Overview
The G2 Axle and Gear 4-YJ-488 is a 4.88 ring and pinion kit that covers both axles of a Dana 30 front and Dana 35 rear setup. It is the deepest of the three YJ-titled ratios here, and each axle gets its own matched Master Installation Kit.
Ratios around 4.88 are generally chosen for big tires, because the numerically higher gearing multiplies engine torque at the wheels more strongly. The tradeoff is higher engine speed at a given road speed. The gears are computer heat treated 8620 steel, double shot peened and double lapped, and the kit carries a limited lifetime warranty.
Check the vehicle details first: the title says YJ, but the feature list says 1984 to 1999 XJ Cherokee. G2 does not explain that difference.
Key features
- 4.88 gear ratio
- Gear sets for the front and the rear axle
- Dana 30 front and Dana 35 rear axles
- Includes matched Master Installation Kits for each axle
- Computer heat treated 8620 steel
- Double shot peened and double lapped
- Limited lifetime warranty from G2
Gearing and tire size
Ratios near 4.88 are chosen when tire size grows beyond stock, because the extra gearing helps the vehicle pull the added weight and rolling resistance. The same gearing makes the engine work harder at highway speeds. Deciding between gearing and tire size is a balance, and it helps to know how the vehicle is driven most of the time.
Both axles change together with this kit, so the front and rear should be set up with the same care. Installation depends on carrier condition and backlash, and a shop with the right gauges is often the most dependable route. Check the gear oil level and the axle seals after the first drives, and listen for noise that changes under load.
- Compare tire diameter with the new gearing
- Re-check bolts and fasteners after the first trail runs
- Inspect the pinion seal for leaks after the first drives
- Keep a record of the gear setup for future service
Specifications
| Brand | G2 Axle and Gear |
|---|---|
| Part number | 4-YJ-488 |
| UPC | 700007521671 |
| Gear ratio | 4.88 |
| Front axle | Dana 30 Reverse |
| Rear axle | Dana 35 |
| Axle location | Front and rear |
| Material | Computer heat treated 8620 steel |
| Finishing | Double shot peened, double lapped |
| Warranty | Limited lifetime (G2) |
Compare the tooth counts and set weight against your current gears before ordering.
Vehicle fitment
The kit is built for a Dana 30 front and a Dana 35 rear axle. The model names used for this kit differ, so match the axles on your vehicle before ordering.
Since the vehicle is unconfirmed, use the axles as your test: the kit is for a Dana 30 front and a Dana 35 rear.
Not confirmed: a particular vehicle or model year. Confirm your vehicle’s year, model and trim before ordering.
Installation notes
Going to 4.88 gears on both axles requires careful pinion depth and backlash settings on each differential. Most owners have a shop do it, then drive gently while the gears break in.
The two Master Installation Kits are matched to the gear sets, so keep each with its own axle.
What’s included
- Front ring and pinion gear set, 4.88
- Rear ring and pinion gear set, 4.88
- Front Master Installation Kit
- Rear Master Installation Kit
Not included: gear oil and other fluids and hardware.
