Yukon Gear High Performance Gear Set For Dana 30 JK Short Reverse Pinion in a 4.88

Yukon Gear High Performance Ring and Pinion Gear Set for Dana 30 JK Short Reverse Pinion in a 4.88 Ratio

The YG D30SR-488JK is a high-performance ring and pinion gear set built specifically for the Dana 30 JK short reverse pinion front differential found in the Jeep Wrangler JK from 2007 through 2018. Running a 4.88 ratio, YG D30SR-488JK is the go-to upgrade for JK owners running 35-inch or 37-inch tires who need to restore lost acceleration and fuel economy caused by the larger rubber. Cut from 8620 case-hardened alloy steel and finished with a proprietary REM surface treatment that eliminates microscopic peaks left by conventional gear grinding, YG D30SR-488JK delivers quieter operation, cooler running temperatures, and longer gear life than standard ground gears. The 4.88 gear ratio provides the ideal balance of low-range crawl performance and highway cruising for 37-inch tire setups.

Features and Benefits

• Designed for the Dana 30 JK short reverse-cut pinion front differential (2007-2018 Jeep Wrangler JK)
• 4.88 ratio ideal for 35-inch to 37-inch tire upgrades
• Manufactured from 8620 case-hardened alloy steel for maximum strength and durability
• REM isotropic superfinishing removes micro-peaks for smoother, cooler, quieter gear operation
• Computer-optimized tooth geometry for precise tooth contact across the full load range
• Sold as a matched ring and pinion set for guaranteed backlash and pattern
• Pair with front Dana 44 or rear Dana 44 re-gear for full drivetrain balance
• Backed by Yukon Gear manufacturer limited warranty

Vehicle Fitment

Specifications

What Is Included

• One ring gear (YG D30SR-488JK)
• One matched pinion gear
• Installation instruction sheet

Frequently Asked Questions

Does installing YG D30SR-488JK affect my factory warranty under federal law?
The Magnuson-Moss Warranty Act prevents dealers from voiding your entire warranty solely due to an aftermarket part. The manufacturer must demonstrate that the specific part caused the failure in question.

What tire size is 4.88 gearing designed for?
A 4.88 ratio is typically ideal for JK Wranglers running 35-inch to 37-inch tires. It restores throttle response, off-idle torque, and fuel economy that is lost when oversized tires are installed over the stock 3.73 or 3.21 ratio gears.

Do I need to re-gear the front and rear at the same time?
Yes. When re-gearing a 4WD vehicle, the front and rear differentials must be set to the same ratio. Mismatched ratios in 4WD mode cause drivetrain binding and premature driveshaft and differential wear.

What is the difference between the JK short reverse pinion Dana 30 and a standard Dana 30?
The JK front Dana 30 uses a reverse-cut pinion that positions the pinion above the ring gear centerline instead of below. This improves ground clearance. YG D30SR-488JK is cut specifically for this reverse-rotation geometry and is not interchangeable with standard Dana 30 gear sets.

What is REM superfinishing and why does it matter?
REM isotropic surface finishing uses a vibratory bowl with fine media to remove microscopic peaks left by conventional gear grinding. The result is a plateau-smooth surface that reduces friction, runs cooler, and extends gear life versus standard finished gears.

Can I install YG D30SR-488JK myself?
Professional installation is required. Gear installation demands precise pinion depth, carrier bearing preload, backlash, and pattern verification using specialized tools. Improper setup causes premature failure and noise.

What install kit should I use with YG D30SR-488JK?
Yukon Gear offers a complete Dana 30 JK master overhaul install kit that includes pinion bearings, carrier bearings, seal, crush sleeve, and shims. Using a complete kit ensures all wear items are replaced during the re-gear.

What warranty covers YG D30SR-488JK?
Yukon Gear provides a manufacturer limited warranty against material and workmanship defects. The warranty requires installation by a qualified technician and is void if the gears are damaged by improper setup or wrong application.

Installation Instructions

1. Safely raise and support the front of the vehicle. Drain the front differential oil.
2. Remove the front driveshaft and disconnect the front axle shafts as needed for access.
3. Remove the differential cover and clean the housing mating surface.
4. Mark and remove the carrier bearing caps. Record shim position and thickness.
5. Remove the carrier assembly and set aside.
6. Remove the pinion nut and extract the pinion from the housing using a bearing press.
7. Press off the pinion bearing races and install new races from the master overhaul kit.
8. Set pinion depth using the appropriate Dana 30 JK setup tool and shims until the correct depth is achieved.
9. Install the new pinion from YG D30SR-488JK with a new crush sleeve and pinion bearings.
10. Torque the pinion nut until pinion bearing preload is within factory specification.
11. Transfer the ring gear from the old carrier to the carrier. Torque ring gear bolts to Dana spec.
12. Install the carrier and adjust backlash to 0.005 to 0.009 inch using shims. Verify with a dial indicator.
13. Verify gear contact pattern with marking compound. Adjust pinion depth or backlash as needed.
14. Torque carrier bearing caps to specification. Install the cover with new sealant.
15. Reinstall axle shafts, driveshaft, and fill with recommended gear oil. Road-test and inspect for leaks.

Proposition 65 Warning: This product can expose you to chemicals including lead, which is known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to www.p65warnings.ca.gov.