what ratio is this?
 

How do I find out what gear ratio I have if the RPM's are 2000 in 5th gear and the speed is 80mph? The tires are 222/60R15



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'82 GT 351W,BBK shorties,
Comp Cam,edelbrock intake
625 cfm carter carb. c-4 tranny w/ pro stick shifter. 4 core radiator
Mallory distributor. 3:27
.........................

Sounds to me like they are 2.73's. I have 3.08 and run 70 mph at 2000 rpm in 5th. Your 15" tires come out to almost the exact same diameter as my 225/55R16 so I don't think the tires would be enough of a factor drop 10 mph. What is the code on your door tag? (driver side).

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Scott93GT
1993 Mustang GT
Silver CC/Titanium Accent GT, Black Clothe interior.
5 speed, 3.08's, 3 chamber Flows, K&N, Hurst Competition Plus.

1991 F150 4x4 XLT Lariat
Six Stick Regular Cab LWB Tow Vehicle

I just looked at the tag on the door. It looks like there is an "M" for the axle code.
Anyone know how to decode that?

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'82 GT 351W,BBK shorties,
Comp Cam,edelbrock intake
625 cfm carter carb. c-4 tranny w/ pro stick shifter. 4 core radiator
Mallory distributor. 3:27
.........................

M is 2.73
Z is 3.08
E is 3.27

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4.10's,long tubes & 75 shot...Goes 12.50's
Check it out at http://www.burnouts.webprovider.com

You can get close a simple old fashioned way. Jack both rear tires just off the ground, chalkmark them at i.e. the exact bottom. Also mark the driveshaft. Spin both wheels exactly 1 revolution while somebody counts the rev's on the driveshaft. You'll get close.

there is also that same tag on the rear end. There is a metal tag that hangs off of one of the bolts. Most of the time, it is worn, but you can still make out the ratio most of the time. I had 3.73's in my 86, from tha factory. But I had never heard of that before, so I checked with Ford. They had me come in, and they showed me the tag I told you about. They also did the test when you turn the tires and count the driveshaft revs.

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12.54 @ 110.90
1.62 60'
best with old car, will let you know once i finish the transfer to the new to me car

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