blunsford

I have a line on a set of 3.55 gears for my Vette. It has a TH 400 auto tranny and tires are about 25.5" in dia. Does anyone have a estimate on the RPM's I would pull at highway speeds (Say 70MPH) with the new gears? I know there are some variables, but just an estimate would be great.

1979toy

At 70 MPH I am going 3300 RPM with my 3:55 gears and a turbo 350. My tires were 255-60-15

Fast81

At 70mph I'm turning 2500-2600 rpm. 700R4, 3.54 rearend, 255/60/15's

blunsford

3300 is what I figured.

2500 to 2600 sounds low. Are you sure you have 3.54 gears and not more like 3.08?

MIKER

You can try every gear ratio imaginable at SmokemUP.com
Speed vs. RPM For Tire and Gear Ratio http://smokemup.com/auto_math/mph_range2.php

redwingvette

I was getting 3200rpm's at 70 (before I put the 200R4 in) with TH400, 3.55 gear, and 26" tires. A lot better now, 2200 at 70, ya have to love that overdrive :D

GDaina

2800 with a 4 speed/5 speed and gr70-15's