Close ratio means that the first set of gears (1st through usually 4th) are VERY close to the same size. The reason they do this is to keep you in the power band.
Your motor will make all its power between 4000 and 6500 RPM. Close ratio transmissions will prevent your engine from dropping out of that range during hard accelerations. Before close ratio transmissions, every time you shifted, the engine would drop below it's power range and would take some time for it get back into that range. That would cause a serious reduction in acceleration time.
Close ratio prevents that by keeping the motor in its power range. This will - in affect - increase your acceleration time.
Back in the day, 4 speed transmissions didn't have close ratios due to the fact that they only had the 4 gears to get up to speed and even then, they didn't really have an over drive. Ratios would be around 4.0, 3.0, 2.0, 1.0 for 1st, 2nd, 3rd, and 4th gears respectively. Close ratio wasn't even a thought since they hadn't even figured out how to do an over drive (Any gear less than 1.0). But once an over drive was possible, close ratio transmissions were an option.
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2002 Corvette Z06 - Totaled
2003 Corvette Z06 50th Anniversary
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