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Thread: Mustang Rear Gear Ratio to RPM Chart.

  1. #1
    Coyote Power Inside. Minaccia's Avatar

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    Post Mustang Rear Gear Ratio to RPM Chart.

    Mustang Rear Gear Ratio to RPM Chart
    Written By: Andrew Cilio

    Use this chart if you're wondering what gear ratio is currently in your Mustang, or looking to change your Mustang's rear gear ratio.

    Estimated RPM Range for Highway Driving (~65MPH)

    Anyone who’s purchased a used Mustang before knows how annoying it can be to figure out if the previous owner changed the rear gear ratio or not. Sometimes, you know they were changed but have trouble identifying what ratio the new gears are. Below, we have mapped out the usual suspects when it comes to aftermarket gear ratios. If you do not see the RPM for which you are reading at 65MPH for your particular transmission you can safely assume by going with whatever ratio of gears falls between the provided sets.

    This chart will also give people who are thinking about changing their Mustang’s rear gears a look at the increase in RPMs they will see for each ratio. Note that the smaller the gear (smaller gears have higher ratios – 4.10s are SMALLER than 3.73, ect.) the more RPMs. Higher ratio gears can actually increase fuel efficiency around town but will use more fuel when driving on the highway, and vice versa.

    Transmission Type_____________3.55 Gears__3.73 Gears__4.10 Gears
    AOD AODE (automatic transmission)_1800 RPMs___2000 RPMs___2300 RPMs
    4R70W (automative transmission)___2000 RPMs___2250 RPMs___2350 RPMs
    T5/T4 (manual transmission)_______2000 RPMs___2250 RPMs___2350 RPMs
    TR3650 (manual transmission)_____1900 RPMs____2250 RPMs___2350 RPMs
    T56 (6 speed manual transmission)__1600 RPMs___1800 RPMs___2150 RPMs


    Fitment includes: 1979, 1980, 1981, 1982, 1983, 1984, 1985, 1986, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016, GT, V6, Cobra, ShelbyGT500, Mach1, Bullitt, Boss, LX, SVO, EcoBoost
    In the Garage: 2011 Mustang GT, Auto, 4.10 gears, CAI, LT's, X-Pipe, HP Tuners, nGAUGE, some suspension parts and a small diet

  2. #2
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    Tire O.D. effects the rpm, the earlier models were much shorter so rev higher at same speed, what tire O.D. was this based on?

  3. #3
    Mod-tastic Speedtospare's Avatar

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    I would guess 26" as my T56 with 4.10's revs about the same
    1993 Fox Coupe Twin Turbo Coyote Build

  4. #4
    New Member leester's Avatar

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    try this gear calculator from Tremec website

    http://www.tremec.com/calculadora.php

  5. #5
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    why not show the C4 too ??

  6. #6
    Member Last5oh's Avatar

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    Who cruises at 104 kph (65mph)?
    95 GT Deep Forest Green 1 of over 27,000
    MCA Certified National Judge: 4th Generation

    "Drive a HYBRID!... I need your GAS!"

  7. #7
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    Is the speedo correct? Are the tires correct size? and the biggest issue... how accurate is the tach? Foxbody tachs are notorious for being WAY off...


    Want to know for sure?

    Jack up the car by the center diff, put jack stands under diff, put transmission in neutral, hand brake off, crawl under and have someone spin the tire one revolution as you count the number of revolutions the driveshaft makes. Other than taking the diff gears out thats the only sure way to check.
    I'm not, I already found an 89 roller with similar goodies yours has but I do know someone else who's looking for one. I'll forward him your info.
    Any more info? Details or pics? Price?

  8. #8
    Mod-tastic Speedtospare's Avatar

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    Best mustang calculator around. You need to add tire size in your equation.

    http://www.paladinmicro.com/pmicro.php#
    1993 Fox Coupe Twin Turbo Coyote Build

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