55 - 59 Chevy Truck Firewall Fabrication

I know many of you have wanted to replace the firewall in your Task Force truck but lacked the equipment or money for the replacement panels. We under took this project with the idea of doing it cheaper than buying a $300 plus shipping firewall and not having to invest in a pan box brake. We will show you how to get nice bends in 16 gage sheet and fab up a nice firewall for under $100 in supplies including a $40 lunch.

Sheet 4'x8' 16 ga.hot rolled $39.00
2 4'x8' Card Board sheets for templates $12
Lunch at a local Italian restaurant $41.00

Plasma Torch
Mig or Tig welder
3' 2"x2" Angle Iron
C Clamps and Vise Grips
Markers and a straight edge about 3' long

We started out with a 57 big window that had a very badly damaged firewall. From what I was told a clutch and pressure plate exploded during a drag race and the result was way beyond any repair. Originally we planned on using a stock firewall for the replacement but decided to go for the smooth look.

55 Chevy Firewall
55 Chevy Firewall

The plan was not to remove all the spot weld around the edge of the firewall but to cut and leave about 2" across the top and cut around the hood hinge mounts.

We left part of the toe board for added support but it may be cut out later. Below we made a mock up of the full firewall and built it the way we wanted it to look when it was finished.

A hot glue gun maked mocking this up much easier. We were able to glue the recess in place. Once the template was correct we cut it apart and laid it out on our 16ga. sheet.

Above are the recess bends we made by hand. With the plasma torch we laid down a straight edge and cut along the line. We started a 1/4" from the edge and cut 1" skipped a 1/4" cut 1" skipped a 1/4" and so on till we got to the end. The plasma torch leaves a .030 slit that's very easy to weld up. All the bends were made with the same method.

Next we fab the piece from the firewall to the transmission cover. Once that's done we weld up all the slits and weld into place. We didn't remove the spot weld along the lip because as you know all those spot welds being cut out makes a mess of the surrounding lip. We also don't need to add ribs to the toe and upper firewall because the 16 gage steel is about 40% thicker that the stock firewall.

We did finally cut out the remaining toe board and left a 2 inch surround to weld to. All that's left is to weld up the slits in the bends and bring the floor to the toe board. Then finish welding around the edges of the firewall inside and out. We left the tunnel un-finished so we could tweak it when the cab is on the chassis. We have about 20 hours in this firewall and less than $100.00. If money is an issue then this is the way to go, If time is the issue then buy a pre made firewall and save about 6 hours.