Re: {Chrysler 300} Undercoat one more time

I worked at a Ford Dealer on LI in the summer of 1968 (I was 17) and I’ll never forget the sound of the compressor “bursts”in new car prep as the guy applied undercoating and the wand expelled the black “tar” out of a 55 gallon drum and with a similar smell to a road paving operation….

On Aug 9, 2022, at 5:54 PM, 'Fern Rivard' via Chrysler 300 Club International <chrysler-300-club-international@xxxxxxxxxxxxxxxx> wrote:

Back in year 2000, I purchased a new suburban and it was undercoated with some type of waxy material rather than that tar crap.

Fern

On 09/08/2022 3:33 p.m., JIM KRAUSMANN wrote:

Rrrr... the undercoating subject. As it's been said, the factory material is sound deadening only. This asphalt base material (and the rubberized cousin) can crack or loosen and will trap water. It also blocks drains. This will foster rust conditions.

As was mentioned, drains are key. Anyone restoring a car should at least enlarge the factory holes a bit. They're too small. If not present, make one. If you're working on a finished car, make sure they're open. The base of the cowl, rocker and quarter panels are the worst. I made a curved tool (photo) from an air blow gun threaded to a scrap piece of brake line to blow out the rockers, frame, quarter panels or any boxed in area using the factory openings. You'd be surprised what's in there. Especially if a car was media blasted. Water mixes with the gunk and increases the wet time. It's a mud pack that takes days to dry.

If you're dealing with a leaking vintage car today, find the water source. Even a good rustproofing material can only take so much wet time (carpet pad, trunk carpet and the modern sound deadener sheets) before trouble starts.

While there were a lot of bad rustproofing jobs back in the day, the good shops knew what to use and where to put it. A best material inside body panels is a thin waxy seam penetrating material. It drips, stays pliable and works. It'll also smell till the solvents flash. After a car is painted, that's what I'd use on a restoration today. No one will see it. The thicker seam bridging materials are bad news. It might as well be undercoating. While on the subject, the fogging materials made a lot of money for the dealer but protected nothing.

Jim Krausmann
More than a few years as a Ziebart dealer

Virus-free.www.avg.com

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