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1972 Porsche 914Repair and Restoration - Part 5 - Driver Side Longitudinal2/8/2009I am working on putting the jack receiver tube and pyramid back in place and would like to do this on both sides at the same time so that they will be identical. Additionally there is more evidence remaining on the driver side as to the exact location (front to rear) of the pyramid. Basically the previous owner had ground off the bulk of the pyramid and the first layer of skin under it, but the edges remain and this allows me to measure it's exact location. One thing that I don't have is the depth of the outer skin under the pyramid. Basically there is an indentation under the pyramid that the receiver tube is recessed into. I want to replicate this depth correctly because it will allow the tube length to be correct and at the same time not stick out beyond the edge of the rocker (once those are installed). I started this 914world.com forum thread to get some info as to what the dimensions are for an unmolested factory jack receiver tube and pyramid are. I had some dimensions, but not enough to determine how deep to recess the tube. Here is the diagram from that thread...
As it turns out, C = 30 mm, so D = 13mm. So the recess needed to be 13 mm. I apologize as the photos look upside down. That is because the driver side in my garage is against the wall, so it was just easier to rotate the car on the rotisserie so that it was closer to my work area, but upside down. The the photos are upside right, but the car is upside down.
As left by the previous owner. You can see the pyramid is mostly gone as well as the outside skin of the longitudinal. This weakens this area as well as exposes the hold in the inner double wall.
More of the longitudinal. It is solid on the driver side.
More of the same.
I will deal with this rust later. I also expect that I am going to need to remove the "sill" on the driver side just like I did on the passenger side.
More stuff to deal with later.
More of the sill.
Another small hole to fix later.
I expect the DOT sticker is not going to survive all of the repair work.
Just like the passenger side, I have cut a bit of the fender away to get at this area. I know some people repair this without cutting the fender, but it sure is easier with a section of the fender removed. I have also done a first pass at media blasting as well as treating with Ospho. The black sections is rust the is not flakey, but is also very hard. Because it's very hard, it's also very hard to remove via media blasting.
More of the problem area on the front. I think that once the sill is remove this should not be too hard to repair.
After measuring the exact location front to rear, I drilled out the remaining spot welds and removed the last bit of the pyramid.
Move media blasting to remove as much of the last traces of rust.
Upside down. 3/22/2009I am welding both the the driver and passenger side receiver tubes in place at the same time. The passenger side receiver tube and pyramid was totally gone. On the driver side the flange of the pyramid was still there. So I was able to measure it's exact location. The pyramid measured 127mm wide. It's edge was 40mm away from the seam from the front and rear sections. It was also 135 mm away from the top edge of the raised section on the longitudinal. There are multiple raised sections and each are about 150 mm apart. I would not be surprised if it as to turn out that the receiver tube was +/- a few millimeters either way on different cars. There is some evidence that mine from the factory left to right were not identically placed.
After finding the position I tack welded it to hold it in place. Then...
Checked the position with the pyramid in place. Here you can see the 135mm measurement.
Now with the position confirmed, I do the final weld. 4/12/2009More work on the jack point...
As with the passenger side, I have used POR-15 to coat the inside of the pyramid. Then weld in the pyramid. Prior to welding I removed the POR-15 in the small area in which I would be doing the rosette welds. You will notice that my pyramid has a non-stock hole in it. I basically added a drain hole and also made it large enough that if debris gathers, I can dig it out. Many people do not replace a rusted jack point and pyramid. In my opinion one of the reasons they rust is that this section is enclosed and can't properly drain. 4/16/2009Now I need to remove the old sill plate. I do this by drilling out the spot welds as well as cutting away the triangular supports.
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