67-72 C10 Rust Repair: Cab Floor & Rocker Panel Replacement
Old Chevy trucks were never meant to be desirable collector vehicles. Instead, they were made to be put to work and then discarded when they were no longer useful on the farm, jobsite, or hauling stuff for the family. But the General screwed up and instead made trucks that were just so beautiful that all these years later we just can't get enough of them. But given their humble origins, often those that are still around are in pretty rough shape. Our '68 C10 project truck was no exception.
Common C10 Rust Repairs
C10 trucks were built with some unfortunate “cup” shaped pockets along the bottom of the truck. While necessary to support the cab and fenders, these pockets tend to fill up with dirt, salt, mouse nests, and just about anything else that can sneak in over years of use. Of course, this debris holds moisture and causes rust in these areas. The problem is made far worse in regions where road salt is common. That’s why the joke around here is that these things came from the factory with rusty rocker panels. There are plenty of rusty C10’s in the Midwest.
What are the real problem areas? First, as mentioned above, it is very common for these trucks to have rust in the rocker panels. These are among the first things to fill up with junk from the tire tread literally pointed right at them. The outer edge of the floor panel forms a vertical “inner” rocker that often rusts right along with the outer. Expect to replace both. Behind the rockers, the cab corners are also almost always rotten. The floor and door panel form what is basically a black hole, with the cab corner at the bottom. Expect to replace these as well. Even if they’re not rusted through, they will almost certainly be thin. The condition of the floor will vary, but often will be thin and require patching. Hidden below the floor are cab supports that form a box section from the cab mounts out to the rocker. There are two front and two rear and they are often rusty as well. Hidden underneath the front fenders are the door pillars where the door hinges bolt on. Very rusty C10 trucks like our ’68 will have rust in the bottoms of these as well.
Moving on from the cab, the front fenders also have some nasty little pockets both in front of and behind the wheelwell. Inner fenders tend to rust at the front corner where the little brace is spot welded on. The core support tends to rust where it meets the inner fenders, and the battery mount bracket is almost always toast. These pieces are easy to replace and are often less of an issue than rust in the cab. Pay attention to the cab first, then the front clip and box.
If you’re shopping for a project, take a close look at these areas so you know what you’re getting into. Ask yourself honest questions about how in-depth you really want to get with your restoration project. Money spent on a better truck at the outset might save a ton of time and money down the road. That said, buying a rusty truck and bringing it back to life like we did is not only a good way to get into a project on the cheap, but it’s also rewarding to breathe life back into something that was left to rot.
Internal Bracing for C10 Cab Repair
In the video above, you’ll see us bracing up the cab with some square tubing. This is a very necessary step on a 67-72 C10 floor pan replacement. We’ll get to that process in a minute, but the general rule here is that any time you cut away a significant chunk of the cab, it needs to be braced to prevent it from twisting out of shape like the flubber car. Welding fresh sheet metal into a cab that’s shifted significantly will cause endless headaches when it comes time to align panels and bolt on doors. Use your best engineering eyeballs and weld or bolt in some 1”x1” steel tubing to keep everything where it belongs. It also doesn’t hurt to take some reference measurements to be sure that the cab stays put.
C10 Floor Pan Replacement
Once our cab was well braced, we were ready to tackle our 67-72 C10 floor pan replacement. Individual floor panel patches are available, as well as C10 cab support replacements, so why did we choose this route? The short answer is that it was the right way to do the job. It may seem daunting to blast the entire floor out of your truck, but in the end it saves the tedious process of patching in little pieces and replacing the cab supports underneath. The floor is entirely fresh sheet metal with no weld seems that need to be covered up. We found that once we had cut, ground, and otherwise beat the original floor out of our truck that our 67-72 Chevy cab floor replacement went very smoothly. Everything lined back up as it should and within an evening we were looking at a fresh floor in our truck. For more on what this looked like, check out our C10 Build Episode 6.
C10 Cab Support Replacement
If you elect not to do an entire 67-72 C10 floor pan replacement as we did, you’ll likely find that the cab support brackets are either completely shot or at least very thin. These brackets are under the floor and brace the rocker panel to the cab mount and are often called cab supports or cab mount brackets. They offer significant strength to the bottom of the cab, so you should pay close attention to these and expect to do a C10 cab support replacement. These are spot welded to the C10 inner rocker panel as well as the floor. If the surrounding sheet metal is good, take care not to damage it while drilling the spot welds. We like to use a Rota-Broach in these situations. Replacement will require some fitting, punching of holes in the flanges, treatment with weld-through primer, and thorough rosette welding where they meet the floor and inner rocker.
C10 Door Alignment
If you’ve taken your rusty C10 apart to tackle all of this C10 rust repair, you may have the doors leaned up against the wall in the shop. It’s very important that these are installed and properly adjusted before you move on to the rockers and cab corners. Pay attention to the gaps at the rear of the door, around the top where the window channel meets the cab, and even at the front. We hung a fender on our cab to be sure that this area of the door was also correct. C10 door adjustment is pretty simple as there are floating nuts inside the door pillar on the cab. Be sure that these are freed up and moving around as they should. These will adjust he door up and down, while the slotted holes in the hinges allow you to adjust the top and bottom of the door independently. Extra care during this step will ensure that your 67-72 C10 rocker panel replacement and C10 cab corner repair are successful.
C10 Rocker Panel Replacement
67-72 rocker panel replacement is almost a guarantee on any truck that has not already been restored. In the video above, we go into detail on this process. You may find, as we did, that the door pillar bottoms are also rusty. You’ll also see us doing some massaging of our replacement rocker panels. The bottom line is that every truck is a little different and these panels are all a little different, so expect to do some hammering, twisting, and maybe even cutting and welding to get these to fit as they should. As with all of these processes, some extra time and attention will yield the best results. It can be frustrating, so if you find yourself lost and about to cut a corner, stop and go have a soda or something. You may find it will all look a little better when you return to the job with fresh eyes.
C10 Cab Corner Repair
C10 cab corner repair is another job that you should be expecting. This process is fairly self explanatory and we go into detail in the above video. Perhaps the most important concept here is that you do not need to blast a giant hole in the cab to replace the big chunk of cab corner sheet metal that will come in the box. Most of these trucks are only rusty on the bottom few inches, and your job will be a lot better and a lot easier if you only replace what’s necessary. You’ll also notice that we used clecos and tabs to do our C10 cab corners. Pay close attention to this process in the video, as it’s a game changer for sheet metal work like this.
C10 rust repair can be a tedious and dirty job, but it’s an important part of restoration of these trucks. We hope that seeing us do this job and the parts we used on what was an extremely rusty C10 helps you to start planning your own C10 rust repair job. We had professional help from our friends at No Coast Custom and Rod Shop, but the same job can be done in the home garage with a good MIG welder, a decent compressor, and an angle grinder. Also note that the same processes will apply to a 4wd truck. K10 floor pan replacement, K10 rocker panel replacement, and K10 cab corner replacement will look just the same.
Speedway Motors carries just about any replacement panel you can think of for these trucks, so we’ll have what you need to get going on your restoration!
For more on our project, check out our ’68 C10 Build Page.
