Curse The Sky

With all the body / metal work finally done, we're starting to get into the final stages of sanding, prepping, painting, interior, etc. The fun stuff!

I'm planning on undercoating the entire inside of the floor, beneath the seat risers, probably the inside of the trunk, etc. Since the headliner needs to be replaced, I was thinking about ripping it out and undercoating the inside of the roof as well. Is there any reason why I shouldn't (for example, because of the heat in the summer)?

Finally, are there any places I should avoid undercoating at all costs? Obviously I won't be doing anything idiotic like parts that will be painted, dash, exhaust, fuel lines, etc.

Randys66gt

If you undercoat the roof before you do the headliner, you'll feel like me. The best investment in the world. I undercoated it and also insulated it with some 1/2" insulation, forgot the name but got it at Summit, but in the summer here in the Mojave desert, it REALLY helps!!!

Nick.Simonds

I would spray/paint a rust inhibitor everywhere first. Then come in with a truck bed liner. The bed liner dries hard and very tough. Unlike most undercoating that is rubberized; and melts which can get pretty nasty. Also this would be perfect time to throw in sound deadener after all the liner and such is in.

Randys66gt

I think Nick is right. The stuff I sprayed got hard so it most likely was the liner stuff. Really helps though.

rbinck

I used POR-15 on my floor and then some radiant barrier underlayment insulation. The POR-15 is much better that any rust inhibitor. Can be bought on-line. Also recommend for inside the doors and quarter panels. Then undercoat. On the roof, POR-15 then radiant barrier underlayment insulation held in with headliner contact cement. Then install headliner.

1971mach1

Why are you undercoating the inside?? For rust? or noise?

Neither makes any sense. (not to mention, it will stink like hell)
Undercoating is just a good place for rust to hide.
Dealers used to spray that under the car in the rust-belt states.
All it did was give the dealer some extra profit.

Fix your leaks instead and spray with rust inhibitor paint (or better yet don't drive in the rain/snow).
Put some insulation in and call it done.

tx65coupe

I agree with 1971Mach1. My car doesn't have nor will it ever have any undercoating crap sprayed on it. Secondly if any work has to be done it will have to be scrapped off.

I would also recommend a rust inhibitor and then paint. Insulation is good as well.

jspagna1

I used Loctite Extend Rust Treatment when I restored my car. I put it in the trunk fenderwells and other areas and have not had any issues. I followed up with Permatex undercoating and this was 13 years ago now.

http://tds.loctite.com/tds5/docs/EXTRT-EN.PDF

http://www.permatex.com/products/aut...dercoating.htm

tx65coupe

The other thing I don't like about undercoating is it makes it hard to tell if there is damage under it.

andrewmp6

I have used truck bed liner on my last two toys and it holds up better and its rock hard.