Swinger Nova: Floorpan Repair with Classic Industries

In the beginning, God created Nova. And that was good.

Did you ever buy something secondhand that looked good cosmetically, and when you went to repair a minor part you found that there was a lot of hidden damage? That’s pretty much the story of our Project car – The Swinger Nova. In this segment we are going to be replacing the rusted floor pan on our project car with some quality floorpan restoration parts from Classic Industries in our very hot, Southern California PowerTV garage.

When we first brought Project Swinger to the garage, we knew that she looked good from far. However, we soon discovered.. she was far from good. We started to tackle the problems that we knew about. Before long, our list has grown by orders of magnitude to at least the 10th power. Like peeling an onion, each layer that we stripped, we cried a little more.

This was the horror scene as we removed the carpet. Rust and more rust. It was not good

It would have been easy to cry over spilled milk on this project, but that’s just not the way we operate in the very manly PowerTV garage. There’s no crying in project builds. Not in this garage. Not on our watch. Armed with a full set of professional tools from Cornwell tools, we dusted off the pneumatic cut off wheel and our welding equipment for the PowerTV version of “cut and paste”.

First, we’re going to give you an overview of the Nova and why these GM vehicles are so suspect to rust. Then, we’ll overview what Classic offers in terms of restoration components. Finally, we’ll show you how to do the job, correctly, the first time.

Nova = GM’s Affordable Car in the 1970’s

GM redesigned the Nova to be an entry level economy car for a younger crowd in the later 60’s and early 70’s. Small enough to fit in any budget, but big enough to hold a family of five, the Nova enjoyed great success. Best of all, it was still available in the small block Chevy V-8 engine. The optional V-8 engine made the Nova a popular platform for the gear heads that wanted a lightweight and muscular street performer.

The Nova, 37 Years Later

It’s been our experience that a car’s life extends to the limit of your warranty. The day after the warranty expires, the car dies. Or at least that is what it feels like. Our Nova has lived a long eventful life, well past any factory warranty. However, time affects everything. Our project is no exception to that rule. In stripping the Nova for a couple of upgrades, the crippling existence of time and age unveiled itself.

We had rust, which is very common an a Chevrolet Nova X-Body such as our 1971 model. The most common areas of rust on this particular body style are:

  • Passenger & Driver side front floorpans (windshield seal leaks)
  • Lower Doors
  • Rear Lower Quarters

Since our car was already painted, we weren’t sure how bad the quarters and doors were (yet), but we knew we needed to do the floorpans. It was obvious. You could see daylight through them.

When you can see the asphalt from the road through the floorboard…..it’s never good.

There are a lot of considerations when deciding to replace or restore part of the floor pan. Sheet metal is fairly easy to work with, but there is some skill and special tools involved in tackling this task. Welding sheet metal is almost an art form, and using the correct welding equipment is essential to do the job properly. Additionally, choosing restoration parts that are comparable to the original is critical to welding success. Restoration floor pans that are made of the same or similar metal as the original make the task easier, and the replacement parts should have the same shape and molding as the existing pan.

There is hope. It’s called Classic Industries.

Amidst the despair and gnashing of teeth in the project build meeting to determine the solution for this problem, a cavalry came to the rescue.

Classic Industries in Huntington Beach, California. Classic is a very well known company which specializes in manufacturing restoration parts for GM cars. Chances are, if you love old GM cars and Trucks, you know about Classic Industries. Classic has it all covered for classic Camaros, Firebirds, Chevy II and Novas, Impalas, as well as GM & GMC Trucks.

“We offer a couple of different product lines that can support almost any budget, from original equipment reproduction pieces to GM licensed reproductions,” explained Tony Columbini from Classic Industries.

We spent some time looking through the Classic Industries Nova Catalog and decided to replace only the portion of the floorboard that was rotten. The front half of the driver’s and passenger’s floorboards and the firewall extensions on both sides, were the only areas that were not solid.

About Classic restoration floor pans:

We found the restoration floor pans from Classic Industries to be an identical match to the original floor pan:

• The sheet metal used in the construction of the restoration pieces was the same caliber as the OEM factory metal, which made the welding easy and consistent.

• The restoration floor pans had every bend, turn and crevice that the factory floor pan had. We gave these products two thumbs up for making what used to be a difficult restoration a much easier project.

Parts

1) Front LH partial floor pan. Part# 107211
2) Front RH partial floor pan. Part # 107212
3) Firewall extension LH. Part # C126L
4) Firewall extension RH. Part # C126R
5) Primer
6) Seam Sealer

Tools:

  • Floor Jack
  • Jack stands (4)
  • Safety Glasses
  • Gloves
  • Pneumatic Die Grinder with cut off wheel.
  • Flat hand file.
  • Utility Knife
  • Pliers
  • Wire brush or rotary brush.
  • Pneumatic hammer with chisel bit.
  • Welding equipment (MIG or TIG).

The Choices

Classic offers floorpans for the Nova in several variations. Full floor pans, front half floor pans, and rear half floor pans – all available in left and right side configurations. Also, a floor pan firewall extension is available which runs from the front of the floor to the firewall (it’s kicked up at roughly a 45-degree angle).

For our application, we needed two front half floor pans – left and right – as well as the same matching set of extensions.

Let’s Get Started

Now we’re ready to start the project. We’ve identified the problem area, found our replacement reproduction floorboards and talked to Classic Industries Tech department to get the skinny on doing the job. Edd Stevens, Classic Industries Technical Advisor, reminded us to “support the body with weight off of the chassis, take your time and weld it straight.” According to Edd, every car is different with it’s own issues, you must assess what you have and based on your experience, how best to approach it. There is no wrong way when installing patch panels, it’s not set in stone, but it is important to arrive at the same point with a straight chassis and a restored floor pan that looks great.

It didn’t take long for the new floor pans to arrive, so we gathered the tools that we would need. We began by raising the Nova and supported it on jack stands. This step allowed us to have easy access under the car and it provided crucial support to the structure. Having the body twist when the sheet metal is cut away would be a disaster. Supporting the chassis with jack stands and only cutting out one panel at a time will help keep the body from twisting.

The first “hands on” step in this project is the one that requires the most patience and a good eye for detail; laying out the new floorboard on top of the rusted floorboard for measurement. The old adage of measure twice and cut once works real well when you’re working with lumber. Metal is a different matter. Literally. Measure twice and cut a little, measure again and cut a little more.

Decisions, Decisions

You will have to make a decision at this point. There are two different ways to weld the new floor pan patch panel into the body. You can use the new patch panel as a template and cut out the old metal to the exact fit of the new panel, and butt weld the panel in. The second method is to cut the old floor pan to nearly the same size as the replacement panel, leaving about an inch of extra material all the way around so that the new panel will overlap the existing floor pan.

Choosing to overlap the metal means that there would be an increased chance for future corrosion and some issues with creating a flange so that the new panel will sit flush into the existing floor pan. However, overlapping the metal may make it easier to weld than the exact fit method. This decision needs to be made based on experience in welding. Welders with limited experience in sheet metal repair may find that butt welding a new floor pan in place difficult and frustrating.

Let the tools do the work

The best practice when cutting the sheet metal is to use your power tools, whether it be pneumatic or electric, and not to force them. Let the tools do the cutting, after all, you paid good money for the tools, let them do the work. Pay close attention to what is on the other side of the metal. You can easily cut through a support or cross member causing damage that may not be repairable. If your floor pan is as rusted as ours was, wearing eye protection is not only smart but necessary to prevent rusted flakes of sheet metal getting into your eyes. A sturdy pair of leather gloves will keep you from a quick trip to the hospital for a tetanus shot when you cut yourself on the rusted metal.

There is seam sealer on the outboard edges of the floorpan that will need to be removed prior to cutting the sheet metal in those areas. A box cutter knife works well to cut that seam sealer and a pair of pliers can be used to pull the sealer out of the crevices.

The old floor pan will be spot welded to any bracing and cross members that are running under the car. Many people drill through the spot welds or grind the spot welds to remove the old floor pan. Of these two, grinding the spot welds would be preferable. We chose to take a path less traveled when dealing with these spot welds. A pneumatic hammer with a chisel bit made a nice clean separation at the weld.


The floor pan is spot welded to the cross brace. These spot welds will have to be broken to remove the sheet metal.

Once the old floor pan metal is pulled away, you can see the sub frame and cross members. Any part of the spot welds that are still attached to the cross member can be ground down and the surface can be prepped for the new floor pan. Edd reminded us to check the toe boards and surrounding areas for any additional hidden corrosion that may be laying in wait.

We had decided to butt weld the new floor pan to the existing pan after we cut out the rotten material. In our opinion, a floor pan that is butt welded has a cleaner or more sanitary look but requires more effort and time. Remember, patience is the key here. Using the new floor pan as a template, measure and cut the car’s floor pan until the new floor pan is a snug fit. Files can be used where small amounts of metal need to be removed around the edges.

Once the opening is the exact size to fit the new floor pan, it can be tack welded in place. There may be some areas where the floor pan and the restoration piece don’t match exactly. Using the pick end of a body picking hammer, tap the metal until they match perfectly.

Putting the new firewall extension in place. Note the separation on the upper left corner. The metal can be moved by using a body hammer until it forms a close seam.

The panel can then be tack welded on all sides. What we found that works well is to tack weld a new panel near the corners first. Then move to the middle of each of the sides and place another tack weld. Then, place another tack weld in between the tack welds you did previously. It is important to keep the heat from warping the sheet metal and these tack welds will serve as a guide.

Start welding from one tack weld to the next nearest one. When you have joined those tack welds with a full bead, move to the opposite side of the floor pan and fill in the gap between two spot welds on that side. Staggering your welding from side to side will help keep the heat from warping the metal.

File fitted. Clean the metal and it’s ready to be welded.

A quick word about welding.

Welding floorpans can be done by several methods. The method most often used seems to be the MIG welding process. TIG Welding the pans is also very popular but takes a little more time and skill. A smaller tungsten rod and 100% argon shielding gas will give the best chance for a perfect weld. The sheet metal used in constructing floor pans is a thin gauge that can be “burned through” rapidly. Heat control setting vary between welding machines, so doing a practice run on some of the metal that was cut out of the floor pan area would be a wise idea. If you don’t have experience TIG welding sheet metal, you can expect to burn through the floor pan sheet metal in several places.

MIG welding can be done with wire and shielding gas or flux cored wire and no shielding gas. When welding sheet metal, .025 welding wire with shielding gas (75% Argon & 25% CO2 blend) is the best method. And remember: You can’t weld rust. No matter what method you use or how hard you try, rust doesn’t weld. Clean the metal before you weld.

Prepping the metal for welding.

To MIG or not to MIG

We compromised. With a little time and effort, we were able to get the panels to line up perfectly with the existing pan. We tack welded the edges and stitched the pieces of metal together with a MIG welding machine. Once we had a full bead around all sides, we touched up the high spots with TIG welder.

Once the floor pan and firewall extension were completely welded in place, a coating of primer was sprayed over the seams for corrosion prevention. We used a shop light beneath the car to look for any pin holes or areas in the seams where there was a gap.

The restoration floor pan and firewall extension from Classic Industries matched the existing

Finishing Touches

To complete the project, we took seam sealer and applied it around the restored floor pan. The job was not complete until we applied sealer around the seams on the bottom side as well. The pictures below show how the final portion of this project came out.

Article Sources

About the author

Bobby Kimbrough

Bobby grew up in the heart of Illinois, becoming an avid dirt track race fan which has developed into a life long passion. Taking a break from the Midwest dirt tracks to fight evil doers in the world, he completed a full 21 year career in the Marine Corps.
Read My Articles

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