The Ford Barn

rer_239 · 02-12-2022, 07:07 AM

what is the best way to fill holes in a firewall safely. i have about a dozen small holes.
thanks
dick

nkaminar · 02-12-2022, 07:18 AM

Most people weld them in and then do the body work as part of a restoration. If you are talking about a running car and the holes are small then Bondo, sandpaper, and paint might be the answer. This would be a temporary repair and the next time the car is apart a more permanent welded fix can be done.

To avoid drilling holes in the firewall, things, such as switches or junction boxes, can be attached with magnets. To avoid scratching the paint a soft piece of cloth can be put between the magnets and the firewall.

edzaha · 02-12-2022, 08:51 AM

If you just want a quick patch, I would use JB weld. It is stronger than bondo and can be sanded and painted

rotorwrench · 02-12-2022, 10:02 AM

I learned from an old DIY resto guy about cutting patches to fill holes. Really small holes can be plug welded with care and the correct use of filler rod. Holes from 3/8" on up should be patched by fabricating little round patches to fit and welding them in. I've used a copper backing plate to plug weld some but a patch just takes a little longer. A person has to get creative to hold a patch in the hole. I use some of these new high strength magnets and scraps of metal to hold things when tacking. A person needs a source for the correct gauge of cold rolled steel to make patches. I keep 18 US Standard gauge 1008 draw quality cold rolled steel around for fabrication.

marko39 · 02-12-2022, 01:16 PM

If you don’t want to weld them and you just want something to fill the holes I have used electrical box plugs. These are generally 1/2” and larger and I had some 3/8” and they look ok when painted and a lot better than holes.

daren007 · 02-12-2022, 11:43 PM

Sponsored Links (Register now to hide all advertisements)

Your local hardware store should have metal and plastic plugs in various sizes

Bruce of MN · 02-13-2022, 07:49 AM

A "friend" uses black duct tape.

Ed in Maine · 02-13-2022, 09:47 AM

The best way is to use steel plugs filed to fit and welded. I have used flat washers and then wafers from screws and bolts to put into the holes in the washer and then weld them in. I felt I really got into the hobby when I got a mig welder. Then grind them flat. In my early days of the hobby, I used fiber glass on the inside and then bondo on the outside, sanded smooth. In my latest restoration I installed a heat insulator on the inside of the car. All the welding uglyness disappears. This was standard in 1932 but there are reproductions that fit the Model A. Ed

02-12-2022, 07:07 AM	#1
rer_239 Senior Member Join Date: May 2010 Location: muskegon, mi Posts: 297	firewall holes what is the best way to fill holes in a firewall safely. i have about a dozen small holes. thanks dick

02-12-2022, 07:18 AM	#2
nkaminar Senior Member Join Date: Jan 2012 Location: Western North Carolina Posts: 3,897	Re: firewall holes Most people weld them in and then do the body work as part of a restoration. If you are talking about a running car and the holes are small then Bondo, sandpaper, and paint might be the answer. This would be a temporary repair and the next time the car is apart a more permanent welded fix can be done. To avoid drilling holes in the firewall, things, such as switches or junction boxes, can be attached with magnets. To avoid scratching the paint a soft piece of cloth can be put between the magnets and the firewall. __________________ A is for apple, green as the sky. Step on the gas, for tomorrow I die. Forget the brakes, they really don't work. The clutch always sticks, and starts with a jerk. My car grows red hair, and flies through the air. Driving's a blast, a blast from the past.

02-12-2022, 08:51 AM	#3
edzaha Senior Member Join Date: May 2010 Location: New Jersey Posts: 206	Re: firewall holes If you just want a quick patch, I would use JB weld. It is stronger than bondo and can be sanded and painted

02-12-2022, 10:02 AM	#4
rotorwrench Senior Member Join Date: Jun 2010 Location: San Antonio, Texas Posts: 16,436	Re: firewall holes I learned from an old DIY resto guy about cutting patches to fill holes. Really small holes can be plug welded with care and the correct use of filler rod. Holes from 3/8" on up should be patched by fabricating little round patches to fit and welding them in. I've used a copper backing plate to plug weld some but a patch just takes a little longer. A person has to get creative to hold a patch in the hole. I use some of these new high strength magnets and scraps of metal to hold things when tacking. A person needs a source for the correct gauge of cold rolled steel to make patches. I keep 18 US Standard gauge 1008 draw quality cold rolled steel around for fabrication.

02-12-2022, 01:16 PM	#5
marko39 Senior Member Join Date: Oct 2016 Location: harpursville ny Posts: 1,040	Re: firewall holes If you don’t want to weld them and you just want something to fill the holes I have used electrical box plugs. These are generally 1/2” and larger and I had some 3/8” and they look ok when painted and a lot better than holes.

02-12-2022, 11:43 PM	#6
daren007 Senior Member Join Date: Apr 2015 Location: Saint Cloud Mn Posts: 745	Re: firewall holes Sponsored Links (Register now to hide all advertisements) Your local hardware store should have metal and plastic plugs in various sizes

02-13-2022, 07:49 AM	#7
Bruce of MN Senior Member Join Date: May 2010 Location: VA Posts: 1,410	Re: firewall holes A "friend" uses black duct tape.

02-13-2022, 09:47 AM	#8
Ed in Maine Senior Member Join Date: May 2010 Location: Washington Cty., ME or Flagler Cty., FL Posts: 1,106	Re: firewall holes The best way is to use steel plugs filed to fit and welded. I have used flat washers and then wafers from screws and bolts to put into the holes in the washer and then weld them in. I felt I really got into the hobby when I got a mig welder. Then grind them flat. In my early days of the hobby, I used fiber glass on the inside and then bondo on the outside, sanded smooth. In my latest restoration I installed a heat insulator on the inside of the car. All the welding uglyness disappears. This was standard in 1932 but there are reproductions that fit the Model A. Ed