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| C4 General Discussion For general topics of discussion related to the 1984 - 1996 Corvette. |
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05-25-06, 05:03 PM
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#1 (permalink)
| | New Member 
Join Date: Feb 2006 Location: New York
Posts: 6
My Corvette(s):
1984 Corvette |  Quick ? About GEARS
I have just a quick question
What are the stock gears in the 84, are they 2.59 or 3.07. Looking at going to the 3.07 if the stock is 2.59. Thanks in advance.
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05-25-06, 05:52 PM
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#2 (permalink)
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Join Date: Jan 2005 Location: Covington, Louisiana
Posts: 354
My Corvette(s):
1987 Convertable |
Manual or auto?
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05-25-06, 06:01 PM
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#3 (permalink)
| | New Member
Join Date: Feb 2006 Location: New York
Posts: 6
My Corvette(s):
1984 Corvette |
sorry about that. It is a Automatic
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05-25-06, 09:42 PM
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#4 (permalink)
| | Member
Join Date: Oct 2001 Location: Oconomowoc, WI
Posts: 242
My Corvette(s):
1989 Medium Blue Metalic Convertible |
I think they are 2:59. I know that in 89, that is what the auto's had. But there was a "perfomance option for the 3:08's. You may have to get under the car and count the number of driveshaft turns to 360 degrees of the wheel. Remeber to have both wheels free to turn. If you only jack one side, the internal differental action will change the results
Hope this helps,
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1989 Medium Blue Metalic Convertible, Hypertech stg 2, 160 deg t'stat, 48,800 mi.
Save the Wave! "In God We Trust"  | |
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05-25-06, 10:09 PM
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#5 (permalink)
| | Member
Join Date: Mar 2005 Location: Sayre PA
Posts: 148
My Corvette(s):
1985 Black coupe 69 Riverside Gold Coupe |
Look at your RPO codes under the rear box lid behind the seat. On my 85, code G44 indicates a 3.07, which was an optional gear for the automatics. I think the 2.59's were GM1 or something like that. Willing to bet that the 84 codes for the rears are the same as 85. Of course this is assuming the rear is stock and nobody's changed the ratio over the last 20 years.
Look in the tech center tab at the top of this page and it will better help you to decode your 84.  | |
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05-25-06, 11:35 PM
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#6 (permalink)
| | Member
Join Date: Jan 2005 Location: Covington, Louisiana
Posts: 354
My Corvette(s):
1987 Convertable |
RPO G92 would indicate that you have 3.07:1 gears.
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05-26-06, 03:53 AM
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#7 (permalink)
| | Member
Join Date: Jun 2003 Location: La Fontaine,Indiana
Posts: 287
My Corvette(s):
Black 89 Coupe |
Unless you bought the car new the rpo code tells you nothing.
How many people change the ratio on their car I know I have and the code won't reflect that change. Jack the car up place a mark on the tire and on the drive shaft. Turn the shaft until the wheel makes one revolution and count the number of turns the drive shaft turns.
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05-26-06, 11:14 AM
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#8 (permalink)
| | New Member
Join Date: Feb 2006 Location: New York
Posts: 6
My Corvette(s):
1984 Corvette |
Thanks for all your input, guys. I think I'm gonna have to jack the car up and rotate the tire. I have a feeling the rearend has been changed. After looking at it I noticed that there is some writing on the bat wings and has "1994" hand written on it as if it were a junk yard part.
Just so I know when I rotate the tire one full revolution and count the amount of times the driveshaft turns can I assume that if it turns 2x that its a 2.59 and 3x- 3.07?
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05-26-06, 12:09 PM
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#9 (permalink)
| | Member
Join Date: Jun 2003 Location: La Fontaine,Indiana
Posts: 287
My Corvette(s):
Black 89 Coupe |
Quote: |
Originally Posted by slrvette Thanks for all your input, guys. I think I'm gonna have to jack the car up and rotate the tire. I have a feeling the rearend has been changed. After looking at it I noticed that there is some writing on the bat wings and has "1994" hand written on it as if it were a junk yard part.
Just so I know when I rotate the tire one full revolution and count the amount of times the driveshaft turns can I assume that if it turns 2x that its a 2.59 and 3x- 3.07?
| 2.59 ratio= 1turn on the wheel and 2.59 turns on the shaft
3.07 ratio=3.07 turns of shaft to 1 turn of the wheel.
Use a piece of chalk to mark it.
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05-28-06, 09:08 PM
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#10 (permalink)
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Join Date: Oct 2005 Location: Calgary
Posts: 63
My Corvette(s):
85 Z51 L98 4+3 Coupe |
The '84 and '85 automatics had 2.73 rear gears.
First year for 2.59 was 1986.
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05-29-06, 05:45 PM
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#11 (permalink)
| | Member
Join Date: Jun 2003 Location: La Fontaine,Indiana
Posts: 287
My Corvette(s):
Black 89 Coupe |
Quote: |
Originally Posted by 85vette The '84 and '85 automatics had 2.73 rear gears.
First year for 2.59 was 1986.
| What it had in 84 and what is in it now very well may be different.
Like I posted earlier the only way to know for sure is to jack it up and check it. Otherwise you are just speculating.
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05-29-06, 10:03 PM
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#12 (permalink)
| | Member
Join Date: Oct 2005 Location: Calgary
Posts: 63
My Corvette(s):
85 Z51 L98 4+3 Coupe |
Quote: |
Originally Posted by Black Bart What it had in 84 and what is in it now very well may be different.
Like I posted earlier the only way to know for sure is to jack it up and check it. Otherwise you are just speculating. | Possibly, but the original question was did the '84 have for stock gears.
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05-30-06, 10:09 AM
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#13 (permalink)
| | Member
Join Date: Jun 2003 Location: La Fontaine,Indiana
Posts: 287
My Corvette(s):
Black 89 Coupe |
Quote: |
Originally Posted by 85vette Possibly, but the original question was did the '84 have for stock gears. | Sorry the way I read it he wants to improve the performance.
He stated that if it was a 2.59 then he was going to change to a 3.07
Sounds like he wants to increase the performance to me. Before one can decide on what to put in you must know what it has now.
Whatever his intention was he has the info to do with it whatever it is he had in mind. | |
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05-31-06, 12:02 AM
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#14 (permalink)
| | Supporting Member [Online]
Join Date: May 2002 Location: CA
Posts: 2,471
My Corvette(s):
'84 White Z-51/4+3 | speedo?
Know also, that you are limited, assuming that you wish your speedometer to be accurate, how much you can change the RE ratio before getting into the tranny. Unlike the 'old days', you cannot merely change the externally-accessable gear for changes more than about 10%, I believe.
You can, however, get an external box to alter the pulses sent to the dash. 
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