We have seen a few different approaches to sheet metal replacement on bodywork and the inner structural components of the 911. The early 911 to '73 uses a welded door threshold/rocker panel as opposed to the '74 and later bolted on type.
Behind a permanent panel such as the rocker is likely to be an accumulation of dirt and rust, depending on where the car has been living and driven. Certainly salted roads are the bane of any unplated metal, especially concealed cavities.
We have seen a few different approaches to sheet metal replacement on bodywork and the inner structural components of the 911. The early 911 to '73 uses a welded door threshold/rocker panel as opposed to the '74 on bolted on type.
Behind a permanent panel such as the rocker is likely to be an accumulation of dirt and rust, depending on where the car has been living and driven. Certainly salted roads are the bane of any unplated metal, especially concealed cavities.
So, if you end up with a car that has such rust, you have to find it and eradicate it. A lot of the metal will be eaten away to the point of needing replacement. The purpose of this thread is to show a little of what I did and gather some thought from others on the subject. Eventually, the information here may be edited for a tech article. There are some tech articles for floor pan and longitudinal replacement in the 914 tech section, but nothing in the 911 section that I could find.
This has been discussed a lot, but the threads are scattered throughout the archives. One issue is whether to drill out spot welds or cut near the seam and grind. I used both methods in this most recent task.
Let me
link to the beginning of my project to avoid being redundant.
The first pic shows some of the 100 or so holes left by drilling spot welds on the inner and outer rocker ass'y. I guess one can use a special stepped bit, but they don't last long and are hard to sharpen. An ample supply of bits, a good drill motor and a drill bit sharpener will make this job go easier.
Here's an inner long from Pelican Parts that is being readied for installation.
I'm holding it down to reveal the cut off original longitudinal member that I'm using as a welding flange. Notice this side doesn't have all the spot welds drilled, just the ones needed at the ends. There is also a hand punch laying on the sill that I used to punch holes. This side will be a lot easier due to the flange. There is no reason to offset the piece or the flange.
Here's a cross section taken from a parts car. At the top, three members of the structure come together and they are spot welded every inch on the top surface and in the door seal channel. You can look back to the first pic and see what it looks like with the inner and outer rockers removed. The door sill is attached to the floor pan and that is the third member shown at the right. The tube for the heat remains in the section. This is where the muffler/heater hose fits on that runs the length of the long.
All clamped up and ready to plug weld the punched holes. You'll notice I didn't replace the jack reciever and support on this side as they were OK. I just shortened the inner piece and wedged it into the jack receiver support
The rocker is now in place to check the door gap. You must have the door on the car at this stage and aligned as you want it with the lock pillar.
It's plug welded now and the lap seams are welded here and there for extra strength.
I'll dress the welds with a grinding wheel and prime before shooting the body schutz (underseal).
Thanks to those that got me this far and please post your unique procedures for doing this job.