[Stan65]

I have a really nice pair of Trans Am fenders, but there is a tiny amount of surface rust behind the lower rear fender braces. These have never been repaired before and have no corrosion on the outside of the skin.

I would like to treat the area and was thinking of soaking them in evaporust, rinse, dry, then pour DP74 the best I can behind the brace.

I really don’t want to remove a section of the brace, clean, prime, then reinstall.

What do you all think?

Stan

[Chief of the 60's]

POR-15 or Rust-Mort

[SR-71]

Evaporust is a fantastic choice. It works best at or above ambient temp. I use a heated ultrasonic cleaner for small thing items and made a visqueen <sp> lined box to soak whole seat frame bases and backs. You can buy it in gallon or 5 gallon buckets. I would recommend a plastic container or something very close to the size of the fender lower to put it into to save on the amount you need. It will leave a coating when dry if you leave it or buy some protectant that Evaporust sells that protects for months. Using a scotch brite on it will help as well and speed up the rust removal.

[nytrainer]

Couple of things to consider. Research your product's (DP-74) compatibility. I do not use PPG epoxy but the epoxy primer I use does not play well with phosphoric acids (like Rust-Mort).
To contradict that last statement I will use Ospho (a phosphoric acid) to remove rust BUT will be sure to neutralize it before applying my brand's epoxy primer. I'd prefer to remove as much rust as possible and seal it with epoxy rather than "convert it".
Most of these caveats are for surfaces that will be painted and since we're talking about the backside of the fender it's not so critical but I still use the method above that, for me, is proven to work best.
I've heard good things about Picklex too but again I'd neutralize that if I was going to prime over it.
Evapo-Rust is not an acid and I have tried it on rusty tools (works well) but haven't used in on any paint projects.
There's a couple of things that would never pass the threshold in my paint shop and that's POR-15 and any silicone products like Armor-all.

[Stan65]

Thanks for all the replies!

I guess one of the results I hope to achieve is to remove the rust between the brace and the skin that isn’t accessible. So a scotchbrite pad or wire brush isn’t an option.

So does anyone have an opinion on if it will remove the rust without scrubbing and be easily rinsed with water?

I planned on pouring the primer into the brace.

[nytrainer]

The Ospho will neutralize with water. If you should let it dry before rinsing you'd need to re-wet it with Ospho solution and then rinse. You can try the soaking in bucket idea mentioned.

[poncho4554spd]

I used a solution from my local paint supplier when we installed a new dump body at work. I can't remember exactly what it was but you could spray or brush it. It neutralized/converted the rust and turned everything black and made a hard shell. It wasn't POR. I can check on the name tomorrow. It was put on a salt truck and seems to be holding up. Evaporust is good but but you will definitely need to get it cleaned off. I have had evaporust loosen up paint and sometimes leave a black coating.

[Stan65]

I will probably just chicken out and cut the skin off blast the rust, epoxy, and replace skin.

I have went this far on this car!

[SR-71]

You don't have to use the scotch brite it just helps. Rinse with water and prime or spray the Eastwood frame coating which I believe is zinc chromate that is water thin and gets into all the little areas.

[mrrat1]

Just drill out the spot welds.........no need for cutting! It's up to you but I think that would be over kill. I would sand blast or use one of the methods mentioned above.

[Stan65]

When I said cut I meant remove the brace. Just used cut as a generic term.

I drilled the spot welds, and blasted the rust. Welded a couple pin holes, and epoxy primed. (Taped off weld spots)

After it was dry I reassembled by priming the are spots with weld thru primer, then welding. I used 3M panel bond adhesive on the bottom while also resistance spot welding the bottom.

Attached a couple picks of the rust hidden behind the brace. There was no rust through from the outside even after blasting with the brace in place.

The pin holes showed up once I blasted the back side.

[TAKerry]

I am a true believer in evapo rust. Like was mentioned earlier, if you can get a tub the correct size to fit the lower end of the fender in, then let it soak for a few days. It will get into every nook and cranny.
I had seat tracks that were completely rusted shut. Would not budge with a hammer. I soaked them for a few weeks and when I pulled them out there was zero rust left. The metal was a bit dull, I hit them with a scotch bright to shine them up a bit, a little shot of lubricant and they worked perfect.