Using a rotisserie, an Eastwood MIG 175 welder, replacement stampings from National Part Depot and a BFH Kevin gets to work replacing the floorpans on the Zed Sled 1978 Chevy Camaro. After stripping the body shell inside and out, it’s apparent the floors are in much worse shape than initially thought. Luckily the under braces are still structurally sound, and the GM F-body has great aftermarket support, so replacement sheet metal is available. The toe boards, the area right under the dashboard, are not available but are relatively simple to make flat metal pieces. The next step is drilling out the spot welds on the braces, and marking and cutting the old floor out. Then the new one is laid so the location of the braces and edges can be marked with a sharpie.
Back in the shop Kevin fits the car to the floorpans using the angle grinder, cut off wheel and a big freakin’ hammer. Next he copies the location of the original factory welds all the way around, and drills about a million holes. After a little more cutting and banging and drilling, the new pan is ready to go in. A handful of sheetmetal screws hold it in place temporarily, and a million little holes get MIG welded through to what’s left of the old floor.
How to Remove & Replace Floor Pans: A Step-by-Step
In this episode of Hands on Cars Kevin shows us how to remove the rusty old floor pans on the 1978 Chevy Camaro Z28 Zed Sled project car and fit new replacement metal. After stripping the car down to the bone, it become apparent things are worse than expected.
1: New floorboards were needed from National Parts Depot, as well as some custom fab work to replace the rusted out toe boards directly under where your feet go.
2. When stripping the car, be sure to save things like rusty old brake and fuel lines to use as a template later for the new ones.
3: Eastwood PRE painting prep cleaner is used to wipe off all the protective rustproof coating on the new floorpan so it can be written on with a Sharpie and welded.
4: Lay the new metal on top of the old and it should be an exact match. Trace around the edges of new piece on the old floor and you instantly have a guide for cutting.
5: Cut out the old floor – There are several different ways to take out old floor pans and it depends on your budget and the car. If you have a plasma cutter you can make short work out of cutting out the old floor, if not a cut off wheel in an angle grinder, and maybe a Sawzall will do the same job, it will just take longer. Leave an inch or so of old metal all the way around to weld the new floor to.
6: Be extra careful to cut around the structural floor braces, you are going to want to reuse them if they are in good shape.
7: Once most of the floor is out, drill the spot welds holding the braces to what’s left of the floor with an Eastwood Spot Weld Cutter. When the spot welds are out finish the removal with an air chisel in just seconds, or manually with the big freakin’ hammer and an old chisel.
8: Use a handful of sheet metal screws and securely attach the new floor to the old edges.
9: Working from the underside, trace the edges of the old floor on the new one so you can more easily locate all the holes for the welds.
10: Take the new floor back out, and mark the location to drill for your eleventy billion plug weld holes. The structure of the unibody relies on the approximately 7000 plug welds GM used in the factory to tie it all together. Drilling holes in the new floor, and welding through to the old from the top helps pull it all together as you weld, for a more solid and water tight job.
11: Start drilling holes around the outside edges of the new floor, and the inner areas where it connects to the cross braces. Try to get as many welds as the factory used, and in the same locations for maximum structural rigidity. Make sure you have a good sharp bit before you start, in fact make sure you have a several spares as well.
12: Next finish prepping the edges of the old floor and the braces to be welded to. Eastwood Rust Encapsulater is a great preemptive measure to spray on the cross braces and any areas that you won’t be able to get at later when the floor is in.
13: The areas to be welded to should have been masked off first, those will be coated with an Eastwood self-etching weld through zinc primer which is made for situations exactly like this.
14: Temporarily attach the floor again with sheet metal screws, then start welding. The actual number of holes and welds is more like 300 vs than 7,000, but it still feels like a heck of a lot.
And that’s it, your project car has new floors, once you finish all those little welds. There is still the matter of the toe boards, but that is a job for another day.