Building a firewall for a hot rod truck (lots of pictures)
Wed Sep 30, 2009 6:14 pm
As a few of you may know, I've been tinkering with an ol' hot rod truck in my spare time lately. I'd been bothering a few folks with updates via e-mail, but this time I decided to just bother everyone here on WIX with this lengthy update. I got this little '39 Ford truck back in February of '08. It was a neat little rat rod, but was in dire need of some attention. And for those of you who know me, I can't seem to leave well enough alone, so in just a short period of time, the truck went from this.....
To this.......
So, fast forward to now. I've got all of the suspension installed, along with the engine and transmission built by Don Obrieter, of Altus "why the heck am I here," Oklahoma. The "motif" of this truck will have a military theme, along with the inside of the truck being more like a Warbird cockpit. I know that isn't very original, but I'm still trying to make a few details along the way that'll set this one apart from some of the other military themed hot rods out there. So hopefully that will help explain the O.D. Green paint I've applied to the engine and the flat black frame, suspension, etc. There are other little details scattered throughout the truck, but I won't pester y'all with that right now.
The main purpose for me starting this particular thread was to demonstrate what it took for me to build just one component on the truck....the firewall. Now, as a disclaimer, I can guarantee you that there is surely a better way that all of this could've been done. There are FAR more experienced sheet metal guys out there that will likely roll their eyes when seeing the way I do some of this, but it seems to work for me, and on this truck, that "personality" is kind of what I'm looking for.
I reckon I probably should've been satisfied with "good enough" on how the old firewall was, but it was full of dents and bondo, which just didn't work for me. I decided to build my own firewall, with the hopes that it would help clean up the appearance of the engine compartment, while still having that military/aviation feel to it. I was going to just make the firewall one single piece at first, but decided against it, as I wanted to rivet several pieces together. Again, the thought being, to have a clean, but built in an aircraft factory look to it.
So, the first step in this process was to simply throw the cab on the frame. Clearly, I'll be removing the cab at a later date in order to do the body work, painting, etc., but for now, temporarily installing it allows me to make sure I get everything fitted in a proper manner........
Here's how it looked after cutting out the worst portions of the original, banged up firewall (the rest was cut out later).......
As with most of the sheet metal projects I do, I start with poster board. Naturally, the poster board is easier to manipulate while getting your basic shapes down, and is much cheaper, should you screw up and have to start over with a fresh idea. Here, you'll see the basic shapes taped to the firewall...
For these two main pieces on the left and right sides, I used steel sheet. The bends were made in my sheet metal brake. And since the tape wouldn't hold up the steel sheets, I went ahead and drilled a few holes in each sheet and held them in place with clecos....
The next piece to build would be the center portion. I knew this would be fun to build, as I had to make a dish in it so that the distributor would have plenty of clearance. (It actually rubbed the old firewall, so something had to be done anyway.)
For this piece, posterboard wouldn't really work as a starting point, as it won't duplicate the dished out portion as I needed. So, it just started out with a flat sheet of 2024-0 (soft) aluminum sheet, .040" in thickness........
I made some basic measurements on the height and width of what was needed for the dishpan and drew them on the sheet. I also drew a 1" border around the first square, as that was going to be my "transition area" (the area in which I wanted the radius of the dish to be)........
The next step was pure therapy. Hitting things with a hammer is a time-hardened way of allowing anger and sadness to escape your body, and this was no exception. The key here is to make the majority of your shaping with the hammers and then use the English Wheel to smooth out the dents and finalize the detail stuff later....
As you can see, the more you "convince" the center of the metal to do what you want, the edges want to join in on the party as well. So, periodically, I would use my leather slapper to pursuade the edges to lay back down........
After I started getting the dish shape in the neighborhood of where I wanted it, I went ahead and used the Wheel to lay the dents down somewhat. It's very important to use VERY LIGHT PRESSURE at this stage, as the idea is to merely get the dents out and NOT to keep moving the metal. I just needed to see how much more moving of the metal was needed, stretching it too much with the wheel is not what the metal wants at this point..........
In order to try and straighten the edges out some more, I changed the dies on the Wheel to a flat die and ran it across a few times.........
The problem with me taking that step, however, was that I got carried away and put too much emphasis on wanting the edges straight. So in the process, I put lots of pressure on the wheel and pretty much just hardened the outboard edges of my dished out area. This was a dumb move, as I still needed the dish deeper, but now the metal was too hard to hammer. If I would've tried to force it to move by hammering with more gusto, I would've eventually just cracked the radius of the dish, turning the piece to scrap.
So, the way to solve this is to anneal the metal. Now, there are others here on WIX that can do a much better job of the black magic involved here, but I'll show ya' how I do it. The first thing I do is light up the torch with a rich mixture and just wave the flame over the metal, allowing it to leave a black soot over the area I wanted to soften back up...........
The next thing to happen was cuss for a little while, as the rosebud tip for my torch broke and wouldn't work right. Ugh! So, I installed the cutting tip, which really isn't the best tool for the job here. The rosebud puts out a large, even flame, which is perfect for jobs like this, while the cutting tip...well, the cutting tip is designed for cutting. So I had to use much care in not allowing a hot spot to occur in my aluminum sheet, which could burn a hole in it.
The idea here is to put even heat along the area you're trying to soften up. I can't tell you what temperature it's supposed to be, but what I can tell you is that the "magic" temperature to soften the metal, just happens to be the same temperature it takes to burn the soot off that was just applied. This is a time where patience is your friend. If you get in a hurry here, you'll just melt the aluminum. However, after a while of making nice, even strokes with the torch (again, a rosebud tip works MUCH better than what I've done here), the black soot slowly starts to fade away and the aluminum will be pretty close to it's original softness.......
After allowing the metal to just cool off on its own, it wasn't hard to figure out that it had "moved" a little during the annealing process. This isn't anything to be concerned about, as the metal is now soft again and can be moved back to where it belongs. Remember, this is just a dumb piece of metal...make it do what YOU want. Of course, any ol' piece of lumber laying around with a straight edge on it, will work just fine for getting those defined edges back in the dished out area.........
Of course, slapping it around a little is kinda fun too........
After a bit more hammering and some final work on the Wheel, the dish is looking just as planned. Just one more whack on the board to straighten out a stubborn edge, and we're ready to move on to the next step.......
The bottom of this center portion of firewall needed to be shaped a bit to clear the top of the engine and transmission. The best way I could figure to duplicate that complex shape was to use this funky little "shape finder" that I picked up at a hobby store years ago.........
It's got a bunch of little steel wires in it that, when pressed down on an uneven surface, transfer the shape to the tool. It can be seen in action here, while looking at the back of the engine.......
Then, it's just a feature of transferring the shape to the poster board, moving the tool over to the next area, transferring it again, and then cutting out the poster board to the shape that is ultimately needed. After that, I made the measurement of where it needed to be on the sheet metal and transferred the shape of the template right on the metal itself......
The next step is pretty simple, but one little trick helps out while cutting this soft aluminum. I use a product called Boelube on my cutoff wheels, drill bits, sanding discs, etc. It literally allows these tools to cut through this aluminum like butter, rather than galling up the tool..........
I always debur my edges and smooth them out with some fine sandpaper....
I thought I was done, until I tried to put the piece in place. I had forgotten that I needed to recess the dish back some. This should've been done at the beginning of building this piece and had potential to be a deal breaker for me..........
However, after making the angles needed on my sheet metal brake, I realized I had lucked out and was able to still use the piece after all. It's certainly better to be lucky than good sometimes............
And as you can see, there is plenty of room for the distributor now.......
The last thing to be done to this particular piece was to shape the upper edge. A little trimming and bending put it right about where I had hoped.....
Now remember, the idea here was to make several different pieces, so that it would have that "assembled by factory workers" look. One piece firewalls look cool on many hot rods, but I just wanted something a bit different here. Some folks may like it, some may not, but it's still the way I want it. So with that being said, the next little trinket to be built was a strip to go along the very top edge. This was a pretty straight forward piece to build......
And obviously, the last pieces remaining were the hole-filler-uppers. These two pieces were a bit of a challenge to make, but were fun all at the same time. I didn't really get all that detailed in the picture taking during this process, but it's not much different from previous stuff. I just started with a posterboard template and went from there. Much of the shaping was done by hand and a body hammer. Naturally, I finished off the pieces by deburring and sanding the edges........
And here's the final product, as of right now. Obviously, I need to rivet everything in place, but there's nothing really special about that, so I wasn't going to bore you with those details. Oh, and those little holes that are left around the radiuses of the last pieces installed, will be filled with an epoxy, to keep heat and fumes out of the "cockpit."
Eventually, the firewall (along with the exterior of the truck) will be painted in O.D. Green before it gets it's stamp of approval. However, that will be much further along in the building process. So, I'm sorry if this has bored y'all to tears, but I was hopeful that at least a few folks might be interested in this little project and how some of it was built.
Gary
To this.......
So, fast forward to now. I've got all of the suspension installed, along with the engine and transmission built by Don Obrieter, of Altus "why the heck am I here," Oklahoma. The "motif" of this truck will have a military theme, along with the inside of the truck being more like a Warbird cockpit. I know that isn't very original, but I'm still trying to make a few details along the way that'll set this one apart from some of the other military themed hot rods out there. So hopefully that will help explain the O.D. Green paint I've applied to the engine and the flat black frame, suspension, etc. There are other little details scattered throughout the truck, but I won't pester y'all with that right now.
The main purpose for me starting this particular thread was to demonstrate what it took for me to build just one component on the truck....the firewall. Now, as a disclaimer, I can guarantee you that there is surely a better way that all of this could've been done. There are FAR more experienced sheet metal guys out there that will likely roll their eyes when seeing the way I do some of this, but it seems to work for me, and on this truck, that "personality" is kind of what I'm looking for.
I reckon I probably should've been satisfied with "good enough" on how the old firewall was, but it was full of dents and bondo, which just didn't work for me. I decided to build my own firewall, with the hopes that it would help clean up the appearance of the engine compartment, while still having that military/aviation feel to it. I was going to just make the firewall one single piece at first, but decided against it, as I wanted to rivet several pieces together. Again, the thought being, to have a clean, but built in an aircraft factory look to it.
So, the first step in this process was to simply throw the cab on the frame. Clearly, I'll be removing the cab at a later date in order to do the body work, painting, etc., but for now, temporarily installing it allows me to make sure I get everything fitted in a proper manner........
Here's how it looked after cutting out the worst portions of the original, banged up firewall (the rest was cut out later).......
As with most of the sheet metal projects I do, I start with poster board. Naturally, the poster board is easier to manipulate while getting your basic shapes down, and is much cheaper, should you screw up and have to start over with a fresh idea. Here, you'll see the basic shapes taped to the firewall...
For these two main pieces on the left and right sides, I used steel sheet. The bends were made in my sheet metal brake. And since the tape wouldn't hold up the steel sheets, I went ahead and drilled a few holes in each sheet and held them in place with clecos....
The next piece to build would be the center portion. I knew this would be fun to build, as I had to make a dish in it so that the distributor would have plenty of clearance. (It actually rubbed the old firewall, so something had to be done anyway.)
For this piece, posterboard wouldn't really work as a starting point, as it won't duplicate the dished out portion as I needed. So, it just started out with a flat sheet of 2024-0 (soft) aluminum sheet, .040" in thickness........
I made some basic measurements on the height and width of what was needed for the dishpan and drew them on the sheet. I also drew a 1" border around the first square, as that was going to be my "transition area" (the area in which I wanted the radius of the dish to be)........
The next step was pure therapy. Hitting things with a hammer is a time-hardened way of allowing anger and sadness to escape your body, and this was no exception. The key here is to make the majority of your shaping with the hammers and then use the English Wheel to smooth out the dents and finalize the detail stuff later....
As you can see, the more you "convince" the center of the metal to do what you want, the edges want to join in on the party as well. So, periodically, I would use my leather slapper to pursuade the edges to lay back down........
After I started getting the dish shape in the neighborhood of where I wanted it, I went ahead and used the Wheel to lay the dents down somewhat. It's very important to use VERY LIGHT PRESSURE at this stage, as the idea is to merely get the dents out and NOT to keep moving the metal. I just needed to see how much more moving of the metal was needed, stretching it too much with the wheel is not what the metal wants at this point..........
In order to try and straighten the edges out some more, I changed the dies on the Wheel to a flat die and ran it across a few times.........
The problem with me taking that step, however, was that I got carried away and put too much emphasis on wanting the edges straight. So in the process, I put lots of pressure on the wheel and pretty much just hardened the outboard edges of my dished out area. This was a dumb move, as I still needed the dish deeper, but now the metal was too hard to hammer. If I would've tried to force it to move by hammering with more gusto, I would've eventually just cracked the radius of the dish, turning the piece to scrap.
So, the way to solve this is to anneal the metal. Now, there are others here on WIX that can do a much better job of the black magic involved here, but I'll show ya' how I do it. The first thing I do is light up the torch with a rich mixture and just wave the flame over the metal, allowing it to leave a black soot over the area I wanted to soften back up...........
The next thing to happen was cuss for a little while, as the rosebud tip for my torch broke and wouldn't work right. Ugh! So, I installed the cutting tip, which really isn't the best tool for the job here. The rosebud puts out a large, even flame, which is perfect for jobs like this, while the cutting tip...well, the cutting tip is designed for cutting. So I had to use much care in not allowing a hot spot to occur in my aluminum sheet, which could burn a hole in it.
The idea here is to put even heat along the area you're trying to soften up. I can't tell you what temperature it's supposed to be, but what I can tell you is that the "magic" temperature to soften the metal, just happens to be the same temperature it takes to burn the soot off that was just applied. This is a time where patience is your friend. If you get in a hurry here, you'll just melt the aluminum. However, after a while of making nice, even strokes with the torch (again, a rosebud tip works MUCH better than what I've done here), the black soot slowly starts to fade away and the aluminum will be pretty close to it's original softness.......
After allowing the metal to just cool off on its own, it wasn't hard to figure out that it had "moved" a little during the annealing process. This isn't anything to be concerned about, as the metal is now soft again and can be moved back to where it belongs. Remember, this is just a dumb piece of metal...make it do what YOU want. Of course, any ol' piece of lumber laying around with a straight edge on it, will work just fine for getting those defined edges back in the dished out area.........
Of course, slapping it around a little is kinda fun too........
After a bit more hammering and some final work on the Wheel, the dish is looking just as planned. Just one more whack on the board to straighten out a stubborn edge, and we're ready to move on to the next step.......
The bottom of this center portion of firewall needed to be shaped a bit to clear the top of the engine and transmission. The best way I could figure to duplicate that complex shape was to use this funky little "shape finder" that I picked up at a hobby store years ago.........
It's got a bunch of little steel wires in it that, when pressed down on an uneven surface, transfer the shape to the tool. It can be seen in action here, while looking at the back of the engine.......
Then, it's just a feature of transferring the shape to the poster board, moving the tool over to the next area, transferring it again, and then cutting out the poster board to the shape that is ultimately needed. After that, I made the measurement of where it needed to be on the sheet metal and transferred the shape of the template right on the metal itself......
The next step is pretty simple, but one little trick helps out while cutting this soft aluminum. I use a product called Boelube on my cutoff wheels, drill bits, sanding discs, etc. It literally allows these tools to cut through this aluminum like butter, rather than galling up the tool..........
I always debur my edges and smooth them out with some fine sandpaper....
I thought I was done, until I tried to put the piece in place. I had forgotten that I needed to recess the dish back some. This should've been done at the beginning of building this piece and had potential to be a deal breaker for me..........
However, after making the angles needed on my sheet metal brake, I realized I had lucked out and was able to still use the piece after all. It's certainly better to be lucky than good sometimes............
And as you can see, there is plenty of room for the distributor now.......
The last thing to be done to this particular piece was to shape the upper edge. A little trimming and bending put it right about where I had hoped.....
Now remember, the idea here was to make several different pieces, so that it would have that "assembled by factory workers" look. One piece firewalls look cool on many hot rods, but I just wanted something a bit different here. Some folks may like it, some may not, but it's still the way I want it. So with that being said, the next little trinket to be built was a strip to go along the very top edge. This was a pretty straight forward piece to build......
And obviously, the last pieces remaining were the hole-filler-uppers. These two pieces were a bit of a challenge to make, but were fun all at the same time. I didn't really get all that detailed in the picture taking during this process, but it's not much different from previous stuff. I just started with a posterboard template and went from there. Much of the shaping was done by hand and a body hammer. Naturally, I finished off the pieces by deburring and sanding the edges........
And here's the final product, as of right now. Obviously, I need to rivet everything in place, but there's nothing really special about that, so I wasn't going to bore you with those details. Oh, and those little holes that are left around the radiuses of the last pieces installed, will be filled with an epoxy, to keep heat and fumes out of the "cockpit."
Eventually, the firewall (along with the exterior of the truck) will be painted in O.D. Green before it gets it's stamp of approval. However, that will be much further along in the building process. So, I'm sorry if this has bored y'all to tears, but I was hopeful that at least a few folks might be interested in this little project and how some of it was built.
Gary
Wed Sep 30, 2009 7:33 pm
Bored?? No way! Keep the reports coming when you can. The firewall looks great!
Re: Building a firewall for a hot rod truck (lots of picture
Wed Sep 30, 2009 7:34 pm
That is really cool.
That would be a contour gauge...
Calling one of my favorite tools funky...
retroaviation wrote:...funky little "shape finder"
That would be a contour gauge...
Calling one of my favorite tools funky...
Re: Building a firewall for a hot rod truck (lots of picture
Wed Sep 30, 2009 7:42 pm
cozmo wrote:That is really cool.retroaviation wrote:...funky little "shape finder"
That would be a contour gauge...
Calling one of my favorite tools funky...
Sorry cozmo, no harm intended. I actually use the tool quite a bit. I just couldn't remember the "proper" name for it.
Gary
Wed Sep 30, 2009 7:47 pm
It was taken in that spirit and I got a chuckle.
I hate it when I need it and cannot find it. Using a piece of wire just doesn't work as well.
I hate it when I need it and cannot find it. Using a piece of wire just doesn't work as well.
Wed Sep 30, 2009 9:24 pm
Please Gary ...bore me to death!
I love it...you have a special talent to make the "how its made" thread one of the best things on WIX!
I love it...you have a special talent to make the "how its made" thread one of the best things on WIX!
Wed Sep 30, 2009 10:03 pm
Nice photos Gary!
With that said was it necessary? Would it have been easier to create a square shaped part and rivet, spot weld or bolt it in? I would think a curved piece would be more likely used on an external surface.
With that said was it necessary? Would it have been easier to create a square shaped part and rivet, spot weld or bolt it in? I would think a curved piece would be more likely used on an external surface.
Wed Sep 30, 2009 10:06 pm
A2C wrote:Nice photos Gary!
With that said was it necessary? Would it have been easier to create a square shaped part and rivet, spot weld or bolt it in? I would think a curved piece would be more likely used on an external surface.
Necessary? Probably not. The way I wanted it? Yup.
Gary
Wed Sep 30, 2009 10:45 pm
The blower (and the rest of the engine) looks cool the way you have painted it!
Wed Sep 30, 2009 10:48 pm
Looks good Gary 
Even good enough to put on the HAMB
It ought to be a fun little truck when you're done.
Even good enough to put on the HAMB
It ought to be a fun little truck when you're done.
Thu Oct 01, 2009 4:01 pm
Very cool Gary!
Are you going to do anything to finish off the top area where the old firewall is exposed? I would suggest make another piece to co cover at the top and rivet together with the pieces you just made. It will look cleaner in the end and you've gone this far.
Maybe consider leaving the firewall NMF. It would be a nice compliment to your NMF edges on the v/c and blower.
Are you going to do anything to finish off the top area where the old firewall is exposed? I would suggest make another piece to co cover at the top and rivet together with the pieces you just made. It will look cleaner in the end and you've gone this far.
Maybe consider leaving the firewall NMF. It would be a nice compliment to your NMF edges on the v/c and blower.
Thu Oct 01, 2009 4:12 pm
Hmmmm...thanks for the suggestions. I'll certainly consider both ideas. 
Gary
Gary
Re: Building a firewall for a hot rod truck (lots of picture
Thu Oct 01, 2009 10:13 pm
Great stuff, Gary. I'm glad i took a look - much more interesting than doing what I should've been doing! 
I've also heard it called a Profile Gauge - on which useless note ends my contribution.
cozmo wrote:retroaviation wrote:...funky little "shape finder"
That would be a contour gauge...
I've also heard it called a Profile Gauge - on which useless note ends my contribution.
Fri Oct 02, 2009 6:22 pm
Yet another cool project, Gary!!
Gee, will this be the first "Off Topic" thread to span a few hundred pages like your last project thread??????
Gee, will this be the first "Off Topic" thread to span a few hundred pages like your last project thread??????
Fri Oct 02, 2009 6:43 pm
Rod Schneider wrote:Yet another cool project, Gary!!
Gee, will this be the first "Off Topic" thread to span a few hundred pages like your last project thread??????
Thanks, but I doubt it. This ol' truck just isn't as interesting as that clunky ol' B-24. I may make an occasional update, but much of what I'm doing with this truck isn't much different than thousands of other guys & gals out there.
Gary