Rear Gear Ratio

[Fozzie]

Thanks Guys for all your input. One thing I forgot to mention is that the rear end is out of the car on the bench, not apart, and I do not want to take it apart. I just want to figure out the ratio while its together. Any ideas from anyone. I need this info asap. Thanks again, Fozzie

 

[Jack Richard]

Just hold one axle from turning and count the number of revolutions the other one makes while a helper turns the driveshaft 50 revolutions. Divide 100 by the number of axle revolutions and you will have the rear-end ratio. In other word, if you turn the driveshaft 50 times and the axle turns 26 1/2 turns (26.5), divide 100 by 26.5 and the ratio is 3.78:1.

 

[Ron Kansas]

That will work, but if you don't want to turn it fifty times, you might try the following:

Secure one brake drum from turning. Mark the other brake drum so that you can get very close to returning the drum to the same exact position. I would wrap some duct tape or masking tape around the drive shaft and gently clamp vice grips to the drive shaft with handles pointing exactly straight up. You don't need much pressure, just enough to turn the shaft and that isn't much. Reason for the vice grips is to have an accurate way of counting the turns. Have an assistant watch the mark on the brake drum. Turn the drive shaft clockwise as you face the drive shaft from the front, while the assistant watches the marked drum turning. Turn the drive shaft until the free brake drum has turned exactly TWO FULL REVOLUTIONS. (The reason for two turns is that with one axle not turning, the other axle will turn twice as fast.) When you have turned three turns on the drive shaft, the mark on the brake drum should be approaching the starting point. Continue turning until the assistant says you are there. If the handles are at about 32 inutes after the hour, you have a 3:54 rear end. If it is at about 46 inutes, you would have a 3:78. If it should go four turns and on past to about 7 minutes, you would have a 4:11.

Ron