C3 Question from a C4 guy
Thread Starter
Drifting
Joined: Dec 2002
Posts: 1,861
Likes: 4
From: Houston TX
C3 Question from a C4 guy
Hey C3 guys and gals. I'm a C4 guy but am trying to expand my horizons :-) I have a customer with a '77 auto and am trying to find out the stock rear gear ratio for this car. I didn't see anything on the RPO codes to indicate a performance axle ratio option on this particular car, but if there was one available for that year, that information would be appreciated as well. Thanks!
Drifting
Joined: Apr 2003
Posts: 1,323
Likes: 2
From: Castle Hills Texas
I don't know if this will help.
http://corvetteactioncenter.com/specs/1977/77prod.html
http://corvetteactioncenter.com/specs/1977/77specs.html
http://corvetteactioncenter.com/specs/1977/77prod.html
http://corvetteactioncenter.com/specs/1977/77specs.html
Last edited by CVT4ME; Jan 10, 2005 at 10:04 AM.
Le Mans Master
Joined: Dec 2003
Posts: 5,727
Likes: 38
From: Fremont CA
More than likely a 3.08 Differential but, the bottom of the Diff center section is stamped with a code that will tell you or you can confirm with a simple check by rotating the driveshaft and see how many revolutions it takes to rotate the 1/2 shaft one turn.
Melting Slicks
Joined: May 2002
Posts: 2,508
Likes: 0
From: Wisconsin
AO = 3.08, otherwise I think it's a 3.70. Mine had a sticker on the top that said AO7. Probably can't see it with it in the car. Otherwise look at the stamping for the AO. It's probably an 3.08. Just take it downt he highway at 60mph. Check the RPM and compare with an online calculator.
http://www.idavette.net/tech/ratioc.htm Fill in the first three and click Compute Ratio.
http://www.idavette.net/tech/ratioc.htm Fill in the first three and click Compute Ratio.
Thread Starter
Drifting
Joined: Dec 2002
Posts: 1,861
Likes: 4
From: Houston TX
Thanks for the replies so far guys. The car isn't currently running, as we're putting together an engine/trans package for it. Just trying to get a handle on the ratio so we can match a stall converter for it. So the two possible ratios for that year were 3.08 and 3.70? I'll check it tonight to see if it has the performance ratio or not.
Team Owner
Joined: Jul 1999
Posts: 26,545
Likes: 46
From: Huntersville NC
I don't know if you could get all of these with an auto trans, but according to my info there were 4 ratios available in 1977. Either way, the code will tell you which one you have. Possibilities are:
OA 3.08
OD 3.36
OB 3.55
OC 3.70
It is possible that one or 2 of those may only have been available with the muncie trans and/or L82 engine.
OA 3.08
OD 3.36
OB 3.55
OC 3.70
It is possible that one or 2 of those may only have been available with the muncie trans and/or L82 engine.
