How to Find a Differential Gear Ratio

You can determine the differential gear ratio of any axle yourself. Axles are equipped with different gears for several reasons. If you want to upgrade your differential with a locker, or need any service done, you will need to know the differential gear ratio. Most axles come with a small metal tag attached to the differential cover that displays the gear ratio. However, it is often hard to read and the gears may have been changed in the past.

• 1

  Loosen and remove the straps that secure the drive-shaft u-joint to the pinion yoke on the axle. The pinion yoke is the yoke that attaches to the drive-shaft u-joint. Remove the drive-shaft from the axle.

• 2

  Place a jack under the axle and lift the vehicle high enough so that the tires can spin freely.

• 3

  Place a jack stand at each end of the axle to support the weight.

• 4

  Slowly rotate one tire exactly one revolution with your hand while watching the pinion yoke on the axle. Count the number of times the pinion yoke makes a revolution. The amount of times the pinion yoke turns represents your gear ratio.

• 5

  Reinstall the drive-shaft and tighten the bolts with a ratchet and socket.

• 6

  Lower the vehicle to the ground after removing the jack stands.