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1 hour ago, seattlejester said:

The ospho stuff you really want to tackle with a wire brush or something before you coat it. The things like the brake booster with the possibility of the reaction disc having fallen out over the last 40 years was easy to just drop off and exchange for a reman. 

 

4 minutes ago, grannyknot said:

jkelly, as far as Ospho  (Phosphoric Acid)  goes, you have to eliminate as much of the rust as you can, if you apply it to well established rust like on your brake booster it will never get down to bottom of the corrosion. A bench mounted wire wheel or even some 60grit paper will break that crust on the rust and allow the Ospho to get down to the bottom. The white powder won't show up for a couple of days until it has dried completely and your right, paint will never stick to that, it must be washed off.

Getting rid of as much rust as possible is always the best method, Ospho is better than nothing but it won't penetrate heavy rust.

Yeah, that's what I'm learning now. The brake booster was intended to be a test piece that represents the level of rust inside the car's enclosed spaces which I can't access with a rust removal tool.  I was going to see if the Ospho would convert the rust and see how epoxy primer would bond to it with only a water rinse and drying, since that is all I can really do in some areas without cutting access panels or acid dipping. Based on this scrap booster it seems like that isn't going to work -- I'm not even going to bother testing the epoxy on it. I'm probably going to end up cutting access holes to get a grinder in those areas before applying the ospho.

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I am going to work on my cowl this weekend. I am going to look around with a borescope and see how it looks in there. Then make an effort to not get too crazy.... Most Z's have a little rust, if it's no big deal I will treat and encapsulate. Last time I said that, I ended up cutting out half the wheel well under the battery tray. 

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23 hours ago, LLave said:

I am going to work on my cowl this weekend. I am going to look around with a borescope and see how it looks in there. Then make an effort to not get too crazy.... Most Z's have a little rust, if it's no big deal I will treat and encapsulate. Last time I said that, I ended up cutting out half the wheel well under the battery tray. 

Good luck! I get the crazy bug. I have to always tell myself not to get to crazy or go too far with it. I feel ya.

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Removed a dog leg this evening. It doesn't look good. Pretty nasty in there. Most of the rust is down low, though, and around the fender lip. Decisions Decisions. I'm not sure if I want to just blast what I can and only replace the dog leg or replace dog legs, rocker, and the fender (inner and outer?)  The more I work on this thing the more shit I find!!! Ahhhh!

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Edited by jkelly

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Honestly it seems like really only the lower panel is really troublesome. The area near the hinges has some slight surface rust which you can probably get away with a neutralizer and some sealing primer. You can order a patch panel for the outside, for the inside really it is just a matter of connecting pieces and sealing it against rust. You can cut out the bad metal and put in a flat piece like the guy did on project hugo, might add a bit of weight, but no one will see it. Back part of the wheel well can be done similarly as well cut out the piece, then get a flat sheet, bend it to fit the curvature, then tack it in, weld beads for strength, then seam seal for water tightness so water does not get kicked back up in that area.

I guess the question is what the purpose of this car is. Is it a forever car, is it a driver, is it something you think you will sell down the road? What kind of repair could you live with? Will even the smallest bit of surface rust eat away at your conscience? If you don't repair it exactly like how it is will you never trust the strength of it? 

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2 hours ago, seattlejester said:

Honestly it seems like really only the lower panel is really troublesome. The area near the hinges has some slight surface rust which you can probably get away with a neutralizer and some sealing primer. You can order a patch panel for the outside, for the inside really it is just a matter of connecting pieces and sealing it against rust. You can cut out the bad metal and put in a flat piece like the guy did on project hugo, might add a bit of weight, but no one will see it. Back part of the wheel well can be done similarly as well cut out the piece, then get a flat sheet, bend it to fit the curvature, then tack it in, weld beads for strength, then seam seal for water tightness so water does not get kicked back up in that area.

I guess the question is what the purpose of this car is. Is it a forever car, is it a driver, is it something you think you will sell down the road? What kind of repair could you live with? Will even the smallest bit of surface rust eat away at your conscience? If you don't repair it exactly like how it is will you never trust the strength of it? 

Interesting ideas. Are you talking about this section as the back part of the wheel well? image.png.ea094450eae615aa41b9ce773f9de257.png

I remember seeing Project Hugo a while back. I'm going to have to do some searching to find the exact pictures -- there's a thread of that build on numerous websites.  It's going to be a daily driver but not when the weather is shitty. It will also see some track days as well. And I may enter it in some car shows, but it's not 100% original and not everything is perfect. I'm doing an L28 swap, aftermarket suspension, aftermarket bits and pieces, etc. I plan to keep this car for a while -- I'm not building it with the intention to sell. I may end up doing another zcar or other restoration that is more of a primary track/race car.

I'm okay treating surface rust with a converter and encapsulating, just not heavy rust like in the picture. I gotta do something about that! On the fender/inner fender overlap circled in red in the picture I would think there's rust all the way around the length of that overlap.

Edited by jkelly

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Yup, mine was similar.

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Cut it out to a shape that is easily replicable.

Then spend some time making a piece to replace it. Given its location you can definitely have it be a bit bigger to overlap inwards.

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Notice a ton of overlap in my case.

Then weld it in.

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My dog legs were bad as well, so I just trimmed off the square portion under it and replaced it with 18 gauge if I recall. You can see the lack of the rear wheel well flange as proof of that panel being replaced as well.

Edited by seattlejester

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I have also torn my hair out trying to paint strip my car. My garage is too nice to fill up with sand, so I first tried paint stripper. It was mostly a waste of time with the 10 layers of paint on my car. I ended up just using the strip discs on the grinder, and even then my back yard was full of dust. Every method is messy, but I think I will have my next project car dipped. It may cost more and I do love doing everything myself, but I think it is the best method for a car with a lot of rust. 

I really enjoy making patch repair panels, although I don't like overlapping, as it makes a pocket for rust in the future. 

 

 

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Off topic a bit, but real aircraft paint stripper will eat through paint like crazy. It really doesn't care how many layers you have there it will eat through all of it if you apply it on in gobs. Now the stuff is really really really bad for you, the legitimate stuff has a crazy long warning label that will paint a gruesome demise if you do not follow precautions. The cheaper spray on stuff I found doesn't do much other then remove a light coat of spray paint.

Honestly roloc discs are pretty awesome if paint removal is your game. I am not sure how they do on rust, but they will eat everything else away except metal. They are pricey and you have oto have an adjustable speed grinder or else yo will blow the bristles off.

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42 minutes ago, seattlejester said:

Off topic a bit, but real aircraft paint stripper will eat through paint like crazy. It really doesn't care how many layers you have there it will eat through all of it if you apply it on in gobs. Now the stuff is really really really bad for you, the legitimate stuff has a crazy long warning label that will paint a gruesome demise if you do not follow precautions. The cheaper spray on stuff I found doesn't do much other then remove a light coat of spray paint.

Honestly roloc discs are pretty awesome if paint removal is your game. I am not sure how they do on rust, but they will eat everything else away except metal. They are pricey and you have oto have an adjustable speed grinder or else yo will blow the bristles off.

I have heard that aircraft paint stripper is the go, but I have not been able to find it here in Aus. The Roloc discs are basically what I have been using and they are great for surface rust.

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Be careful using any acid product under certain epoxy primers.    Many epoxy primers are not compatible with acid rust convertors or etch primers.    In the House of Kolor tech manual, it states over and over not to use any acid product under their epoxy primers including etch primers.    Check the tech data sheets on the paint system you plan on using to make sure you dont end up causing more headaches down the road.

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26 minutes ago, 331CI 280z said:

Be careful using any acid product under certain epoxy primers.    Many epoxy primers are not compatible with acid rust convertors or etch primers.    In the House of Kolor tech manual, it states over and over not to use any acid product under their epoxy primers including etch primers.    Check the tech data sheets on the paint system you plan on using to make sure you dont end up causing more headaches down the road.

When ever you use an acid based rust converter, wether it is off the shelf, or white vinegar, you need to ensure it is thoroughly cleaned away, no matter what you are topping it with. If the tiniest bit remains, it can cause headaches later. 

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Of course, neutralizing acid products is a must. 

I've only used the bristle ones for getting gasket material off an engine. With a vertical/not angled die grinder you basically have a big eraser. DIdn't know they had flat ones. Depending on the use a wire wheel or cup may last longer for that application.

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9 hours ago, jkelly said:

When you guys mention Roloc discs are you talking about the bristle ones or the flat ones? I've used the flat Rolocs. They do work well on flat panel surface rust. Never used the bristle ones.

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OR

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Earlier I mentioned the 3M bodymans bristle disc, the purple ones. They are awesome for irregular shapes, or materials that overload sanding or convoluted disc (IE undercoating, seam sealer). 

https://www.3m.com/3M/en_US/company-us/all-3m-products/~/Scotch-Brite-Roloc-Body-Man-s-Bristle-Disc?N=5002385+3293083481+3294297763&rt=rud 

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On 10/25/2017 at 4:31 PM, LLave said:

I am going to work on my cowl this weekend. I am going to look around with a borescope and see how it looks in there. Then make an effort to not get too crazy.... Most Z's have a little rust, if it's no big deal I will treat and encapsulate. Last time I said that, I ended up cutting out half the wheel well under the battery tray. 

I drilled the spot welds in the cowl vent cover yesterday to get a better look at mine. It's pretty rust. I'll probably cut the vent tube out and see what I can fabricate to replace the rot in there. Hopefully yours wasn't too bad.

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That looks good! Looks like there was probably a good bit of rust there to warrant that kind of repair! Did you guys cut away the metal covering over the entire cowl area for better access?

Mine has some holes around the inside where the vent tube meets the cowl area floor.

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16 hours ago, seattlejester said:

Oh man you are going all out. 

V-fib did the same repair. His had actual holes.

I roughed out the shape for him and put in the curves and suggested he go out and grab a box section for the vent chimney. He welded it in.

 

Good idea on the box section too. I think I have some laying around here somewhere.

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1 hour ago, jkelly said:

Good idea on the box section too. I think I have some laying around here somewhere.

It really is just designed so that you don't pull in water into the car with the fresh air. If you really want you can match up to whatever heater/blower you plan on running, but yea a box section is way easier to work with then trying to use use sheet metal and spot weld.

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I ended up just drilling the spot welds from the bottom side and removing it to sandblast it and sandblast around the cowl area. I'll just spot weld it back in from the bottom. It has a few rust holes in it. I think I'm just going to fill these with body filler or something easy, instead of welding them.

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