<VV> Powerglide musings....

[Karl Haakonsen (cityhawk@pobox.com)]

Sorry for jumping onto this topic way-late in the game, but I was just looking back over some conversation topics because of Smitty's recent post and came across the talk about the powerglide and safety regulations. 



As the owner of a PG-equipped Corvair, I have done more than my share of reading about the transmissions.... I was looking back at a thread of conversation in early December about safety regulations and people talked about the lack of a "Park" position, but Bob Helt pointed out in "The Classic Corvair" that the main reason for the death of the 2-speed automatic had to do with the fact that new safety regulations prohibited manufacturers from locking out the speed at which a driver could downshift an automatic transmission (1965 and earlier PG-equipped Corvairs-- and I assume other PG-equipped cars as well) had a lockout mechanism preventing a downshift to LOW at speeds over about 50mph, preventing engine damage. 1966 and later cars lacked this mechanism due to safety regulations. This wasn't too much of a problem for the 3 speed automatics of the day since they could downshift in steps, but was detrimental to the 2-speed automatics and this was the main reason for the death of the two-speed automatic. 



For those who complain about the lameness of having only 2 gears, remember that the theory behind the PG was that there were two mechanical speeds and a theoretically infinite number of speeds handled by the torque converter which had a maximum reduction of 2.62:1. (there's a great tech topic on this in the "Transmissions" section of the Corsa Tech Guides titled "Praise the Powerglide" or something like that). 



My guess is that modern transmissions with more mechanical gears perform better because the additional mechanical gears give better precision in terms of keeping the transmission in the ideal torque band of the engine than afforded by the two-speed PG-style. But the PG wasn't really as bad as some of its detractors think ... remember that it did somewhat better in 0-60 acceleration than the 3-speed manual Corvair. 



Karl in Boston 

66 Monza Convertible 110/PG 

www.chezhawk.com/VairBlog