resto series number 4: replacing floor pans

By Angelo VanBogart. Photos by Kris Kandler and Jerry Kopecky.

From the salty tip of Texas to the moist summer air of Maine, sheet metal can take a beating. With precious few exceptions, the metal floors of most cars turn to swiss cheese after 50 years and tens of thousands of miles of exposure to water, snow and salt. Though floor pans are seldom seen and sometimes forgotten, most restorers know they will have to repair them on cars that enter their shops. Among those restorers is Jerry Kopecky of Kopecky’s Klassics in Iola, Wis.

Kopecky has restored several types of collector cars, but his restoration business has evolved to specialize in finned MoPars, especially convertibles. Thanks to his attention to detail, restorations out of Kopecky’s shop have commanded record prices for finned MoPar convertibles at Barrett-Jackson’s January auction. Kopecky’s latest project car is a customer’s 1960 Chrysler 300-F convertible, one of today’s hottest postwar cars. That 300-F is the subject of this article, though the principles that Kopecky undertook to repair the floor pans apply to all finned MoPars, as well as most other metal-floored vehicles.

Sponsored by:

Mercuryland Restoration Specialties & Supply
Grundy Old Cars Weekly

When this particular 300-F came into his shop, it was wearing an older, driver-quality restoration that still looked presentable. Its owner was looking for a correct, show-quality restoration on the rapidly appreciating Chrysler, and he knew Kopecky and his team were the right shop for the right car.

Kopecky knew immediately that the 300-F would need floor repair. The rocker panels were swelling, and like most old cars, any sign of rust indicates more rust was probably hiding, particularly in a car’s floors.

Sponsored by:

Jenkins Restorations Librandis Plating
Auto Twirler Rare Parts, Inc.
Boardwalk Classic Car Auction Totally Stainless
Bumper Boyz Brake Tech Solutions

“Before the driver who delivered the car left, we had it on a hoist,” Kopecky said. After scraping the undercoating off, it was clear the floors had already been replaced, but with incorrect flat metal, rather than the correct ribbed material. Using flat metal to repair cheese grater-like floors was once common, but the material flexes when stress is applied, even from the light touch of a passenger’s feet. Flat metal also lacks the correct rib marks, which manufacturers added for strength and to prevent flexing.

To best assess the situation, Kopecky Klassics sandblasted the floors after the interior and undercoating were stripped. Sandblasting is the best way to get metal as honest-looking as possible, as even tiny holes become evident.

Sponsored by:

A&C Casting Rebuilders Fatsco
S&M Electro-Tech Egge Machine Co
Classique Cars Unlimited JC Auto Restoration
Steele Rubber C&G Early Ford Parts

“We pull the interior out, the carpeting, seats — that’s when you get the real story,” Kopecky said.

With the floor and trunk pan completely stripped, Kopecky called R Car Fabs to determine which floor parts were  available. Fortunately, everything Kopecky needed could be ordered.

Sponsored by:

Nomad Paul's Chrome
Rhode Island Wiring Corvette Raffle

While waiting for the new pans to arrive, Kopecky sprays a primer over the exposed metal to prevent flash rust from appearing.

Here’s the 1960 Chrysler 300-F’s floor pan “before.” This car’s floors had already been replaced, but incorrectly with flat metal that flexed (note where the ribs stamped into floor abruptly stop). A previous owner also drilled several holes in the floor for reasons unknown; these were welded shut as the area they were drilled was not part of the replacement floor.
The support brace beneath the floor also had to be replaced, due to an inadequate repair job to the area. (A previous restorer had simply welded a new patch over the original rusted piece — not good in any aspect of restoration).
Here’s new metal installed in the brace. The new patch had to be made larger than the old brace due to progressing rust from the bad earlier repair.

The new floor plan section is laid in place. Al tack weld will be put in one corner when the floor is in the correct position, then the old floor will be cut out from around the edge of the new floor. This is done one side at a time, using a MIG welder to butt weld the part in place. 

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