2011-2024 F150 Rear Gears & Differential

Why would I even need to change my gears?

Well, there's always the wear and tear issue, but by far the most common reason you would want to jump up to more aggressive gearing is for your tire size. When you increase the diameter of your truck's tires, you effectively lower your truck's final drive ratio which alters your F150's power curves and leads to misplaced shifting, smaller power band, and all-around unimpressive drivability. Shorter and more aggressive gearing fixes all those issues by moving your truck's drive ratio back into a proper range. The graph below (that we borrowed from F150online.com) shows a general idea how larger tire sizes change the power band and what gears work best with a given size tire.

But wait, how do I know my stock gear ratio?

By far the easiest way is by checking your truck's driver's side door, where you'll find your vehicle's information sticker from the factory. On the last line, there's a box labeled "AXLE" with a code the denotes your F150's axle ratio and whether it has a locking, open, or limited slip differential.

Having the code is all well and good, but it doesn't really tell you what you need to know. The following is a list of Ford's F150 axle codes and what they actually mean:

• 15: 3.15 ratio, open differential
• 27: 3.31 ratio, open differential
• 19: 3.55 ratio, open differential
• 26: 3.73 ratio, open differential
• H9: 3.55 ratio, limited-slip differential
• B6: 3.73 ratio, limited-slip differential
• L5: 3.15 ratio, electronic locking differential
• L3: 3.31 ratio, electronic locking differential
• L9: 3.55 ratio, electronic locking differential
• L6: 3.73 ratio, electronic locking differential
• L4: 4.10 ratio, electronic locking differential

If your F150 doesn't have a sticker for whatever reason, there's also a tag on the rear pumpkin that should denote the size. If that's also missing or if you're not sure it's correct, the best way to do it manually is to mark a spot on the driveshaft and then turn one of wheels. All you need to do is count the number of rotations for the driveshaft to get a rough estimate of your F150's gear ratio.

If you have a 4WD F150 and it comes time to swap out gears, you absolutely must get matching gears for your F150's front IFS differential. You can check out our F150 front gears here.