My shop manual shows the following for 56 TBird



Standard 3.73

Overdrive 3.92

Fordo 3.31



I have checked mine (Fordo) and its the 3.31 as near as I can figure.

54 Victoria 312;  48 Ford Conv 302, 56 Bird 312
Forever Ford
Midland Park, NJ

My 56 tbird 312 w/od came with a 3.92 rear gear and with my 9 inch upgrade I now have a 3.89:1 which was as near as I could get to the original and I'm happy with that.

-Gary Burnette-

I'm not surprised your manual torino has the same gear ratio, my car is a manual 1963 Fairlane.

Thanks for the numbers, that makes me feel a little less uneasy about keeping the Fairlane back axle. 3.89 isn't crazy far from 3.25, and I am looking to eventually put in a limited slip which will make my gears the Fairlane K-Code ratio...coincidentally, 3.89

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People should not be afraid of their government, a government should be afraid of the people.

--Alan Moore

Hi ted, best wishs for 2010! while we didnt have all the vehicle types you mention, i could point out that the 56 vic with 292 and O/D had the 3.89 you mention but had fine spline axles compared to say 55, 56 std trans with coarse spline axles, and best to check axles and centers if swapping parts. I think this will be busy year with new cars, engines and projects well on the way by members! its exciting! Regards bill.  Note; i now know how to add these little faces, shown to me by my 13 yr old daughter!! Go figure!

  AussieBill            YYYY    Forever Y Block     YYYY

 Down Under, Australia

I just checked my `57 t-bird with three speed OD and it was 3.75 but I havent determined whether it was a transplant thou I have no reason to believe it is. Just another data point. 

Brian

Cylinder Index = 84

Current Experiment = `57 Tbird, Grand Rapids, Michigan

Pickups did not come factory equipped with 312’s in the U.S. but 3.89:1 gears were popular in many of the early Sixties pickups such as yours when equipped with a standard 3 speed tranny.  You didn't mention what transmission you're dealing with and that's part of the equation.

 

Automatic transmissions typically had gear sets that were smaller numerically than standard transmission equipped cars.  As the cars got newer, they came equipped with numerically smaller gearing (less steep) which fell in line with the improvements in the torque band that was occuring.  A ’57 car with a 292 and automatic came with 3.10’s while the standard transmission version w/o overdrive would be a 3.56:1.  With overdrive, the rear gear would be 3.89:1.  My ’50 with V8 and overdrive came with 4.27:1 rear axle while my ’54 Ford with overdrive came with 4.10:1 rear gears.  My '55 with 272 and O.D. came with 3.89:1 rear gearing.  I’ve since changed the rear gears in my ’55 Customline to a set of 3.56:1’s which compliements the upgrades I've performed to the 272.  On the flip side, my '69 Torino with 428 and 4 speed originally came with 3.25:1 rear gearing.  This is all just food for thought.

Lorena, Texas (South of Waco)

Anyone know what ratio the back axle gears of a T-Bird with the Y-Block had (year not so important, this is for reference) and what a 1960 F-100 with the 312 had?

...please say 3.25...that's all I have...

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People should not be afraid of their government, a government should be afraid of the people.

--Alan Moore