# Figuring final drive ratio



## 67lemans (Oct 30, 2009)

I am figuring it right that a turbo 350 has a final drive ratio of 1.0, and so with a 3.32 rear gear, the final ratio is 3.23. 

And then a 2004R would have a final drive ratio of .67. And if the rear was a 3.73, then the comparable final drive would be 3.73 X .67 or 2.5. And so the 2004R scenario would actually do down the hwy at a much lower RPM?

Thanks,


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## Old Man Taylor (May 9, 2011)

Yes.


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## 67lemans (Oct 30, 2009)

Thanks.


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## 67lemans (Oct 30, 2009)

Do you think a relatively stock pontiac 326 in a Lemans would be happy with that combination on the highway?


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## PontiacJim (Dec 29, 2012)

67lemans said:


> Do you think a relatively stock pontiac 326 in a Lemans would be happy with that combination on the highway?


Could be a little stiff for a stock 326. You may find your foot in the pedal a little more to keep the car rolling with regards to grades/steep hills as your RPM's may be a little on the low side and you be lugging the engine. It'll keep RPM's down, but that does not necessarily equate to better gas mileage if you are looking for that if you find your foot in the pedal more than not. If too much of a load, the trans may be downshifting/upshifting more than you like as well.

Try plugging in all your numbers in one of the RPM/Tire size/MPH online calculators to see what you get. I have the TKO600 with the .64 final gear in OD and am going with a 3.90 gear out back and 28/29 inch tall tire which should be about right for 70 MPH cruising.


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