decoding rear gear numbers

[dab67]

Jerry:

So it is possible the rearend came from the factory this way? I really can't see someone switching out the rear gear for something like that. Going from a 3:08 to 3:56 or 4:10 yes.

Dave

[Jerry@CHP]

Dave,

If the housing date and R&P date fall in line with the build of your car, I'd say it's correct.  I read your earlier posts and I'm not sure how you were coming up with such an odd ball reading on the tire turns vs drive shaft turns. 

Jerry

[dab67]

Jerry;

I was only turning one tire, (driver side rear) when I was counting the revolutions of the driveshaft. Did not know I had to turn both tires at the same time to get the correct revolutions. I could have sworn I have seen posts (maybe not here in CRG) that to check your rear end gearing you jack up one side of the rear end, put your car in neutral mark the driveshaft and tire you are turning and rotate the tire one complete turn while counting the revolutions of the drive shaft. This would give you the ratio. 1:to whatever the drive shaft turned.

Dave

[JohnZ]

That's true, but only if you have a functional Positraction diff (so both axle shafts turn together with both tires off the ground); with an open (non-Posi) diff, you have to turn both tires together.