Dana 30 Short Pinion Ring & Pinion Set 4.88 Jeep TJ

This is a matched ring and pinion gear set for the Dana 30 short pinion front differential, cut in a 4.88 ratio. USA Standard Gear part number ZG D30S-488TJ. It fits the standard-rotation short pinion Dana 30 used up front in the Jeep TJ Wrangler, YJ Wrangler and XJ Cherokee. It does not fit the reverse-rotation Dana 30 found under the JK and JL, and it does not fit long pinion housings, so confirm which head you have before ordering.

The 4.88 ratio is the common regear for a TJ running 35 to 37 inch tires. Stock 3.07, 3.55 or 4.10 gears leave a Jeep on tall tires lugging in every gear, hunting for overdrive on the highway and cooking the transmission on grades. Dropping to 4.88 puts crawl ratio and highway RPM back near where the factory had them, which is as much a transmission life issue as a power issue.

Gears are sold as a set only, and the ring gear and pinion are lapped together as a pair at the factory. Do not mix a ring gear from one set with a pinion from another. Installation is a setup job, not a bolt-on: you will need a master install kit with new carrier bearings, pinion bearings, crush sleeve, pinion seal and a shim pack, and you need to set pinion depth, backlash and pinion preload with a dial indicator and a marking compound pattern check. Budget for the install kit separately - it is not included here.

Ring gear bolts are reused only if they are in good shape; most shops replace them. On a short pinion Dana 30 the front axle also has to match the rear ratio exactly, so plan to regear both ends at the same time.