Modified Mustangs & Fords
9-Inch Rearend Axle Assembly - Dressed To The Nines
Our Mustang Project Gets Rear Ended (But That's Good)
Now the Strange tech can measure the actual backlash via a dial indicator. He zeros the indicator on the drive side of a gear tooth and then rotates the ring gear without moving the pinion. The backlash must be within 0.008 to 0.012 inch, otherwise you will need to rotate the adjusters to get the backlash into spec. Check it at three points around the ring gear and ensure they do not vary by more than 0.004 inch. Once the backlash is set, the gear pattern must be checked with marking compound to ensure the gears will be quiet. The pattern should be centered from heel to toe and from root to top of the teeth. If the pattern is too close to the heel (outside edge of the ring gear), then you need a smaller shim between the pinion support and differential case. If it's too far, you need a thicker shim. Finally, check that the preload is between 45 to 50 in-lb by rotating the pinion nut with a dial wrench attached. If the preload is less than desired, tighten the differential adjuster nuts evenly-and vice versa for too much preload-and the install the adjuster lock tabs and tighten their-head cap screws to 15 ft-lb.