From 1979 to 1993, more than one million Fox Mustangs were produced for a span of just under 15 years. Let that sink in for a moment. While there probably aren’t a million left on the planet, it seems there’s no shortage of them either. Heck, look around any local drag strip on a given night and count how many Foxes there are.

Whether they have Blue Oval powerplants or not, we’ll bet they are still wearing Ford rearends. The question is if those rearends are strong enough? Whether you’re true blue or not, Moser Engineering has a rugged solution for folks with Foxes. And the good news is, these rearend solutions aren’t designed specifically for just one type of racing.

The Super Fox line of rearends gives a dedicated Sportsman racer the ability to take their car to the limit of the stock chassis. — Jeff Anderson, Moser Engineering

This Fox is owned by Lee and Daniel of Sweitzer Performance in Temecula, California; the brothers plan to use their hatch for half-mile events. Fortunately for Mustang enthusiasts, the Moser 9-Inch Super Fox rearend we installed on Sweitzer’s Fox Mustang isn’t available just for ’79-’93 Mustangs — it is also available for SN95 (’94-’98) and New Edge (’99-’04) folks too.

Whether you want to use a larger tire in the rear via a mini-tub kit or you just keep snapping stock rearends like twigs, upgrading the rear end of your ride for a more robust piece is always an improvement. Stick with us as we bring you a full download on the Super Fox rearend. You’ll learn why you should consider this bulletproof axle setup for your next high-horsepower Fox build.

The Super Fox System

We laid all of our cards out on the table.

Adjustable Package

According to Jeff Anderson of Moser, the Super Fox package truly shines because of its many adjustment points, including its coilover mounts; the double-adjustable upper and lower control arms; and a tuned built in anti-roll bar. These features give enthusiasts the ability to control body-roll on the suspension and plant the tires equally.

 

All of these options will give enthusiasts the ability to set their car up to match the track quickly when testing, and — more importantly — fine-tuning, when in the heat of battle.

 

As with all Moser rearends, the Super Fox will include all of the necessary hardware for installation, as well as brakes of your choice and the necessary upper and lower control arms.

 

The advantages of running a 9-inch rearend on your muscle car have been well documented over the years — there’s no debating that — but what sets Moser’s Super Fox rearend apart from those junkyard 8.8s?

As time has progressed, so have the options for a custom-built 9-inch rearend assembly, and the Super Fox is catered specifically to Fox, SN-95, and New Edge Mustangs ranging from ’79-’04. One major difference? This rearend is built specifically for going straight.

“The Super Fox line of rearends gives a dedicated Sportsman racer the ability to take their car to the limit of the stock chassis,” Jeff Anderson, Marketing Director for Moser Engineering, told us. “All while delivering maximum useable adjustability and confidence without the expense of a full tube-chassis conversion.”

According to Jeff, the Super Fox package is much more beneficial than when compared to an 8.8-inch in some notable ways. Jeff said that, economically, the 9-inch ring and pinion will last longer, and will also give enthusiasts more passes per dollar spent than with an 8.8-inch rearend.

“The Fabricated M9 that is the skeleton of this conversion also does away with the flex that is found in the stock unit,” Jeff explained. “With the geometric shape of the fabricated design, it also incorporates a back-brace which ties-in the backbone of the larger tubes over factory. It also gives you more choices for a larger and more reliable spline count, along with more options for brake choices depending on the housing ends enthusiasts request.”

Because Sweitzer Performance plans to use this car for half-mile racing duty, custom coilovers from JRi were brought on for the build. JRi was able to supply Sweitzer with a pair of its rear shocks and coil springs, custom made for this specific application.

Stock Doesn’t Rock

After securing the car on its lift, Sweitzer Performance began the swap by removing the old, tired factory 8.8-inch rearend.

While we’re on the subject of that old, worn-out, factory 8.8-inch rearend, we picked Jeff’s brain on what the inherent weaknesses or drawbacks are in the factory components.

“The 8.8-inch rearend from the factory is a decent assembly when someone is just starting out,” Jeff said. “However, as the car is exposed more to race events and enthusiasts start tuning their Fox’s suspension, the shortcomings become quickly apparent and frustrating.”

As Jeff pointed out, reliability is a huge factor when you are stepping up your program; and you do not want a broken internal part stranding your run at the winners circle.

“Enthusiasts need a cost-effective fix and a game-changer; and they need something that is a complete package and will work with their stock chassis,” he added.

Removing all of the links such as the rear sway bar, upper and lower control arms and the springs will allow you to separate the rearend from the body with ease.

“The Moser Super Package was designed, engineered and built specifically for the weight range of the most competitive Fox chassis setups. It is made to work with stock wheel openings, or even a mini-tub kit. This gives enthusiasts the ability to use the largest tire they can fit under the factory chassis without converting to an expensive back-half or tube-chassis conversion project.”

Moreover, the Super Fox allows the adjustability Mustang fans need without incorporating unnecessary engineered solutions that are just not made for a stock chassis. Moser’s goal is to help enthusiasts get what they need - and can use - while helping the budget-conscious racer remain competitive and financially solvent at the same time.

The differences of the factory 8.8-inch unit versus our new Moser Super Fox assembly are readily apparent.

Engineered By Design

We mentioned earlier in this segment that the guys at Sweitzer Performance plan to use this Fox in the half-mile events across the country. The car’s powerplant will consist of a turbocharged 351 Windsor small-block coupled with an EFI fuel system designed to supply plenty of E85 to keep the engine in its happy place.

Lee Sweitzer begins by measuring for clearance of Moser's included anti-roll-bar kit, followed by mounting the support brace, then the anti-roll-bar itself.

You could say that ordering its Super Fox assembly wasn’t a basic order by the folks at Sweitzer. That said, Jeff and his crew knew exactly how to handle this assembly, and they will yours too, no matter how crazy of a build you are pursing.

“It really is a simple process when calling in to Moser Engineering,” Jeff told us when asked what information Moser would need in advance. “We will need to know the normal items like what carrier/spline combination the enthusiast wants, and what brakes they will be running.”

After successfully securing the anti-roll-bar mount, the guys at Sweitzer began fitting the new and included upper- and lower- control arms to their new Moser rearend, along with the new anti-roll bar.

Jeff explained that the most critical information is going to be the spacing from back of wheel to back of rim.

“This is basically the surface the brake rotors touch on the back of the wheel from drivers side to passenger side,” he explained. “We will run the numbers and generate a custom-made setup that is exactly matched to the dimensions that person supplies us – it really is that simple.”

The Final Stretch

Since the coilover setup from JRi was custom for Sweitzer’s half-mile racing goals, there is no part number associated with the new setup. However, if you’re interested in replicating this suspension setup, JRi will be happy to assist you.

One thing you might find yourself asking is, “Why does a car built for half-mile racing care about using an anti-roll-bar assembly if they aren’t launching it from a dig?”

Fortunately, Jeff explains why integrating this crucial component from the get-go is important for both drag racing and our own unique application. Jeff said that the use of an anti-roll-bar helps keep the car straight during the entire event, as Sweitzer expects to see trap speeds in excess of 180 mph.

Once the rearend was mounted, Lee Sweitzer installed the third-member and axles.

“Anti-roll is used to help position and hold the rear in a very tight space while also helping to adjust preload,” Jeff told us. “This preload that I refer to will help control body-roll and equalize traction to both tires, which for drag racers, will dramatically decrease 60-foot times. This is something the stock unit can’t do, and anti-roll works best when your suspension is square in the chassis.”

According to Jeff, when using an anti-roll-bar, enthusiasts can use housing- and chassis-mounted units. For our application, the chassis-mounted unit will work best, and is easier to square in the chassis and gave the best repeatable times in a car setup identically for both choices. Jeff said that the width of the bar, along with diameter, all play into ultimately deciding what works best, and that these setups are tuned for each version of the Super packages available.

Speaking of packages, if you’re interested in continuing to see how Sweitzer’s all-new Moser Engineering Super Fox 9-inch rearend performs in the half-mile events it will compete in, drop us a line in the comments and let us know if we should continue to follow the build. Until then, you can learn more about Moser Engineering‘s rearend offerings here.