resto series number 4: replacing floor pans page 2


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When the new panels arrive, Kopecky checks them for fit. The 300-F panels worked well, so he was ready to proceed. Rather than cut out all the rusty metal at one time, possibly leaving the entire floor open, Kopecky braces the convertible body tub in the door openings and cuts out and replaces only one section of the floor at a time. (The focus of this article is the front floor pan of the 300-F.)

With the new section of floor in hand, Kopecky Klassics employee Kevin Dombrowski lays the new floor pan over the existing pan while it’s still in the car. Dombrowski usually uses the entire pan sent, because the parts typically extend to a flat area of the floor, which is a good place to complete the butt weld, then apply the finishing touches.

Sponsored by:

YNZ Nordstrom's
Snyder's
Sta-Bil Chesapeake Soda Clean
Howell's Sheetmetal CWI

With the new floor pan in place over the old floor, Dombrowski tack welds one corner of the new floor to the old floor. He then runs a 3-inch cut-off wheel along the edge of the new floor pan to cut out the old pan. This allows the new pan to fall perfectly into place. Although some body professionals use a plasma cutter, Dombrowski prefers cut-off wheels because they cut in a precise line without warping the metal.

After the length of one side of the new pan has been cut from the existing floor, Dombrowski goes back and uses a MIG welder and wire-feeds the side of the new pan in place. Sometimes, a putty knife must be placed between the new floor pan and the surrounding area of the floor to line up these two areas. Dombrowski is also cautious to avoid heating up the surrounding floor or new floor pan section to the point each part warps during the butt weld process.

Sponsored by:

Car-Dolly.com Horkey's Wood & Parts
Axis Products LeBaron Bonney
Nomad Paul's Chrome
Rhode Island Wiring Corvette Raffle

The process is repeated for the other three sides of the floor pan. The process of laying the new floor pan section over the old floor allows the new section to fall into place as Dombrowski is working, and also prevents the pan from shifting out of place.

With the pan completely welded in place, Dombrowski goes over the welds with a cut-off wheel to bring down the weld, then smooths the weld with four stages of sanding using 36-grit sandpaper, then 80-, 180- and finally 320-grit. The area is again sandblasted to eliminate any flash rust and welding splatter, leaving a clean area to allow the primer and paint to bond. At this point, a cataylzed, two-part seam sealer is laid over the seam between the new floor sections and original floor as an additional safeguard against water entering the vehicle from below.

After paint, the floor again retains the original structural rigidity built into the car, and in an authentic fashion.

Sponsored by:

Tee-Bird Products Soda Works
Garage-Toys.com Buick Heritage Alliance



Although Kevin Dombrowski usually leaves all of the original floor in place before cutting it out with the new piece laid on top, he cut the middle of the area out to get at the rusty brace beneath (it also functioned as a relief cut). There’s still more metal here than will be needed, as the floor pan section is larger than the hole he cut. He can now place the new floor pan over this opening, then cut around the new pan so it falls into place.

The pan after all four sides have been butt-welded into place as the old floor was cut out. The welds have not been ground down.

The floor pan section is completely welded in place with the welds ground down. Four steps of sanding will further even the weld. When primed and painted, it will be impossible to determine that the floors were replaced.

A two-part, catalyzed seam sealer is placed over the butt-weld seams to add another layer of protection against water entering the car.

Ta-da! The finished floor now looks just how Chrysler originally built it.

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