There have not been many trucks that have come through the shop in the last 20 years that didn't need firewall work. We spent years welding up all the big and little holes. Spending hours block-sanding them on the show trucks for paint. Sometimes they had been butchered up badly, but were actually the worst parts of the truck. I have cut several "donor cab" firewalls to piece in sections I didn't want to make. So when Mid Fifty F-100 Parts announced a few years ago that they had replacement firewalls, we couldn't get one here fast enough.
The fit is beautiful and the install is a snap. The hardest part is being patient and drilling out all the spot-welds with a spot-weld drill. There are a bunch of them when you're removing the whole firewall. All up each side, across the top, on the visible lip, and at the toeboards. Not having an engine in the way sure does help. I actually slid the cab back on the chassis and did the work. When I got ready to do the floorboard replacement, I slid the cab back into place on the mounts.
This particular truck was in dire need of a driver side firewall and floorboard replacement. It looked like somebody in the past had tried to mount a Saginaw steering box in the truck and wanted to do it all from inside the cab. Then the gapping hole was covered with some bent road signs. Screwed down of course 'cause duct tape just wouldn't last here.
Knowing how well their firewalls fit, I ordered a driver side firewall, a driver side floorpan, and a trans cover from Mid Fifty. When it comes to parts for your Effie, you need Mid Fifty on your speed dial. These girls are the best to deal with and their customer service is second to none.
Once the parts got here, I started drilling out all those spot welds as mentioned before. It really only takes an hour or so. It seems like you are actually spending less time and ending up hours ahead. It may take you what seems like hours to drill out all the spot-welds and remove the firewall that way, but when it's out, the new one pops right in and you just have edges to spot-weld and you're done. When filling a stock firewall, you still have all that bodywork after the holes are all filled. It's pretty much guaranteed that this way is going to end up being easier and look better – things you try to reason with when building these old cars and trucks.
This firewall is actually for the 1956. It has the raised area to mount the windshield wiper motor that the 1953-55s don't have. But, if you can believe this, the firewalls are the same if you carefully cut off the raised area for the 1956 wiper motor, the rest is correct and will fit into the 1953-55s. There was some engineer doing some real thinking back then.
After the firewall is welded in, there are a couple of brackets that need to be replaced/reattached. The inner fender bracket to the firewall that wraps down under the cab and the fender brace rod brackets mount up at the top almost center of the firewall.
The brackets for the inner fenders are easily attached by bolting the inner and outer fender in place, bolting them also to the air dam in front. Then simply bolt the bracket to the inner fender and spot-weld it in place. They are available in reproduction form. The brackets for the fender rods can be welded back on or stainless versions from Mid Fifty can be bolted on instead. You really should run these as they help steady the front fender group and can be used as an adjustment for proper fender to hood line fit.
Follow along as I install half a firewall and a driver side floorboard. It's not as hard as it seems. Just don't be intimidated by the big holes you create. The bigger the hole, the nicer the patch.