Originally posted by Big Jim:
Accelaration will be even better with 5.00:1 final drive gears, but you may need to shift through three or four gears just to get across the street.
I can attest to that. I have driven a Mack Dump truck with a Fuller 18 spd. transmission. Can you say shift? Man, with this transmission you literally have to shift 5 times to get across the street. Another I've driven is a '78 Peterbuilt with a 14 speed Roadranger and a 2 speed rear end, thats 28 gears
I think a reason for auto manufacturers switching to transmissions with more gears in them is to allow them to use low ratios on the lower gears to help with acceleration, but then more gradually work up to high ratios to maintain lower engine RPMs at cruising speeds. The larger number of gears allows the engine to stay more within it's power band while shifting. This way when one gear is ran to the upper end of the power band, the revs don't drop off too much when shifting to the next gear. Generally, the the RPM range in which an engine makes the best power is also the rev range that it runs with the greatest efficency.
