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I was wondering what rpm's i would be looking at if i run 4.10 gears in a 89 mustang Gt with an AOD and the tranny in Overdrive? Also what would it be turning in Drive? This is assuming you are running 60mph with 265/50 tires (about 26" tall).

Thanks alot!!

Ford Man
 

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Ford man, assumeing the final gear in your AOD is the same as my 5 speed, you will be turning about 2400-2500 rpm`s at 70 mph. That what mine does with 245-50-16`s
 

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FINAL GEAR RATIO IN AN AOD IS 0.64:1 IN OVER DRIVE
 

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uuuuuumm

I beleive the OD in an AOD is .68-1 like the T5

Now my speedo is way off but according this little handy dandy program I got from a friend 265/50/15's are 25.43(very close to the hieght of the stock 225/60/15's that came on 85-90 5.0's) and 60 mph is right at 2200 rpm. I run that same tire on the street.
 

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Dont quote me but I do think the final drive is the same or very close between the AOD and the 5 speed, the AOD acting like a regular 3 speed auto with 3rd being 1-1 and 4th being overdrive, the 5 speed with 4th as 1-1 and 5th being .068 over drive I believe. But there are formulas to calculate what Fordman is looking for, I just dont know them, but there are guys here that do or have links to sights that have them.
 

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The RPM at 60 for 4.10 gears and a transmission ratio of .68 with tires 26" tall. Is 2162. This is assuming no convertor slipping.

I multiplied .68 and 4.10 together and came up with 2.788. Then I plug it onto the calculator on the front page of FM. It is in the lower right hand corner.
 

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Check out Moderndriveline.com, I just checked my tranny and it has a .063 5th gear, depedning on your trannys part number it could be a .068 or .063 5th, it looks to me that the trannys with 300 ft lb tq rateings have a .068 5th, and the 330 ft lb tq rated trannys have a .063 5th.

Hope this helps.
 
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