undercoating

[boerboel313]

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I've heard that undercoating is bad new and that it cracks and peels and holds in moister which leads to the cancer of metal. what if one used a product like line-x or Rhino Guard? What is the consensus on that?
Thanks,
Chris, Oh, we have an 84 FJ 60 with less than 50,000 origional miles on it.
Thanks again.

 

[Lusedekache]

I've seen some nice results with spray-on bed liners used as undercoating. It's hard to say how it will look in 10 years but the stuff seems pretty tough and should hold up well.

Like you said, lesser products should be avoided for the reasons you mentioned.

 

[ian]

My rig was Ziebart'ed by previous owner. I'd say at least 60% of it has peeled off. Luckily the genius hit the undercarriage with a decent enamel prior to undercoating. The upside.. not too much rust in the rig (had good steel to begin with). The downside.. now I have to try to peel all that junk off. It sticks quite well in some areas.

I'd POR-15 or Rust Bullet and be done with it. Even if you do scrape the junk off on the trail, it's easy enough to touch up once a year.

I tend to share the same opinion of spray-on liners as Mark (see his excellent FAQ @ marksoffroad.net). It is almost guaranteed that they won't stick in all locations and the result is the worlds best environment for creating rust. If you must use one, use a rust inhibitor first.

 

[TexomaFJ40]

Undercoating has come a long way. It is best to make sure to have an absolutely clean surface to start with, but you will need that regardless of what you put on (primer, liner, or undercoat). Laquer Thinner works best along with a bunch of rags. The best set up I have seen was two coats of acid etching primer, a single coat of liner, and two coats of undercoater. The undercoater protects the bedliner from rock impact which will eventually shatter the liner. The etching primer seals the metal and "eats" surface rust and moisture to ensure there is no rust under the liner. Major rust must be removed with sandblasting in any case.

The undercoater will also help with road noise. I prefer Transstar undercoater above anything else. It will not crack and remains fairly rubbery and sticky.

 

[Degnol]

I've known several guys who used boiled linseed oil and mineral spirits about 1 to 3 and sprayed it on with a Hudson tank type sprayer. It is thin enough to "wick" into areas where a thick material would not, it's essentially clear , cheap and easy to apply. Leaves a thin protective film.
I sprayed POR on the underside of mine and everywhere there was some surface rust, it stuck really well, but where there was residual paint, it peeled off.
The absolute best thing to do IMHO is take the tub off and sandblast the underside and have the whole thing Line-X'd, then you're done.
GL
Ed

 

[Bennett]

I would suggest alll cruiser owners follow the example of the "british"... use a form of waxoyl and spray on several times a winter for protection.They use it liberally and inside doors and frames ..anywhere there is a possiblity of moisture collecting.
I have used it 2 years and it is great.
I ahve also heard of guys using WD 40 ( 7.95 a gallon at Harbor Freight.) and spray it liberally.

Formula for Waxoyl

Here is a recipe for home made "Waxoyl". It's an old fashioned rust treatment / undercoating:

2 1/2 quarts turpentine
12 oz. beeswax / candle wax
1 quart light machine oil

With a cheese shredder, cut the wax into the turpentine, stir until the wax has dissolved, usally 130 degrees, (takes a short time; you can use very low heat (a warm room) to aid but be careful) and thin with the machine oil to a brushable / sprayable consistency. Apply liberally. You can use a hand spray bottle to get into closed-off sections if you have a small access hole.


Please be sensible when you make this stuff; don't go breathing the fumes or applying heat and burning down your house. If you have any doubts about it, err on the side of caution and just buy a commercially available product.

 

[CruisinGA]

I strongly dislike bedliners as a form of undercoating. They are for lining pickup beds, not the undersides of landcruisers. IMO too thick, do not adhere well enough.

Mine was done with 5 coats of epoxy enamel and 2 coats of flat black urethane auto paint by the PO.

(He owned an industrial coatings buisness).

It is very hard, adheres VERY well (there has been no peeling). It is thin enough that it can be applied over bolts etc and the bolts are still removable.