Repairing 79 and newer Mustang floor rails for subframe installation.

The floor pan on both sides of this particular car had some damage from jack stands and floor jacks. This is not uncommon for cars that have seen some track time.

Photos A , B and C.

The main objective for installing a subframe is to

1.Increase protection to the passenger compartment.
2. Reduce twisting of the uni-body.
3. Provide faster load transfer for improved response.
4. Provide jacking locations.
5. Increase the integrity of the floor

This area where the cross member bolts on, and where the boxed rail supports cross the floor to the outer rocker rail, constitutes part of the forward bulkhead area. This is the strongest area up front protecting the passenger compartment. At this location is where our Global West subframe is going to tie in. That area requires the surface to be flat for achieving the utmost strength when we weld the subframe to the car.

Note: We will also repair the side toward the outside of the car for proper subframe fitment.

To the right you will notice the damaged area at the rear bulkhead area. This is the strongest part of the uni-body protecting the passenger compartment from the rear. This is just before where the lower control arm attaches. Notice the dimpling and stretching of the metal.

The location on where the floor rail repair must be repaired, is determined by holding the subframe in position up to the floor.

The forward frame rail up by the front cross member is smashed making the bottom surface uneven (pushed upward). You can easily see the rail concave.

The edges of the rail are also smashed causing the sides to flare to be uneven.

The first repair we will do is square up the forward area where the subframe will be installed. We first flatten out the sides of the rail as best as we can by tapping the high points with a proper body hammer. Once we get the rails acceptable we make a box out of 1/8 inch plate at least 6 inches long with the sides about 1 inch high.

The base of the box most be parallel to the floor. If the bottom of the floor rail is concave to the point of an extreme gap between the base plate of the box and the bottom of the rail. A small filler plate maybe required.

Once the box is fitted - go ahead and weld the box to the floor rail.

Notice how far the box is forward on the rail.

Before the subframe can be installed the rear floor area must also be repaired and prepped.

Photo F shows the area being marked for the subframe location.

Photo G shows us prepping the area for welding.

Global West subframes are full length meaning they span the full length of the passenger compartment. We tie into the bulkhead areas of the car for obtaining the most strength.

Again we had to do a little massaging of the floor area in order to get the subframe to set flat. Buffing is required so we can weld to bare metal rather than getting impurities in the weld from the paint.

Installing the subframe will require some prep work.

The subframe is powder coated. The area where the welding takes place must have the powder coat removed. This is easily done with a buffer or hand sander.

This is the front of the subframe. You will buff off the powder coat around the 4inch plate and end cap plate on the tube.

The back plate is also buffed around the edges.

The next step is to hold the subframe up into position and weld the subframe to the floor. Tack both end of the subframe before running a full pass. Make sure the subframe plates are resting flat the body.

Weld the subframe. ( We use mig and tig welding processes --- It all depends on the situation).

Once the subframe is attached there is a 4 inch long plate that goes up along the rear square rail and butts up against the subframe plate. This is also welded. In the photo you can see this is up next to the muffler.

Photos J and K.

A 4-inch long angle brace is then attached to the end of the factory floor rail and to our subframe.

Mark and buff the paint off for welding.

Photos L and M.

Note: The wide side of the angle brace goes along the floor rail.

Weld the brace the floor rail.

After completing the welding, prep the floor around the welded areas and spray paint to protect against corrosion.

Close up of how the front repair appeared after completion.

Notice the subframe extends the full length of the passenger compartment.

No ground clearance is lost --- Notice the muffler and exhaust pipe hang lower.

Additional subframe components are available from Global West.

!979-93 Mustangs are noted for having floors crack stemming from the rear front seat bolts. The seat supports weld to the Global West subframe and then pickup the rear seat mounts. The load is then removed off the floor and placed into the subframe.

This is not as common on 1994 and newer models however Global West makes seat supports as well for these models..

Competition subframes ---- The subframes pictured below are recommended for racing applications and convertibles. The ladder looking subframes have jacking rails that reach out to the rocker rails below the doors. The cross tubes tie the rocker rails to the main subframe. This gives tremendous amounts of strength to the chassis. These subframes also provide a location for tying a roll cage to the subframe..

Jacking rails for competition and convertibles are available separately. This allows you to upgrade your existing Global West subframe. If you wanted to upgrade I would also install the seat supports as well.

Note: Seat supports are standard with the competition subframe kit.