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-   -   Protecting the undercarriage (https://www.rx7club.com/new-member-rx-7-technical-256/protecting-undercarriage-1129934/)

duckraisin 09-13-18 03:45 PM

Protecting the undercarriage
 
My FB has what seems to be some surface level rusting spread thinly across the undercarriage. I figure it's not really a problem, but I was wondering if it's safe to treat somehow - either chemically or just sanding it out - and shielding it with some kind of high-temp paint or something. I'd like it to look nice and uniform down there, but if it'll do more harm than good, I'll take my golden-brown finish just fine.

I can throw in some pictures of it after work, assuming it's not storming (again).

Sgtblue 09-14-18 10:41 AM

I have an antique car and have had good results with a product called POR 15. https://www.por15.com/
The surface has to be clean of dirt and oils but it does what it says. It doesn’t like UV but that’s not a problem under the car. And you could spray rubberized undercoating over it if you wanted and still be confident the rust is handled.
Be sure to use gloves. If it gets on your skin and dries, nothing cleans it up and it’ll have to wear off. I always have an empty paint can to put the unused in afterward for the same reason. If it gets on the pressed lip of the old can and dries, you’ll never get it open again. That’s how well it sticks.

Southern_Rotary 09-14-18 10:54 AM

I don't see why some POR 15 and undercoating spray wouldn't work, like Sgtblue said. You just need to make sure to get rid of all the rust before you coat it. If you don't the rust will continue to spread underneath the coating and still rot everything out.

duckraisin 09-14-18 11:06 AM

Alright cool, POR-15 and some undercoating spray seems like a great way to go about it. But as far as actually removing the rust, any recommendations for how to go about that? Sandpaper, wire wheel, or what else might you use to ensure you don't damage the metal underneath?

Sgtblue 09-14-18 11:12 AM


Originally Posted by Southern_Rotary (Post 12300992)
...You just need to make sure to get rid of all the rust before you coat it. If you don't the rust will continue to spread underneath the coating and still rot everything out.

No you don’t. And it won’t spread. Just clean from dirt, oils and any loose scale...and paint with this stuff. https://www.por15.com/POR-15supregsu...ating_p_8.html
They say it molecularly bonds to the iron oxide (rust) and stops it. Thats my experience and I first used it 30+ years ago.

duckraisin 09-14-18 11:35 AM


Originally Posted by Sgtblue (Post 12300994)

No you don’t. And it won’t spread. Just clean from dirt, oils and any loose scale...and paint with this stuff. https://www.por15.com/POR-15supregsu...ating_p_8.html
They say it molecularly bonds to the iron oxide (rust) and stops it. Thats my experience and I first used it 30+ years ago.

Alright that sounds like a plan. Did you use their 3-step with the degreaser and surface prep or just cleaned it up and applied? And do you just apply with a brush or did you use a spray gun or something?

Sgtblue 09-14-18 02:31 PM

No I didn't use their 3-step plan. Not sure they even had it last time I bought the stuff. I think I did use some brake parts cleaner to make sure there was no oils in some areas...probably what one of their "steps" does now. And I used a brush. Buy the cheap throw-away ones because you're not going to reuse them. Stuff dries hard as a brick.
.

FEED AFFLUX v5 09-14-18 02:47 PM

I also approve of the POR-15 route. I have used their 3 step products with great success (see my build thread where I painted my front suspension components and wheel arches).

I especially like the fact you can put it on with a brush as it means you can use it without making a giant mess on your floor. It also dries streak free and hardens in a similar fashion to powder coat. My front steering knuckles feel like they were ceramically coated or something and are 100% streak free. Amazing for a brush on product.

As mentioned - avoid getting it on yourself or other surfaces..... it does not come off. I unknowingly got several splotches of black on my face, not a good look for an office environment :blush:

As for prep, i would start with a scrub brush and/or a metal bristle bush and some simple green by hand and see how it looks after that, You can then tackle and bad spots with a brush attachment on a drill if needed. After that you can use the POR-15 prep chemicals.

Also - be sure to invest in a proper respirator - they aren't that expensive. I think i got mine for about $40 or $50 that can filter out paint/chemical fumes. Safety first :icon_tup:


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