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Mustang Rear End Gear Installation: Ford Racing 8.8 Ring & Pinion

Posted 12/9/2013 by Jeff Jimenez

Watch our 8.8" Mustang Rear End Gear Installation Video here. We also cover many ring and pinion questions that most Mustang enthusiast ask about when replacing their rear end gears.

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Installing a new set of rear end gears in your 1979 to current Mustang is one of the best ”bang for the buck” performance mods you can do. This is especially true of SN95 and Fox Body Mustangs that came with gear ratios below 3.55. Besides forced induction or nitrous kits, there aren’t many mods that will give you noticeable improvements in straight line acceleration like a set of higher ratio ring and pinion gears. Not only will they improve your straight line acceleration but they also help keep you in your upper power band; thus, making installation of rear gears a must for any drag racer.

Now you might be asking yourself, can I install a set of rear end gears in my Mustang? There isn’t a clear yes or no answer to this; however, if you have a good mechanical skill level and a host of specialty tools this project can be done in your own driveway. Be sure to watch the how-to video in this article. It walks you through installing Ford Racing 8.8 rear end gears in Mustangs with a solid rear axle setup.

Mustang Rear End Gear Installation Tools:
  • Bearing and Seal Driver Set
  • Two-Jaw Puller
  • Beam Style Torque Wrench – Inch Pound
  • Large Drifts (Heavy Duty Punch) Tools
  • Dial Indicator (Magnetic Base Works Best)
  • Pinion Flange Tool
  • Slide Hammer
  • Hydraulic Press w/Press Plates and Bearing Separators
  • Common Hand Tools

Another useful tool to help you with the installation is the Ford Racing installation instructions. They can be download here - Ford Racing Gear Install Instructions. Even if you decide to let a professional install your gears, it is definitely worth your time to watch the video and look over the instructions to ensure you know what questions to ask the installer.

So I have covered the why you want new rear gears and even how to replace your gears but you still might be asking yourself what gear ratio is right for your Mustang. For most applications my immediate answer is go with a set of 4.10 ring and pinion gears! For most Mustang enthusiasts with lightly modified to full bolt-on Stangs, 3.73 or 4.10 gears will drastically improve your acceleration and keep you in your powerband. You might hear a few people complain about reduced fuel economy (MPG) with the 3.73+ ratio gears. This can be side effect of these gear ratios; however, you can also see some improvements by getting into better cruising gears sooner. Let’s face it if fuel economy is your top worry then you might need to reconsider modding your V8 Stang. Guys with superchargers, turbochargers or even fully built engines, it may be best to contact your tuner to maximize your rear end gear with your dyno powerband. Having owned many Mustangs with different gear ratios my gear of choice is 4.10 followed by 3.73. If you have a full bolt on ride – especially with a Ford Modular Motor – that sees a lot of drag strip time then you might even consider 4.56 gears.

Mustang Rear End Gear Installation: Ford Racing 8.8 Ring & Pinion - Mustang rear end gear installation

Mustang Speedometer Correction

Once you pick your new rear end gears and get them installed you now have to re-calibrate your speedometer for the new gear ratio. There are a couple different methods of this and they vary by year model. Let us take a look at some of the options for re-calibration:

Fox Body Mustang Speedometer Correction:

Your options are limited on the Fox Body platform. You will need to select the correct speed correction speedometer gear to recalibrate your speedo for new rear end gears. Now you might be thinking this sounds a little complicated but no worries! We have taken all the guess work out of this process with our Speedometer Gear Calculator. Click here to see our calculator: Mustang Speedometer Gear Calculator.

SN95 & New Edge Mustang Speedometer Correction:

If you own a 1994-04 Mustang you have a few different options available to you. The first option is to use an electronic speedometer correction tool most commonly referred to as a Speed-Cal. This has been a proven way to correct speedos for years. It requires some installation and simply reading a chart to ensure you have the correct gear settings entered. If you own a 1999 to current Mustang you have a secondary option – handheld tuners such as SCT SF3 Tuner. With a SCT tuner you can simply plug in your tuner adjust for your new gears and upload the new tune file. While the tuner route is slightly more than a Speed-Cal it opens the door to more benefits that the tuner has to offer – such as custom tunes and a whole list of other adjustments built into the device.

S197 Mustang Speedometer Correction

If you own a 2005 to present Mustang the only option you should consider is using a tuning device such as the SCT SF3 or SCT iTSX Tuner. Tuners like these offer a vast array of options for the S197 Mustangs and even include pre-loaded custom tunes. If you plan on adding things such as cold air intakes or off road exhaust systems these tuners are also a requirement for these to be installed. For 2005-10 Mustangs you can use the Speed-Cal device to save some money but it won’t bring you the benefits that a tuning device can bring to your vehicle. Do yourself a favor and invest in the tuner.

Mustang Rear End Gear Installation: Ford Racing 8.8 Ring & Pinion - mustang speedometer correction

Common Questions We Get About Mustang Rear End Gear Installation:

Does My Mustang Have A 7.5 or 8.8 Rear End?

  • Easy rule of thumb – If you own a 1987 to present Mustang with a V8 you have an 8.8 rear end
  • Also 2011-2014 Mustang V6s came equipped with a 8.8 rear end
  • 1994-2010 Mustang V6 models featured a 7.5 rear end
  • For more information click here: Mustang 7.5 versus 8.8 rear end

Do I Need To Replace My Differential?

  • If your Mustang only spins one wheel – it is time to replace your differential.
  • If you have a higher mileage Mustang and you know it has never been replaced – do yourself a favor and replace your factory differential or replace the traction lock clutches.
  • The Ford factory differential has clutches inside that wear out over time. Replacing them when changing out your gears can save you a lot of time, motion and money if someone else is doing the work.
  • See our complete list here: Mustang Traction Locks and Differentials.

Do I Need To Replace My Axles When Installing New Rear End Gears?

  • To simply install new rear end gears – No, you don’t have to replace your axles
  • If you are drag racing your Mustang a lot – now would be the time to make the upgrade! You will have your rear end apart. You can save yourself some labor by upgrading now.
  • Shop axles here: Mustang Axles

Do I Need To Replace My Axles Bearings & Seals?

  • No, this is not a requirement to install rear end gears; however, if you notice any leaky conditions or know they have never been changed - this is the perfect opportunity to replace them.
  • It isn't everyday you have your rear end apart - take advantage of this situation to replace any old or dated parts. Save yourself some headache down the road.

Do I Need To Install A Differential Cover or Girdle?

  • No, not to install a set of rear end gears.
  • Aftermarket Differential Coves do offer some added benefits and features that are a nice improvement for your rear end. These include:
    • Oil Fill Plugs
    • Magnetic Drain Plugs
    • Main Cap Load Bolts - Reduces cap walk and distortion
    Since your rear end will be apart it is the perfect time to add one to the installation
  • Shop our full line of covers here: Mustang Differential Covers

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