I'm fixing to get started on my project car. which is a 82 Z28 W/a BW Super T-10 4speed. the problem I'm facing is the build sheet for the car says it came with a 3.23 Posi rear. but with the rear jacked up. one wheel spins forwars the other backward. which tells me the gears might have been changed can someone please tell me how to calculate the gear ratios NO MOTOR In THE CAR so I'm going to half to pull the rear end cover. my second question is does anyone know of a place in the FT.Worth Dallas Area who rebuilds BW Super T-10 4speeds if so it would be appreciative as to who, and such. Thanks
Kaker

 

I'm in a similar situation as you are in that I know I have an aftermarket rear, I know that it's throwing off my speedo, but I've got no idea what gears it really is. My cousin suggested to do what he did with his elky:

jack the rear end, chalk the bottom of the wheel / axel (same location) then mark the driveshaft. calculate the ratio of rotation when turning the wheel by hand. I hope this helps!

 

pull the cover and look, it's the only 100% accurate method to know what you really have

 

Might as well pull the rear diff cover and see what you have. Be a nice time to change the fluid too, who knows when it was last done.

 

I'm definatly going to pull the rear end cover off but still how do I know what the gears are? sould the ratio be stamped on the gears? I was told by someone that you count the teeth on the ring gear then on the pinion, and divide the number on the pinion by the number of teeth on the ring.

 

number of teeth should be stamped on the gears, like 13:43