1976 280Z Restoration Project

[ksechler]

 

 

My first thought was to call you.... 

 

 

I'd start by cleaning all the rust out on the frame (where the anti-sway bar was).  That's the worst of it from what I see and the most likely to derail the whole project.  My frame wasn't bad that far forward.   

 

This part worries me:

 

Do you know how to weld?  That's a pretty important part of the structure and it needs to be strong when your done.

[ksechler]

For what it's worth, I used Eastwood weldable primer inside the areas I patched.  I also used Easwood's internal frame coating when I was done.  I put the nozzle they provide in the boltholes and sprayed it everywhere until the car just sat there with green paint leaking out of every seam.  

[Consigli]

 

 

I think my plan for now is to clean the bottom of the car like I'm doing, by hand, then wipe off most of the remaining undercoating with isopropyl alcohol, then tent the frame in the garage and sandblast the remaining rust and paint off. This is not ideal, I know as I don't have a proper blasting facility, but I can't justify the (local) cost of blasting at around $3000...

I guess my plan might change as I go. I am still unsure how to treat the metal after blasting and before painting. Do I coat it in Zinc Mate to prevent rust? Do I go straight to POR 15 and seal it right away? If I do that do I have to coat it in self etching primer within the tack window so it can be painted body colour later? Can I leave the exposed metal sit as is until the entire car is prepped and then go to Marine Clean, Metal Ready, then POR 15, then primer, then paint? A lot of questions and everywhere I go, someone has a different method as to what THEY would do...

 

 

My first thought was to call you.... 

 

 

I spent a couple of hours reading last night after googling acid dip vs media blast. I did not realize how controversial a subject matter it is. I'll see if I can do a quick & dirty summary of what I read. 

 

If chemical strip is done right, many agree it is the best. The body is dipped in acid and/or alkali and then neutralized and immediately e-coated to prevent flash rusting. The key step is neutralizing the last chemical dip, otherwise it will leach out and destroy paint years later. E-coating is a process similar to powder coating. Google it to learn more. 

 

There are many advocates of media blasting. Most agree NOT to use sand, as it is too aggressive and can easily warp thin sheet metal. The downsides of media blasting are that it gets into every nook and cranny and is difficult to remove before painting. 

 

There are upsides and downsides to each. Its sort of pick your poison. Makes me glad I have an Arizona car! 

[wheee!]

I'd start by cleaning all the rust out on the frame (where the anti-sway bar was). That's the worst of it from what I see and the most likely to derail the whole project. My frame wasn't bad that far forward.

This part worries me:

rail.JPG

Do you know how to weld? That's a pretty important part of the structure and it needs to be strong when your done.

My son in law is a B Pressure professional welder. He will be doing the difficult stuff.

I have access to a lot of good tools, so I imagine I will be fabricating new patches on good thick steel and prepping them as you mentioned. I plan on making it stronger than stock but with as little evidence of a repair as possible.

[wheee!]

The most damage is in places that someone did a poor job repairing previously. I plan to repair/replace a lot of those spots on the car.

[Patcon]

Wheee!

the picture in post #427, the reinforcement plate right above the frame rail is gonna have a hole behind it.

 

I did sort of what ksechler did by shooting Eastwood internal frame rail coating in every space I could find until it ran out every where. I even shot it inside the concealed areas in the hood

 

Consigli summed it up pretty well acid dip gets all of it but must be neutralized well, typically costs more. Media blasting is more common but can damage a car if they get careless. My blaster used sand on the car I am doing now. It is hard to get all the media out of the car.

 

Wheee!

If you blast to clean metal get some "After Blast" from Eastwood. Spray it on wipe it down, the metal will store for years if its kept dry and won't flash rust. If you use self etching primer you can't use epoxy and vice versus. After talking to the guys at the paint supply they advised me to go epoxy. It's tougher, sticks better and is more water resistant.

[wheee!]

I have seen the dreaded "acid creep" on a car a couple years after restoration. It was sad because the repair was going to be more difficult than the original rust damage!

I am blasting with fine grit glass. No sand. It stays cooler and cuts better. It will be messy I know but it should clean up the bad spots well enough.

I have the metal prep spray here too, should be the same as the Eastwood stuff.

[Patcon]

Eastwood is an acid for sure, you can smell it, but gets sticky like urethane if you let it sit too long, don't know what all is in it. It does work good though.

[wheee!]

The Metal Prep is supposed to sit wet for 30 minutes then washed off.

[Consigli]

Eastwood is an acid for sure, you can smell it, but gets sticky like urethane if you let it sit too long, don't know what all is in it. It does work good though.

It makes me queasy thinking that a chemical stripper can hang up in your car only to percolate out years later and dissolve your paint. How do you know if you have gotten it all out or neutralized it? I guess if a few years pass and your paint job isn't bubbling up you know you did good. 

 

I once read that early on Detroit considered using galvanized sheet metal in all their cars. But they killed the idea because it added a few hundred dollars of cost to each car. 

[Patcon]

The "After Blast" dries hard if you don't wipe it down. I spray it on out of a windex bottle. Let it sit a few minutes then wipe it down, no washing. The metal turns purplish blue so I know it is phosphating any rusted areas. Then I shoot epoxy when I get ready, then body filler, more epoxy if needed, then on to high build primer and blocking, then finish paint

[Mark Maras]

 Creeping rust in the welded seams is the tough one to deal with. The seams that are overlapped or folded over and spot welded allow moisture to eventually eat away everything but the spot weld. There's no way to media blast between sandwiched layers so acid and a water rinse :( or neutralizing agent must be used. Or unfold it and take it apart.

 Does anyone know of a one-step product that will creep into the seams, neutralize the rust, dry to a paintable surface and maybe even seal the seam at the same time. I'm not asking for everything? I'll apply it.