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Discussion Starter #1
I was thinking of all the different ways I could approach this and Im just not happy with the idea of having to weld everything then end up having to use putty anyhow. I know this has probably come up before so Im wondering if the simplest thing is to just have a flat blank of 16 guage steel made up of the firewall and just welding it over the old firewall. Im thinking I wont have do do anything special to the seam if I just weld the outer edge then just smooth everything over. Im going to drill some holes in the sheet as well in some areas to spot weld the center of the sheet.

Just wondering if anyone has any good info to offer about doing this otherwise Im going to try and make a template myself and take it to a machine shop close to here and have it made up.
 

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Shaggy...the only problem with welding directly over the old firewall is you will likely have all kinds of squeaks with the two rubbing. I know you've looked at my build, but in the end I'm not using that much putty on mine. Part of the reason I have more putty in the centre is that someone in the past used a hammer to put a HEI distributor in. I'm using the putty to clean that up. As for the actual smooth firewall...I didn't use much at all. I also ran the way I did mine past Frank at Prodigy Customs and that's the same way they do theirs. Here's the link to the smooth firewalls on 3rd gens. http://www.stevesnovasite.com/forums/showthread.php?t=98202
 

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Discussion Starter #3
Why would it squeak if I drill holes in the blank at strategic locations like at the supporting points behind the firewall and seam area? I then will follow up with some spot welds. I would think it should not squeak. I could even just cut out some areas of the firewall to save weight. I already have the heater box cut out on mine.
 

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To be honest, I'm not sure why it would it would squeak. I was going to do the same thing as you and then the more I talked to Frank and the more people that agreed it could squeak, the more I decided to cut out. I guess it you welded a bunch of different spots it will help, but if you're already cutting, why not just get rid of the old metal to be safe. That's just my 2 cents.
 

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Discussion Starter #5
To be honest, I'm not sure why it would it would squeak. I was going to do the same thing as you and then the more I talked to Frank and the more people that agreed it could squeak, the more I decided to cut out. I guess it you welded a bunch of different spots it will help, but if you're already cutting, why not just get rid of the old metal to be safe. That's just my 2 cents.
Im not sure what I would need to be safe about. I got another opinion about putting sound deadener between the areas but by the time I cut the areas out that I dont want there isnt going to be a whole lot the blank will be contacting and where it does contact I will have spot welds. I see this done alot and I never heard of squeaking. It would save alot of cutting and the welding would be equal. The spot welds should be pretty easy.
 

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smooth firewall

Smooth firewalls do look good when there done but it is alot of work and is not as structurly sound, that is if you remove it and put in a flat piece of sheet metal. The curves of the sheetmetal actually stiffen the firewall. I just filled in the holes I did not need like the a/c lines, fan, and other ugly holes by filling them with sheet metal. I put a piece of sheetmetal behind the hole and scribed the outline of the hole. When I cut the sheetmetal I left a small amount of extra metal so I could grind the metal until it fit perfectly in the holes with no gaps. After weld up I grinded off the welds flush and used only a small amount of filler. It looks clean, I can still use my wipers, and it only takes a few hours.

I would not recommend installing a second firewall over the top. You will never get it to look smooth and could be a place for critters to make a nest. I would think that would be like putting wheelcovers over your aluminum wheels.
 

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Discussion Starter #8
Smooth firewalls do look good when there done but it is alot of work and is not as structurly sound, that is if you remove it and put in a flat piece of sheet metal. The curves of the sheetmetal actually stiffen the firewall. I just filled in the holes I did not need like the a/c lines, fan, and other ugly holes by filling them with sheet metal. I put a piece of sheetmetal behind the hole and scribed the outline of the hole. When I cut the sheetmetal I left a small amount of extra metal so I could grind the metal until it fit perfectly in the holes with no gaps. After weld up I grinded off the welds flush and used only a small amount of filler. It looks clean, I can still use my wipers, and it only takes a few hours.

I would not recommend installing a second firewall over the top. You will never get it to look smooth and could be a place for critters to make a nest. I would think that would be like putting wheelcovers over your aluminum wheels.

I dont see why it wouldnt look smooth 16 gauge is pretty rigid. But its going to take some banging of the firewall to get it to lay nice. I may end up using some kind of auto body adhesive so no I dont think critters will get in. Ive already read about guys doing this with good success so I dont know where your getting your info from. Ive already given the firewall some wacks here and there and it looks like I can get it fairly flat. It should be smoother than using filler and last longer too. Ive seen a few of the filler jobs and they dont look that smooth to me. That tells me its not that easy to get it smooth with filler.

I dont see how this even remotely close to putting wheel covers on.
 

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Sounds like you have your mind set, these guys are giving tips from experience. What advice are you after?

To me it seems kinda hoakey to just lay a piece of sheetmetal over the existing firewall rather than cut and start over fresh, but thats just my opinion.
 

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Discussion Starter #10
Sounds like you have your mind set, these guys are giving tips from experience. What advice are you after?

To me it seems kinda hoakey to just lay a piece of sheetmetal over the existing firewall rather than cut and start over fresh, but thats just my opinion.
Sorry fine ill do it your way. Seems like your determined to change my mind. I seen a few shots of it done the way Im saying and it doesnt look "hoaky" to me and noone would know how it was done but me.

I dont mind responses like scherps who pointed out issues I may have. I have ideas to prevent those issues.

But saying it will be "hoaky" is just an opinion and not stating fact.
 

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Discussion Starter #11 (Edited)
I believe this is what this person did. Im not crazy about what he did but Im going to try and template over everything this person did but do the entire firewall even under the fender areas. In comparison that I have seen to putty jobs it looks smoother to me. Ive already heard from many that the filler will eventually fail especially at the seam. Ive already seen it fail all too often.

Edit:
I was thinking of using products like 3M Panel Bond. I was also considering something like lab metal to do the edges. Any opinions on either of these two products?


 

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Hey, I remember this road, the firewall smoothing.

I really didnt know what I was doing (my direction for this car of mine) at first, back in the mid 90s, I didnt have much for tools and just kinda went through the process. So I made many steps forward, just to take many more steps back.

I shot pics of the whole event, just to remind me of what I did wrong? No, cause I thought I knew what I wanted and wanted to show the progress, but in reality I didnt.

I looked at my bare firewall and knew there were some holes I didnt need anymore. So I made patch panels to fill the holes. Blended the firewall nicely.

Then years down the road, still working on the car, yet to drive it I needed to make a new floor pan and tranny tunnel. So this was my big time into sheetmetal stage. My tunnel looked good, but it was higher than the original. So as I was mocking it up I knew I had to cut out some firewall. And the more I looked at the firewall that I spent so much time on I decided to cut it out and start fresh.

So ALL my work was removed in a flash with the plasma torch. What a shame. Well, I fabbed up a new firewall in 16 ga steel.

And thats not the only time I have cut out some long worked out metal work, still doing it. ERRRR!!!

Ok, solly, back to you..

I really dont have a problem facing the original firewall with some 16ga. I would cut off the protrusions as much as possible to get the new firewall to lay back as much as you can. Dont wanna loose that precious rearward space.

So if you can cut out the "bumps" from the original firewall and lay the panel up as tight to the original firewall I REALLY dont see a problem with it.

I mean really, it sounds like you know to tie the new panel into the original firewall at several places to keep it from flapping in the wind. And umm, LOL 16 ga steel isnt gonna have much movement. I know, I use it alot. Some properly placed welds and its gonna be solid, specially if you can get it up tight to the original FW. But after a few well placed welds its gonna be SOLID. 16ga is really stiff.

I dont see any problem with overlaying the firewall...

The thing is, If you tell folks about it, or ask for advice many people will cringe and say umm, not good.. LOL Funny thing is, if they see it without the particulars of the process the same folks will say it looks great..

Ummm, this is one of the reasons why construction folks dont want you on the site when they are building your house. They dont want all the nit picking before the final product is ready. Same with machinists, car builders, or any manufactures. Let them see it after its done and structurally sound and they love the look of the final product..

Thats why its so hard to show build up progress pics here. Theres always gonna be some critique. Yup, everyone has an opinion, wait for the final product... Thats what I show. Ok, well, I do show my screw ups too. Just to help a guy out. Learn from my mistakes.... JR
 

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Discussion Starter #13
Great response.

I was discussing the idea with my brother today and he didnt see any issues with this. He gave me two places to get the sheet metal I need and I think I can get it to look better than the photo above since I have some ideas. I have yet to pickup the material Im making my template with but honestly the more I read today about doing it and after a week of just stewing over it I had to go with what I felt I can get to work well.

Its difficult to get some actual info about doing it without it being critiqued too harshly.
 

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the pic posted of the red firewall doesn't look to good IMO, its wavey. If you plan to drill holes in the sheet metal and weld them your going to end up puttying them anyways aren't you, after welding to smooth it back out. And I think with that many spot welds it'll be wavey.

It seams like your going for the sheetmetal look vice the original contoured look, if thats the case then wouldn't it be better to cut the whole firewall out, or as much as possible, and weld another piece in, with stress release rolled in to the sheetmetal for rigidity? Then you could just kinda push the old firewall to the 16gage new firewall and tack in place near the outer edges. This would put less stress on the new to ripple and keep it smoother. Anyways, just another point of view, good luck in which ever route you go.


I don't know jack about the 3rd gen cars but here are pics of my 2nd gen firewall before and after. Still some orange peal to be sanded out, but hey, I'm going to have to repaint anyways since I'm changing the black and have supports to weld on the inside.



 

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From past experience laying sheet metal over the existing firewall is no problem. It will not rub or squeak as long as it is welded properly. Also I think there is something to be said in retaining the original firewall on the interior of the car. Also if done this way all your structure is maintained and in the end minimal filler is needed. Just make sure you seal the firewall and inside of your panel before welding in place to avoid rust.





 

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Sorry fine ill do it your way. Seems like your determined to change my mind. I seen a few shots of it done the way Im saying and it doesnt look "hoaky" to me and noone would know how it was done but me.

I dont mind responses like scherps who pointed out issues I may have. I have ideas to prevent those issues.

But saying it will be "hoaky" is just an opinion and not stating fact.
Do it however you want to, its your car. This hobby is about experimentation, I just found it funny how you asked for advice but every time someone gave you advice you shot it down and said your way will work better.

I see alot of race cars and the ones with smooth firewalls are usually done by removing the existing firewall and starting over. They look great if that is what you are after. Now if the stock firewall is removed then the rollcage has to have a kneebar across the front downtubes for strength.

Now for a streetcar if you want a smooth firewall I guess you only have one choice. But if it was my car I would cut out the sections that I was going to lay a flat piece of sheetmetal over and weld it inplace, not on top of the the recessed sections.
 

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Discussion Starter #17 (Edited)
I found a few examples where they welded a panel and it didnt come out wavy at all. I think just about every putty job I have seen came out looking far more wavy with a few exceptions. The red one I dont think looks wavy and your just seeing reflections. Its still a bad example because they seemed to have cut it back before the fenders and thats not how I want it. I want a complete sheet that ends at the bottom and outer seams.


I like the idea with the welded steel over the firewall because if I have to use a filler then its minimal and not gooped all over the seam. From the look of it this is where it would be the heaviest. Im also concerned about the structure if you end up cutting the whole firewall.


I did ask for advice but to just flat out say its hoaky or its like putting caps over aluminum rims doesnt seem like advice at all.

I think rust72bucket welded over a sheet of steel and it looks good to me.
 

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Discussion Starter #18 (Edited)
So I completely changed my mind and went with something made out of paper. My steel came today.

Thanks for the help.

 

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Discussion Starter #20
That looks good. I dont plan on doing anything that extreme. Most of the guys around here where I live wouldnt even do anything and if they do they will just putty over the seam not even try and weld it.

The idea was to do something that will make it look better with minimal effort.
 
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