Rear Axle Ratio

[Steve Carter]

I've looked carefully but in vain for the code for my axle ratio for my '67 Riviera. The tech page states its on the bottom of the axle tube to the right of the axle center. The only number I can find on the rear axle is on the differential housing, upside down, and is 1372231. Is there another way to determine my rear axle ratios, or can someone assist me in locating the one I have. The car is on the rack right now(10 AM CST) getting brakes so would be convenient time to look.

Steve Carter

[The Old Guy]

Steve
Just put a mark on the drive shaft and both tires. Then turn the wheels together one revolution. If you count the turns of the drive shaft, that will be the ratio. 3 1/4 turns =3.23 a little over 3= 3.08 a little under 3 =2.93 and almost 3 1/2 = 3.42

[rlbleeker]

If the car's not on a lift, you can just jack up one tire and give it two revs while you watch the drive shaft.

[NTX5467]

If it's like other GM vehicles, you'll be looking for a "stamp code" on the axle tube rather than a casting number. Sometimes, the stamps can be a little shallow and not be easily seen. When you find it, you'll need the service manual or a parts book to see which codes match the respective gear ratio.

If, per chance, the vehicle has a limited slip differential, you'll need both wheels off of the ground as they'll both turn together.

Enjoy!
NTX546

[Lapham3]

Steve-A good time to pull the cover, count the teeth,(ratio is also stamped on the ring gear) inspect and fresh lube-have fun-Dan

[NTX5467]

Unfortunately, this is probably the best way to find out what's in there. The ratio could be expressed as something like "37-10" on the outer edge of the ring gear . . . just have to turn it until you see it and probably the particular part number for the ring gear (as a complete number), although the ring gear and pinion gear are always sold as "a set".

Enjoy!
NTX5467