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EXCEL from Richmond Ring Gear and Pinion Kit - 3.90 Gears (10-14 V8)

Market Price $186.39 You Save 12% ($21.44)
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  • Item 21527G11

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    Features & Details

    • Superior Quality
    • 3.90:1 Gear Ratio
    • 8.8" Ring Gear Diameter
    • For Street or Track Use
    • Made in the USA
    • Fits 2010-2014 GT, BOSS and Shelby GT500 Mustangs
    Improve Off The Line Acceleration. From the factory the 2010-2014 V8 powered Mustangs came equipped with either 3.31, 3.55 or 3.73 gears, all of which are good choices for daily drivers who are looking for good performance and fuel economy. However if your a spirited driver who is looking for an increase in torque and quick jack rabbit like starts a set of Richmond Excel 3.90 Ring and Pinion Gears may be a better choice. By upgrading to a set of steeper ratio 3.90 Excel Gears your Mustang will enter into its power band much sooner which will help to improve low end torque and give you the rapid off the line acceleration you're craving.

    Superior Quality. Richmond proudly manufactures their Ring and Pinion Gear Sets right here in the USA. Using state-of-the-art manufacturing processes and extensive quality control testing, Richmond produces a superior quality Ring and Pinion Gear Set at an excellent price. Richmond is so confident in the quality of their products that they back them with a 6 month, 50,000 mile no-nonsense warranty.

    Required Upgrade. Starting in 2010 Ford changed the inner rear gear pinion bearing in all 8.8" equipped Mustangs. Because of this you will require a new 8.8" rear gear pinion bearing (Ford part# 9L3Z-4630-A) for proper installation, please see drop down option above.

    Recommended Upgrade. Please note that when changing the gear ratio of your Mustangs rear differential that the calibration of your speedometer will no longer be correct and will display the wrong speed. However, you can easily fix this annoying issue with a Handheld Tuner (sold separately).

    Application. This 3.90 ratio Richmond Excel Ring and Pinion Gear set will fit all 2010 to 2014 V8 Mustangs equipped with an 8.8" solid axle rear end, including the GT, BOSS and Shelby GT500 models. A master bearing kit is recommended by most installers, especially on high mileage vehicles, see drop down option above.

    Technical Note. Installation costs will vary, but a good rule of thumb is between $250 and $300. Be sure to work with a reliable shop that you trust for installations. You can also save money on your installation labor by having your Trac-Lok rebuilt at the same time as your gears are installed, see drop down option above.

    Fitment: 2010 2011 2012 2013 2014 Details

    MPN# F88389

    CA Residents: WARNING: Cancer and Reproductive Harm -

    What's in the Box
    • (1) Ring gear
    • (1) Pinion gear
    Installation Info
    Tech Specs

    Approximate RPM for 2011-2014 GT

    Gear @25 MPH @35 MPH @45 MPH @55 MPH @65 MPH @75 MPH
    1 4402 6163        
    2 2923 4092 5261 6430    
    3 2033 2846 3659 4472 5285 6098
    4 1588 2223 2858 3493 4128 4763
    5 1203 1684 2165 2646 3127 3608
    6 782 1094 1407 1720 2033 2345

    Gear @25 MPH @35 MPH @45 MPH @55 MPH @65 MPH @75 MPH
    1 5016          
    2 2814 3940 5066 6191    
    3 1829 2561 3293 4024 4756 5488
    4 1375 1925 2474 3024 3574 4124
    5 1043 1460 1877 2294 2711 3128
    6 831 1163 1496 1828 2161 2493
    Will it fit my Mustang?

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    Customer Reviews (2) Write a Review

    Overall Rating 2

    out of 5 stars

    • 3/5

      October 14, 2010

      Richmond Gears 3.90

      The 3.90 gears really improve your acceleration and are the cheapest way to go faster without sacrificing too much fuel mileage/drivability. I was impressed by the quickness in which my order was received to my front door. However, after installing my 3.90 gears (making sure that both the pinion depth and backlash were correct) I noticed a whine. The whine did not subside after the break in period. I contacted AM who was very helpful and was instructed to speak with Richmond. Richmond did not really do anything to help me and hopefully the gears hold up. So far noise is the only problem. If I could do it again I would purchase Ford Racing gears.

      Bill Henry

      Helpful (8)

    • 1/5

      January 09, 2010


      Good ratio...VERY NOISY at cruise...and yes it is set up right ..pattern was perfect......replacing with FORD Gears....also Motive Kit for 8.8 did not include any small shims....only 14's and 30's.

      chris s

      Helpful (8)

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