I learned this years ago from an old hot rodder. If you have an open
differential mark one wheel and the pinion flange so you can count the
revolutions. Lock or hold one wheel, rotate the opposite wheel two
revolutions and count the pinion flange rotations. You will have to
estimate but a little shy of 3.5 is the 3.45. Almost 3.75 will be the
3.7. A little more that 4 is the 4.1 etc. This never fails if you pay
attention and make sure you have taken up the backlash before you make
the reference marks. Of course with a posi it is a direct read - 1 wheel
rotation and you get the ratio by couning the pinion flange ratations.
Torsens are a different story and I don't know how to derive the r&p
ratio from the outside. If somebody has figured this out I would like to
know.
Greg Lund
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