Throwing a new set of rear end gears on your Mustang may be one of the best ways to make your Pony come alive and gain blistering acceleration off the line and through your shifts. Your factory gear ratios are solely designed to get better fuel economy at the expense of performance. Performance 8.8" or 7.5" gears increase your Mustang's drive ratios and get you back some of the performance that it rightly deserves. All of our gears come from powerhouses like Motive and Ford Racing to get you quality, performance, and longevity in one package. Stage 3's Mustang rear end gears range from perfectly decent 3.73 gears all the way up to intense 4.56 gears that can be one of your best weapons at the track or drag strip.
How do rear end gears work?
Your gears help determine your Mustang's final drive ratio, or in layman's terms the amount of drivshaft rotations it takes to turn your rear wheels. For instance, say your bone stock Mustang came with 3.31 gears from the factory. That means it takes 3.31 driveshaft rotations to rotate your wheels once. By using larger ratio gears, your driveshaft has to spin at a higher RPM to turn your wheels than with lower ratio factory gearing which causes higher torque generation lower in the powerband, and thus better performance. The down side is that higher RPMs mean lower fuel mileage. The place this gets confusing is that using a smaller gear ratio is actually called "higher gearing" while using a larger ratio is called "lower gearing" or "gearing down." Don't ask us why. We don't make the rules, we just play the game.
What size is my Mustang's rear end?
This would be a good time for a "YOUR MOMMA" joke, but we'll refrain. All 1987 to 2014 Mustangs with a V8 came with a trusty Ford 8.8" rear end, including the 1999 to 2004 SVT Cobras with their IRS. 1987 to 2010 Mustangs with a four-cylinder or V6 engine came with a 7.5" rear end. 2011 to 2014 Mustang V6s, due to their increased power, have 8.8" rear ends like the V8 Mustangs.
Which gears should I choose for my Mustang?
That's really dependent on your application. Most Mustangs come from the factory with 3.23, 3.31, or 3.55 gears, and the jump up to 3.73s is just large enough to get some excellent performance gains without needing to constantly shift all the time or seriously impact your fuel mileage. 3.73s are a good choice for street-driven Mustangs that need some extra performance or for the naturally-aspirated Ponies that see a decent amount of track or autocross time. 4.10 gears are a great choice for pretty powerful Mustangs equipped with forced induction systems that like to hit the drag strip or road course on a regular basis. 4.56 or lower gearing is best left for the dedicated track or drag strip Mustang, unless you want to give your arm and Mustang's transmission a good workout.
What are these "Master Install Kits" and should I get one?
Master install kits from both Motive and Ford Racing contain everything you need to do a pretty series maintenance and overhaul of your Mustang's rear end and differential. We recommend grabbing one of these kits if your Mustang has at least 60,000 miles on it since the last rear end service or build date, or if you're planning on doing some hard driving. If you've done some work on your Mustang's rear end in the recent past, then you can probably get away with just a standard gear kit.
Do gears require tuning?
While gears don't technically "require" tuning, changing your drive ratio will throw off your Mustang's speedometer, which can be corrected with Ford Racing's Speedo Tool or with just about any type of Mustang PCM tuner or programmer.