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Best undercoating option

4.6K views 6 replies 6 participants last post by  Pats55  
#1 ·
Guys,

I’m cleaning up the undercarriage of my 70 GTO and looking to reapply the undercoating that appears to have been originally factory applied. I’m looking for a real nice, clean, uniform, factory like appearance. I picked up some 3M undercoating in a rattle can from my local auto zone but not against going with something more professional like an Eastwood product that I can apply with a spray gun. Anyone have any experience with this 3M stuff? See attached pic. Any advice is appreciated.

Mike
 

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#2 ·
I don't believe there were any "factory applied" undercoating, they were applied at a dealer or local business. So, that being said the quality and look varied widely. I would apply what you have and leave it at that.


Brian
 
#3 ·
I used that exact product on one of my old Lightnings and was pretty happy with the results. The hard part for me was first spending 1/2 a day under there removing mud and surface rust with wire brushes, sand paper, scrapers, and anything else I could find that worked.

It was obvious the original owner had not once washed, waxed, or cleaned the truck for it's entire life. I got it for the right price and borrowed my friends garage and lift for the day and got it to a point I was ok with...
 

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#4 ·
Yeah probably not very many differences in the chemistry. One better than the other, not much product thickness maybe.

Undercoating as I remember was tar like, living in FL all cars had it.

Good to have road noise control another benefit. I do not think it is even offered today. And very well should be seeing some of the rusted under bodies and frames posted.
From the salty winter roads driven.



Pep
 
#7 ·
I'm not crazy about rattle cans. Here's what I did under my 55. After I cleaned up the bottom and degreased it. I picked up an engine cleaning gun from harbor freight took a can of my primer (Mastercoat) punched 2 holes in the top of the can, stuck the siphon hose through one hole, the other hole was the vent. I sprayed two coats of the silver primer on the entire bottom. This took all of 20 minutes.I apply two coats about two hours apart Then I mixed up the can of AG 111 satin and sprayed that over the silver primer. The advantage to doing it this way it has the highest resistance to brake fluid, battery acid, stone chipping and if it is chipped the rust will not travel beyond the chip. It's also repairable unlike powder coating