Rust Busters begins with the...
Rust Busters begins with the seat pans by drilling out the spot welds. Along the transmission tunnel, conventional welds are ground clear. Spot welds have to be drilled out carefully, which separates the pans.
Rust has been a problem for Mustangs for as long as there have been Mustangs. Just several months after the Mustang was introduced in 1964, a Ford Technical Service Bulletin was issued to notify dealers about possible cowl-vent leakage and a fast service department fix. Still, cowl vents leaked all over the carpeting anyway, causing serious floorpan and kick-panel rust-through. This has been the lament of classic Mustang enthusiasts for at least the last 20 years.
Mustang rust doesn't stop at the floorpans. Trunk areas are another problem area because rear-window and trunk-lid seals leaked as much as the cowl vents, causing quarter-panel and wheelhouse rust-through. Front framerails and inner fender aprons are yet another corrosion problem because Ford didn't always galvanize these areas. It certainly didn't E-coat them either, since the first E-coated ones were the '74 Mustang IIs, which were completely dipped in an electrostatic primer process that not only allowed primer to flow into hidden areas, it also promoted good adhesion with the steel.
This shows just what a throwaway...
This shows just what a throwaway car Mustangs were 40 years ago. Absolutely no corrosion prevention here--just raw steel that was never primed or painted. Note the stamped opening in the seat pan of Art's early production '64 1/2 hardtop. This went away later in production.
Art Cairo is a longtime Ford engineer who has been with the company since the '70s. In 1974, he found a Raven Black '64 1/2 Mustang hardtop in the Detroit classifieds for well under $1,000. The ad said, "Owned by the Ford family..." Because Art is fascinated with the Ford family, he purchased the car. Its serial number, 5F07K100148, indicates a low serial number K-car with the original 289 High Performance engine beneath the hood. Art knew the car was significant to Ford history.
During a Mustang Monthly interview in 1983, Edsel Ford II confirmed that the black hardtop had been his father's car. It was assembled at Dearborn and shipped to Ford Design before it was delivered to Henry Ford II. We'll likely never know how often Mr. Ford drove this car, nor how interested in it he was at the time. But we do know this Mustang, possibly the first production Mustang K-car ever produced, was worth saving.
Last winter, Art concluded his Mustang needed to be restored to its original rust-free condition, so he took it to Rust Busters Classic Automotive Restoration in Redford, Michigan, for an evaluation. The body was severely rusted out from the harsh Michigan climate despite being stored inside a garage. By most standards, Art's Mustang was a total loss. Even though it looked sharp on the surface, it badly needed a full-scale restoration, including replacement of the floorpans, trunk floors, and rear framerails.
While the majority of our readers possess neither the equipment nor the skills to replace sheetmetal, this article will give you some knowledge about the procedures involved when you're selecting or talking with your body repairman.
Rust Busters begins the process...
Rust Busters begins the process of cutting out the floorpan along the transmission tunnel. The pan is carefully cut as close to the seams as possible. The objective should always be to follow the factory seams.
The main floorpan is cut out...
The main floorpan is cut out in pieces.
Expect more surprises underneath...
Expect more surprises underneath the floorpans. Rust Busters separates the floorpan from the front framerail extension. They learned quickly that both front framerails had to be replaced as well.
With all of the floorpan cut...
With all of the floorpan cut out, it's easy to see how a Mustang unit-body is put together. With hardtops and fastbacks, there isn't much there. Note the front framerail extension, which ties the front framerail to the floorpan.
The front framerail extensions...
The front framerail extensions were filled with a mountain of rust particles. They'll be replaced as a separate how-to article in Mustang Monthly at a later date.
What's left of the main floorpan...
What's left of the main floorpan is peeled away from the rocker panel. Some patchwork rust repair will be necessary.
The rear torque boxes are...
The rear torque boxes are separated and opened like this. The easiest way is to drill out the spot-welds, then nail it with an impact chisel like this.
Rust Busters uses a straightedge...
Rust Busters uses a straightedge to cut and trim the transmission tunnel for the new sheetmetal. There's a lot of work to do here.
Mating surfaces are cleaned...
Mating surfaces are cleaned up and readied for the installation of new metal from National Parts Depot.
The floorpans in the rear-seat...
The floorpans in the rear-seat area are removed by drilling out the factory spot-welds. An impact chisel gets the rest.
The front framerails and extensions...
The front framerails and extensions are removed at this time. They come out easily because they're so badly rusted.
The toe boards are cut out...
The toe boards are cut out next. We must be careful not to cut too much. Cowl-vent leakage does its greatest damage here, right under the cowl openings.
Rust Busters has installed...
Rust Busters has installed the new front framerails and extensions from National Parts Depot. Now it's time to fit the new floorpan.
The new front framerail is...
The new front framerail is fitted and welded into place. Note the groovy fitment jig Rust Busters has for Mustangs and other Ford compacts and intermediates. This jig ensures a perfect fit, just like the factory did 40 years ago.
The front framerail extensions...
The front framerail extensions are primed with a self-etching epoxy primer, then sealed with a super-tough spray coating.
With the new front framerails...
With the new front framerails and extensions welded to the unit-body, we're ready to lay in the new floorpans. We like this panoramic view photographer Chris Richardson gave us.
The new sheetmetal from National...
The new sheetmetal from National Parts Depot is measured and trimmed for a nice fit...
... then Rust Busters has...
... then Rust Busters has to cut, fit-check, then cut some more.
The rocker panels suffer from...
The rocker panels suffer from patches of rust. Rust Busters grinds these areas and welds in patches as necessary.
With new framerail extensions...
With new framerail extensions and rocker-panel repair finished, we're ready for the new long floors from National Parts Depot. Rust Busters lays them in place.
The new pans are held in place...
The new pans are held in place with aircraft-style Cleco fasteners, which are temporary. Then Rust Busters begins the busy task of rosette-and bead-welding these pans into place. Rosette welding is a plug-and-fill form of spot-welding.
Anytime you have to weld sheetmetal...
Anytime you have to weld sheetmetal to frame members, such as the transmission crossmember, holes are drilled...
...and bolts are used to pull...
...and bolts are used to pull the sheetmetal flush with the frame member.
Once bolted flush, the pan...
Once bolted flush, the pan is welded to the framerail extension and transmission crossmember.
There's a lot of welding associated...
There's a lot of welding associated with floorpan installation. It's best to rosette-weld as much as possible, then grind the weld smooth, which gives the installation a factory look. You want to see welds only where the factory made them visible (such as a bead weld).
The rear-seat floorpan looks...
The rear-seat floorpan looks like this out of the box. It needs to be trimmed and tweaked for proper fitment...
...The rear-seat anchor point...
...The rear-seat anchor point has to be removed from the old pan and welded to the new.
Our installed floorpans look...
Our installed floorpans look like this. For corrosion prevention, we use self-etching epoxy primer/sealer, then body sealer at all the seams. Underneath, we use a high-quality, bulletproof sound-deadener and undercoat.