I undercoated the entire bottom of the floors when I built my 56 Chevy. I intended for it to be a driver and not a show car. I undercoated the inside of my fenders with bed liner on my 34 pickup to protect from road rash. The old 48 Ford coupe I bought a couple of years back had been undercoated years before, probably in the 50s and it had very little rust out underneath so I think it helped this car. I have heard some people say that undercoating can make rust worse but maybe it was put on improperly.
I had Rhino-liner professionally applied to both sides of my running boards on my 41 PU. He has the fenders now to coat the underside of them and the cab is going next for the floor and seat riser area.
Back in 1963 my daughter helped me undercoat with 3M water mixed undercoat, this has proved very protective on all under side including fenders too. (300,000 miles to date).
I’ve never been a big fan of rubberized or similar undercoating. I always felt like when moisture gets behind it; you can’t see it until damage is done (rust/rot) I prefer cleaned & painted under carriages. Sent from my iPhone using H.A.M.B.
My favorite is Wurth gravitex. It’s a better sound deadener than bed liner. Tougher than rubberized undercoat.
I have been recently thinking about what to do. My 1948 Effie’s floor has a nice clean bottom ready for a fresh coat of something. I want to do it right and last .
I just ordered 3 more liters of Wurth SKS to make sure I had enough to finish my 49 Buick's huge fenders and wheel wells. I won't use anything else. If you ever use it, you won't either. Much better than the bedliner type products and cleans up with H2O.
https://www.jalopyjournal.com/forum...-question-for-the-pros.1215678/#post-13876612 Hello, Having lived near the ocean all of my life, I can look back at those times when salt water on our cars was a daily fact of life. Whether driving through high tide flooding on streets, sitting at the beach parking lots, backing up the car near jetties until the tide came in and coated everything, etc. Even in Baja Mexico, where we had to cross a high tide flow of water to get to the other side of a road embankment. Sooner or later, one will come in contact with salt water, in the air or on land, when living in coastal So Cal. One of my brother's rental housing was on a small island in coastal OC. When the tide came in or especially when the “King Tides” were upon everyone, his driveway was under water or the entrance road had puddles of salt water. He was conscious to the fact that salt does damage to cars. so, when he got the new 58 Impala, our friend in Los Angeles told us to come up and get the undersides of the car sprayed professionally. Yes, I know this site is mostly a do-it-yourself project site, but if the ch***is or car is prepared with a clean underside. Then find a reputable professional spray on undercoating place that can do this job for you. It will last until your car(s) are sold many years down the line and no worries about rust or corrosion. Any cost is worth the long term effect. The home spray cans cannot get the professional thicker coating on every area that needs protection. Jnaki A new 1958 Chevy Impala had it done and no worries about any salt corrosion, despite the salt air/water location. Then in 1964, the same thing (same professional application) was done on my new 1965 El Camino. It lasted, at least for 11 years of, up to our rims in salt water, salt spray and resting in some salt infused sand near the beaches in So Cal and Baja Mexico. The buyer of the El Camino in 1976 was a surfer/boater from Dana Point. He was happy with the purchase as it met his needs. The bottom professional undercoating was perfect for his needs as a local surfer and obviously on the boat ramp of the harbor where the bottom would be totally in salt water of the harbor.
I wouldn’t use under coating or spray bead liner on anything with exception of floor boards inside a carpeted floor. When looking at a nice 50’s-60’s Ranchero or ElCamino and see the **** in the bed I walk away. Personal choice and it’s mine.
I like what undercoat does I just hate how it holds dirt and turns dingy brown quickly. I've seen people paint it to help combat that but I've never seen the paint stand up real long to daily drivers without coming off and chipping badly... Still looking for options on my tudor.
I recently scrubbed the frame and underside of my 1930 Tudor with co**** Scotchbrite and a wire wheel, then spray painted with Rustoleum rust converter primer to stop further rust (I hope) then brushed on bedliner. I tried a small area with some spray undercoat but it was just tar in a can. It has been a few months and the bedliner still looks pretty good. I have read about better bedliner than I used but, in general, I wanted the easy clean surface and its resistance to impact from stones etc.
The SKS doesn't do that. It dries firm and is not tacky. You can paint over it if you want but it looks great just left black.
I have no idea what kind it was or when it was put underneath my Lincoln, but it has held up well throughout the years. There were a few places under the fenders that had hardened and were turning loose, when you pried off a piece, it was still fastened pretty good, but what was amazing was the paint underneath, it looked brand new. Some of it that wasn't exposed to heat is still pliable, not firm but not real mushy, either. I suspect it's tar based. Where it hardened and began to turn loose it appeared to be about 1/8" thick. I'd say it helped preserve the steel a lot. The areas that were rusted were around the floor mounted heaters and the inner sides of the rockers. The heater area probably sweated a lot, and the rockers didn't have much of anything on them, maybe they forgot to coat them.
The PO of my panel truck had the underside of the plywood floor undercoated. That's the way it came to me.
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