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What does CJ 18 63 on rear end of 1963 car stand for

moxie62

Member
Joined
Feb 2, 2013
Messages
12
Location
Paducah, KY
Corvette
1962
On the 1963 rear end there is a number CJ 18 63. I know the CJ stands for 3.08:1 ratio but what are the other numbers, maybe Jan 8th, 1963. Also the little black book for 63 states as an option "G91 Special Highway 3.08:1 Axle (not posi). According to another book the CJ is for positraction but when I was checking the rear brakes with one rear tire on the ground and the other on a jack, I could rotate the tire on the jack. So if it was a posi, should I be able to do that.
 
Joined
Jan 1, 2002
Messages
7,246
Location
Washington, Michigan
Corvette
'67 Marina Blue Convertible
On the 1963 rear end there is a number CJ 18 63. I know the CJ stands for 3.08:1 ratio but what are the other numbers, maybe Jan 8th, 1963. Also the little black book for 63 states as an option "G91 Special Highway 3.08:1 Axle (not posi). According to another book the CJ is for positraction but when I was checking the rear brakes with one rear tire on the ground and the other on a jack, I could rotate the tire on the jack. So if it was a posi, should I be able to do that.

The "Black Book" is wrong - the 3.08 non-Posi axle was coded "CZ". The numbers are for January 8, 1963. :thumb
 

kpic

Well-known member
Joined
Mar 29, 2014
Messages
2,292
Location
Columbus, NC/NE Georgia
Corvette
1997 boosted silver coupe
This might help:

axlecodes1_zps150c1e04.jpg


I'd chalk the drive shaft and count how many turns the tire makes as my 66 was a 3.36 and is a 4.56 unless the current owner changed it.
 

moxie62

Member
Joined
Feb 2, 2013
Messages
12
Location
Paducah, KY
Corvette
1962
This might help:

axlecodes1_zps150c1e04.jpg


I'd chalk the drive shaft and count how many turns the tire makes as my 66 was a 3.36 and is a 4.56 unless the current owner changed it.

I always get this bass ass backwards. At 2000 RPM a car will run faster with a 3.08 ratio then with a 3.55, correct?
 

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