How to Replace Trunk Floor Panels- 1967 Chevelle
This car. You know the one I’m talking about. The beloved ’67 Chevelle that was such a great barn find. Well, it was a little bit of a rot box. By a little bit, I mean it had most of the top half intact. From the doorjambs back and the beltline down the old body man got pretty creative. After going for a $3000 ride with a body guy who was quickly cut beyond his skill-set and bringing the car back home in disgust, I was at the bottom of a very steep learning curve. I had never done extensive panel replacement or structural prior to this quagmire.
Fortunately, a friend of mine, Chris, changed all of that. He is an experienced body man and old drag racing friend and he came to the rescue on this lost cause about a year ago. We worked, talked and I of course watched. What I learned was that there’s no quick or easy way. There’s the right way, which takes as long as it takes, and then it’s done. I learned more in a couple hours that week than any book could teach. I’ll do my best to break it down into general rules.
Rule #1 – Find the factory seam and spot welds anywhere you can. Once found, drill and cut the spot welds and separate the offending panel.
Rule #2 – Don’t cut off more than you need. It’s hard to put it back when you make the hole too big. The previous hack taught me this lesson.
Rule #3 – Take your time and test fit everything carefully. The better it fits the quicker you will finish.
Rule #4 – Don’t take too big of a bite. If you need to replace a few pieces don’t cut them all out at once. You can use the old stuff to ensure correct alignment and maintain integrity while you mend the areas that years and nature took away.
Rule #5 – Replacement parts will probably need some work to fit. It’s a fact of life.
Okay, enough rules. Let’s pick up our program already in progress. At this point, Chris had already replaced both inner and outer wheelhouses, wheels arch panels, the lower quarters and the left side trunk floor section.
So really, this section of trunk floor is the last hurrah of heavy metal work for this car. As it worked out, Chris was pulled away by other projects and it was time for me to spread my wings and see if I’d picked anything up over the last year.
Fortunately, Chris left me in a good spot. He’d already replaced the left 1/3 of floor in the trunk after he did the wheel houses. Once he had pinned that section down and had spot welded it back onto the gas tank support brace then the center section while he cut it free. This was a huge advantage because I had no idea how or where to reference that support brace. Had both sections of rotten floor been removed at the same time the brace would’ve come with them.
I used Speedway's Sherman 705-76CT Restoration Center Trunk Floor . The panel was a little bigger than the area that was cut out, which is exactly what you want. I test fit and trimmed the patch panel. It had a flange stamped into both long sides that needed trimmed off. I should’ve taken more time to cut it twice, leaving a ¼” extra to play with. The ideal gap to butt weld the new metal in place is 1/16”-1/8”. This allows the spot welds penetrate well and burn flush with less grinding. I got it a little loose in a few spots. I did end up making a couple of filler strips to make up the difference.
As you can see in the photo below, you’ll want to drill your replacement panel along the braces and other structural engagement surfaces so you can plug weld them together. You need to scribe a line along the braces underneath to have a reference for the holes.
Once the panel is welded to the braces, you can slowly and methodically begin the process of butt welding the sheet metal in. The key is keeping your cool. Move from side to side front to back in order to keep warpage out of your work. Let an area cool before putting a weld in that area again. When it is cool enough to weld again, put one a couple inches away. Then split the difference when it comes around again. Once there’s a weld every inch, put one right next to the original spot. Do this until all the spots are connected. Tedious. However, once you grind everything smooth, you should be good to go.
Here is the completed trunk floor project.