What to do about the factory undercoating.

[Bulldog69RT]

I started to chisel off the factory undercoating from the inner fenders and it seems to be still doing its job. Pretty green paint underneath and no rust. Should I just sandblast the bare and painted metal underneath and the undercoating that doesn't come off, just leave it? Because this undercoat is not easy to remove! And what should I use on the bottom of the car? POR15? Truck Bedliner? Undercoating spray?
Thanks

[Troy]

I left mine on (as long as it was still holding tight). I drive my cars a lot more than others though. If you really want to remove it I have a few methods:
1. Heat and a scraper. A heat gun might work but a torch is better. Beware the flaming hot tar though!
2. Kerosene. I've been told it works but likely makes a huge, toxic mess.
3. Knotted wire wheel. I use a 6" one on my grinder. It works fast but makes a major mess!
4. The media blast place I use says they have some solution that removes it easily (probably kerosene). After you spend 4-5 weekends removing your you may wonder why you didn't pay someone.

Wear protection!

As for replacing it, why not use undercoating? Remember that the factory undercoating had multiple purposes: rust protection, dent/scratch protection (inside fenders), sound deadening (inside doors and quarters), and heat shielding. Epoxy primer should be the first step. I don't put POR15 on anything as it's designed to go over rust (Paint Over Rust) and my cars don't have any rust when I paint them. One restoration shop I had a car at uses sprayable/paintable truck bed liner. It has a slighlty rough texture but otherwise looks good. Most people seem to like painting the entire underside - even though the factory didn't. I plan to use something like Lizard Skin inside the car to cut down on heat and noise. I've never tried it but have heard great things.

Troy

[Bulldog69RT]

Thanks for the response! Whatever the sandblaster doesn't take off then, Ill just leave it there and spray the whole thing with undercoating.
Is it ok to spray the factory undercoat with epoxy primer?

[FLG]

Thanks for the response! Whatever the sandblaster doesn't take off then, Ill just leave it there and spray the whole thing with undercoating.
Is it ok to spray the factory undercoat with epoxy primer?

Exactly what i did, if the undercoating is good and the metal rust free just leave it alone.

The epoxy primer shouldn't effect the factory undercoating.

[DC_1]

This works

http://www.youtube.com/watch?v=jzv38W1DDic&feature=youtube_gdata_player

[Troy]

I have also seen a video where dry ice was put on the floor which froze the undercoating and it all fell off with a hammer blow. That's probably the cleanest method I've seen - although it takes some planning and could be dangerous.

Troy

[E5 Charger]

Eastwood has a spray for that. I haven't tried it myself, but might be worth a try.
http://search.eastwood.com/search?w=undercoating+removal

[Daytona Guy]

I'm doing what Dodge did in the truck - how they painted over the coating - Clean it and paint (color of your car) over it. I think it will look good and clean.

Dane

[404NOTFOUND]

I'm doing what Dodge did in the truck - how they painted over the coating - Clean it and paint (color of your car) over it. I think it will look good and clean.

Dane

That's how my cars is. It does look good and clean like you said.

[bull]

I didn't want to remove mine as most of it was in decent shape and I like the benefits of undercoating. So I just cleaned it as best I could and then reshot it all. The one exception is my front wheel wells. On those I scraped off all the undercoating from the inner/outer fenders and coated it with Chassis Saver. Once the fenders and spash shields are back on the car I'll scuff it all and shoot it with new.

As for reshooting the rest of it, I kept it thin where the factory coating was good (just enough to create a uniform shade) and laid it down thick where it wasn't so good. I used the Resto Rick undercoating product because it's a good match to the original. Here's a thread showing some before/after pics prior to the final touch up.

http://www.dodgecharger.com/forum/index.php/topic,67850.75.html

[defiance]

Removed mine - sandblasted it - then recoated it with raptor liner.  In retrospect I'd have probably been better off leaving what was there in place; I thought as old as it was surely it was going to be cracking, flaking off, rusting under it, etc.etc.  A few hours into the job I realized the metal underneath was pristine and this stuff was STUCK.  Stupid pride said I'd already started, so might was well finish and have it all coated with the same thing.  Countless hours late I finally finished, recoated with raptor liner (which was easy and is solid stuff), and realized I'd just spent all that time for barely any gain!  Should've just found any bad spots (very few) and dealt with them individually.