Proform 66516 Pinion Depth Setting Tool with Dial Indicator

Setting up a ring and pinion is where most rear-end and differential rebuilds go wrong. Pinion depth, how far the pinion head sits from the ring gear centerline, controls the tooth contact pattern, and if it is off you get whine, premature wear, or a howling axle on decel. The old way is to guess a shim, press the pinion in, paint the gears, check the pattern, tear it back down, change the shim, and do it again. This Proform 66516 tool measures the depth directly so you get the shim right the first time.

It is a dial-indicator gauge that bridges the carrier bearing bores of the housing. You mount the stand across the differential case, drop the indicator down through the adapters with the extension pin that reaches the pinion face, zero it against the calibration setup, and read the distance from the bearing bore centerline to the pinion head. Compare that reading to the depth number etched on the pinion and you have the exact shim thickness to install behind the pinion bearing. No marking compound, no trial and error, no repeated presses.

The gauge is red anodized aluminum, comes with the dial indicator, extension pins, the adapters and stand, and a fitted storage case. It covers the common automotive ring-and-pinion axles found in Dana, Ford, and GM rear ends, and it is the inexpensive alternative to the $400-plus factory depth fixtures that do the same job. Set-up takes a little attention the first time, so read the instructions and verify the calibration length before you take a reading.