Inliners International Forums General Discussion Drive Train Differentials

Have a 9" Ford rear end, how do I determine the ratio using the formula where one wheel is blocked, and the driveshaft is turned "X" number of times counting the unblocked wheel's number of rotations and ? SOB

Rotate the wheel one complete 360° rotation and count # of revolutions of the driveshaft. Example: A 4.11 gear will spin the driveshaft slightly more than 4 revolutions for the tires 1 revolution.

There should also be a Tag on the member which will tell you what the gearing is. Unless it has been removed. The ring gear is also stamped if you wanted to pull the member out. Other wise do what he said.

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If one wheel is blocked double the number of rotations you counted at the driveshaft yoke. The driveshaft will have turned just a little over two complete revolutions in the case of a 4.11 ratio.

Of course that assumes you do not have posi style (equa-lock) differential - in which case you will not be able to rotate the free wheel at all when one wheel is blocked. In that case both wheels must be jacked up off the ground and revs counted out until both tires have revolved 360 degrees.