have a 56 with a aod trans rear is a 378. only had a test run of 5 miles. it shifts to soon t think some one must have made the same thing. what gear ratio should I have. thanks

First, if you've got an AOD, you have to set the cable with a gauge on the trans. I don't know the particulars, but that's a trans you can kill in 5 miles if it's not set right.

After that, depending on your application and tire size, in 56 the 3 sp O/D ratios went from about 3.7 to 4.27. Car, truck, wagon, 8 cyl, 6 cyl. All varied. Maybe more ratios, depending on which axle was used.

Do the research on the set up, if you haven't done it already. Folks here with AOD's will chime in and help.



miker
55 bird, 32 cabrio F code
Kent, WA
Tucson, AZ

If the AOD has been set with the TV pressure correctly and the shifts are at too low an RPM then change to a higher RPM governor. Ford has 3 different ones. The 5.0 Mustang has the highest RPM shifts. If that is still too low install the Trango kit. The 3.78 should be great with an AOD as the Ford Mustang GT came with 3.73. Pete