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What to Look For When Buying a Fox Body Mustang

Written By: Connor MC

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When purchasing a Fox Body, there are a host of concerns you want to look for. From dry, rotted belts to rusted floor pans and other common 1979-1993 Mustang problems, AmericanMuscle has the restoration parts to bring a tired Fox back to life.

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Are you considering buying a Fox Body Mustang? Here are the most important things to look out for when you're inspecting a used Fox Body.

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Finding the Right Fox Body

The 80’s run of Foxbody Mustangs was a milestone decade for Ford. Their iconic Mustang finally surpassing the 200 horsepower plateau once again in 1985. The Fox Mustang posted some of the best sales numbers in a long time, likely due to the resurgence of actual power.

Surprisingly, Foxes remain highly desirable amongst young and less young. They are not nearly as valuable as the original pony cars from the sixties (nor do I believe they will ever be), however they are becoming a more sought after vehicle due to their relatively inexpensive and easily modifiable platform. Now, being a minimum of at least 20 years old, there will of course be some squeaks and rattles. How do you pick a stud from a dud? Let’s find out!

Cobra R Style Rims on a 1987-1993 Foxbody Mustang

Fox Body Mustang Buyer’s Guide Checklist

  • The body and frame—Look at the pillars by the windshield and rear quarter windows for bulges or cracks; it's a clear sign of a shifted frame
  • Rusting strut towers—Check all common areas for rust, and parts that must be replaced due to rust
  • Leaking rear main seals—Check for evidence of oil dripping down the back of the motor or transmission
  • Failing clutch cables—It will be obvious, the clutch will never disengage

What are the Trouble Spots When Buying a Fox Body Mustang?

The biggest area of concern for Fox Mustangs is the actual body and frame of the vehicle itself. Fox Mustangs (well, all Mustangs) are built with a unibody structure, meaning the car is constructed of various subframes connected by the floor pans instead of a full frame design. This in itself is not a problem. Pretty much every vehicle on the market uses a unibody design (except mainly for trucks and large SUV’s) because of their weight and cost advantages. However, the factory bracing is inadequate to deal with the power of the 5.0L V8 up front. After years of abuse it's not uncommon to see twisted frames simply because of a lack of bracing (which is also why a set of aftermarket subframe connectors are highly recommended as the first modification).

To check for this, take a look at the pillars by the windshield and rear quarter windows. Bulges or cracks are a clear sign the frame has shifted under the stress. If you don’t mind getting dirty, lie on your back and have a gander at the torque boxes. Another notoriously weak area. The stock torque boxes are just tack welded in often come apart, particularly when pushing more than stock power levels. Cracks or rips in the torque boxes are not the end of the world either, but it will, again, cost a pretty penny to have repaired. The actual kits out there to repair it are not the major cost, but rather it is the labor involved.

SR Performance Black Subframe Connectors Installed on a Mustang

Is Rust and Decay a Serious Issue?

With any aging vehicle, rust is always an issue. In particular, Fox Mustangs are notorious for rusting in the strut towers. When left alone, strut towers can become extremely expensive to repair if worth repairing at all. Many a Fox Mustang has hit the scrap yard simply because they fell apart after rusting through the shock towers. A Fox with clean strut towers definitely earns a big check mark! If you do see rust, it isn’t the end of the world. There are aftermarket replacement panels out there, however expect to dish out at least one arm and one leg in labor costs to have it cut out and patched back in. To summarize – rust on the strut towers, tread carefully.

Of course you want to check all the other common areas as well, such as the fender wells and lips, the floor pans, around the windshield, and T-tops/sunroof (if equipped). Rust bubbling around any window opening typically means some moisture is passing through a seal somewhere, so it will need to be replaced.

Foxbody with Rusted Floor Boards

What Issues Should You Look for with an Old Fox Body’s Motor?

After talking about some potentially serious issues with the frame, you’ll be happy to know as far as mechanics go, Foxbody equipment is pretty robust. In the event a repair is needed, it’ll probably be significantly less than most frame or body jobs.

Onward to the motor. The 5.0 is a very tough engine. When properly maintained, these things can last a long time before throwing in the towel. Leaking rear main seals seem to be a pretty common problem with these vehicles, so check for any evidence of oil dripping down that back of the motor or around the transmission. Any oil around the pan typically means a leaking oil pan gasket, or the drain plug is not tight enough. The water pumps too, for whatever reason, like to occasionally fail. A quick check that the shaft is not loose and the weep hole (on bottom) is dry indicates a water pump is still good to go.

View of a Rear Main Seal on a Foxbody Mustang
Rear Main Seal

Transmission & Differential – What to Look For

Concerning the transmission, if it is a manual car, check that all gears engage smoothly and do not pop out (test drive needed). The clutch should engage mid-range, not off the floor or at the top. If so, the clutch could simply be in need of adjustment (via the cable and clutch quadrant) or could be worn out. Speaking of clutch cables, this is another favorite item to fail on these 80’s Mustangs (as well as the clutch quadrant). It will be immediately obvious if it has failed as the clutch will never disengage. Also note: the reverse gear on T5 transmissions are NOT synchronized. Thus, if you grind the gear when going into reverse, unfortunately, this is normal. A trick to contend with this is while stopped, shift into any other gear (my favorite is 1st), wait a few seconds for everything to slow down, then shift the car into reverse.

Automatic transmissions are a little trickier to diagnose. Abrupt shifting can either be a sign of wearing components or that an aftermarket valve body has been installed. Definitely check the fluid if you can for AOD transmissions. It should be nice and red and have no burning smell to it.

Ford Racing Foxbody Clutch Cable
Clutch Cable

Fox Body Rear End Inspection

The last major drivetrain part to check is the 8.8” (or 7.5”, depending on year and trim level) differential unit. Check around the housing for leaks, which can sometimes happen. More commonly found, however, is that the Trak-Lok clutches have worn out, resulting in one wheel peels. Replacement clutch packs cost around $100-$150, so again, not too bad.

What About the Fox Body GT and LX? What's the Difference?

In the long run, not much. Depending on the options from the factory, the LX model could be up to 50-250 pounds lighter than the GT. The LX also doesn't have the same ground effects as the GT model. From the factory, the GT was offered with more options as standard whereas the LX came as a blank slate. In fact, the only option you couldn't get on the LX from Ford was fog lights. However even if you go with an LX model, you can add fog lights at a later date. The wiring harness is designed to make fogs an easy addition.

Foxbody Mustang with Axial Chrome Headlights

When Shopping for a Fox Body, Nobody Wants a Lemon

Listed above are the common wear areas on these Mustangs. Of course, there is suspension and brakes too, but with any car they will wear with mileage. I consider those two latter categories to fall under “routine maintenance and ownership costs.” As stated, these Foxbody Mustangs are pretty stout and can last a long time. Frame and body should be the first priority as pretty much anything else mechanical can be fixed within a reasonable cost.

Fitment includes: 1979, 1980, 1981, 1982, 1983, 1984, 1985, 1986, 1987, 1988, 1989, 1990, 1991, 1992, 1993, GT, Cobra, LX, SVO