Rust Detection and Paint Stripping Question

[V-Fib]

This is a question about order of operations and the process as I progress in my build. I've read up on the subject on here and from several restoration books but still require some "sage advice" as to how I should really do this. Bear in mind that this is my first restoration/build of this nature.

 

Some background information:

 

It is a 1977 280z (no motor or transmission) the factory red paint has been painted over with a semigloss black coat of paint several owners ago. The car has minimal surface rust in the wheel wells, undercarriage and floor pans but otherwise seems to be in good condition (no rust pitting or holes in the undercarriage or floor pans, tiny surface rust in the stripped interior). It has been sitting for a couple of years in its current state, prior to me taking it away.

 

The issue:

 

The topmost coat of paint is making it difficult to detect and therefore treat any prior surface rust (aside from the obvious blistering in two spots). I don't see any severe pitting (could be concealed by most recent paint coat) or any major rust outs (could be concealed by filler + paint) on the outer shell.

 

My question:

 

How should I go about taking care of the rust detection/elimination and paint removal process? (Note: I would like to eventually media blast the car for a full prime and repaint).

 

Should I hit it with an orbital sander and remove the topmost coat to see what's hidden underneath, then treat and patch whatever is underneath? Should I spray the exposed sections or patch panels with a primer to prevent further corrosion? Then as a final step have it media blasted?

 

Any guidance on the order if operations or just general suggestions would be fabulous... I'm a little out of my comfort zone and just need some help.

Edited January 29, 2014 by V-Fib

[seattlejester]

Welcome to the forums!

 

You may want to change the title if possible, got a typo up there.

 

Just for your reference, your description of the vehicle and plan are a bit contradicting. If the car has minimal rust, then it would be advisable to NOT strip the car and have it sand blasted. It would be financially more viable to sand back the paint a bit, address any spots that need patches, re primer the car and paint it.

 

You would want to media blast if you had serious reservations as to the integrity of the car, or suspect that rust is hiding somewhere unseen, or wanted to do a bare metal respray. 

 

If you are planning on having the car media blasted, then there is no need to try and detect rust. The media will find it all for you (if it is a thurough blasting job).

 

If you plan on having it blasted, then wait for that to be done. The benefit of having a car blasted is that it will find all the rust, take off the paint, and it will even leave a type of finish that more resistant to flash rusting then bare metal.

 

From your desire to blast the whole car, it sounds like you want to have a full resto for at least the chassis.

 

Basic outline is...

Strip car of all components

Take it to be media blasted

Cut out all the areas that have pitted from the blasting

Order repair panels, replacement parts, or steel to fabricate your own repair panels

Fit repair panels/patches, etc (this would a great time to tweak the alignment of the chassis to make it straight if there are any concerns

Weld in new panels

Blend panel to car

Finish any modifications that will require welding to the chassis, camber plates, bracing, floor panels, frame rails, radiator support, spare tire well etc

Wipe down and primer

 

If you need help making your decision, you can use a magnet to look for any bondo patches, and you can use a pointed dowel to tap against areas that you suspect of structural infidelity. If you tap the metal lightly and the paint flies off or the panel dents excessively the metal in the area is quite weak and will need replacement, if there are a lot of areas with bondo it is kind of a split decision, either bite the bullet, have it blasted, and plan on extensive metal repair, or turn the other cheek if that is opening up a can of worms you are not ready for.

 

And I hope you have a budget set out. The local blaster quoted me 1000 just for blasting the shell, panels, and such (I think 1$ a minute was the rate, plus a basic fee etc), if the floor and rails have to be replaced, the replacement parts alone are ~500, plus the labor to fit and install will be quite a substantial amount. Blasting will be kind of moot, unless you have a repair shop or a welder lined up to repair anything that is found that needs repair.

 

Good luck mate, read lots of threads, and look at the dates, there are quite a few members on here that have spent an extensive amount of time on their cars. Setting realistic budget and realistic goals will also help us help you.

Edited January 29, 2014 by seattlejester

[V-Fib]

Thank you for your reply, I greatly appreciate the info. Sorry I was using my smartphone to type the thread so the result is autocorrect jumps down my throat and guesses what I'm going to say next.

 

I see how my question/statement is somewhat nebulous - based on my rookie assessment the floor pans have good structural integrity. I scraped the rust on both the bottom and the interior of the pans then tapped it with not denting, chipping or pitting. Same story with the frame rails. They are in fact the nicest I've see on the dozen or so Z cars I have looked at while shopping around. It is the top "painted" part that I'm concerned about - if that makes any sense... I'm simply hoping that the paint hasn't concealed rust allowing it to progress unseen.

 

A picture is worth a thousand words so I'm attaching photos of my floor pans and sections of the undercarriage.

 

I read in one if the restoration books that when the car has been painted multiple coats that it is preferred to chemically strip or blast the surface to prepare for painting, is this not true? If I sand down to the original primer and the body work looks sound - what would be the integrity/longevity of the new paint job?

 

The media blasting outfit here in Tacoma is asking $800 for the shell - it's a reasonable price. If it opens up a can of worms I'm prepared to eat the cost - just need to have a quality/reasonably priced shop aligned for the work.

[TeemuM]

I used nylon brush that was attached to power drill to remove all paint from my body panels. It doesn´t do any harm to panels and is quite fast to use, althought quite messy.

 

[V-Fib]

I thought I had more photos than the one above but apparently not... will have to add more.

 

I'm working in a confined space so I don't know how well the rotary brush idea will work for me.

 

Also once it's media blasted do I coat it with a weldable primer or would epoxy primer work just as well since I can always sand down the section to be patched/repaired and then reprime the bare metal section afterwards?

[socorob]

epoxy prime the whole thing and then sand off areas you need to weld. Epoxy primer will hold it from rusting for a while and sticks better to bare metal.

[seattlejester]

Hmm, I really haven't seen bubbly sound deadening. Not exactly sure what to make of that.

 

At some point, yes it is indeed better to start over. I think there is a restoration of a Porsche where they pulled off 15 pounds or something ludicrous from a small panel just because it had been a race car that had different livery every few years or so. Layers of paint do add weight, but if the paint isn't bad it can serve as a workable surface that you can sand down to make smooth curves etc. If you take it down to bare metal, you have to fix all the dents and dings with hammers, dollies, and repair panels, or else add workable material (body filler). Depending on your final color it may be advisable to remove the black if you want something bright.

 

As long as the paint isn't bubbling, sinking in, or flaking off. It means it has a good connection with the material underneath. Even if the paint is flaking off, that could just be due to cheap paint, not necessarily rust. Take a rubberized magnet, and run it over the car, you can find any sizable filler spots that way without taking the paint off. If you are searching for rust, it usually hides in very common places, if those places are in good shape, that means the chassis has been cared for somewhat. If it is still a concern, you take a look from the other side of the panel, under the painted surface. 

 

Taking the car takes up a lot of space, and I do mean a lot. If your workspace is small, you may run into problems with storage.

 

Socorob is on the money. The weldable primer is neat, but it still does burn (which can contaminate welds). Best to save that for spots that you know you have to weld, but won't be able to access to protect right after the welding is complete. If your garage is dry, and you plan on working quickly, you can just leave the car blasted. The finish it leaves protects it from rust to a fair extent as long as there is no direct water contact.

[socorob]

Both mine and my friends Z's, both 78s had bubbly sound deadening on the tunnel. I let mine idle for a very long time in my driveway and saw it start bubbling. I grabbed a putty knife and that area scraped right off while it was hot. Right under the area is where the resonator was.

[socorob]

Also a freshly blasted car will rust quickly. You can treat the bare metal with Ospho or something similar and it will hold bare metal for a short time from rusting. At least down here it will where we have high humidity pretty much all the time. If you do leave it bare, make sure it stays inside with a car cover on it as much as possible to keep it dry as possible.

[V-Fib]

Thank you for all the advice!

 

I will start with a closer inspection, mark areas of concern and will definitely try the magnet trick. I think I will also sand down the areas around the paint flakes/blisters to see what is going on underneath.

 

If I find an overwhelming amount of rust I will have to switch to media blasting.

 

As I continue to strip my car I'm simply trying to plan ahead and get a good handle on what the next steps should be, what supplies to purchase and how much overtime I'll need to log to pay for it all.