3:73 gears in a automatic 3 speed?

Dads 71 Toy · 06-29-2006

In my '71 coupe the prev. owner took out the 351 the car came with and put in a 302

. I have no idea if the trans. is from the stock 351 or if it is was changed out to, but it is a auto. 3 speed. If I put in larger gears in the rear would that kill my 3 speed?

Thanks for all the advise!!!!!

5.0 in a 66 · 06-29-2006

it wont hurt the tranny, but the engine will be screaming on the freeway (especailly at 80mph in texas

)

that and the gas mileage will suck!

Dads 71 Toy · 06-30-2006

O.K. 373 gears are too much. What would you suggest.

dodgestang · 06-30-2006

You could always put in an AOD

Then you can 3.73 and have low RPMs on the freeway/gas mileage

Otherwise...I have found 3.25 to be a good compromise between quicker starts and highway RPMs.

What is the RPM band of the motor anyway? Higher numerical gears will decrease the top speed of the car.
A car with 4.11 and a 1:1 final drive with a 25 inch tall tire and a 5500 redline is just about puttered out at 85.

Dads 71 Toy · 09-29-2006

Allright. Thanks for the advice.

Preacher17 · 09-29-2006

3.73 with an overdrive tranny.

3.50 if it's mainly driven around town.

3.23 if you're planning on doing a lot of hi-way driving.