Pitted roof 71 Charger

[Donny]

no prob, everything is relevant! I have a Sullair 50 HP rotary screw compressor, it has no tank. As soon as I turn it on, it's making air, tons of air! In my work, I don't worry about PSI that much; only to move the media through the piping to my blast room. I run nearly 50 psi at my blast pot, which is 85 feet away, so, as the media comes out the blast nozzle it's at about 20-30 psi. The key is cfm; Cubic Feet per Minute. This is where you will spend money on air compressors. But, you can't blast on anything very well if it's under 100 cfm, it will take you forever!

I just completed the 'Cuda convertible and delivered it, I kept accurate blast time records and it took 8.53 hrs to blast the entire car; think about it, that's fast! How long have we all spent on a door or hood or fender with sanding discs? I know I've been there, and done that before; they all have their place and time (grinding down welds, etc) but, as for finding the best way/method, I think I've got it nailed. Too bad you all were not closer, as I'd be able to hook you all up!

 

[scotts74birds]

Maybe YOU need to move! I'm just sayin'! Rust removal in Texas CAN'T be as lucrative as it is here in the mid-west! HaHa! Or maybe we'll just talk, and I'll open "Donnys North"?

 

[Donny]

Rust is so hard to get removed, trust me, I only add as much of the aggressive media as needed to dig it out, but, if it's so badly pitted there will be holes and this metal is not worth saving -- can't be saved, you've got to replace it. Look here, a floor sample from a recent project of mine I did; look, this was pitted; much like your roof, in the worst case it will come out like this; with holes.

[/IMG]

 

[YY1]

Thanks for sharing.

I can see already that finding an adequate compressor will be "fun".

Interestingly, most gas powered models with two small horizontal tanks and "handlebars" are about 10-15 CFM, which is more than even the largest vertical tank unit at Lowes (about 8-10 CFM).

There is a 75 CFM gas powered unit locally advertized, that is off of a heavy equipment field service truck. Asking price is $800. Looks like the most cost effectve compromise.

If it ends up not working for blasting, then I still have damn nice shop compressor.

Right now I am using my wife's (yes wife's) 20 gal nailer compressor.
Ya gotta love a woman that owns more than one air nailer and a battery powered compound sliding miter saw

 

[rocky61201]

Here is the latest pic, only half-way done. Been way to busy with other stuff lately. Like I said before, the pitts have a white residue due to somebody slapping mud on it and its a pain to get all the way out. Doesn't help that it seems like its never really cured or didnt have enough hardener mixed in.

But from what I've seen so far is nothing thats gonna wind up being a hole like in the pic above. Weird thing is this stuff is more like acne. (bumps instead of pitts)

Could a good blaster do this a lot faster and more efficiently - YES!

Do I feel like paying for it - NO.

Bottom line is I still don't know EXACTLY what I'm gonna do yet until I put somre more hours in.

 

[YY1]

I advise working on a 6 or 8 inch square at a time with your fiber wheel until you get down to true bare metal. I had some black fleks that looked like pepper that wouldn't come out, but you couldn't feel them with your hand/finger. Everything else in the square was super silver shiny, with no sign of red color anywhere. When I got one square done, I used etching primer, and moved on to another square. After I got the whole roof done, I put on a couple of coats of epoxy primer, then the color coats.

Mine's been outside since last year at this time, with no bubling (which will probably start tomorrow, now that I've said that).

What are you going to do with the drip rail?

Is that regular seam sealer from the factory?

 

[rocky61201]

Yes, thats seam sealer in the drip rail. Factory??? Don't really know, maybe this isn't the first roof on this car, lol.

Since I don't have the drip rail molding and I can't find anybody willing to part with theirs, I was considering just cutting the drip rail off and filling it in.

 

[YY1]

I don't think I'd cut it off.

They don't look too bad just painted body color.

That would allow you to wait until you find the trim.
Eventually a set will turn up.

I think it is also structural...with the roof panel spot welded through the drip rail to the bracing panel underneath. Someone correct me if I'm wrong on this.

I took a chance and left my "seam sealer" in place and poured some Ospho over them and gave them several of days to dry while I was working on the rest of the roof.

I didn't want to dig out all that sealer and wrestle with tring to fit a grinder down in the trough.

That "sealer" seems like it's harder than the seam sealer you find on the floors. maybe cause it's been baking in the sun.

 

[66_B_Body4ever]

From your picture here is my best prescription. All the stripping disc's in the world aren't going to bring that roof back...you will never get rid of all the rust with a grinder, sander or stripping disc, they work good on light surface rust. The pitting that the rust has caused is much deeper than you think, the picture that Donny submitted shows a cleaned up piece of badly pitted metal, which pretty much sums up the majority of your roof I believe. The stripping disc will never reach the base of your pitting, and if you grind it out you will have next to nothing left of your roof. What does it look like from the underside?

At the end of the day, you will be leaving rust behind and alwys have the concern of it coming back. I am not tryig to be negative here, just trying to save you a lot of grief later on. I think you need a new/used roof skin or at least have it media blasted.

Good luck!

And YY1, yes, anything spot welded together on a unibody becomes a structural component of the car. The roof, 1/4's and cowl along with the pillars make up the strength of the upper body!

 

[YY1]

Every now and then you see a 71-74 factory sunroof roof section on ebay for a couple hunderd bucks. Might be worth the effort to gain a good roof and the s/r.