Personally I like 3.73:1 but 3.90:1 is a good compromise if you can't decide. If you are really having a hard time deciding and you know what you want to do with it, Find your transmission ratio online and do some #'s on paper. Pro's do this all the time.
MPH= (rpm x tire diameter) divided by (final gear ratio x 336)
or
engine rpm= (mph x final gear ratio x 336) divided by (tire diameter) so
NOTE: final gear ratio is found by multiplying the transmission gear ratio by the driveshaft ratio.
In reply to the 2000 rpm @ 55 with 4:10's gears- yes it is possible-theoratically
2000 rpm=(55 x final gear ratio x 336) divided by lets say 22" diameter
lets say final gear drive is 2.8:1.
This would make his transmission overdrive around .68:1
This would put him @ 2352 RPM @ 55 MPH. So either he could do it with one huge tire or one very very low transmission overdrive gear. Like I said theoratically he could do it
Keep in mind when you change this gear it will throw off your tach. I'm not sure what it would cost to have another speedo gear installed. I think the part alone is around $10.00 and fairly easy to install. It's a plastic gear in your transmission usually nest to the output shaft.
Hope this helps. Sure did for me. I'm going with 3:73's as soon as I get the engine put together, broken in and a few runs on stock gears.
on another note--I am new to the stang forums--Just bought an 89 GT for $100 and am in the process of rebuilding it. If anyone has a carfax I would sure appreciate it.
MPH= (rpm x tire diameter) divided by (final gear ratio x 336)
or
engine rpm= (mph x final gear ratio x 336) divided by (tire diameter) so
NOTE: final gear ratio is found by multiplying the transmission gear ratio by the driveshaft ratio.
In reply to the 2000 rpm @ 55 with 4:10's gears- yes it is possible-theoratically
2000 rpm=(55 x final gear ratio x 336) divided by lets say 22" diameter
lets say final gear drive is 2.8:1.
This would make his transmission overdrive around .68:1
This would put him @ 2352 RPM @ 55 MPH. So either he could do it with one huge tire or one very very low transmission overdrive gear. Like I said theoratically he could do it
Keep in mind when you change this gear it will throw off your tach. I'm not sure what it would cost to have another speedo gear installed. I think the part alone is around $10.00 and fairly easy to install. It's a plastic gear in your transmission usually nest to the output shaft.
Hope this helps. Sure did for me. I'm going with 3:73's as soon as I get the engine put together, broken in and a few runs on stock gears.
on another note--I am new to the stang forums--Just bought an 89 GT for $100 and am in the process of rebuilding it. If anyone has a carfax I would sure appreciate it.
