| Author |
Message |
Verell Boaen (Verell)
Junior Member
Username: Verell
Post Number: 202
Registered: 5-2001
| | Posted on Tuesday, July 16, 2002 - 4:11 pm: | |
re:"how finish outer skin?}
I have an Eastwood spot blaster that blasts a spark plug sized hole. It has a rubber nozzle that you jam against something. The nozzle traps the sand & returns it to a small bag where it's picked up & re-used. It's really great for something like rust bubbles. No mess & no blasting anything you don't want sanded. I just tap the trigger, shift it over the width of the cleaned spot & repeat.
I'm using reduced air pressure & the fairly fine zirconium abrasive that came with the gun. Glass beads shoud work fine as well.
So far I haven't found any rust that's all the way thru the metal, just shallow pits that produce paint blisters. Possibly the same thing that Bruno described in the 1st post in this thread. Possibly there may be pinholes that I can't see altho most of the pits appear to be only about 20%-30% thru the panel. Given this, I'm going to etch the sanded area with a phosphate conversion etch as I mentioned earlier, then fill them with with body filler & the usual sand/prime/sand/seal/paint.
I thought about filling with lead, but that would mean heating a long strip of the panel hot enough to burn the paint on the more or less inaccessable back side. Also,I have rust just above the rocker panel seam between the door opening & the rear wheelwell. ie: The gas tank is just behind where I'd be working!
Where I can get to the back side of a rusted area, I'm going to check it to see if it needs the same treatment. If there's no sign of rust, I might just give it a few coats of zinc galvanizing spray to ensure it stays that way. It can't hurt & could give galvanic protection as well as provide further sealing.
If I did have a small rust-thru, I'd MIG weld on a galvanized steel patch. There's a local body shop owner that I talk with a lot. He picks up A/C ducting scraps from an A/C installation company. Says they're heavier gauge & have much better galvanizing than electro gallvanized body repair metal. Claims he's never had a patch brought back because it rusted. He's done some work on several cars for me & my sons over the last 5 years. So far no signs of rust. |
Robert Davis (H2oquick)
Junior Member
Username: H2oquick
Post Number: 157
Registered: 8-2001
| | Posted on Monday, July 15, 2002 - 8:11 pm: | |
Rust is like cancer once it is there it is hard to get rid of.....all you can do is try to control it...I am a painter at a body shop and the only true way to get rid of the rust is to replace the skin...We usaully prime the surface before installing the skins with a metal etching primer, after installing the skin, use seam sealer between the outer and inner seams. Be sure that all the door drains are open...in some cases in problem doors we add extra drains....do not leave bare primer in doors unless it is a 2 part urethane primer...primer out of a spray can is usually lacquer which will absorb and hold water...and will rust over a few weeks...Door repairs with minor rust should be repaired with a 2 part epoxy such as marine tex......plastic puttys will also absorb water if left bare on the inside. That is why you see bondo bubbling on older repairs...all bare metal should be treated with a metal etch before any repairs are made.....if done correctly a repair should last quite a while...but remember it is only a repair and not a cure.... |
Bill Sebestyen (Bill308)
Member
Username: Bill308
Post Number: 274
Registered: 5-2001
| | Posted on Monday, July 15, 2002 - 7:24 pm: | |
I think Verell describes a plausable plan of attack. The crimped seam must be the principle culprit.
I'd be careful with sand blasting to open the seam. If you overdo it, you will distort the outer panel. I once sand blasted my entire Comaro body. Since it was a big job, I used a big sand blaster and a construction sized, gas powered, compressor. It still took all day. Because the rust was quite deep in the front fenders and it was easy to get to, I went a little too far and caused waves in the panel. You may get a similar effect if you work too agressively on the seam.
The two most highly touted rust encapsulation paints are probably POR-15 and Corroless. I believe both of these products convert the rust to magnetite, a more stable form of rust, then seal the area from further water and air intrusion. I haven't tried the POR-15 but have tried the Corroless. Because it's a paint, there is enough viscosity to prevent it from seeping into small cracks or seams, unless thinned appropriately. I suspect thinning to the consistancy of water will compromise its chemical capabilities to convert the rust. I'm thinking that perhaps a pure rust converter, without the paint sealer, might be a better choice for penetrating into the seam. The pure rust converters, I've used seem to have a near water consistancy, so should penetrate well. Once penetration and drying have occured, then maybe seal it with a marine epoxy primer. The rust converters really don't do anything for bare metal, they require some rust to chemically change to magnetite. |
Paul (Pcelenta)
New member
Username: Pcelenta
Post Number: 12
Registered: 7-2002
| | Posted on Monday, July 15, 2002 - 5:22 pm: | |
how will you finish off the outer skin? I am assuming that rust has attacked there, as well...braze holes closed? mig weld patches? or plastic fill? |
Verell Boaen (Verell)
Junior Member
Username: Verell
Post Number: 199
Registered: 5-2001
| | Posted on Monday, July 15, 2002 - 4:53 pm: | |
I'm tackling my doors later this summer. My current thinking is to do what I just did with an Rx7 door:
- Sand blast the outside rust off & etch w/phosphoric acid. (Naval Jelly, or Eastwood's Oxy-solve or Dupont Kwick-Prep. POR-15's Metal Prep sounds like it's the same thing).
- Inside the door sand blast the seam to open it up. If there's rust, etch what's left after sand blasting with phosphoric acid.
- Let the seam dry thoroughly. (At least overnite or longer w/a 500W work light about 18" away gets a door up to about 200 degrees. Really speeds drying.
- Thin RustOleum damp-proof red primer with mineral spirits until it flows easily. Give the inside of seam a thin coating, flowing as much as possible deep into the seam. Goal is for the thinned primer to penetrate to the bottom of the seam. Let dry overnite. Repeat 2-3 times. Seal the seam w/seam sealer, then brush on another coat of RustOleum to moisture-proof the sealer.
I've got most of a quart of the original fish oil based rust-oleum damp proof red primer. I've de-rusted several things & primed/painted them with it and rust hasn't re-appeared in over 10 years. Don't know how well their new formulation does. Eastwood's rusty metal primer seems to work on the same O2/moisture exclusion principle. Also seems to be what POR-15 is based on.
Short of undoing the seam & etching/priming/painting the metal & closing it up again, this seems to be the best that I can do.
The problem w/an aluminum panel is that you'll get galvanic action between it & the door frame.
I guess for an all out effort: The skin would be separated from the door frame. The frame & skin completely stripped, degreased, etched, etc. then electro galvanized, zinc chromated, reassembled & the seams sealed. This should be a pretty close approximation to Porsche's process that is claimed to be the best available. |
bruno bandaras (Originalsinner)
Member
Username: Originalsinner
Post Number: 261
Registered: 5-2002
| | Posted on Monday, July 15, 2002 - 11:56 am: | |
Yes I used por15. Rust comes right through. Seems por15 works best on rusted surfaces, I grind the doors clean before I fix them. |
Paul (Pcelenta)
New member
Username: Pcelenta
Post Number: 10
Registered: 7-2002
| | Posted on Monday, July 15, 2002 - 9:20 am: | |
Have you tried that POR-15 paint? I rebuilt my floor on my XJ6 by mixing it with kitty hair...crude fix...but dried as hard as cement...I haven't used it on a surface that would be top-coated with paint (exterior metal) |
bruno bandaras (Originalsinner)
Member
Username: Originalsinner
Post Number: 255
Registered: 5-2002
| | Posted on Sunday, July 14, 2002 - 11:22 am: | |
Also my autobody gut tells me that the door skins were assembled and crimped before prime and paint. That means bare metal behind seams. Ferrari was nortorious for painting only what u saw . "If it dont make it faster,What do I care". You should see what is not painted on my 250. It's scary. |
bruno bandaras (Originalsinner)
Member
Username: Originalsinner
Post Number: 254
Registered: 5-2002
| | Posted on Sunday, July 14, 2002 - 11:19 am: | |
I have all receipts and dealer stamps for the 78 since new. 73k miles. 1 repaint. 4 door repairs.3 adjusted doors, hinges/handles etc. Seems like doors are as expensive as timing belts.I'll add up the charges one day.As all repairs were from dealer you can imaGINE$$$. |
Paul (Pcelenta)
New member
Username: Pcelenta
Post Number: 9
Registered: 7-2002
| | Posted on Saturday, July 13, 2002 - 9:51 pm: | |
Ed is right you have to come up with a way to route water to the drain holes...the bottom 2 inches has no drain holes so after a car wash or a little rain...water just sits there. I think the recycled olive oil can metal they used is also a problem...Bruno, I bought my first set from Italian Racing...I think it was $800 for the pair...bonded them on with Duramix adhesive...they are a full door skin...but you can cut them down at the body line and just use the lower portion. If you are interested I have another pair (<800).
Henryk, FNA should have listed this in the manual 15K valve adjustment 30K valves & belts...every 5 K repair doors.
Funny thing, for my 78' GTS I have the original receipt from 1980 showing the first repairs to the doors....just 2 years!! |
Henryk (Henryk)
Junior Member
Username: Henryk
Post Number: 74
Registered: 8-2001
| | Posted on Saturday, July 13, 2002 - 9:39 pm: | |
Bruno,
I had the same problem on my 246 GT. A steel skinned door WILL rust, whether it is on a Ferrari or a Chevy. The steel door doesn't know the difference; it just does what it knows best, and that is, to RUST. My 308 and 246 where coated inside.....but, if you scraped it away, you would see rust. Unless you store your car in the living room, I don't believe that there is ANY solution to rust when it comes to a 20-30 year old car!!!!!!! |
Edward Gault (Irfgt)
Intermediate Member
Username: Irfgt
Post Number: 1574
Registered: 2-2001
| | Posted on Saturday, July 13, 2002 - 8:41 pm: | |
The rust comes from the INSIDE of the door skin where the inner and outer panels are crimped together and where the water inside the doors collects and does not dry out properly. The secret to keeping the rust away is to properly rust proof the inside of the doors to keep the water sealed away from the crimped area and routed out the drains. This not only happens on Ferraris but on all makes of cars. |
bruno bandaras (Originalsinner)
Junior Member
Username: Originalsinner
Post Number: 246
Registered: 5-2002
| | Posted on Saturday, July 13, 2002 - 8:35 pm: | |
Also, I dont think you need a aluminum bodied car to avoid rust. I have had no other rust problem on any of my Ferraris except the 308 bottom doors. Quarter panels,bottom,etc. all ok. no rust no bubbles. There is something about the door skins.I wonder if replacement metal skins would do the same???? |
bruno bandaras (Originalsinner)
Junior Member
Username: Originalsinner
Post Number: 245
Registered: 5-2002
| | Posted on Saturday, July 13, 2002 - 8:32 pm: | |
I would go for the fiberglass door skin also. As long as u keep the originals who cares. As far as the zinc weld goes. I got to see it to beleive it. If anyone tries it and gets it done please let me know. What was the cost for the fiberglass door skins? From where?. |
Henryk (Henryk)
Junior Member
Username: Henryk
Post Number: 73
Registered: 8-2001
| | Posted on Saturday, July 13, 2002 - 7:49 pm: | |
Paul,
It really isn't frustrating at all; just accept the fact that it WILL happen again, as I did, when the paint specialist warned me in advance.
I like your idea about the fiberglass door skin; don't care for the zinc coating......I don't trust the guy. As a daily driver, I wouldn't be that concerned about originality. |
Paul (Pcelenta)
New member
Username: Pcelenta
Post Number: 7
Registered: 7-2002
| | Posted on Saturday, July 13, 2002 - 7:32 pm: | |
I've gone Henryk's route stripping, grinding, etching primers...one year later, vain like rust begins, followed by rust bubbles...Very frustrating...on a daily driver gtb I gave up and replaced them with fibreglass doorskins...this solved the problem but isn't original..Did find a guy in Hemmings Motor News that will sandblast and sprayweld pure zinc on to the doors which will fill any holes and which he guarantees will never rust again...haven't tried this on my 78 gts but I will probably give it a try this fall. |
Henryk (Henryk)
Junior Member
Username: Henryk
Post Number: 69
Registered: 8-2001
| | Posted on Saturday, July 13, 2002 - 6:53 pm: | |
I had a 308 with similar problems. The black spots appeared to be dirt entraped in small rust holes, or just "black" rust. I had the door repainted by a top notch professional car painting facility. I was told that once a door rusts, even though it is not through, as mine wasn't either, that, the rust WILL return. They sanded cleaned, etched it, used special metal bonding primer, etc. Sure enough a year, or two later, the paint started to bubble.
The ONLY cure for rust, on a long term basis, is to replace the door skin in it's entirety. Or, have it repainted and sell the car. Be careful, because the next one you buy, will probably have the same problem.
Start looking at aluminum bodied Ferraris; my Boxer is aluminum (top half) and fiberglass (bottom half).
Good luck |
bruno bandaras (Originalsinner)
Junior Member
Username: Originalsinner
Post Number: 244
Registered: 5-2002
| | Posted on Saturday, July 13, 2002 - 5:14 pm: | |
I just completed yet another rust repair on the bottom of the doors of a 308. We all know where I am talking. Once again it bubbled the paint only. It did not rust through to the inside. The rust comes from the middle of the metal out. I try to grind out little black particles that are suspended in the metal but can not as It is through and through. The rust on the doors on these cars is amazing.This touch up was to a 78gtb. I also encapsulated the entire lower 1/2 door in epoxy (my thought being no air no rust). Lets see how long it last. Any body else see this mysterious black (cancer) particles. |