JEGS 81655 Ring & Pinion Depth Setup Tool Kit

This is the JEGS 81655 pinion depth setup kit, the fixture you clamp into a differential to measure how deep the pinion gear sits before you ever install the ring gear. When you swap a ring and pinion, pinion depth is the number that determines whether the gears mesh on the correct part of the tooth. Get it wrong and you get gear whine on acceleration or deceleration, accelerated wear, and eventually a failed gearset. This kit takes the guesswork out by reading the depth directly instead of relying on paint-pattern trial and error.

The kit uses an arbor and a machined calibration block that seats across the carrier bearing bores, with a JEGS dial indicator and three extensions dropping down to the pinion head. You read the gap in 0.001-inch increments, compare it against the etched pinion depth number on the gear, and pick the pinion shim that lands you dead on. All the aluminum components are hard anodized so the tool holds its dimensions over years of use, and it ships in a molded storage case with laminated instructions that shrug off gear oil. Item weight is about 2.75 pounds.

It is engineered for center sections that use 1/2-inch diameter carrier cap bolts, which covers a huge range of GM 10-bolt and 12-bolt, Ford 8.8 and 9-inch, and many Dana axles. It can also be used on housings with 5/8-inch cap bolts by holding the fixture in place while you take the reading. Note that this tool sets pinion depth only; you still set carrier bearing preload and backlash separately with shims or the adjuster.

If you are building a rear end, a locker install, or a gear ratio change, this is the difference between a quiet setup that lasts and a howling one you have to pull back apart. Ships from the USA.