cajos

I just order a TKO 600, and they (Keisler) need to know my Rear Axle ratio. I have looked at this before but couldn't find it. Can some one please post a picture of it and where it is located.

Thx

Kellys~hotrods

your best bet may be to open it up and count the teeth, but that isn't always practical. It may be listed on your tank sticker too, but again that may not be easy to get to. Did you ever remove the tank and take any photos of the tank sticker? If so, find them and see if you can make out the info. Hope this helps.

Kelly

cajos

No tank sticker

68/70Vette

I assume your speedometer is calibrated in miles per hour?

If you tell people how many rpm the engine is turning at 60 or 70 mph, that will be enough information to determine what year end ratio you have. (Actually rpm at any speed will work of course, 60 or 70 is just a conventient number.

(This assumes the little plastic gear pickoff in your current transmission is the correct one installed at the factory.)

Another more tedious method would be to jack up the car and have someone turn a rear wheel over 10 times, while you count the number of rotations of the drive shaft.

DRIVESHAFT

This would probably be a good time to try jacking the car up,
and counting the turns of the drive shaft, while you turn a rear tire.
Turning the tire completely around one time, and seeing how
many times the driveshaft turns, will get you pretty close.

Tumarr

simple- jack up the rear and count how many drive shaft rotations happen per one complete tire rotation. say the drive shaft spins around about 3 and a half times, when your buddy rotates the tire once. you got a 3.55 ratio gear.

cajos

But there should be a code on the dif. shouldn't it?

cajos

My car was a severe case of Bubba Mania

...Roger...

The code will tell you what it left the factory with...not what is actually in it.

GaryS

This works quite well and is accurate too. However, I would add that you need to put a piece of tape on the tire at 12:00 and another piece of tape on the fender as an index to be accurate. Do the same thing on the drive shaft, an index point and a marker.
Gary

Kellys~hotrods

You have to take in to account tire profile, wheel diameter, and wheel and tire width. All these can affect your speedometer reading. If you plan on going this route, here are a couple calculators that may help:

http://www.classicchevy5speed.com/RPM-Calculator.aspx

http://www.miata.net/garage/tirecalc.html

In my own experience, counting the turns of the driveline is good for a ball park nu mber, but not entirely accurate. As I stated before, the best way is to open it up and count the teeth on the ring and pinion.

Kelly

cajos

Dayum, only thing I ask is a picture of the code so I can locate it.

Any way I will try you suggestions.

69monzacpe

If it's stamped in the same place as a '69, then it is stamped on the bottom of the housing, just in front of the axle cover. It will be a code that you will have to decipher. I don't know if they're any different than a '69, but there is about 17 codes, depending on transmission and engine combinations, and if it was heavy duty or positraction or not. Someone with the '72 codes may post them, or you might get close counting the revolutions of the main drive shaft to the wheel. It could be tough though, there's 7 different ratio's on the '69, and some are pretty close together:

2.73
3.08
3.36
3.55
3.70
4.11
4.56

Good luck. If I find my "little black book" I will post the information on the codes.

69monzacpe

Found this, should help!

Attachment 47626890

BKarol

Check post #4.

http://forums.corvetteforum.com/show....php?t=1596299

wolfemc

Info you're looking for is on the bottom of the casting just in front of the leaf spring. You'll have to jack it up to see it anyway, so I agree that you should do the rotation check to make sure noone changed the internals. Here' one of the better on-line code cifers...

http://www.corvette-world.com/corvet...tification.php

PeteZO6

With the tape. I was taught to rotate the wheel 10 times and have another person count the driveshaft revolutions. By turning the wheel 10 times you reduce the chance of error, because you don't have to gestimate say, 3.54 turns of the driveshaft. In that case you would have 35.4 turns. Just a thought.

Cheers,
Pete

Donald #31176

If you want to calculate RR without getting under the car try this formula.

http://www.angelfire.com/fl/procrastination/rear.html

Measure your tires diameter and go out on a highway and cruise in 4th gear @3000 RPM and note MPH.

Durango_Boy

I dug out my old info because I thought that I had it all right for my '77 and just want to make sure while we're all on this subject.

The codes for my '77 are...

AX - LR - 3.36
AC - 4.11
AB - 3.70
AA - 3.55
AW - 3.08
AV - 2.73

The number stamped under my case was...

0A289W7E1

Am I to assume that the important letters are A and W meaning I have a 3.08 set?

Did I decode that right or am I way off?

Durango_Boy

Wow my codes were way off. Thanks.