The rusty sections of this floor needed to be treated to stop further rust. It was then repaired using traditional body work techniques.
Tips for do-it-yourself unit-body floor pan restoration
By John Gunnell
Many unit-body cars need floor panel repair or replacement. Whether it’s best to fix an isolated rust hole in the existing floor or cut it out completely and install an entire floor pan depends on the size of the hole and your preference. The floor pan is an important structural part of a unit-body car, so large rust holes or widely dispersed pinholes mean a new floor pan is in order. However, if the rust is isolated, new patch panels can be installed, thus saving some of the original sheet metal and money in your wallet.
The actual size of the hole is rarely visible before sandblasting. It’s not until the panel is blasted, poked and the rusty metal is cut away that the actual damage is obvious. What started out as a small opening can become a huge crater. If you have a crater, you’ll need a full floor panel. New panels can come as a single piece that is part of a complete replacement floor or as right- and left-hand panels that run the full length of the floor on each side of the center transmission tunnel, or as quarter pieces for the right front footwell, the right rear footwell, etc.
 |
BAD Dust® Containment Systems Reusable, modular containment bags designed to shield airborn dust and friable materials created by treating surfaces with media-blasting equipment or other mechanically operated hand held tools. www.baddust.com |
 |
Auto Paint Specialists Tower Paint™. APS/Tower Paint |
 |
C&G Early Ford Parts C&G Early Ford Parts for 1932-1979 Ford car and Ford truck parts! Service, selection, knowledge, and quality. Come experience what folks who have old cars can do for you. www.cgfordparts.com |
 |
Continental Western Group It’s all about value! No matter if you’re talking about Agreed Value |
Out with the old
Before cutting out the old floor pans, make sure the body is fixed squarely on the ground or in a rotisserie (this is especially important on convertibles). Bracing the body while it is square will ensure the floor pans are not welded in place while the body is twisted, thus twisting the body. Brace the body in the door openings and from side to side and front to back and anywhere else there is an opportunity for the body to twist.
If you haven’t already done so, remove the seats, carpet, console (when equipped) and anything else that may hinder access to the floor. If possible, use a media blaster to clear paint, rust and other debris from the top and bottom of the floor pan for an accurate view of the rust’s extent. Then examine the floor section that will be replaced. Many restorers prefer using a one-piece panel and replacing the entire floor. However, two-piece full-floor panels or even half panels are easier to install if they are big enough to replace the rusty section.
For example, if only the driver floor and passenger rear floor in a unit-body car such as a Camaro are rusty, you may wish to install these two footwell replacement panels.
Cut out the rusted-through sections of floor that can’t be saved and give other parts in the area a coat of red oxide primer to stop rust.
 |
LoJack for Classics Classic cars are stolen every day. Get yours back with LoJack for Classics. Providing a 90% success rate in tracking and recovering stolen cars and trucks, LoJack now offers a stolen vehicle recovery system designed specifically for your one-of-a-kind pride and joy. Visit www.lojackforclassics.com, use promo code CCEML295 to save $400. |
 |
Qual Krom For the past 24 years Qual Krom has been meeting the needs of their customers by providing chrome restoration service second to none. Count on us for your next chrome refinishing project! |
 |
JC Auto Restoration JC Auto has been in business for 34 years restoring a variety of vintage automobile components. We have an extensive inventory, specialing in hard-to-find parts for Chrysler products. www.jcauto.com |
 |
Steele Rubber Protect your vehicle with quality rubber parts. Don’t forget to check the quality of your original rubber seals. Over time, weatherstripping and rubber parts can degrade. Steele Rubber offers a complete line of quality rubber parts for American-made vehicles from the 1920′s-1990′s. |
Cutting out the bad sections of the old floor can be tricky, so do this carefully and try to get the best tools available. An Air Whizzer tool will help and an air saw with a very small, thin blade comes in handy. An angle grinder fitted with a cut-off wheel can also be used.
Another option is an air-powered chisel, if a large compressor that won’t leave you high and dry on air every few seconds is available. The ultimate tool for the job is a plasma cutter.
Now, cut out the bad sections of the old floor and trim the replacement panels to fit inside the cut out area. They will be butt-welded in.
 |
Midwest Power Products, Inc. We specialize in rebuilding treadle-vac, master-vac and hydrovac power brake boosters for classic cars and trucks. In addition, military, agricultural and industrial applications. We also offer .304 stainless steel sleeving service, rebuilding kits and a full line of new brake components. |
 |
CUSTOM PLATING SPECIALIST We specialize in restoration, show quality plating and salvaging damaged chrome parts that other platers have ruined. |
 |
Northwestern Auto Supply An old time parts store since 1946 with 4 buildings full of old inventory of antique and classic parts for the quality minded owner who wants to avoid off shore products. Engine, chassis, ignition, and brake parts shipped world wide. Machine shop and babbiting also. www.northwesternautosupply.com |
 |
RestoreATag RestoreATag, the premier tag restoration company, uses a unique process that makes even the ugliest, rustiest tag a beauty to behold. Regardless of your state, we can restore an existing tag or create a vanity tag just for you. The options are endless! restoreatag.com |
Install only the portion of the reproduction panel needed to replace the rusted out metal. After the panel is welded in, finish the seams using waterproof fiberglass filler and sand the fix smooth.
In with the new
Butt-welding eliminates overlapping sheet metal with gaps where corrosion could re-start. With a MIG welder, weld the trimmed panels in place, putting tack welds at all four corners and filling in the seam with tacks every few inches around the perimeter. Once the new panel is tacked in place, weld different areas a few inches at a time to keep the pan from heating up and warping. When welding, wear a welding helmet and welding gloves.
 |
soundmove.com Restoring a classic car or truck? Compliment your restoration with a classic look radio that fits and blends right in. Our radios have the appearance of the factory original but with today’s electronics. www.soundmove.com |
 |
Tee-Bird Products, Inc. Stocks a large selection of quality parts for 1955-1956-1957 Thunderbirds and 1955-1956 Ford. Prompt shipping and knowledgeable service since 1973. Call 610-363-1725 or visit our website. |
 |
Vintage Thunderbird Club International Vintage Thunderbird Club International is the largest ALL Thunderbird Club in the world! You can find us at www.vintagethunderbirdclub.net. Stop by and check us out, you can join the club on our website, we also have a very informative forum for all your Thunderbird questions. Get the “VTCI Experience!” |
 |
ClampTite The CLAMPTITE TOOL provides a means of tightening wires wrapped around an object and then locking it in place. The tool can be used with various wire sizes which eliminates space and strength issues often encountered with screw operated worm gear type clamps. 1-800-962-2901 www.clamptitetools.com |
On top of the floor, where carpets will cover the very solid repair the waterproof fiberglass filler can be left unsanded if you want only a basic repair.
Once the panel is welded in place, grind the welds under the car smooth. Leave a little weld on top for extra strength. Then, use Marson Mar-glass fiberglass filler to add strength. This green filler is a waterproof fiberglass filler that mixes like regular filler with a small amount of hardener. It’s applied like filler, but has added strength due to the small fiberglass strands in it. Use it for initial coats over the welds. Then, apply tan Marson Golden Extra on top of the repair for final shaping and forming. After applying tan filler, use whitish-blue Evercoat polyester glazing putty for final fills. It’s thinner than filler and fills sanding scratches and air holes.
Also use Marson Golden Extra filler to smooth the underside of the floor patches to make the surface look factory new. This work can be done without a rotisserie, if you’re willing to spend hours laying under the car with dust falling in your face. A rotisserie is a nice piece of equipment, but not a necessity.
 |
Automotive Wiring and Electrical Systems is an enthusiast’s guide that takes the mysteries out of automotive electrical diagnostics and repair. |
 |
In Automotive Bodywork and Rust Repair, Matt Joseph shows you how to tackle both simple and difficult rust and metalwork projects. |
A word about replacement panels
Complete one-piece floor pans are favored by many restorers. Prices for full floor pans range from $250 to $400, depending on the source and application. Note that all replacement panels may need minor tweaking to perfectly fit, but better-quality, U.S.-made replacements tend to need the least amount of preparation and installation work. Quality floor panels come with better features such as caged nuts for attaching the floor pans to a unit body sub-frame mounting, seat belt anchors, rear seat bottom anchor hooks and torque boxes.
If you liked this article on floor pan restoration, you might be interested in:
- Old Cars Guide to Auto Restoration CD Volume 2
- Eddie Paul’s Paint & Bodywork Handbook
- The Collector Car Restoration Home Video Library DVD Set
More Resources For Car Collectors:
- Classic car price guides, research, books, back issues of Old Cars Weekly & more
- Get expert restoration advice for your classic car
- Get car pricing, data and history all in one place
- Sign up for Old Cars Weekly’s FREE email newsletter
- Need to buy or sell your classic car? Looking for parts or memorabilia? Search our huge online classified marketplace
while your repair is good , to really keep rust away ,cause rust accumalates under body filler and yes fiberglass too i always use epoxy primer first ,then apply the filler,, the way you did it is tyhe old fashion way