73 Z Cleaning the underside

Discussion in 'Tips 'n' Tricks Topic' started by Bob Lane, Nov 2, 2019.

  1. migzisonfire

    migzisonfire Restoring 2 71’s

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  2. thesalboy

    thesalboy Veteran Member

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    Mine had undercoating on most of it. I used a torch and scrapers to get most of it off. I then used twisted knot radial discs on my angle grinder, flipping them as they flattened. Twisted knot cups were harder to use and couldn't be un-flattened. I got some smaller radial and cup twisted knot brushes and used them on air tools in the tighter spaces. I went down to bare metal - even on my California car, there was rust under the original primer. It makes a mess, but not as bad as blasting - I've done both. Wear welding leathers and a full face shield - wires spit out at enough speed to break skin.

    For protection, after scrubbing with red Scotchbright and Ospho wiped off before it got tacky, I sprayed Summit epoxy primer, then UPOL Raptor bedliner within the 4-day curing window. I had to modify the shifter opening, and confirmed that everything is very durable. FYI for rattle can, I like 3M 03584 Professional Grade Rubberized Undercoating - I've used that in other spots, like the inside of the cowl sides.

    http://nastyz28.com/threads/camaro-rs-ls1-build-thread.312352/page-10
     
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  3. Silverback

    Silverback New Member

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    I used a pressure washer on both my truck and my Trans Am. In both cases I sprayed it down with a 5:1 solution of Superclean, scrubbed it a little with a stiff tire brush in the worst spots, pressure washed till I was tired of it, and then blew it off with an air hose.

    In the case of the TA that dissolved the bit of undercoating/tar that was on the bottom of it, a nice coat of diff lube and in most places where it was coated it took off the paint/primer down to the zinc coating on the steel. I fogged it with some etching primer and some paint and called it good (it's a "race car" that rarely even sees rain).

    On the truck this got most of the loose stuff off the bottom of the truck. Any remaining rust got a quick spray of HF Rust converter or Rustoleum brush on (both the top rated for a spray and brush on converter), but the rest got sprayed with Rustoleum rusty brown primer and then fogged with semigloss black Rustoleum (Using an HF spray gun, I have better ones, I didn't see the point in getting them dirty). It's been that way for a couple of years now and if you spray it off with a hose it's still a nice semi-gloss black, it REALLY looks like a new truck underneath (the bed sides are rusting now... but that's a different issue)
     
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  4. Staccato

    Staccato New Member

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    I just use a pressure washer, the result is ok but could be better.
     

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