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WANTED: hints, tips, tricks, for my firewall install

15K views 45 replies 11 participants last post by  la4dice 
#1 ·
well, I ready to start on the firewall :thumbup:

its roughly trimmed to size, and has a couple of screws poked through it
still need to do some fine tuning :D

I have reread the instructions (not very specific)


I'm looking for any thoughts or tips :D


my only real questions that I can think of are....

How close to the edge should I make it fit?
hang it down some? (where I'm thinking it should be)
or right up to the edge, flush with the outer body line, making a groove between the two edges?


my other question is....
how do I fill the little triangle shaped hole on the side, from the seam that goes across the top?

(I was just going to cut a little piece and weld it in)
 

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#3 ·
There are only general installation instructions because they sell those to hotrodders who are creating stuff and don't need no stinking instructions. :D

First off, do you plan on moulding it all in flush? If that's the case I would weld it in just as you have it, screwing it tight of course. On that one triangle area that sticks out just make a little piece of metal to fill it and mould that baby in.

The one tip I would give is screw it tight all over, welding up the screw holes is a breeze. But the big tip would be to weld small tacks just a quarter inch or so with a hot setting. Do some tests, including destruction tests on scrap so you are confident with each of your welds. Get a piece of metal and put a fold in it just like your cowl has and lay a piece of scrap over the top just like your new firewall and weld it just like you will be welding on your car. Do a few welds and look on the back for penetration, put the piece in a vice and try to pull them apart, get comfortable so with every one of your welds you will be confident they are perfect.

I will weld something like that with a pretty hot weld, that way you make a QUICK weld and not heat up the surrounding metal much. Cut off the wire with EVERY SINGLE weld so you have a nice sharp wire to hit the metal and start and arc, that with a hot setting on the welder and you can make a super quick, penetrating weld.

Skip all over while welding in this firewall. Make a short 1/4" weld over on the right side, then on the left, then up on the middle upper. Then WALK AWAY and work on something else to let it cool. It will NOT cool if you sit there and stare at it. :drunk:

WALK AWAY after a few welds and leave it the heck alone to cool on it's own. When you can come back and place your hand on the weld and it's no warmer than the metal where you haven't welded, you can make three or four more welds, again, WELL SPACED, one side to the other, then walk away and let it cool on it's own.

You don't have tickets to the theater in an hour right? Good, because you want to take ALL DAY or more welding that firewall. I am not kidding, welding that in should take ALL DAY LONG. But of course you are going to be working on something else while you let the welds cool so you will get a lot done today. :)

If you weld it in like this you are likely to have very, very little warpage to that every easy to warp flat firewall. If you don't do it like this and weld long welds and cool them with rags and crap like that you will have a warped mess that will require a bunch of bondo work to make look presentable.

Brian
 
#4 ·
123pugsy said:
I would cut right around it and butt weld it in about 3/8 - 1/2" from the bend.
You would have to trim it down a bit first.
me and butt welding dont get along :pain:


123pugsy said:
I would also butt weld the little triangles but would do those first.
however, I will do this :thumbup:




MARTINSR said:
The one tip I would give is screw it tight all over, welding up the screw holes is a breeze.

But the big tip would be to weld small tacks just a quarter inch or so with a hot setting.

I will weld something like that with a pretty hot weld, that way you make a QUICK weld and not heat up the surrounding metal much.
Cut off the wire with EVERY SINGLE weld so you have a nice sharp wire to hit the metal and start and arc
that with a hot setting on the welder and you can make a super quick, penetrating weld.

Skip all over while welding in this firewall. Make a short 1/4" weld over on the right side, then on the left, then up on the middle upper.

Then WALK AWAY and work on something else to let it cool. It will NOT cool if you sit there and stare at it. :drunk:

WALK AWAY after a few welds and leave it the heck alone to cool on it's own.
When you can come back and place your hand on the weld and it's no warmer than the metal where you haven't welded
you can make three or four more welds, again, WELL SPACED, one side to the other, then walk away and let it cool on it's own.

you want to take ALL DAY or more welding that firewall.

I am not kidding, welding that in should take ALL DAY LONG.
But of course you are going to be working on something else while you let the welds cool so you will get a lot done today. :)

If you weld it in like this you are likely to have very, very little warpage to that every easy to warp flat firewall.

If you don't do it like this and weld long welds and cool them with rags and crap like that you will have a warped mess that will require a bunch of bondo work to make look presentable.

Brian
O.K. lets see if I got this :mwink:


1) I'm thinking I will trim it so it is about 1/4" in/down, from the roll/beveled edge of the body line

2) screw it down tight and if I need to I can use a hammer to tighten up the gap before/as I weld

I pretty much knew both of those (steps 1 & 2) just double checking ;)

and to clarify #3) :confused:

3) .... I can do very short , hot welds? (cooling in between)
I dont have to do endless tack welds? like when I put on my lower front repair panels?

4) grind, smooth and pretty when done welding :pimp:
 
#5 ·
matts37chev said:
me and butt welding dont get along :pain:


however, I will do this :thumbup:




O.K. lets see if I got this :mwink:


1) I'm thinking I will trim it so it is about 1/4" in/down, from the roll/beveled edge of the body line

2) screw it down tight and if I need to I can use a hammer to tighten up the gap before/as I weld

I pretty much knew both of those (steps 1 & 2) just double checking ;)

and to clarify #3) :confused:

3) .... I can do very short , hot welds? (cooling in between)
I dont have to do endless tack welds? like when I put on my lower front repair panels?

4) grind, smooth and pretty when done welding :pimp:
And let me clarify my opinion on the butt welding. Of course butt welding would be the "best" way. Overlapping a half inch lip of the old firewall around the edge like I am suggesting would be the "bestest" way. :thumbup:

And yes very short little welds, a 1/4" at the most. And please be sure you LET IT COOL, not "cooling" it as you just described.

And remember when you weld you need to cut off the wire so each weld you are hitting the metal with a nice, new, sharp wire so the arc is started immediately so as not to waste heat, unwanted heat trying to start an arc. Hit it with that nice sharp wire and WHAM you are doing a little 1/4" weld in a second or two, literally a second or two at the most. Hit the underlying metal first right and then bring the arc over to the edge of the new firewall. When you are finishing this up and you are welding next to a previous weld you hit right on the underlying metal next to the weld then go up onto it and over to the new firewall.

If you want to tackle butt welding we can go over that in detail as well. The most important thing is of course a super tight fit with no gap. You can do that by trimming some more of the new firewall off, about a half inch or so. Then screwing it to the old firewall. Scribe around the edge with a sharp scribe so you get real close. Then cut the lip of the old one off at that line, on the INSIDE of that line so you can see the line and very carefully trim it down so you can just see the line, that would be close enough to start trial fitting the new firewall and filing or grinding it to fit to perfection.

But honestly, no one is going to be pulling your firewall insulation out and looking how you welded it as you are driving down the road with a smile on your face proud of a job well done. :)

But again, I do agree it is the best way to do it. :thumbup:

Brian
 
#6 ·
I dont know which way is better or best-est :boxing:

but the "overlapping" way sure seems easier to me :mwink:



Thanks for the help :thumbup: , it all sounds like what I was going to do :D

I wanted to double check, make sure I wasnt missing anything :D

I will post some pics as I go and finish :pimp:



anyone else want to add their 2 cents ? ? ?
 
#8 ·
123pugsy said:
If you want to overlap, keep the material 1/8" from the bend as you have it now and you should be able to blend the weld/grinding into the bend to look as one piece.

If its too far in, there will be a defined step after you grind off the welds.

Make sense?
I am going to have to make some adj. and tighten it up a little in a couple of spots

its just slapped up there now, but I dont think the fit is perfect yet

I really appreciate the help :thumbup:

I will start on it, in the morning :cool:
 

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#9 ·
matts37chev said:
I am going to have to make some adj. and tighten it up a little in a couple of spots

its just slapped up there now, but I dont think the fit is perfect yet

I really appreciate the help :thumbup:

I will start on it, in the morning :cool:
Take all day welding it! Just let them cool naturally and take it slow with fast hot welds.

Brian
 
#10 · (Edited)
Matt,
You may have already thought of this ahead of time, but if you haven't, I would install my Engine and Radiator to make certain that you have enough space for everything, and that you can mount your accessory drive and all-you don't want ot have to notch that beauty AFTER it's all in and purty :D -

Just a thought-
 
#12 ·
35WINDOW said:
Matt,
You may have already thought of this ahead of time, but if you haven't, I would install my Engine and Radiator to make certain that you have enough space for everything, and that you can mount your accessory drive and all-you don't want ot have to notch that beauty AFTER it's all in and purty :D -

Just a thought-

X3 on this. I assumed it was already done.
 
#13 ·
35WINDOW said:
Matt,
You may have already thought of this ahead of time, but if you haven't, I would install my Engine and Radiator to make certain that you have enough space for everything, and that you can mount your accessory drive and all-you don't want ot have to notch that beauty AFTER it's all in and purty :D -

Just a thought-
I really appreciate the suggestions/tips, and that did run through my mind at one point :thumbup:

I might be putting my cart in front of the horse, but.......


I am going to work from the firewall forward, because I don't have any of the other stuff ready :(

I want the front susp. done, before I make the engine/trans mounts, and I don't have any of that, yet.


I do have the firewall now, and I feel like need it installed, to make the body rigid enough to remove from the chassis.

I feel like I need to keep moving forward, even if its 3 steps forward and 1 step back :spank:


If we need to trim it, to fit it , when I get that far, its ok

I just hope the engine fits :pain:


I kinda planned on it not fitting the trans. correctly, I don't even know if I will need a full, floor length trans. tunnel :confused:

I am leaving my body mount/floor support cross-members full width (see pics)

with the intentions of cutting/modifying them to fit the drive-train, later (also to support the body for removal)



Again, thanks for the suggestions and tips :thumbup:
 

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#14 ·
35WINDOW said:
Matt,
You may have already thought of this ahead of time, but if you haven't, I would install my Engine and Radiator to make certain that you have enough space for everything, and that you can mount your accessory drive and all-you don't want ot have to notch that beauty AFTER it's all in and purty :D -

Just a thought-
MARTINSR said:
HOLY MOLY, HECK YES that's a good suggestion! I just assume so I didn't say anything Very good point! I am a nut on trail fitting stuff.

Brian
123pugsy said:
X3 on this. I assumed it was already done.
man, my computer is running slow and/or you guys type faster than me :smash:


I feel like I'm really letting the hotrodders community down here, by not having all that done :( :spank: :(

I do plan on having the body off and on, very many times through out this build

I am also going to revisit many things on this car, after I get it running


sometimes I just cant do what is best-est , because of time and money issues (mostly motivated to work, time) I gotta keep moving forward on this thing :pain:

so I am going to have to settle with, what is best for the momentum of the build and my ambition level (as I have problems getting out there sometimes) :(
 
#15 ·
You have nothing to worry about, unless you plan on taking the body off without a firewall and rolling it on it's side. :rolleyes:

Honestly, you are breaking the first rule of rodding, trail fit EVERYTHING! I would never even think about welding that firewall in if I hadn't fit the motor, no friggin way. Listen, you ARE doing it properly and no steps back, you have fit the firewall, it's screwed in, you have taken the proper steps, now put the motor in and take the next step.

My very first job I ever had was at a rod shop after school when I was 17. I was taught this early when my boss apparently didn't trial fit ANYTHING. I will never forget him assembling his blown small block powered 29 Highboy and putting the chromed headers in to find that they hit the scatter shield, and I mean hit it bad. And of course things like that always are deceiving on how MUCH it's hitting. So he tapped it in, not enough, tapped it in, not enough, he ended up with a smashed pipe and still not enough and put stock exhaust manifolds on it! A blown motor with stock exhaust manifolds. :rolleyes:

Next was the front axle, he had all the axle and components chromed before trial fitting! The friggin tie rod hit the frame! So there he was dropping the spindle steering arms on freshly chromed spindles! That was my first lesson about the akerman angle, we discussed it and I have never forgot.

But the biggest lesson I learned was to trial fit parts, EVERY part.

Brian
 
#16 ·
MARTINSR said:
You have nothing to worry about, unless you plan on taking the body off without a firewall and rolling it on it's side. :rolleyes:

Honestly, you are breaking the first rule of rodding, trail fit EVERYTHING! I would never even think about welding that firewall in if I hadn't fit the motor, no friggin way. Listen, you ARE doing it properly and no steps back, you have fit the firewall, it's screwed in, you have taken the proper steps, now put the motor in and take the next step.

Brian
matts37chev said:
I want the front susp. done, before I make the engine/trans mounts, and I don't have any of that, yet.


Again, thanks for the suggestions and tips :thumbup:
OK, OK
hard left turn

This is one of the reason I started this thread :welcome:



I just got too excited, when I was seeing some progress :spank:



I will finish fitting the firewall, screw it down really well, put only a couple of welds on it, and stop there!

If it does need mods. , it will be a lot easier on the bench, then welded into the car :thumbup:

I will make a new game plan, and find something else to do, while I wait for the front susp. to show up (I haven't ordered it yet, because I cant make up my mind on what to get) :confused:
 
#21 ·
I hear you loud and clear on the motivational front, Matt. :D

I've subscribed to this thread in the event that I ever get "a round tuit" and deal with my own 66GMC - 454 dilemma.

Where did you buy the firewall?
Was it Direct Sheetmetal?

They have a few installation instructions / suggestions on their site as well, I think.

It sounds like Brian has made it fairly clear on the welding technique ... thanks for that. You can be sure that there will be a new MIG welder and several practice sessions involved before I tackle it myself. :embarrass
 
#22 ·
66GMC said:
I hear you loud and clear on the motivational front, Matt. :D

I've subscribed to this thread in the event that I ever get "a round tuit" and deal with my own 66GMC - 454 dilemma.

Where did you buy the firewall?
Was it Direct Sheetmetal?

They have a few installation instructions / suggestions on their site as well, I think.

It sounds like Brian has made it fairly clear on the welding technique ... thanks for that. You can be sure that there will be a new MIG welder and several practice sessions involved before I tackle it myself. :embarrass
yes, I got it from direct sheetmetal

they were great to deal with :)
 
#26 · (Edited)
if you weld it right at the bend and just lap it on you won't have to worry about warpage. That curved area will take the heat just fine and it's nothing crucial that you have to open butt weld it. If you're just an inch away from the curve you get warpage easier. Just screw it in all around and use a long screw driver to hold it tight when tacking it in. Soon as it's tacked in all around you can then go back and do your 1/4" tacks, and I don't keep my finger on the trigger. I just do a 1/4" of RED hot tacks overlapping eachother in succession instead of dragging and getting less penetration. Then when I'm done with that 1/4" hot tack I skip to the otherside for the next. I try to stay at least 12" away from the last 1/4" tack to do the next. You'll have it done in no time and when your welds meet in a corner your welds turn out pretty clean...check out my last pic I added and look at the corners of edges, and these are open butt welds! It's a neat trick and makes work easy. With that window channel patch I just perfected the lower channel area in the initial cut and once that was tacked those other areas where it meets at a edge were THEN shaved down with a grinder flush then tacked down. It's a trick when fabricating to leave it a little long cause it saves time and leaves you with a better fit. Only drawback with doing welds at the line is that your curve might not end up perfect but you won't have warpage and your welds turn out waaay better, and it's easier. I know guys who like to do that trick on quarters where they flange the prexisting quarter, lay the new quarter in, and then shave the rough cut on the body line a little so the new panel is cut right at the bodyline. That's one area where I rather make the cut above or rather below the bodyline and take more time to weld and to preserve the natural curve of the bodyline but some guys love doing them that way. My point is, the firewall is perfect for that as long as there's not too much curve and you don't mind getting the exact curve around the corner. From the pics it doesn't look like there's much curve around the corner and would be a perfect candidate for that.

Ok, but probably a little too much info. Don't get me started! :cool:
 
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