Front frame rail assembly installation

Time to install the new frame rail/shock tower assembly. It drops into place by settling into the floor support and then bolted to jig so I could start positioning it for welding. I used lots of clamps and measured everything many times before actually welding anything.

Welding in the new assembly consists mostly of plug welds and a few bead welds, all per the Weld & Sealant manual:

  1. Rear apron to Firewall
  2. Floor support to Frame Rail (inboard, outboard, and bottom
  3. Strut rod mount to Frame Rail
  4. Transmission Support to Floor Support
The welds where the frame rail meets the radiator support will be done after I get the new radiator support in place, so that whole front corner isn't welded here.

 New assembly placed into the jig and screwed to the car for fit testing. It took a while to get it placed just right - the jig gets it close, but a human needs to get that last 1/16" inch all around. The tolerances are wider than modern cars, but you still need to try to get it right.

 Fenders and Hood are placed on car and bolted in for fit testing. This was exciting, it sort of looks like a car again for the first time in a long time.

 Hood to cowl gap is checked to make sure the hood hinge on the passenger side is located correctly.

 Gap checking all around the hood and fenders. Those are original factory parts, so these gaps are not due to poor reproductions.

I also took the time to mock up some plates for welds and place them at similar orientations so I could practice plug welds upside down while on my back.


Each pair of plates is the same gauge as the real pieces on the car, and I pull-tested the welds to make sure they were properly penetrating.

Here's the test stand - really just a portable workbench that I set the test panels on upside down so I could practice how to weld inverted and get proper welds out of it.

Sheet metal screws were used to tie the pieces together nice and flush, the holes are plug welded in, and then the sheet metal screws are removed. I'll go back later and fill those holes as well.

Remember this gap between the rear apron and the firewall? Ordinarily, you'd just pull the pieces together and spot/plug weld them together. But my gap is a little larger so I needed something clever...

Now for something clever. I pulled out my rear apron replacement (ordered back before I knew I had a frame rail issue as well) and decided to section out the rear flange and use it as a 'bridge' between the new apron and the old firewall. You can see where I already cut a piece out for patching the floor pan way back when.

This is way easier than trying to custom-fabricate this piece from scratch.

Drill a bunch of holes on both edges, screw it into place and weld it in. Yes, that's a lot of welds - the factory would've had about a dozen at this interface, so I wanted more than that.

Welded the strut rod mount to the bottom of frame rail, using factory locations again. Another inverted welding session - I'm really glad I spent time practicing this. Only dropped one red-hot flaming glob of weld metal on me. Yowza!

My union-mandated sideways pic here is showing the inside of the transmission brace where it's welded to the floor support, factory-style. This is much harder with the floor in place, just sayin'.

A couple more welds through the floor support to the tab on the bottom of the transmission tunnel brace. I used one sheet metal screw here to hold it in place for the two welds.

And follow it up with the last of the red oxide SPI epoxy primer. I'll weld the floor patches in later.

The new assembly is in place and measures up correctly according my list of dimensions. The export brace and Monte Carlo bar on top were used to help get everything placed correctly.  This was a lot of work over several weeks, but I'm so glad to put this little saga behind me.

Next up is removing and replacing the radiator support and front crossmember assembly.