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Ford Performance 4.09 Rear End Gear & Install Kit | 15-22 Mustang by Ford Performance

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Ford Performance 4.09 Rear End Gear & Install Kit | 15-22 Mustang

Upgrade your S550 Mustang's stock gear set and improve your 60 ft times with 4.09 gears from Ford Performance!

Item #LRS-4209FRM-K

Everyday Low Price: $434.99

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  • Replaces Stock Gears
  • Improves Acceleration
  • Complete Installation Kit


  • 4.09 Gear Ratio
  • Steel Ring & Pinion
  • Bearings & Shims

 What's in the Box

  • See Below

2015-2022 Ford Performance 4.09 Gear Kit

Significantly improve your S550 Mustang's acceleration and increase your 60ft times with a set of Ford Performance 4.09 gears. Featuring heavy-duty steel ring and pinion gears, upgraded bearings, and shims, and all of the necessary installation components, this gear kit includes everything needed to complete the job. While these Ford Performance gears do not increase horsepower, they will definitely allow your Mustang to launch harder and faster!

Motorcraft Friction Modifier

This friction modifier is a specially formulated additive to provide smooth operation of clutch-type limited-slip differentials. 1 bottle of friction modifier is required when changing the gear oil in rear ends equipped with Ford traction-lock units.

What's In The Box

  • 4.09 Pinion Gear
  • 4.09 Ring Gear
  • Crush Sleeve
  • Pinion Nut
  • Pinion Bearings
  • Pinion & Carrier Shims
  • Pinion Seal
  • Ring Gear Bolts
  • Carrier Bearings
  • Gear Marking Compound
  • (1) Bottle of Motorcraft Friction Modifier
  • (2) Bottles of Royal Purple 75W140 gear oil

Installation Note

  • Although the Royal Purple gear oil has a friction modifier mixed in, it is still recommended that you use the bottle of Motorcraft friction modifier to supply your Super 8.8" IRS rear end with the proper amount of modifier.
  • LMR recommends the 75W140 viscosity for all 2015+ 8.8" differentials as it is appropriate for most climates, fuel economy, and performance.
  • The 3.15 ratio differential is not compatible with 3.31, 3.55, 3.73, and 4.09 ratio gears. Use differential M-4204-M.


  • Fits 2015-2022 Mustang w/ Super 8.8" IRS Rear End

Ford Performance Racing Parts "Packs" and Component Parts Limited Warranty - Click Here
Ford Performance Racing Parts - NO WARRANTY - Click Here
Ford Performance Racing Parts Crate Engine Limited Warranty - Click Here

  • Ford Mustang - 2015, 2016, 2017, 2018, 2019, 2020, 2021, 2022

California Residents:
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About This Brand

Ford Performance
Ford Performance - Mustang Ford Racing Parts
Ford Performance Parts is the leader in performance parts and accessories for Mustang and Ford Lightning.

LMR.com is proud to offer Ford Racing Performance Parts for your project. Ford Racing is dedicated to manufacturing the highest quality products offered in the industry. Choose from suspension, exhaust, wheels, and other performance parts at Late Model Restoration. If you want the best for your Mustang or SVT Lightning, look no further than Ford Performance Parts!

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