i don't understand final drive ratios.

both the '89-'94 v6 trucks and the tacoma v6 5 speed trucks have the same transmission gear ratios. (both are R150F).

the '89-'94 5 speed v6 trucks had a diff ratio of 4.56.
the tacomas come with a diff ratio of 3.9.

why?

because the tacoma had the bigger engine?

so (hypothetically) if i swapped in a 3.4 into a 3.0 truck, would the diff ratios need to be changed to 3.9? or i could keep the 4.56 and get bigger tires to match the factory final drive ratios?

I have several theories on this...

1st... The lower gear ratio uses more fuel on the highway through more RPM's. The manufacurers are always looking for ways to sneak a couple more MPG into a vehicle, even if it sacrifices performance.

2nd... The newer engines have more power, and can overcome the 3.90:1 ratio. If the 3.0 was subjected to this, a 22-RE would smoke it in all aspects of performance (assuming it kept the 4.10, 4.30, 4.56 factory ratios).

Many others have theories on this, but these are mine. <img src="/forums/images/graemlins/cheers.gif" alt="" />