With a 25" tire and running at 70 mph you'll turn the same rpms with a 2004r and 4.60 rear gear as you do with a non overdrive (th350 or th400) and the 3.08 you have now. So as long as you keep the rear gear below 4.60 you'll still see an improvement on the mileage. Your current 3.08 ratio mated to the 2004r will turn the same rpms at 70 as a non overdrive does with a 2.06 rear gear ratio. Not sure you need to know any of this stuff, but numbers are fun :laugh:
WOW,a 4.60 gear,that wil make it shift in overdrive a about 30mph with normal driving!LOL And I agree,numbers are fun!:TU:
I now have 235/60-15 tires on the car which gives me a tire height of 26.10 inches. I was leaning towards 3.73 gears over my 3.08's but now I realize there is much to consider based on all the different responses. I would really like to improve my off the line but still need to cruise on the highway without screaming. Decisions, decisions!</SPAN>
Do you have a calculator? Rear Gear X OD = Final Drive 336/tire height X Final Drive X MPH = RPM. The OD gear on a 2004R is .67 3.73 X .67 = 2.499 336/26.1 X 2.499 X 60 = 1930 RPM 336/26.1 X 2.499 X 70 = 2252 RPM 3.42 X .67 = 2.291 336/26.1 X 2.291 X 60 = 1770 RPM 336/26.1 X 2.291 X 70 = 2064 RPM How easy is that?
I say swap in a twin turbo kit and leave the 3.08 gear and th350 alone! Double the HP, double the smiles!
3.73's it is. I try the turbo install if my new tranny and gears don't work out! LOL Thanks for your help Sean.
