Revolution Gear & Axle Jeep Wrangler JK/JL Dana 30 Reverse Front Axle 4.88 Ratio Ring & Pinion Set
Most non-Rubicon Wranglers that go to 35 inch tires end up at 4.88 gears, and the front axle has to match the rear exactly. The Revolution Gear and Axle D30JK-JL-488R is a new 4.88 ring and pinion for the reverse-rotation Dana 30 front axle under the 2007-2018 Wrangler JK and the 2018-and-later Wrangler JL in non-Rubicon trims. If your Jeep feels flat on the highway after a tire upgrade, hunts between gears on every grade, or the old front gears have started to howl in four-wheel drive, this is the front half of the fix.
The ring and pinion set the final drive ratio: at 4.88 the driveshaft turns 4.88 times for each turn of the tire. Bigger tires effectively raise the gearing, so a Jeep that left the factory with 3.21 or 3.73 gears loses torque at the wheels and spends its time in the wrong transmission gear. Regearing to 4.88 brings engine speed back where the powertrain was designed to work.
The front Dana 30 in these Jeeps is a reverse-rotation, high-pinion axle. The pinion enters above the axle centerline, which keeps the front driveshaft higher and flatter, but it also means the gear set turns the opposite way from a conventional axle and must be cut for that. Revolution lists this set as reverse rotation with a 7.2 inch ring gear, a 26-spline pinion, ten 3/8 inch ring gear bolts, 8620 steel, and a carrier break at 3.55/3.73.
First confirm the axle. Revolution's own guide to Wrangler axles notes that non-Rubicon JKs use a Dana 30 front while Rubicons use a Dana 44, and our Dana 30 vs Dana 44 comparison shows how to tell them apart. Next, find your current ratio from the axle tag or build sheet using our gear ratio and axle code guide. Because 4.88 sits on the high side of the 3.55/3.73 carrier break, a Jeep that came with gears numerically lower than 3.73 needs a 3.73-and-up carrier such as the JK Dana 30 3.73-and-up carrier or a locker for that series. The JK regear buyer's guide walks through the full parts list.
Revolution lists D30JK-JL-488R for the front Dana 30 reverse-rotation differential in the 2007-2018 Jeep Wrangler JK and 2018-and-later Jeep Wrangler JL, non-Rubicon models only. It does not fit a Rubicon Dana 44, the standard-rotation Dana 30 in the TJ, YJ or XJ, or any rear axle. Swapped axles are common on used Jeeps, so check the housing tag, or send us your year, trim and VIN and we will confirm before it ships. Gear sets for other axles are in our gears and hard parts section.
Install the gears with new bearings. For a JK, the Revolution JK Dana 30 front master install kit or the Yukon JK Dana 30 master overhaul kit covers the bearings, races, shims, seal and crush sleeve. Revolution publishes separate setup specs for the JK Dana 30 and the JL M186 front, so JL owners should use a bearing kit built for the JL axle. Revolution's JK Dana 30 row lists a 0.065 in. starting pinion depth, 12-15 in-lb pinion bearing preload, .006-.010 in. backlash and 60 ft-lb bearing caps; start from the original pinion shim stack and check the pattern on both sides of the teeth, since the coast side carries the load going forward in a reverse axle. Our backlash and pinion depth guide explains how to read it. Regear the rear to the same 4.88 ratio, for example with the JK Dana 44 rear 4.88 set. Revolution's break-in calls for 80W-90 or 85W-140 GL-5 conventional gear oil, short heat cycles, no towing or off-roading for 500 miles, then an oil change. Recalibrate the speedometer for the new ratio and tire size before you drive it far.
| Brand | Revolution Gear & Axle |
| Part number | D30JK-JL-488R |
| Fits | Revolution Gear & Axle Jeep Wrangler JK/JL Dana 30 Reverse Front Axle 4.88 Ratio Ring & Pinion Set |
| Type | Ring & Pinions |
| Condition | New |
| Ships | Same business day (in stock), from the USA |
| Warranty | 1-year |
Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
Yes, for the non-Rubicon Dana 30 front. Revolution lists it for the 2007-2018 Wrangler JK and the 2018-and-later Wrangler JL non-Rubicon front axle. It does not fit a Rubicon, which has a Dana 44 front.
Only if your Jeep came with gears numerically lower than 3.73. Revolution lists the carrier break at 3.55/3.73, so 4.88 needs a 3.73-and-up carrier or a locker for that series.
A master install kit for your axle. On a JK use a JK Dana 30 front kit. The JL M186 front has its own setup specs, so JL owners should buy a kit made for the JL axle.
No. The front and rear must be the same ratio. Mismatched axles bind the drivetrain in 4WD and can damage the transfer case, so order a 4.88 rear set at the same time.
Revolution recommends a name-brand conventional 80W-90 or 85W-140 GL-5 oil for break-in, then a fresh change at 500 miles to remove wear particles and the gear coating.
