Gears can be a pretty general term simply in this case, they refer to the ring and pinion gears residing in the rear differential. Your entire Mustang'southward rear consists of your axles, the gear housing, a power transfer device (IE a spool, LSD, posi-unit, etc.), and of course the ring and pinion gear set. Without getting too much into the technical details of how gears work, they convert the power coming from your driveshaft to power needed to turn your wheels.

Gears are referred to by ratios, such every bit iii.31 gears. This means the driveshaft needs to plough three.31 times in order to turn your tires once. People upgrade to numerically higher gears because increasing this number gives your engine more than leverage and makes it easier to accelerate faster. Higher gears, such as 4.10 gears, tin can exist referred to every bit a steeper gear. A gear up of 4.10 gears volition also result in a decrease of your acme speed which is why they can likewise be referred to as shorter gears.

• Replacing a Mustang's stock rear gears with a higher ratio volition give you quicker dispatch, greatly improving your 60 foot times--depending on what ratio you cull
• A ratio of 3.55 will go y'all down the drag strip quicker than almost stock ratios, but 3.73s or 4.10s are an even greater improvement and so on
• Going with too extreme a gear ratio can upshot in lost traction and reduced summit speeds, depending on your overall setup
• For a street car that might also see the track, 3.55s, 3.73s and 4.10s gears are recommended, with 4.10s existence the gear of pick for automated transmissions
• 3.73 vs four.10 gears: four.10s will let you experience quicker revs & lower gas mileage, but greater passing power on the highway (recommended shift point - 3,000 rpms)

At that place are many reasons, merely the well-nigh mutual on a late model Mustang is to get your car into the power band faster, or like mentioned in a higher place, to accelerate faster. The cause for such languor, at least for the late model Mustangs is when Ford switched from the 5.0L pushrod motor to the iv.6L modular motor. A common complaint was that the new motor was slower off the line. This is considering the 4.6L does non start making its torque until higher up in the RPMs unlike the 5.0L. Changing to a steeper gear will get that pig out of its coating, and really wake it upwards off the line.

By changing the ratio, yous are not actually changing whatever ability levels, but you lot are manipulating the available torque. This is why it's considered the all-time bang for your buck modern. No actual power changes, merely in that location can be a huge difference in performance and race times after swapping gears. If you are plenty happy with the way your Mustang drives, there is absolutely no demand to change the rear gears.

About owners tend to choose a 3.55, 3.73, or iii.90 for a Mustang that is daily driven. If yous are serious nigh speed, and so you might consider the 4.x or a iv.30. However, the college the ratio the faster you will accelerate, but it will too result in much higher engine RPMs when cruising on the highway (this handy gear ratio to RPM nautical chart volition show you what your Mustang's estimated RPMs will be at cruise). You'll also be sacrificing your summit end speed and some fuel economy. If highway gas mileage is a major concern, a good compromise is a lower ratio such as 3.55 or 3.73. Also note irresolute your rear gear will affect your speedometer readings, and to correct them you will need a handheld tuner.

Choosing gears for autocross/road racing can be similar, even so different from 1 some other. 1 major particular to consider is the course itself (one will primarily be racing on). The full general idea is to remain in gear for the majority of the rail; shifting as little as possible. Shifting consistently slows down times by not putting the ability to the wheels. Somethings to consider for proper gear option tin be items as average grade speed, distance, the degree of turns, etc.

iii.73's tend to be a pop pick, but it actually comes downwards to a variety of factors. Your all-time bet is talking to people with similar Mustang's to yours to become an idea what works best.

Some additional options to squeeze every little advantage out of a new gear install are to have the outer ring lightened. This process removes about ane lb to two lbs of rotating weight. Other options include cryogenic handling for some additional strength, and/or micro blueish coatings that help in lubrication.

On a Mustang or any vehicle, tires work like gears do. This means that changing the tire meridian volition impact how the final drive performs. Generally speaking, taller tires will make information technology act like a higher gear ratio and volition fifty-fifty impact the vehicle'south pinnacle speed capabilities. It tin chop-chop go a balancing act as you desire the car to launch harder, simply a taller tire still offers more contact with the ground. If you have besides much contact, the tires can possibly hook up enough to destroy axles.

Taller tires are too heavier and the gears volition have to work harder to turn them. Ultimately, yous want to consider how powerful the motorcar is and what you demand out of it. If information technology tin can accept the beating and more top end is needed taller tires are a must, but for street/strip applications, you shouldn't reach for the tallest tire you could fit in the wheelhouse.

Over the years, Mustangs accept been offered with a myriad of gear ratios, so figuring out which ones are in your car tin be tough. Especially with late model Mustangs, information technology can be difficult to effigy out what gears your Mustang has since Ford has offered everything from 3.31s to 3.73s from the manufactory 2011 and up. Typically, the stock ratio is on the build sheet, or could be on a sticker on the door panel or glove compartment. You tin as well find the gear ratio stamped into the differential encompass or written on to it from the factory, merely these aren't ever visible and can be hard to locate. Using a VIN decoder tin can assistance and as a last resort you lot can get to a dealer and have them cheque to tell you.

If you doubtable the gears already may have been inverse, you can MacGyver information technology by jacking upwards the rear stop, spin the tire one time and count how many revolutions the driveshaft fabricated (it'due south a good idea to utilize white-out or a sharpie to make a reference betoken on the driveshaft). Or, remove the differential encompass and count the teeth. Just exist sure you know what you are starting with. If you're starting with three.55s and feel they are not enough, it's difficult to say going with 3.73s will rock your world, as it is merely an incremental footstep. Beneath is a breakup of Mustang gear ratios by twelvemonth:

You accept a couple of options as far equally correcting your Mustang'south speedometer and odometer reading. Depending on the twelvemonth of your Mustang, the correction can exist done by installing a speed calibrator, reprogramming with a scrap or tuner, or installing the adjustment gear available through Ford racing.

A custom tune requires the use of a chip or handheld tuning device such as the SCT Eliminator, X3 PowerFlash, or LiveWire tuner. Your dealer will create a custom melody that specifically calibrates your speedometer and if you accept an automatic, it will calibrate your transmission'due south shift points. This method volition work on all Mustangs with computer controlled electronic gauges (1999 Mustangs).

Manual Transmissions with 7 Molar Drive Gears:

• 1983-1989 T-5 OEM
• Pre 1993 T-5 Aftermarket
• 1996-1998 Cobra T-45 OEM
• All Tremec Transmissions

Manual Transmissions with 8 Molar Drive Gears:

• 1990-1998 T-5 OEM
• 1996-1998 T-45 OEM Except Cobra

Automatic Transmissions with vii Tooth Drive Gear:

• 1983-1989 Automatic Transmissions

Automatic Transmissions with viii Tooth Bulldoze Gear:

• 1990-1998 Automatic Transmissions

• 1979-1985 V8s: 7.v
• 1986-2010 V6: 7.5
• 2011-2018 & EcoBoost: 8.8
• 1987-2018 Mustang GT and LX - 8.8
• 1999-2001 & 2003-2004 IRS Mustangs: 8.viii

From 1979-1985 Mustang'due south came with the vii.5" rear. Upwardly until 2011, the seven.5" was factory for everything without a V8. The 8.8" rear was the differential of choice for the V8 engines (4.vi, 5.0, and the 5.4). Later on 2011 the 3.7L V6 and the Coyote powered Mustangs shared the 8.eight". The Mustangs with IRS (Independent Rear Pause) under them as well came with the viii.viii" rear stop (99-01 and 03-04).

Granted, people change out the stock rear differentials for a number of reasons. One manner to tell the deviation is past the cover gasket and the pinion gear splines. The 7.5" rear has 2 flat edges on the gasket whereas the eight.8" is generally round with 2 divots. Lastly, the seven.5" pinion has 28 splines, and the eight.eight" has 30 splines.

Go along in mind if you lot have a vii.5 differential information technology can't accommodate 8.8 unequal gears. You tin, however, get the same ratios as those institute in the 8.viii diffs. In other words, your V6 can house the same ratio as a GT.