Has Anyone Undercoated Their Car?

[60TR3A]

My mechanic suggested spraying on a German-made undercoat to protect the car from the salty humid air of Sanibel Island where my car now lives. I like to keep the car as original as possible but he's got a point since the car is in a very bad environment and rust is a real threat no matter how well I store the car and never get her wet. Since I'm only going to use her for driving around the island and the occasional car show just for fun and pride, not points or anything serious, do you think I ought to get her undercoated? If I did go that route, I'm inclined to want to then get the undercoat painted white to match the car. Your thoughts?

 

[charlie74]

late last season i had one of our daily drivers undercoated locally with lanolin. the mechanic said that it should be done 2X/year but the coating seems to have lasted pretty well, and a for a fair weather car such as ours it would probably last quite a long time. my six has had all the insides of the panels done and also the inside of the frame. this was ages ago, but aside from 1.5 years in vancouver BC, it has never lived in a corrosive environment.
i'll probably do the 6 as some point soon.
lanolin was inexpensive, seems to have lasted pretty well, is non-toxic and wont leave oily spots in your garage although their is a slight odour that will go away after a couple of weeks.
c74

 

[Brinkerhoff]

I wouldn't undercoat it but I'm a big fan of using commercial auto body rustproofing and tools to coat the insides of the boxed areas of the cars after refinishing , before it gets put back together. Messy, but will add 50 yrs to the life of your car.

 

[60TR3A]

Well, my car was restored about 11-12 years ago so it's too late to coat any of the hidden boxed areas, and as for lanolin, I bought some once thinking I could use it on my 2 dogs' coat to make it more water-repellent (they are a breed with "hair" instead of "fur" and have no natural oils so their hair absorbs moisture and all sorts of sticks and spurs and stuff stick to their legs), but the stuff was stickier than heck. It's like petroleum jelly & like wax but thicker and stickier. Maybe what's used on cars is thinned out so it can be sprayed on but if it's sticky, all sorts of gravel and dust would stick to it. If I were to go the undercoat route, maybe I can get it painted after it cures so it would be white like the body and therefore less noticeable. My only concern is doing something like that which is almost irreversible and therefore detract from the car's value as being mostly original.

 

[charlie74]

i'll try to look underneath my car today and see how it looks as far as dirt and crud but i had the wheels off earlier this year and it did not look too bad. it was indeed applied by sprayer so it sounds like something different from the dog stuff you had

if your paint and finishing were done well with good products to start with you probably wont have too much trouble anyway. my restoration is over 20 yrs old now and my frame and body have not rust.

c74

 

[60TR3A]

i'll try to look underneath my car today and see how it looks as far as dirt and crud but i had the wheels off earlier this year and it did not look too bad. it was indeed applied by sprayer so it sounds like something different from the dog stuff you had

if your paint and finishing were done well with good products to start with you probably wont have too much trouble anyway. my restoration is over 20 yrs old now and my frame and body have not rust.

c74

Where do you live? Bear in mind that my car spent the past 15 or more years of its life in the Maryland area and is now in Sanibel, FL, an island off the west coast of Florida that is surrounded by salty water form the Gulf of Mexico (300 yards across the street in front of my house) and the Sanibel River which my backyard is directly on, so we are surrounded by salt water. In fact, my house is on an island within the island of Sanibel (an island inside an island!), so salt is everywhere and FL is notoriously humid, so no matter how well I've insulated and air conditioned my garage, just driving around the island will mean that the undercarriage will be exposed to salt and the humidity will make it stick, a surefire recipe for disaster. My paint & body shop is looking for a white undercoat to spray on just the white body panels and wheel wells and not cover axle, differential, frame, transmission, etc., just the parts that are painted white. I'm now leaning toward going that route if white undercoat is available, or else use the black stuff and then paint it white to match the body...but no final decision has yet been made, so I'm still waiting to get more opinions and suggestions from forum members before I make the final decision. Thanks everyone for your input so far!

 

[tdskip]

I wouldn't undercoat it but I'm a big fan of using commercial auto body rustproofing and tools to coat the insides of the boxed areas of the cars after refinishing , before it gets put back together. Messy, but will add 50 yrs to the life of your car.

+1

 

[tdskip]

Well, my car was restored about 11-12 years ago so it's too late to coat any of the hidden boxed areas

No, not really. The sills etc can still be treated.

But if you keep the car garaged and dry and there isn't any existing surface rust I'm not sure how much of a problem any of this will be.

 

[glemon]

i don't like undercoatings, they usually protect some maybe most of the car better, but where not fully sealed over time create more pockets for rust to develop. If the underside of the car is was primed and painted in the restoration I would not worry about it too much. I would worry about the inside of the frame and rocker panels, I would use waxoyl (commercial product) or some such which are supposed to be self spreading and sealing in these areas.

I think you can mix your own similar product, don't know if lanolin is similar, that is a new one for me.

You might have to drill some holes to squirt the stuff in, but that is not a bad thing either, as it will allow any moisture that gets in to drain out and better air circulation in the cavities, moisture/salt etc. is bad, trapped moisture and salt is much worse.

 

[apbos]

If some is looking for lanolin, it is available in 4.5 lb tubs from your local farm stores.....Bagbalm about $33. Put it in the microwave and melt it like butter. We use it in the Veterinary practice.

Paul

 

[60TR3A]

My paint & body shop (a well-respected restoration shop) says they can use color-matched undercoating. They would clean up the surface rust that is already showing on the floor pans and would mask off everything not already painted white and only coat the white surfaces on the underside of the car. As the owner explained to me which I completely agree with, "When you drive on Sanibel Island, you are effectively sand-blasting your undercarriage with salt and sand, so it doesn't matter if you never get your car wet and if you store it in an air conditioned garage, it will eventually get rust." Since it already has rust underneath, and since I live on Kinzie Island, an island inside the bigger island of Sanibel, my house is surrounded on two sides by salt marsh and I have a gravel driveway made up of ground-up coral and sea shells so no matter how well I treat the car, it is going to rust if I don't protect the undercarriage, IMO. As you can see, I am strongly leaning in favor of the idea of having the paint shop do it.

 

[60TR3A]

Howdy, neighbor! You're right, Woodstock is summer and fall but none of my cars are ip there. As for undercoating trapping moisture, I can't imagine it being any worse than paint or lanolin, but if applied by an expert paint & body shop, should protect against rust, not promote it. I've got to do more research before I do anything. Thanks for your input!

 

[PeterK]

Lanolin is the main ingredient in Fluid Film used on tractors and other machinery to seal agains corrosion. It comes as bulk as well as a pump spray. I goes on as a thick white liquid which clears a bit and smells like a wet sheep. I use it on tractor hardware to prevent rusting. Google Fluid Film for more.

 

[tdskip]

and smells like a wet sheep.

You say that like it is a bad thing Peter....ha.

 

[PeterK]

It actually smells like a clean wet sheep so not bad and as a bonus leaves your hands nice and smooth and soft.

But wet goat smells a lot worse <- really not a good thing.

 

[MichaelG]

Yes, I had mine done, but it doesn't look at all like the rubberized undercoat that typically comes to mind....some of the modern products look more like paint, and if its color matched it will look fine.

Believe you will have no regrets given the humid, sandy and salty environment.

Also there is a great product called Boeshield T-9. Comes in an aerosol can. You can use it to prevent rust on many surfaces under the hood, emergency brake cables, hinges, suspension etc. Great product

https://boeshield.com/features-benefits/auto-cycle/

 

[glemon]

I will admit I am not familiar with the more modern undercoatings, but the reason I don't like the older type, unlike paint or waxoyl or lanolin, is that if paint separates from the body it will tend to flake away, the thick undercoating can separate but it has enough body or strength not to break off or flake away, leaving a pocket for moisture and crud to collect.

My TR250 was undercoated, where it stuck the metal was good to pristine underneath, where it did what I described above rust formed, possibly worse than it would have had there been no undercoating.

Of course as I stated, newer products may be less likely to do this, but opinions were solicited so I gave mine.

Regards, Greg

 

[60TR3A]

Good point, Greg. Maybe the trick is to strip the paint first and spray the undercoat wherever there was paint directly to bare metal. All I want to cover are the white-painted surfaces, not the black frame, cast transmission housing, differential, suspension, etc. In other words, the body, not the chassis, drivetrain or suspension.

 

[Andrew Mace]

Good point, Greg. Maybe the trick is to strip the paint first and spray the undercoat wherever there was paint directly to bare metal.

Maybe I'm wrong, but I think that's the LAST thing you'd want to do, as I don't think any sort of "undercoat" is intended to be applied to bare metal. Primer, then proper topcoat, THEN any additional undercoat or "rustproofing" or whatever....?

 

[glemon]

I would hope shop that is going to apply it would know/have the surface in the proper condition for application. In my experience rust through almost always starts from the inside out, but I don't live anywhere near saltwater, just salty roads in the winter that midwest cars are exposed to.