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I have had my speedo re calibrated to factory specs even though I've installed 205/60x13 tires.  The speedometer is way off, farther than just the tires should make it.  I stopped a local cop and had him radar me at 40 mph.  My actual speed was 35 on the nose.

The only change from stock in the drive line is a 74 transmission, my car is a 73.  Would this contribute to the variance from factory calibration?

I've also gone to several tire websites to see what they say the variance should be and it's about .80 mph, not 5 mph.

I'm also resigned to doing the "push test" to see how far off I am.

George

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Your 4 speed transmissions will both be the same gearing in 4th.  That is direct drive or 1:1 so your speedo should not be reading any differently than it was prior to the swap.

Of couse it is early and I've only had 1 cup of coffee.

Have a nice day

Steve

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Thanks Steve, the one to one makes perfect sense.  Evidently your thinking better one one cup of coffee then I have been for the last 2 months. I've been putting off the dreaded "push test" but I better get to it before winter sets in.

George



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