rear end gear ratio

[SMKN97GP]

what where the available rear end gear ratios in 81 and whats the easiest way for me to tell what i have?

 

[RedLdr1]

According to the info in the link below you have a 2.72 if it has a 4-Speed or a 2.87 if it is an automatic...


http://corvetteactioncenter.com/cgi-bin/archives/imageFolio.cgi?action=view&link=1968_-_1982/1981/Sales_Brochure/United_States&image=us81_8.jpg&img=&tt=

 

[Glensgages]

what where the available rear end gear ratios in 81 and whats the easiest way for me to tell what i have?

One source-book I have states that '81 automatics had 2.87:1, while stick-cars received 2.72:1, and that no optional gears were offered;
the Corvette Black Book lists "G92 Performance Axle ratio", for $20.00, but doesn't state the ratio.

The time-honored method of raising the rear of the car, and counting drive-shaft revolutions vs. tire revolutions works;
Take an old tape-measure, or seamstress' measuring tape, and wrap it around the drive-shaft.
Put a large chalk-mark on exact bottom of the drive-shaft, and at the exact bottom of an inside sidewall of the rear tires; both should be at the exact bottom.
Next, place smaller hash-marks opposite the original mark on the drive-shaft, and 90* to it (you now have the drive-shaft equally divided into 4 'quarters'), using the tape-measure to help mark these locations.
Place small hash-marks between these markings; now your drive-shaft is equally divided into eighths (1/8-increments). Each of these 1/8-increments represents .125 in gear ratio.
Now, with both large (drive-shaft & tire) marks at the exact bottom, and the car in neutral, rotate the drive-shaft, counting 'FULL' revolutions, until the mark on the tire is once again at the exact bottom (the term "exact-bottom" is relative in this excercise; but accuracy does matter).

If you count 2 'FULL' revolutions of the drive-shaft, and 6 'hash-marks, that would be 2 + (6 x .125), or 2.750, which is approx 2.72:1 gears;
2 'FULL' and 7 hash-marks is 2.875, or approx 2.87:1 gears;
3 'FULL' and 1 hash-mark is 3.125, or approx 3.08 gears, etc.

Hope this helps...

 

[SMKN97GP]

wow i didnt think they were that low. thanks for the info

 

[Jack]

Have to hand it to Glensgages for an EXCELLENT post on how to check for rear gear ratio .. clear & concise.

JACK:gap

 

[Glensgages]

Have to hand it to Glensgages for an EXCELLENT post on how to check for rear gear ratio .. clear & concise.
JACK:gap

JACK:
My bill is already in the mail; please pay in U.S. American currency...

 

[shawn wills]

speedometer

speedometer reads fast. had 2.7 rearend now i have 3.07 rearend. What speedometer driven gear do i use to correct this? automatic transmission

 

[Bob_K]

Discalimer: ***I just woke up and haven't made coffee yet***
Woudn't that make your speedo read slower that you were actually going?