


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