1955-1959 Chevy Truck Firewall Replacement - Firewall Fixin'

After removing the transmission cover, Kevin could assess the floor damage. The area in front of his foot was forced down when the firewall came back, but the mounting bolt at the front of the step was still in its correct location, making this an easy repair. If that had moved too, the cab would require pulling back to shape on a jig or be scrapped.

Using a 2x4 and a floor jack, the floor was pushed back up along the crease, while another 2x4 was hammered down either side of the crease. When the pressure from the jack was released, the floor remained flat. The lower section of firewall had been pushed forward again too, back to its original position. The trick is to work out how it's been damaged and then work backwards from that point.

With the damaged A post closing panel roughly cut off, the kink in the cowl (arrowed) could be worked out. With much of the stressed and bent sheetmetal now removed, this came out easily using a pry bar and a block of wood to press against, spreading the load on the inner panel.

Kevin could now turn his attention to the upper firewall area, again using a length of 2x4 and a hammer, this time through the glovebox aperture, to beat the metal back to close to its original shape.

With most of the damage roughed out, Kevin drilled out the spot welds holding the remaining section of firewall in place. He prefers to use a Roto-broach, but you can buy dedicated spot-weld removal drills.

This is what you should aim for, each spot weld drilled out but without drilling all the way through the second layer of metal behind that which you wish to remove.

With all the welds drilled out, the section of firewall was removed and discarded.

Once the remainder of the firewall was removed, Kevin was able to dress the lip and straighten it in preparation for the new sheetmetal. The remainder of the kink in the upper firewall was also straightened using the hammer and dolly at this point, having been roughed out in step 10.

Ready to install the new section. Note the original firewall was split down the center of the trans tunnel to allow the passenger side of the firewall to come forward more easily while the floor was being repaired. You can see it's back to where it should be now.

As the new firewall is recessed, the section of the steering column support bracket nearest the center of the truck will no longer fit, so Kevin trimmed it and will rebuild it to reach the new firewall later.

After deliberation, Kevin decided he'll fabricate the toeboard sections of the firewall rather than attempt to repair the damaged original, and we'll show you this in part two of this story, along with replacing the A post closing panel.

Clamped in and ready to weld. As this particular truck had been damaged, Kevin took care to ensure everything was in alignment, and that the fold halfway down the firewall was in the same place on both sides.