Tech: How to Clearance Fox-Body Mustang Wheel Wells

Everybody that has tried to stuff a good sized tire under a Fox-body Mustang with a stock suspension knows it will rub. Oh yea, it will hit everything, make white smoke on the top end, and possibly even cut the tire. Did we mention it will rub everywhere.

With Project 666, our ’86 Fox Body, we wanted to stuff a 275/60/15 Drag Radial on a 15 x 10 wheel and not have it look like a inner-city low rider with the wheels hanging out the wells. We wanted that lean, Pro-stock slammed look with the tires tucked nicely in the fenders. That meant it was time for the hammer. It was time – to clearance the wheel wells.

We figured, since this was such a pain in the ass, why not document it and save thousands of future Fox-body wheel well pounders the trouble of making a mistake. This is our Guide to Fox Body Wheel Wells.

Why I loved this project…

Most of the time I get projects that cause more frustration than they relieve.

I have finally stumbled on a project that relieves more stress than it generates, and yes, it involves using a hammer on your car. Actually, several hammers. Whomever takes on this project should have careful attention to detail and should not cringe at the thought of swinging a hammer mere inches from a nicely painted quarter panel. By default, I was the unanimous choice as the wheel well fabricator.

As we mentioned, our project car is a 1986 Fox Body Ford Mustang. We have recently changed the rear end from the stock 8.8 rear end to a Moser Engineering M9 rear end assembly. We ordered the new rear end assembly slightly shorter in width than the stock one so that we could bring the tires in closer to the frame. Bringing the inside of the tires closer to the frame would allow us to run a wider tire and still have them fit into the stock wheel well.

Where can this be done?

This can be accomplished in the driveway, staging area, street or any other flat surface where you can get the car up on a jack stand and the wheel removed, I found it easiest on a lift. Putting the car on a lift and raising it to about eyeball level, gives you a better chance at creating the leverage needed to strike the wheel wells with some meaningful blows. Just like in little league baseball where your coach yelled to keep your eye on the ball, having the surface that you are going to be hitting closer in your visual range will increase your accuracy. Get the work up where you can see it and you will have fewer problems. Use a lift if possible, but we’ve done it on jack stands many times.

After removing the wheels, we lifted the car about eye level. This afforded us the perfect swing area for our 5 pound mini sledge. There are many tools available to shape metal, and the most common are mallets and hammers. Most fabricators consider these essential tools when forming metal and hand shaping techniques a must when learning how metal reacts when being formed. While there is nothing complicated about using a hammer, there is a learned skill involved in getting predictable results when forming metal by hand. Start easy and develop a “feel” for how the metal reacts to the hammer blows.

These are the tools that we used and we recommend that you start with:

• 5-lb sledge – this is used for the major “easy” blows to move metal.
• Dead blow hammer – used for corners or dangerous rebound areas
• Regular/Conventional House hold hammer – for targeted blows/high spots
• Lock-jaw Wedge Pliers – to prevent sheet metal seperation

We are going to start out by looking at the front half of the Fox Body wheel well. Above us is in yellow is the area that will need to be clearanced to eliminate tire rub. How much – well that depends on your specific wheel and tire combination. In our case, with the 15 x 10 and the 275/60/15, a significant amount of metal needs to be pounded back.

When you start with the front half of the wells, you are generally going to work in a circular motion starting with the 5-lb sledge. The areas that will be the toughest are near the spring perch. Unfortunately, this is also an area that needs a lot of work.

Notice where the metal is formed around the bottom edge of the inner wheel well. When sheet metal is bent, it adds strength. This is also the area where sheet metal is joined together. Use caution when forming the metal in these areas. Remember that the Fox Body platform is a unibody construction vehicle. Where the edges of sheet metal meet, like in the rear shock mounting areas or the upper spring perches, are spot welded together. Striking these areas with too much brute force can rip the metal at the spot welds.

A good rule to follow is: hit the metal with a firm blow in the center of the area you want to form, and work your way outward to the flanges. Be advised that the hammer may rebound from the hit causing the hammer to strike the inside of the quarter panel leaving a dent visible from the outside. There is the possibility that the hammer operator may get stuck by the rebound, leaving a dent in the forehead visible for all to see. To prevent either of these incidents from occurring, you always want to use a strong and firm blow to reduce the rebound. Try to keep the hammer blows even and at the same strength.

Work from the inside to the outer edge of the inner wheel well.

Do your best to work from the inside area out to the edges. Keep working the metal with repetitive and overlapping blows so that the metal stays somewhat smooth. Most of the time I like working the metal in a circular pattern. I have found this to be helpful in stretching the metal without creating too many ripples in the form. Patience is going to make a huge difference in the success of your metal forming. Continue stretching the metal until you see that some space has been created. Fit the wheel on the hub and check for clearance. This will give you a good idea of how much metal you will have to form. Keep in mind that the suspension is lower than ride height at this point, so you will have to guesstimate how much clearance you need at the upper portion of the inner wheel well.

Work the metal until enough space has been created for clearance.

Try and Try again

Ok, now this is where the patience comes into play. If your wheel looks like it has enough clearance, you will need to tighten the wheel up to the hub with lug nuts, lower the car to where the wheels are barely touching the ground. As soon as the wheels touch the ground, you will need to watch the clearance between the wheels and the wheel well the rest of the way down. It might be a good idea to get a helper that you trust to either lower the car or be your eyes. If you have good clearance through the suspension travel, then your all set. If not, you need to bring the car back up in the air. Take off the wheel and move some more metal. You may have to do this process more than once. And yes, your patience will be tested.

Mount the tires and bring the car down to ride height. If you’ve got the car on jack stands this part will be a pain in the ass.

Once the car is on the ground and at race/ride height – check tire clearance all the way around. We’re looking for at least 3/8-inch if possible.

It’s important that the procedure listed above be followed. If you leave a flap of metal sticking out, there is a potential that you may experience tire rub which will eventually cut down a tire. Usually with very bad results when this happens on the track. There never seems to be a real convenient time for a tire to explode or cut and force you into the guard rail.

I’ve yet to be successful keeping off the wall after a blowout, but I will still keep trying.

Here is what our wheel well looked like once we finished.

This is our wheel well, our tire and wheel combination. Not yours. You may have to beat on your wheel well more or less than ours, and potentially in different spots.

Also, please keep in mind, after you install the tire, you must load the car to ride height before you check for clearance issues. Make sure that the car is not supported by the frame and the rear end is hanging down to its bottom length of travel when you are checking for clearance. Load up the chassis by lowering the car fully to the ground.

Bounce the rear suspension a couple of times by pushing down on the rear bumper. After checking for clearance at static ride height, you will want to check the clearance at race ride height. To do this you will want to raise the front end of the car one to two inches. This will settle the car on the rear suspension. Check the entire wheel well area for clearance. Don’t forget to check for wheel clearance on other parts in the area, like exhaust system pipes that run close to the aft edge of the tires.

Painting the wells – pretty?

We think if you take the time to do this right, you should go ahead and do a nice job painting the wheel wells. This has been done poorly (and it looks like crap) more times than we can count. Many people just take out a spray can and go to town.

Over spray, drips, and a shoddy looking chassis can be easily fixed with 30 minutes of time, masking paper and painters tape. Everything your Home Depot or local auto part store can easily have in stock. We masked off our wells and painted them a nice flat black.

A few other areas to think about..

A couple of other areas worth mentioning concerning wheels and wheel clearance are brakes and wheel backspace. The Fox Body 5.0 Ford Mustangs have a great many bolt on performance enhancers. It’s pretty easy to double the stock horsepower, and in the case of our project car, triple the horsepower. Keep in mind that you must upgrade your brake system proportionately. Our project car started out with rear drum brakes. Realizing that was not going to provide the stopping power that we needed, an upgrade to rear disc brakes was in order. Changing braking systems from drum to disc can interfere with backspacing on shallow backspaced (and sometimes deep backspaced) wheels. Keep an eye out for clearance issues there as well.

About the author

Bobby Kimbrough

Bobby grew up in the heart of Illinois, becoming an avid dirt track race fan which has developed into a life long passion. Taking a break from the Midwest dirt tracks to fight evil doers in the world, he completed a full 21 year career in the Marine Corps.
Read My Articles

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