Not being familiar with the construction of 356's.... If I blast the underside of the front fenders will media be able to get into the cab of the car from anywhere inside the fenders?

Also, is the front fender, just in front of the door, (the section that always rusts) joined to the inner fender (closing panel) or is there a gap there? Not sure I am being clear with my description.

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Mark,
My experience with media-blasting is sorta like my experience with sheet-rock dust; no matter what you do, it will end up where you don't want it. And there will be a *lot* of it.

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If you go to John Willhiot's web site - on vendor list - there are pictures of cars in various states of restoration - that might answer your question.
Strictly speaking, though, if you're just blasting the inner fenders, the stuff shouldn't get in - water would get in by the same pathway - but as Ron says above, the fine powder gets everywhere.
I had the shell of my car media blasted - all apart, of course - and it takes a big effort to get all the media out - or more correctly, to get most of it out

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Greg Bryan

356Talk Moderator

Our good friend, Bill Jones used to say,in his warbonnet lectures, " Sand blasting can put sand inside a golf ball"
KTF

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Gerry Mc

Mark,
There is a gap at the top of the closing panel/inner trunk wall where media could enter the passenger compartment. There is a small horizontal rectangular channel with a strip of rubber which ostensibly seals the passenger compartment from water (or media) intrusion. But, that rubber strip is invariably old, hard, shrunken, dry rotted, or missing entirely in most of our cars. It probably was an imperfect seal even when new. You can find this from under the dash. On the passenger side, you will see it above and to the right of the relays. Same location on the drivers side but harder to see because of all the stuff over there. The seal itself is a piece of soft rubber tubing. It can be prised out and replaced.

Upstream of that area, there is gap at the top of the closing panel, where it curves back towards the rear of the car, that was originally stuffed with some form of body caulk. Its generally gotten hard, shrunk, and fallen out over the years. But even so, the purpose of blasting is to remove that sort of stuff, so its not going to be any use to keep media out of places you don't want it.

That same rearward curve of the closing panel along the vertical edge creates the fender/closing panel joint you were inquiring about. At the rear edge of the fender (the door gap) you have the fender and closing panel sandwiched together. The fender sheetmetal is wrapped around the end of the closing panel sheet metal to create the finished edge. So this is why we so frequently see rust in this area. Two overlapping pieces of metal, probably imperfectly sealed when new, and getting less as the car ages.

In most cases, blasting will create new entry points into the interior, door wells (where it can enter the passenger compartment through the vent doors) and chassis sections, as it finds weak rusty spots and eliminates them. The very reason you want to blast in the first place!

As Ron, Greg, and Gerry noted, media is going to go everywhere in the car, and get into every component on the car, no matter what you do. Blasting is certainly useful (a necessary evil?), but harbor no illusions and don't expect to be able to contain it to specific areas.

DG

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David Gensler

I agree that sand blasting is a huge mess and something I truly do not look forward to. I also agree that dust would end up in a golf ball. The problem is I don't know how else to get rid of the surface rust. Two areas. The inner fenders are super solid, but there are very small rust pits everywhere from water intrusion under the undercoating and they need to go. On the outside there is surface rust from sitting for two years after being stripped of its paint. The use of Phosphoric acid on the outside has been shown to cause problems with the application of epoxy primer. Thanks for the help.

Edit, David, I was posting while you were posting. I know of the caulk you speak of, I have already removed it. Have not seen the rubber yet. I have blasted two cars before and there truly is no way to keep out the grit. This car is not completely disassembled and I do not want to do a rotisserie resto at this time so I am not sure what to do. I think I can deal with the outside body by hand, but the inner fenders is impossible. I could try to seal the top of the fender, but as you said that is one of the most important areas that needs the blasting. Humm what to do. Thanks again.

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Mark, I'm certainly no expert but if you have cleaned the undercoating off and dug out all the old sealant in the recessed area and have only minor surface rusting and pitting, I would be temped to use sandpaper, Scotchbrite, wire brushes, etc. to scuff up the metal and then further clean it with air and lacquer thinner, etc. Then paint it with POR 15 or some similar product, which is designed to paint over this type of corrosion and will seal the surface very well and prevent further rusting. You could then cram some strip caulk back in to the small recess and then go over that with a good body seam sealer. Prime that and then undercoat and I bet the car will last much longer that you ever will.

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Cliff Hanson
1964 356SC

My recommendation is to use an industrial heat gun or propane torch to soften the undercoating and then scrape it off with various shaped putty knives. If you are concerned with the exterior paint, then I don't recommend adding serious heat. Wear a respirator and work outside or in a well ventilated area.

You will still be left with a mess. The next step is to use varoius wire wheels on a 4" angle grinder. This will get you bright shiny metal. Wear lots of face protection and goggles.

Good luck, its a messy job no matter what method you do. The wire wheel throws big chunks, so your golf balls are probably safe.

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I guess I should have been more through with my description, but all the under coating has been removed. Yes, I used a combination of all the above suggestions and yes it is a thoroughly nasty job. You must suit up completely with all the PPE one should use for a job like this. After many hours you will be black. I have done this sort of work many times and it is never fun, but very rewarding. In this case, very nice to see fresh clean solid metal under layers of road film and undercoating vs. the alternative, rust holes.
Back to the original question, what to do now? I am anal to say the least and I feel that with blasting I can see that the metal is nice white and rust free. With the modern rust converters such as Picklex20, they claim that the rust is converted, but I have no personal experience with this stuff. I have used POR15 and am not impressed. I have used Zero Rust and am more impressed, but again, I don’t have long term experience that I can take to the bank as they say. White metal and Epoxy primer are guaranteed. But what to do here for this situation? This is not a full on rotisserie restoration, the car is still together and I cannot allow media to get inside the car and all the gauges etc. That would be bad. After 5 years, I am still removing media from my 912 and Toyota Land Cruiser projects, which were sand blasted. I was hoping that I could at least seal off the undersides and blast the inner fenders, but that does not sound like a feasible option. I know how it is, sand finds its way in somehow. Just not sure what to do. Maybe all I can do is the best combination of all the manual methods, wire wheels, sanding discs, etc and then metal treat followed by Zero Rust. I was wanting to apply undercoating now while the front end is completely disassembled, but that might not work either bc I still have to do the metal repair to the fender in front of the door and I was not planning on doing that right now. Lots to think about. Keep the input flowing, thanks for the help.

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Mark,
That's some nice work!
And probably quicker than getting the sand out of every damn bushing and bearing in the car. And getting it out of the gauges.

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I just happen to be working in that area on Foam Car. You can see the end of the rubber piece just at the edge of the horizontal cut line at the top. My rubber is still in pretty good shape, and I have no idea how to install a new piece, as there is a flange behind it that almost touches the cowl, so installing from under the dash seems impossible. Anyway, hopefully you can see where media could enter from the edge of the rubber outward and rearward. But, you caulking should prevent much of it from getting past.

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Phil Planck

Mark,
Looks like you're doing a fine job so far. If it was my car I would continue with the wire wheels. You didn't say what wire wheels or motor you are using. The ones on a standard drill or small air powered die grinder are too slow for my taste, but still useful for tight areas. That is why I recommend the angle grinder route. Another good tool combo is called the strip it disc from Sunchaser tools. Link below:

http://64.78.59.162/merchant.mvc?Screen ... ode=SIDBLK

Its good for large open areas, so it may be of limited use in your fender well case. Anyhow, the strip it disc works wonders on anything including rust. The strip it disc must run at the correct rpm, so their sander is highly recommended.

Then I would use a good metal conditioner such as 3M 2712?. If you wet the area with the metal conditioner for 30 min it will eat/loosen the rust. Then hit again with the wire wheel. Keep repeating until you're happy with the results.

Then 2k epoxy prime, then undercoat. Makes me tired just typing this.

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Ok guys, I will keep at it with the chemicals and the grinder/sander assortments. As mentioned, there is no one tool fits all. I have pulled out all my arsenal of tools. I agree that the speed of the electric angle grinder does best but unfortunately it does not go everywhere it is needed. After seeing the picks of Phil's metal work I realize that when I cut that area open I will have a chance to catch any rust up in there that I cannot get to now. Tom, it makes me tired thinking about it too. I really like the benefit of a rotisserie but do not have that luxury on this car. Makes for a lot less back breaking work. But I know that if this car goes on a rotisserie it will not hit the road for many years and I do not want that especially since I already have two major rotisserie restos going right now. It is hard keeping track of three major projects. Once I make head way I will post them in my build thread. I guess I should have started the conversation on it, but often times those threads do not get the attention necessary to carry on this type of discussion. Thanks for the advice. Will post more pics.

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Hate to change your mind again, but has anyone had any success with a spot blaster with vacuum attached as shown in the video?

http://www.youtube.com/watch?v=_xYYbi-vuUE

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I have seen that before. I am sure it works but I would not consider it practical for large areas. After seeing that setup I think I am going to try to build my own contraption just for the heck of it to see how it works. There are times when it would be great if you could just blast a little. Thanks for sharing.

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