I am getting ready to POR 15 my interior and underside after welding in new patches and prepping according to the directions. What I was thinking of was after I was done I would use some spray on rubber undercoating under the car just for added protection. Does anyone see any problems with that? What do you think of doing the same on the interior and inner doors for a little added sound proofing and protection?

 

No problem with that at all. May want to scuff up the POR15 a bit for adhesion.

 

Main thing is to make sure you use Marine Clean and Metal Ready prior to spraying the Por-15 especially on clean metal. It'll make it stick much better. Some of the cheaper spray can rubber bed coatings will want to melt and get sticky if they get hot. I've never had an issue with the gallon can size brush type before.

 

Sounds good I have a bunch of marine clean and metal ready. I am using it as directed. I was planning on using 3m spray coating. I Think it will go well with what I am doing.

 

just recently did that to my girls Z28. Have previously done it to 2 of my own cars and it worked out great. Using the 3M undercoat is about the best, Duplicolor Professional works well too. The cheaper stuff comes out looking like crap.
before

during

after

 

I agree that you will need to scuff the por-15 before adding a coat of anything except primer.... I definetly wouldnt use a rubberized undercoat on the interior, usually rubberized stuff has the tendancy to rub off over time and you would probally smell it on a nice hot summer day..... use a spray on sound dampener (lizard skin) or stick on(hushmat, dynomat...ect.) Post some pics when your done if you can.

 

There is some brush on stuff from Al's Liner that is heat/noise resistant and seemed to work really good on my car. Only problems is its a ugly off white color but I used some generic black spray undercoat that goes on really thin to cover it.

 

GTFiero - how did you get the old undercoating off?

 

Looks like a wire wheel would work.

 

the stuff that was on the car was poorly done, most of it came off with a regular scraper, also wire wheel and brushes to strip the rest and the surface rust off. Just be prepared to get real dirty and wear safety glasses!

Also I didnt want everything covered in undercoating, up inside the trans tunnel and the frame rails i went over the POR15 with Epoxy chassis paint as well

 

gasoline and a rag... wipes right off