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Post #11 brings up a valid point. Automotive automatic transmissions rely on the torque converter to pump ATF to the cooler. If you downspeed the TC, you reduce oil flow to the cooler. You'd risk cooking the transmission and getting spectacular transmission failures.
Close, the front pump of a automatic is driven by the spinning engine, via the TC. And the lower RPMs can lower it pumping action, so coming off a big mountain by dopping into natural can with only idle to lower the pumps action and can harm you auto, BUT at 1000RPMs I believe things are good.
I have the GV second-stage overdrive, and like in Post #12, I view it as sub-optimal but I am already down on the lowest ratios commercially available. I suppose I could substitute a Tremec 6060 with its 0.50:1 top gear for my setup (net 0.56:1 in double overdrive) but it seems like a big project to gain not much more overdrive.
You did not tell Make, model, year of you car, nor is it stock or hot rodded.
You need to have an engine that can make use of lower RPMs, you need to map out you engines torque peek, and find where it loses power and starts lugging.
Example: SBC 350 1980/90s, torque peek at 2800/3000 RPMspms, drop that engine to
1500 and it will be lugging. the lowest most likely will be 2200 RPMs.
But take a 350/383 where the torque peek is 2000, then dropping it to 1500 can work.
Rich
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