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Old 11-11-2018, 02:27 PM
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Default '69 Corvette gear ratio

How can I find out what the original gear ratio was in a '69 Corvette? It's a 390 HP 427 with a 4 speed and it has 4.56 gears in it now. I have the rear end out for repairs. It belongs to my uncle and he is thinking of changing the gear ratio. The speedometer is way off and it's not much fun to drive very far.
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Old 11-11-2018, 04:18 PM
earntaz earntaz is offline
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Quote:
Originally Posted by big gear head View Post
How can I find out what the original gear ratio was in a '69 Corvette? It's a 390 HP 427 with a 4 speed and it has 4.56 gears in it now. I have the rear end out for repairs. It belongs to my uncle and he is thinking of changing the gear ratio. The speedometer is way off and it's not much fun to drive very far.
Freddie -- check a stamping on the bottom of the rear end housing, just forward of the cover ... check out this site for codes. TAZ

http://www.corvettec3.ca/axle.htm
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Old 11-11-2018, 05:23 PM
RobR RobR is offline
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Freddie, I used to have a 390hp 69 Corvette 4 speed with air-conditioning, the default ratio was 3.08 to 1. I believe the same combination w/o air-conditioning was 3.36 to 1, Rob.
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Old 11-11-2018, 05:26 PM
L78steve L78steve is offline
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If it has the original speedo driven gear you can get the color and go the the gear chart and find out the rear ratio.
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Old 11-11-2018, 06:51 PM
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Thanks for the replies. I was wondering where the stamp would be. I'll check the code and see what it is. I have a 3.08 gear if that is what it turns out to be.
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Old 11-11-2018, 07:25 PM
69z28302 69z28302 is offline
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I would also post on the Corvette forum
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Old 11-14-2018, 11:45 PM
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Code FA, which is for a 3.70 heavy duty with the 427. This explains why the speedometer is off so much. Thanks for the help.
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Old 11-15-2018, 03:25 PM
TimG TimG is offline
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That's the steepest gear you could get on a 427/390. It would be a fun combination.
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