[Anthony]

Al,

it is the relative % change between gears, not the raw number that the engine "sees". So 1st to 2nd is a %34 drop in rpms. 4th to 5th is a %36 percent drop in rpms, so the engine sees a larger drop in rpms between 4th and 5th than between 1st and 2nd, even though the raw number difference is smaller. Most transmissions are designed such that as the car is goes faster, the percent change is less, as torque multiplication is less, trying to keep the engine in the best possible hp rpm range.

So shifting at 6000 rpms from 1st to 2nd would be a drop of 2040 rpm, so the engine would be going 3960 when shifted into 2nd.

Questions to ask yourself about picking a tranny are:
How much is cost a factor? availability ? Durability ? Street Driveability ? Performance (racing) factor? Originality? Overdrive capabilty? How much overdrive?


So with the TKO600, the rpm % changes would be
34%, 32%, 22%, 36%

In a standard 3550/TKO
39%, 32%, 25%, 32%

In a wide ratio TL
30.6%, 29.5%, 26.5%

In a Close ratio TL
27%, 24%, 22.4%

In a Richmond 5sp
35%, 26%, 21.6%, 19%

Muncie M21/22
25.5%, 24.4%, 19.4%

When I was determining which tranny I wanted, I had calculated all these figures out, except obviously for the TKO600, comparing the trannys to help make my decision.


All of these transmissions are fine, but the I think the key after determining which transmission you want is to then pick the rear diff ratio to maximize the use of the tranny, as 1st gear can vary a great deal. Generally, performance trannys have closely spaced ratio's (low % change between gears).

When I was deciding on which tranny I wanted, the delimma I had was to try to figure out what diff ratio I needed as well. I spoke to Bob Putman at a ERA, who knows a lot of guys seriolus about racing, who have experimented with different tranny/rear ratio's, and for drag racing "maximal acceleration from a dead stop", he told me that you didn't want to go much higher than 9 for first gear multiplication (1st gear ratio X rear diff ratio). Although I haven't perfected drag racing yet, his formula seems right.