Tech - Frequently Asked Questions

Each ring and pinion set has a drive and coast side. The teeth are designed for force on the drive side. A low pinion 3rd in the rear uses the drive side to go forward, as does a high pinion 3rd in the front. A low pinion in the front or a high pinion in the rear use the coast side of the gears to move forward. Because most of us drive using rear wheel drive, and the coast side is significantly weaker, it is not recommended to use a high pinion in the rear, and it will not be covered by any warranty. Likewise if your front 3rd is a low pinion you should consider upgrading to a high pinion.

We recommend standard 80w/90 gear oil. Also note, to avoid premature damage to the gears follow this brake-in procedure. For 20-30 minutes drive the vehicle with the transfer case in Low. Park and let it sit for 40-60 minutes to cool. Repeat. Change the oil after 500 miles, then again at 1,000 miles. If you want to run synthetic oil do so after the break-in.

Transfer case gearing allows for slower speeds and greater power to the tires. This means that in off-road situations you can drive more slowly and safely, potentially lessening the damage to the vehicle and it's cargo. When in low gears it is also harder to stall the vehicle. Transfer case gearing does not make a vehicle less driveable on the street.

Re-gearing your 3rd members will help the engine push larger tires. Larger tires may drop the engine out of its' "power band" resulting in poor performance and fuel economy. To restore performance you must change the axle gear ratio to compensate for the change in tire size. 

For Example: Switching from a 30" tire to a 35" tire changes the final drive ratio by about 17%. If you originally had 4.10 gears you need a ratio that is approximately 17% lower, such as 4.88. You may even want to chose a 5.29 ratio if you've got a 4cyl engine and/or extra weight.

Most folks running a gear driven case behind their 1985-'95 automatic transmission overfill the fluid level in the transmission so it doesn't slip when moving up extremely steep walls/inclines. They also put a plug inplace of the tranny dipstick so fluid doesn't drain out the tube when going down extremely steep declines. We recommend starting with 2-3 quarts extra fuild, and carry a couple more in your rig to add if needed. Some competition rigs are running with 6 quarts of extra fluid.