RPM's with 3.73 gears

[coop]

All you guys running 3.73 gears with an auto what are your rpm's at 60 mph. I just bought a 1990 that is 3.07 gears from the factory but my cruise rpm @ 60 is 2050 in OD and 2950 in Drive. I figured with 3.07 gears it should be about 1675rpm in OD and 2400 rpm in Drive. I am wondering if the previous owner installed 3.73 gears at some point(which is not a bad thing)

 

[Tom Bryant]

Here is a gear ratio chart that is found in the Tech Center at the top of this page.. Look under Tool Box for this and other caculators. All you need to do is measure your tire's diameter and go to the chart. These rpms listed will be in direct drive 1:1, not o.d. Looks to me though like you're real close with the 3.73 estimate.

Welcome to the CAC.

Tom

Gear ratio chart