Differential Gear Decision help...

[gruveb]

The short of it is I'm asking for advice on differential gearing. I'm currently running a 31" tire with a 700R4 that has a crazy 0.55 OD. I believe the current gear ratio is 3.73 and was thinking of going with 4:10.

Right now, at 80 mph I'm doing about 1700 RPM. With the lock up off, I'm doing around 2300 RPM at 80 (the gear is 0.70). With a 4.10 gear, according to this calculator I'd be running around 2000 rpm in OD and 2500 rpm with the lockup off.

The highway sounds fine, but I'm worried about first and second gear's manners on the streets.


For what it's worth, the only drivetrain item not new is the differential gearing. The POSI is worn out, needs to be fixed anyway. The motor is a 383, 10:1 compression, putting out 450 ft tq at 3,000 rpm (dynoed). The tranny is a 700R4 with that "double overdrive" gearing.

Thank you in advance.