Ziebart, undercoat or what?

[erikgiles]

I own a '70 Z that was stripped and restored, no rust. It was a west coast car, but now I own it in the east where Z's rust.

I am thinking about undercoating it with off the shelf undercoating, or, having it professionally ziebarted. Some people tell me I don't need to do either.

Opinions?

[2ManyZs]

If the paint on the underside is in good condition without a lot of chips and you don't drive the car daily I think I would leave it alone. If the car is stored inside and only driven occasionally it would probably be a waste of money. If you do drive the car quite a bit you might consider putting some type of coating inside the wheel wells just to make sure you don't have any surface rust popping up from rock chips.

You could brush on some POR-15 and then either wet sand it down or use their primer and re-paint the fender wells in body color. Or you could get some of the brush on bed-liner coating and put that in there. In fact, I think I just saw some advertised you could mix your body color paint with to color match it to the car. Now, if I could just remember where I saw that advertised.:tapemouth

BTW, I found where I saw the tintable bed-liner kit. It's in the newest Eastwood catalog. It's a bit expensive, but it might look fairly decent since it could be color matched. It's made by SEM.

[erikgiles]

Thanks for the advice, as well as the advice on the engine. Where is Woodstock VA? While I'm on the subject, do you know any good shops that can help me with the engine?

Regarding undercoating, should I do just the wheel wells? Z's get alot rust, well I guess you know that better than I do, so, why not coat the floor pans and other places?

I think I like the bedliner option. I think I'll just use plain black even though the color is 'black current pearl'. Do you see any potential issues there if the color is not exact?

Thanks again!

Erik

[jcdozier]

As usual, 2ManyZs is spot on. (Why is it that I seem to always FOLLOW his posts? :tapemouth ??)

I stay away from undercoating. In addition to adding weight, (especially in the case of bed liner) it also can lead to more rust problems instead of less. Under a "clean" car, any water will soon dry. There is a potential for chips and/or cracks in a "hard" undercoating from road debris, which will then provide a "safe haven" for water to collect and do it's rust work.

If you are really concerned, I suggest following 2ManyZs recommendation for coating the wheelwells. My '71 240 has spent it's time in California and SC and the only rust that shows up is at the leading edge of the rear wheel wells, (got some now :mad: that needs attention).

OBTW, I like your idea of black in the wheel wells.

JIM DOZIER

[2ManyZs]

Well, I don't know about shops in your area, I'm up here about 60 miles north of Staunton. You probably could find out through the Tidewater Z club, or if I'm not mistaken, I think there is one in Richmond isn't there? You could try the Z Club of Northern Virginia also.

I personally like the idea of the POR-15 better than undercoating as it is not as thick and it is a designed as a rust preventer, and it is harder and probably less prone to let moisture in and trap it underneath. I just got some but it sounds like it may be difficult to do without making a mess in the garage (I'm good at making a mess, bad about the clean-up). Eastwoods has a product now that is very similar to POR-15 so that might be an alternative. I guess the main deciding factor will be how much you are planning on driving the car. If you plan on driving it a lot then I would suggest at least doing the wheel wells, it all depends on how much work you want to do. My car is going to be mostly a garage queen so I'm not going to put any back on, the original undercoating is in good shape for the most part so I'm just going to seal and paint over it. I'm wondering how much might have been left on your car, or if it was taken down to bare metal before it was painted.

jcdozier, I don't know why you follow my posts. Maybe it's because I sit here and spend too much time on the site waiting for the weather to improve to where I can go work on mine again. From your posts I've read you can take my place, you have just as much good info to share as I do. So, crack your knuckles and get ready to type a lot, summer's gettin close.

[jcdozier]

2ManyZs

Thanks for the kind words, but I know when I'm outclassed. You are way out of my league in both knowledge and experience. I'll just continue to pick and choose and contribute on those few occasions when I can.

JIM DOZIER

[EScanlon]

I didn't vote, since I'm just going to give my opinion based on what I know.

Ziebart:

EXCELLENT stuff when applied to good rust-free metal, i.e. brand new cars fresh from the dealer / manufacturer. When applied to older vehicles that have already had some rust begin in hidden places it pretty much seals it in and IF no further air or water can get to it, will SLOW down the rust pretty much for ages. Note I said SLOW down.

The problem with rust, is that once it starts it's pretty much a chemical process that has begun and it doesn't just ~STOP~ because you put a coating on it. Ziebart for the most part is a tar / oil based product that will "penetrate" everywhere. They need to drill access holes for various panels (depending on the vehicle) and will need to keep it for a given number of day's to allow the excess stuff drip out and have them clean it up.

UNDERCOATING:

Some definition in order here. There are various types of "undercoating" out there. The most popular is a product called Shutz, which is literally liquefied tar with some additional filler material to give it a "spongy" feel when it finally dries. This is what you very commonly see on the undercarriages of cars and wheel wells with that "gritty" black look. It's somewhat hard, but will "give" when pressed. It's main function is to protect the painted undercarriage from paint chips due to gravel, sand, ice, snow, sludge etc.

The other type of undercoating is a rubberized undercoating that can either be tinted to match the color of the car with some of the paint for the car, or it can be painted by itself. If painted alone it is usually a milky translucent shade. This stuff is that pebbly looking stuff that is used on the outer side of rocker panels, and behind wheel wells to absorb and deflect rock chips and impacts from the debris kicked up on to the car from the tires.

Shutz should never be used on the "exterior" or "visible" side of the car, and although you can use the other on the undercarriage portion, it's cost is usually too high to give you the benefit that other undercoatings can. The main reason for Shutz not being used on the visible portion is that it literally looks as though you smeared road tar on your car. It stays flexible and pliable for years, and as a result protects from dings and scratches excellently. Additionally it adheres to the underside without prior sanding, scuffing or other preparation. About all you need to do is ensure that it's not being shot on top of dirt or other stuff that might flake off.

There are also some other undercoatings that come in spray cans or even brushable, but in my experience the Body Shutz works much easier and better.

However, NONE of these will STOP rust.

POR-15 purports to stop rust. I've bought some, and I'll admit to looking forward to using it but I don't have any personal experience with it, so all I can repeat is what the rep says.

POR-15 is closely related to Isocyanate Glues (super glues) these glues use a given amount of humidity (water) from the atmosphere to catalyze and set. From what the rep says, the POR-15 stuff has been specifically formulated to continue to need humidity, not just use a small amount and set. This is the critical "ongoing" protection phase of POR-15, since it purportedly "leeches" out the moisture from the rust and "reverses" the process of rust. Additionally since the additional moisture helps it set harder, it actually ~improves~ with time.

Now, I will admit to being a bit skeptical about it "leeching" out the moisture and reversing the rust process, since my chemistry professor pointed out that once you have a chemical reaction, in order to change the product of that reaction it needs to be a reaction that the material will naturally transcend to OR you need to add energy in order to make the change happen.

Brief example; Sodium Chloride (NaCl) is plain old salt. But Chloride will react with Aluminum very readily, so much so that it will break the union with Sodium to mix with Aluminum and create Aluminum Chloride. This is the main reason that you will never see vehicles that transit roads that have been salted; in use in airport taxiways and around aircraft.

So, for me, the selling point of POR-15 was that it forms a tough and FLEXIBLE barrier that SEALS the metal. Rust can not form in the abscence of Oxygen, and although the rust that will have been coated will not be eliminated (in my view) the remainder of the steel that is coated will not be exposed to the air, and hence allowed to rust.

Personally, other than the thickness of the material, and the problem with applying it everywhere, I would literally DIP the entire car in it. But, putting a nice finish as we like on a POR treated surface is difficult.

So, what I will do is coat those surfaces that are hidden and hence rust prone with the POR stuff. Floor-Boards, inner fenders, rocker panels and just about everywhere I can brush or spray the stuff EXCEPT where I can see I am going to apply a nice painted finish.

Undercarriage? Steam Clean, and then POR on any rusted areas, and finally BODY SHUTZ everywhere else.

Sorry for the length. I used to be a body man so I have a bit of experience with all but the POR.

Good Luck, let us know what you find.

Enrique Scanlon