Short of replacing the firewall on an AD truck with a "smoothie", what have some of you other bolters done to close or cover the shotgun blast firewall?
When I restored my '36 Chevy PU in the early 1970s I counted over 50 holes in the firewall. They varied in size from sheet metal screw size to big ones left by others who passed heater hoses through the firewall and mounted a brake master cylinder and other objects long removed before I got the '36.
I regard substances like bondo and fiber glass as crutches that cover body damage, not actual repairs of body damage. So I repaired my firewall by filling small holes under about 1/4" with oxy-acetylene welding rod deposits and welding patches into the larger holes, also with oxy-acetylene. The attached photos show what the results look like 45 years later.
Only very simple tools were required, an oxy-acetylene welding torch. a body repair hammer, flat dolly and slapping file, a sanding disc on an angle grinder and some scrap sheet metal. This is why I've suggested to you in the past that welding is an essential skill in vehicle restoration and/or fabrication. After all the non-original holes were repaired and the welds ground smooth the heat-induced warping was corrected by shrinking metal in warped areas to eliminate the local "oil can" swelling of the metal.
Rocket Man - like Ray W, I chose to weld/patch the numerous holes. Speedway Motors, Paul Horton's Welder Series, and others sell the correct gauge, various diameter circle patch plug kits, or unholes as they also call them. I plug welded holes smaller than 1/4" and welded in the unholes for those 1/4" and above. I never counted all the holes, but there definitely was a lot, but being retired, I was in no hurry. Good luck!
I guess I'm a kook. I like to keep all of the unused holes in place whether I am building a truck as it came, or modernizing it significantly. I use adhesive backed heat/sound deadener on the inside to cover all of the unused holes. I do this after the fire wall has been painted. This is how they were done on the assembly line, and I like that look.
1952 5-window - return to "as built" condition | 1950 3100 with a 235 and a T-5 transmission
Ray and Clarsen3100...I kept my dad's oxy-acetylene welder when he moved into a nursing home. What rod did you use or was it just wire? I assume a small tip...just like brazing? Clarsen3100...did your vehicle ever get over the measles? I'll check with Speedway for the unholes...I have them on speed dial!
Should be 18 or 19 gauge. 19 gauge isn't readily available as sheet metal stock, but 18 gauge is, slightly thicker. If you're doing any other patching, just buy a larger piece and cut your plugs out of that. Use a '0' tip on your OA torch and buy some real welding rod 1/16 inch diameter. People have used coat hangers or bailing wire, but there's no QC on those. [on edit] Just measured mine. 0.052" including primer on both sides. 18 gauge is 0.048" Also, some of the holes are oval, not round, so you'd have to cut your own patches anyway.
Last edited by klhansen; 07/11/20206:16 AM.
Kevin 1951 Chevy 3100 work truck Follow this saga in Project Journal Photos 1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car) Busting rust since the mid-60's If you're smart enough to take it apart, you darn well better be smart enough to put it back together.
"Ray and Clarsen3100...I kept my dad's oxy-acetylene welder when he moved into a nursing home. What rod did you use or was it just wire? I assume a small tip...just like brazing?"
Good morning Rocky.
In 1967 when I was a college kid I had a summer job welding headers at Doug's Headers, now known as Doug Thorley Headers. There I got to see the equipment and techniques the pros use. This is the style torch handle they use:
It is small and light weight so you can weld all day without any strain, and importantly for body work, the knobs are at the top, not the bottom. That makes it easy to turn off the torch instantly with one hand when doing things like metal shrinking that requires putting down the torch and picking up the shrinking tools while the metal is still red hot. Even though this torch handle is small it takes a wide range of tips as well as a cutting attachment. I have tips down to size 000 but as I recall I used tip 00 for welding on body panels. That's not a reliable recollection because that work was done so long ago, about 50 years.
Most oxy-acetylene welding rigs have big, bulky "manly man" torch handles with the knobs at the bottom, near where the hoses connect. That heavy construction is strictly for appearance and would give a welder a pretty sore wrist if it were used continuously for an 8 hour shift.
If you're going to weld on your vehicle body panels I'd suggest practicing on scraps first until you have total control over the weld puddle and can add rod seamlessly. That comes with practice, especially on vertical surfaces. That 3500 degree F flame can do a lot of damage in a big hurry if you don't have it totally under control.
I know some people weld with stuff like coat hangers but actual welding rods are inexpensive and available in a variety if sizes. For body panels and exhaust tubing I use 1/16".
I guess I'm a kook. I like to keep all of the unused holes in place whether I am building a truck as it came, or modernizing it significantly. I use adhesive backed heat/sound deadener on the inside to cover all of the unused holes. I do this after the fire wall has been painted. This is how they were done on the assembly line, and I like that look.
I belong to these same “kook klub”. Carl
Those unused holes allow us to discuss “what went there”.
I was fortunate to have a couple of pristine '36 Chevy pickups to look at while doing my restoration and also a great VCCA technical advisor, Jim Payne, who provided detailed information. He even had a collection of GM Service Bulletins pertaining to the '36 PU. All of that showed that when the '36 PU left the factory the firewall holes consisted of:
10 1/4" holes for the wire loom brackets and the elongate 4-hole (oil pressure, temperature, throttle cable, choke cable) grommet and rear hood latches.
4 3/32" holes for the VIN plate.
3 larger holes for the vacuum line, dashboard positive electric feed wire from the starter motor switch post and electrolock cable.
All of those holes, along with about 40 others were in my firewall when I got the '36. Now only the 17 original holes are there.
Jim Payne's library of '36 Chevy information was so complete that it included a Service Bulletin on an optional fan shroud that is so rare that in 55 years of owning my '36 and being acutely interested in the '36 Chevy trucks the factory fan shroud on my own '36 is the only one I've ever seen. It took about 40 years of searching to find this one.
I use a Mig welder for my welding, used .023" solid wire for the sheet metal work, it helps to minimize distortion and I think it's easier than oxy-acetylene welding. The measles are still there, I haven't started body working the firewall yet. My plan is to complete all of the metal work on the vehicle before I start body working any panels. Just my preference.
I use nothing but 3M Panel Bond on cut to size patches. No heat, no warp, and done in an hour. Just rough up with 36 grit around holes and the same on the patch. Smear enough on to squish out around the edges and the patch is waterproof. All airliners and super sonic fighters are panel bonded so an AD pickup shouldn't have a problem.
Evan Doesn't panel bond need an overlap? I've never used it, but I would think that patching little holes that the OP is talking about would either require a backer or something to support the patch level with the original metal. Of course on a firewall, the backers would be covered up by the blanket or floor covering. Do you have any pics or an explanation of the process?
The "after" photos do look nice.
Kevin 1951 Chevy 3100 work truck Follow this saga in Project Journal Photos 1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car) Busting rust since the mid-60's If you're smart enough to take it apart, you darn well better be smart enough to put it back together.
The firewall patches are about a half inch bigger than the holes and the top ranges from 3/4 to 1 1/2 inch overlap. Picture of truck is recent on what was done 16 years ago and Model A was done 5 years ago; zero problems with either.
So they have to be smoothed over with body filler, then right?
Kevin 1951 Chevy 3100 work truck Follow this saga in Project Journal Photos 1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car) Busting rust since the mid-60's If you're smart enough to take it apart, you darn well better be smart enough to put it back together.
"I use a Mig welder for my welding, used .023" solid wire for the sheet metal work, it helps to minimize distortion and I think it's easier than oxy-acetylene welding."
Cklarsen,
You make an excellent point. Oxy-acetylene welding does put a lot of heat into the workpiece, and with sheet metal distortion results. My firewall repair was done so long ago that Mig may have been around, but it was not in widespread use and I had not even heard of it then.
Because I had taken 3 semesters of evening adult education classes in auto body repair I knew how to shrink sheet metal and that allowed me to get the firewall flat after all that welding. Metal shrinking was also required on the bed of my '36 PU that (no exaggeration) looked like a sack full of rocks because it was so lumpy.
Just for fun I looked at what Panel Bond is and it seems to be glue for sticking on patches. Being old school, I prefer an actual welded in patch in body sheet metal. When the welds are ground smooth what remains is a solid panel exactly like what was there before the hole was made. I do understand the appeal of a product that is quick and easy to apply, not requiring any metal working skill. It's the same appeal that Bondo has.
Panel adhesive is not Bondo. Not even close. It is what I use on the pinch weld seem at the belt line of the cab. replace rusted out spots, media blast, epoxy prime, fill seam with panel adhesive, and sand to butter smooth.
Last edited by 52Carl; 07/12/20201:58 AM.
1952 5-window - return to "as built" condition | 1950 3100 with a 235 and a T-5 transmission
Ray W (Yar), If you have owned a Chevy pickup anywhere after the mid 90's you have experience with panel bond. The door hinges are bonded to the body---no weld no bolts. Haven't noticed a lot of Chevy pickup doors that have fallen off and are laying on the roadway which is pretty good for Bondo. Might be best to watch for parts falling off an F22 or F35 JSF fighter since they are "Bondo'd" together. I will go back to rivets and weld right after I move from my house back into a cave.
I had a 34 year career with 3M in my hometown. It is a Industrial Tape site. I shipped Acrylic Foam tape everywhere...almost exclusively used in the automotive market. You would be sick if you saw what we sent to the landfill on a daily basis...all widths, all thicknesses. Plenty good for you and I. (Fortunately, employees could by a big roll for a quarter). I am aware that 3M made a product that supposedly held jet aircraft wings together! I don't know off hand what facility produced it. I'm going to run this down and try it on a few plugs. 52Carl...thanks for mentioning...I forgot about it.
