Undercoating question

[phat46]

I have the day off so I am finishing the floorpan on my '40 P.U.  I am about to apply the seam sealer and I thought maybe after I had it painted if it would be a good idea to spray on some undercoating to make sure I have it all sealed up. The pan is homemade and is about 20 different pieces with lots of seams skip welded together. Is there any downside to using that spray-on undercoating on something like this?

[40]

I seam sealed the * floor/firewall in my 36 project with 2-part seam seal and then sprayed a generous coat of rock gaurd over the top of the entire floor pan and painted it.Though I'm not real wild about the textured look,it turned out nicely and I think it will stand up well to the road abuse.I have used the rubberized undercoating in the same manner in the past with good results....just thought I'd try the rock gaurd this time.

[purplepickup]

I personally don't like undercoating because I can't see what's going on underneath it and it's a bear to get off if you have to.  I prefer to just paint the bottom.  You don't get any rocks up under the cab anyway.  Most of them are out in line with the tires.  If it does chip you can easily scuff it and spot paint it with a spray can.  Since I've been driving on the salt I want to see where the rust is and deal with it before it gets bad.

The Rambler I got last summer has undercoat inside the fenders and I can see just a hint of rust showing and I don't know how bad it is.  The guy said he drove it on Daytona Beach so it probably got salt water on it.  Now I've got to strip the darn thing and you can bet it will be painted next time around.  Sometimes rust can really take hold before you notice it thru the undercoat.

This is just my own opinion.......a lot of people like to use undercoating.

[paul2748]

You could use something like POR 15.  Probbly should use their metal etch first.

[40]

George,Good point about the rust.I always start with clean,raw metal and the first thing I do is use a good etch primer immediately.How's the foot doing?

[zzebby]

On my next project I'll take it to the spray on bed liner guys.   Really good adhesion.   I've had two beds done and have 5-6 years on one and still looks new.  I never found the undercoating to stick well enough to prevent rust growing under it  and painting only is little protection and no sound deadner.  
The beadliner guy will spray the floor and inner sides for about $5-600  which is a little pricey,  but the sound and seal will be worth it.
Any input on this stuff?

[phat46]

I thought about it and i have decided just to paint it.  George is right about the rust under the undercoating. We used to have two Undercoating places in town, Tuff Coat and Ziebart, you couldn't buy a new car here that wasn't undercoated, when the cars were delivered to the dealer they would take them straight to the under coaters and passed the price along to the new car buyer. I bought a new Pontiac in '85  that had been undercoated and it was rusting in two years! Every person i knew that had a new car at that time was having the same experience. The undercoating would crack, trap water and rust away. Both of those undercoating places no longer exist. I don't think Ziebart of Tuff Coat is in business anywhere anymore, I don't hear of them or see them advertised anymore.

Also the mufflers are going to be about two inches from the floorpan so the undercaoting may have melted onto the muffs anyway!   Maybe I'll put some of the sprayon bedliner on the insde of the pan, then if I spill a beverage it won't rust out my truck...

[38fordcoupe]

I would seal the seams and paint it making sure to take your time and get paint in every nook and cranny you can find.   I've even heard of some guys painting ,seal the seams and squirt it again . In that order.
Which ever way you go it will probably outlast most of us.

[enjenjo]

I don't think Ziebart of Tuff Coat

Don't know about TuffCote, but Ziebart is going through some kind of reorganization. They lost a suit by a large percentage of their dealers, and had to pay a big settlement.

I like the chip guard myself.