Where to Start? Firewall Repair

[SierraMtns]

Hey Guys,

I am starting on my other cab. Planning on repairing the firewall first around the heater area. I am going to delete the heater box area. Not sure where to start?

Firewall and work my way in to the cab? Or start inside the cab inner firewall and work my way out?

Thanks

[joesscamaro]

In my opinion, I think you should just start wherever you are most comfortable. If you haven't welded in a while, it may be easier to start on the exterior of the firewall and get into a bit of a rhythm before doing repairs under the dash. It'll be easier to dial in the welder on the right settings.

[dennislbrooks]

I would sandblast inside and out and see what you have.

[SierraMtns]

Originally Posted by joesscamaro

In my opinion, I think you should just start wherever you are most comfortable. If you haven't welded in a while, it may be easier to start on the exterior of the firewall and get into a bit of a rhythm before doing repairs under the dash. It'll be easier to dial in the welder on the right settings.

Yeah I am new to sheet metal welding. Gap or no gap? I used a copper backing plate and .023 wire.

[SierraMtns]

Originally Posted by joesscamaro

In my opinion, I think you should just start wherever you are most comfortable. If you haven't welded in a while, it may be easier to start on the exterior of the firewall and get into a bit of a rhythm before doing repairs under the dash. It'll be easier to dial in the welder on the right settings.

Originally Posted by dennislbrooks

I would sandblast inside and out and see what you have.

Dont really want to do this because I would like to keep the look of the old paint on the outside.

[tinydb84]

I'm with Joe and Dennis.

Blast and start where you are comfortable. You are going to have to grind off a lot of that paint and put in patches anyway. Not sure how much of the original paint will be there after.

I am a no gap person myself. I do my best to fit up and there is always a bit of a gap somewhere though. When I mig I weld hot tacks so it doesn't stand as proud and require a ton of grinding.

Tig

Mig

[BossHogg69]

I usually gap about the width of the wire I'm using. I like the butt clamps for this, you can grind down the spacers to different widths for whatever wire you're using.

On my cab, I did all the inside stuff first, then did my firewall, but it really doesn't matter. Blasting does help - it's almost always worse than what you thought it was going to be after the sandblaster 'uncovers' everything. Anyway, could you mask off/back tape what you don't want blasted so you can keep the exterior paint like the windshield pillars, etc, and then just repaint the firewall & interior later? I would think a competent blasting place could work with you on this.

[SierraMtns]

Update:

Sold the white cab and found a new cab. Picked it up from a friend for $400. Now the fun starts.

[SierraMtns]

Couple more pics....

[tinydb84]

Looks like a much better start. That $400 was well spent.

[Indian113]

Looks like you saved over $400 by buying that Cab just in Body Work!

[lango]

Yeah, you done good.

[Clatterville trolley]

Looks like a lot nicer cab than any I have seen in a long, long time. It is for sure a keeper!

[lks dcvn]

Agree here - the $400 was a great deal. Those are worth several grand in Ohio.

[SierraMtns]

I have been working on my welding skills.

From the bottom up. #1 and #3 are the sittings the welder recommends.

#2 and #4 are two sittings higher on volts and one sitting higher on speed. These two have flatter welds but I am worried about the back. Looks like it is a little to hot?

What do you guys think?

[tinydb84]

Number 4 looks the best to me. Its sheet metal so if you don't penetrate 100% it isn't going to be a big deal.

I doubt your fit up will be that nice when you actually cut a patch in (it takes a ton of time and practice to get that perfect fit up). If you have a gap of .030 you will likely burn through with the setting for number 4. Play around some more with a bit of a gap. You will see a lot of differences with penetration and profile with the different gaps and settings.

[SierraMtns]

Originally Posted by tinydb84

Number 4 looks the best to me. Its sheet metal so if you don't penetrate 100% it isn't going to be a big deal.

I doubt your fit up will be that nice when you actually cut a patch in (it takes a ton of time and practice to get that perfect fit up). If you have a gap of .030 you will likely burn through with the setting for number 4. Play around some more with a bit of a gap. You will see a lot of differences with penetration and profile with the different gaps and settings.

I got my first panel fitted but I have a couple more questions.

1. Where should tack first? Corners? Middle?

2. Should I but the welds next to each other or over lap them with the next weld?

[

[tinydb84]

That is some great fit up!

As a general rule you tack all your features first (i.e. body lines, ends, etc). I then tack corners and then a tack every inch or two. Check for movement as you do this as the piece will shift. Make sure your piece is cool enough to handle between each tack (I generally work on two patches at time so I don't get overzealous and put too many tacks on).

Once you have it all tacked in place and checked that it hasn't moved I grind the tacks, planish, then add in a second set of tacks overlapping the last set of tacks by 50% (basically aim the wire right at the end of the tack). Grind, planish, repeat.

[sevt_chevelle]

You have little to if any penetration on those welds, you need 100% penetration 100% of the time. Turn up the heat!

Any time you weld sheet metal you want a zero gap, easier to weld and shrinks less.

Make a tack weld, then move down the seam say 3 inches make another tack weld, do this til you reach the end of the seam. If you place random tacks you run the risk of losing panel alignment.

Once you reached the end of the seam, take a grinder and smooth out the tacks til they are just proud of the surrounding metal. Now place a new tack with say 30% overlap over the existing tack.

Repeat this weld grind weld grind til the seam is welded shut

[SierraMtns]

Hey Guys, I have been plugging away on the cab.

I was able to pull out a lot of the rocker panel. However it wont come out anymore and now I have some small holes to fill.

How should I attack it? I was thinking about buying a rocker panel replacement panel and just cutting out the damage area and replacing it.

What do you guys think?

[MP&C]

If you are cutting out any part of the rocker, cut out the entire thing. The spot (plug) welds to replace a full rocker will cause far less damage/distortion than trying to piece meal something together. You may be trying to save some work, but if you want straight panels, you're not really. Do the whole thing, once and done.

[SierraMtns]

Originally Posted by MP&C

If you are cutting out any part of the rocker, cut out the entire thing. The spot (plug) welds to replace a full rocker will cause far less damage/distortion than trying to piece meal something together. You may be trying to save some work, but if you want straight panels, you're not really. Do the whole thing, once and done.

Cool thanks. I have about 6 hours in this rocker and its still not straight.

So I will order a rocker and just replace it.

Thanks for the help.