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Is this a correct method to determine rear axle ratio on Rallye 350 4spd?

Is this a correct method to determine rear axle ratio on Rallye 350 4spd?

Old February 23rd, 2019, 03:06 PM
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1971 442 conv
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Is this a correct method to determine rear axle ratio on Rallye 350 4spd?

The car is a 1970 Rallye 350 4 speed. Today, we wanted to verify the rear end ratio. The rear end has the posi tag. I did not want to scrape off the undercoating to find the axle code. Here is what we did:

We secured the car on Jack Stands
We turned the passenger rear tire forward. We noticed the driver side turned forward as well.
We turned the passenger rear tire backward. We noticed the driver side turned backward as well.

We marked the drive shaft with a piece of tape
We marked the passenger rear tire with a piece of tape
We turned the passenger rear tire ONE FULL turn forward while counting the number of revolution of the drive shaft.
We counted just under just under 4 drive shaft turns for 1 tire revolution (~3.9 turns)

Did we do this correctly? So does that mean we have somewhere around a 3:91 gear? If not, what should we have done differently? Thanks
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Old February 23rd, 2019, 03:17 PM
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You did it right!
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Old February 23rd, 2019, 03:25 PM
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Posi

Now Go Use that DIFF.
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