need help with gear ratios, stock final gear ratio's not spaced out evenly - why? Options

[jimkelly]

for me - chevy v8 - stock 2nd is fine as a first gear, but it winds out fast, as does stock 3rd, as does stock 4th, and 5th is fine, but taller would get rev's down for highway cruise-ing ( 3000 rpm at 65 +- ) on 195x60x15 tires.

my question is why are stock final ratio's not spaced out evenly?

stock
3.091
1.889
1.261
0.926
0.710

3.091 x .61 = 1.889
1.889 x .66 = 1.261
1.261 x .68 = .926
0.926 x .77 = .710

evenly would be ...

3.091
2.496
1.901
1.306
0.710

for my v8, i am thinking of course to delete cantilevered first - thus i can use a beat up slider ; )
stock 2nd 1.889
?? 3rd - i need the right gear for inbetween stock 1.889 and 0.710
4th - use stock 5th ZD 0.710
5th - use flipped H 0.59 as an overdrive gear.

how the hell do i calculate the correct final gear ratio for my 3rd gear?

looks like an R (1.080) 25:27 - or - a flipped V 27:25 - is about right ??

jim

[ArtechnikA]

my question is why are stock final ratio's not spaced out evenly?

The short answer is that the faster you go, the more air you're pushing.
You can deal with a big rpm drop 1->2 because you don't feel the effect of being so far below peak torque as much.

Anderson and Carroll Smith both spend a bit of time on this subject if you want more background than I am qualified to distill into a paragraph...

In a perfect world, the drop would be the same - from about 50 rpm over peak HP to peak torque. But at higher speeds, you can't afford to give away that much HP and continue accellerating.

And there are lots of other factors that may lead you to optimise one operating regime at the expense of matched rpm drops.