Help wanted Rear Axle ratio (urgent)
#1
Burning Brakes
Thread Starter
Help wanted Rear Axle ratio (urgent)
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
Thx
#2
Racer
Member Since: May 2008
Location: Sacramento California
Posts: 398
Likes: 0
Received 0 Likes
on
0 Posts
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
Kelly
#4
Team Owner
Member Since: Jul 2004
Location: Redondo Beach, California
Posts: 39,514
Received 546 Likes
on
374 Posts
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.
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.
Last edited by 68/70Vette; 07-23-2008 at 01:16 PM.
#5
Drifting
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.
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.
#6
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.
#9
Race Director
#10
Melting Slicks
Member Since: May 1999
Location: Moon Township PA
Posts: 2,897
Likes: 0
Received 0 Likes
on
0 Posts
Gary
#11
Racer
Member Since: May 2008
Location: Sacramento California
Posts: 398
Likes: 0
Received 0 Likes
on
0 Posts
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.
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.
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
#13
Burning Brakes
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.
#15
Melting Slicks
#16
Racer
It's on the casting!
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
http://www.corvette-world.com/corvet...tification.php
#17
Drifting
Cheers,
Pete
#18
Melting Slicks
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.
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.
Last edited by Donald #31176; 07-23-2008 at 06:54 PM.
#19
Team Owner
Member Since: Aug 2006
Location: Columbia Missouri
Posts: 24,125
Likes: 0
Received 9 Likes
on
9 Posts
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?
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?