Over Drive Ratio ??

[Carl Purdy]

My over drive is .730 my rear end is 3.73. What is the ratio in O.D.??? I can't figure anything any more.


7G-Q1 49 2R12 10G-F5 56B-D4 56B-F2

[StudeRich]

I am numerically challenged like you but, it may be a backwards way but, couldn't you just take .73 from 1.00 =.27 and subtract that from 3.73 =3.46 final drive ratio?

The trouble with the RPM calculators, is that they have only the common 700R4 and AOD Overdrive ratios.

StudeRich

[brngarage]

Hi:
The correct thing to do is multiply the rear end ratio (3.73) by the overdrive ratio (.73) to get a final ratio of 2.72.



Howard
53 Commander Starliner
56 Sky Hawk

[jcstude]

Not sure what you are looking for here. Try this calculator: http://www.csgnetwork.com/multirpmcalc.html. The "Transmission Final Gear Ratio Manual Entry" allows you to enter 0.73 in the "Transmission Final Gear Ratio (2.54, 1.43, 1.00, etc.)" to get rpm. Key word is "Transmission" since most older transmissions had a "transmission" final gear ratio of 1.0 before the overdrive is engaged.

[Carl Purdy]

I have a 833-10 Transmission behind a 6 cylinder it is a standard shift 3rd gear is 1to1 4th gear is .730. I think Howard has it figured out about right.
THANKS GUYS.


7G-Q1 49 2R12 10G-F5 56B-D4 56B-F2

[curt]

I THOUGHT the overdrive reduces the RPMs by 30%.

[PackardV8]

Hi, Curt,

quote: I THOUGHT the overdrive reduces the RPMs by 30%.

Yes, by 30% in the T86/T96, by 27% in the T85, 18% in the big truck 5-speed and and by 50% in the B-W T56 Viper 6-speed. So, it depends.

thnx, jack vines

PackardV8