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How to Find Gear Ratio on Rear Differential 09-14 Ford F150

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How to Find Gear Ratio on Rear Differential 09-14 Ford F150

Created on: 2021-01-16

How to find the gear ratio on a rear differential on 09, 10, 11, 12, 13, 14 Ford F150

  1. step 1 :Finding the Gear Ratio
    • Count and record the number of splines on the ring gear
    • Count and record the number of splines on the pinion
    • Divide the total number of splines on the ring gear by the total number of splines on the pinion
    • Or find the ratio stamped on the pinion

Tools needed for replacement

  • Materials, Fluids, and Supplies

    Marker / Writing Utensil

Installation Video
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What's up, guys? I'm Andy from 1A Auto. In this video I'm going to show you how to find your gear ratio. If you need any parts for your vehicle, click the link in the description and head over to 1AAuto.com.

One way to figure out your gear ratio is you're going to count the splines on the ring gear, so I just mark it. Take a marker, mark it, and then count around. So one, two, three, four, five, six, and then all the way around you're going to go, and we have 41 splines on this ring gear. And then you're going to count the pinion, so do the same on the pinion. Just make a mark and count. We have 11 splines on the pinion.

We're going to take this number, so 41, and divide it by this number, 11, and it comes out to 3.727, and you're going to round up, so it's going to be 373s. That's your gear ratio for this. This set-up, at least.

Another way to check if you have the pinion out is to look on the pinion. This actually has it stamped right on there, 373s, so we know that's the gear ratio for this vehicle.

Thanks for watching. Visit 1AAuto.com, your place for DIY auto repairs, for great parts, great service, and more content.

Tools needed for replacement:

    Materials, Fluids, and Supplies

  • Marker / Writing Utensil


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