ET Differences Between Varying Powerglide Low Gear Ratios?

[Jeff Jewell]

A bunch of years back when I was messing with our A/SA '67 Corvette, I had a glide with a 1.98 low. 1.94 - 1.98 always seemed to be the sweet spot. I broke the planetary at a division race and the only spare I had handy was a 1.82 geared bracket glide. Car left like a turd and lost .04 in 60', but only slowed .02 in ET. Most if not all of the .02 was the bracket trans didn't have the lightweight parts and all the other tricks. While all that gear helps the leave, doesn't really make much of a difference in overall ET.

Your mileage may vary...

[Crew Chief]

Using a gear ratio - RPM - MPH calculator you can figure out what RPM the engine drops to when the transmission shifts to high gear. If the RPM is below the stall of the convertor, there will be slippage until the RPM reaches the stall speed. Plug in different 1st gear ratios to figure it out.

http://www.wallaceracing.com/gear-speed.php

[Angelo DiTocco]

I agree with Jeff especially with the HP you're making. A 1.82 should be more than enough.

[2021STK]

Looks to me in that calculator the trans and rear gear data inputs are reversed. Should be: tire diameter, rear gear, trans 1st, trans 2nd, trans 3rd

[jimmyparker]

If the same converter is used in low gear comparisons the results may be slightly off. A 1.76 low gear will work the converter harder leaving than a 2.18, the 2.18 will work the converter a lot harder on the high gear shift. At one time I bracket raced an A/SA some, when on slick tracks I would leave in 2nd gear and always saw more quite a bit more flash.