Why do they still use the rubber undercoating on cars?

[SammyChevelleTypeS3]

It’s my 2017 Chevrolet SS Sedan with an LS3…
View attachment 243349

AWESOME machine if you ask me. Like the color too. Sweet!

 

[Nessism1]

I spent some years inside auto plants, and at the plants I'm familiar with, the cars received a thick urethane rustproof spray under the car. This material was thermo set, and thick. It looked like the rubberized stuff that many are familiar with, but only it was not black. Black spray paint was applied as a top coat, because customers want to see black down there.

 

[tookien]

I spent some years inside auto plants, and at the plants I'm familiar with, the cars received a thick urethane rustproof spray under the car. This material was thermo set, and thick. It looked like the rubberized stuff that many are familiar with, but only it was not black. Black spray paint was applied as a top coat, because customers want to see black down there.

 

[JHZR2]

To be honest it does not seem like the waxy stuff. At least it didn't when I put the bed wheel well liners on.

Where is it applied? Spots beyond frame wax? Is your frame waxed? Gm has wax dipped frames forever… Or are you talking a product that was sprayed elsewhere.

Some makers spray a textured product under the paint. Makes for bumpy paint.

 

[ls1mike]

Where is it applied? Spots beyond frame wax? Is your frame waxed? Gm has wax dipped frames forever… Or are you talking a product that was sprayed elsewhere.

Some makers spray a textured product under the paint. Makes for bumpy paint.

I think it is just the wax crap GM puts on it the frame. I went out an touched it. That was a mistake.

 

[Hootbro]

I would not call anybody that applies this stuff a "mechanic".

 

[Nessism1]

Don't confuse the stuff I mentioned with rubberized crap. The stuff I've seen is applied in the plant body shop, and it dries hard, much like stone guard applied on the rocker panels. In fact, it may be the same stuff.

 

[IndyIan]

I spent some years inside auto plants, and at the plants I'm familiar with, the cars received a thick urethane rustproof spray under the car. This material was thermo set, and thick. It looked like the rubberized stuff that many are familiar with, but only it was not black. Black spray paint was applied as a top coat, because customers want to see black down there.

Yes, my Focus has some of that, but only in areas they wanted to protect from rocks off the tires and for sound insulation, or add weight to prevent the floor pans from resonating at a bad frequency. It's good, until it isn't, and salty water gets behind it and then rust works away unseen until there's no metal behind it... The Outback now covers all those areas with decently durable plastic undertray, which does the same thing but leaves a gap for the metal to be oiled, and dry out.

 

[Nessism1]

Yes, my Focus has some of that, but only in areas they wanted to protect from rocks off the tires and for sound insulation, or add weight to prevent the floor pans from resonating at a bad frequency. It's good, until it isn't, and salty water gets behind it and then rust works away unseen until there's no metal behind it... The Outback now covers all those areas with decently durable plastic undertray, which does the same thing but leaves a gap for the metal to be oiled, and dry out.

Are you suggesting that OEM style urethane underbody protection coatings are detrimental to the life of the vehicle?

 

[IndyIan]

Are you suggesting that OEM style urethane underbody protection coatings are detrimental to the life of the vehicle?

Once they get beat up a bit and chip through to the metal and rust begins, they aren't great! Next time I buy an older used car I will check out areas like that with more diligence, sharper screw driver...
I think the plastic shield type is better as its removable, and you could repair any surface rust pretty easily at home, then put the shield back.

 

[JTK]

I spent some years inside auto plants, and at the plants I'm familiar with, the cars received a thick urethane rustproof spray under the car. This material was thermo set, and thick. It looked like the rubberized stuff that many are familiar with, but only it was not black. Black spray paint was applied as a top coat, because customers want to see black down there.

The entire underbody floor/frame/unibody was covered? That is interesting. I'm not sure I've ever seen that.

 

[SHOZ]

My '08 Accent came with a rhino liner like covering and painted body color. About the only thing that hasn't rusted is the underbody.

The Gen Coupe came with the black waxy like stuff. It sticks good but wears off. It's got a full undercoating recall going on now. Never been driven in the salt though.

 

[Nessism1]

The entire underbody floor/frame/unibody was covered? That is interesting. I'm not sure I've ever seen that.

Selective application areas. It went on before the body was color coated. And again, black paint was applied on top, also selectively applied

 

[addyguy]

The gooey, black asphalt undercoating is very old school. Cars, like my dad’s 1967 Mustang, used to get sprayed with it in the 1970’s.
Problem is, if there was any rust or moisture trapped under it, it actually sped up rusting - my dad’s Mustang was rotten right through by about 1977.
Did it slow some rusting down? Probably.
We still sell a lot of it at CT stores in Canada, plus better-quality products that are just like bedliner, and dry hard.

 

[Delta1]

The gooey, black asphalt undercoating is very old school. Cars, like my dad’s 1967 Mustang, used to get sprayed with it in the 1970’s.
Problem is, if there was any rust or moisture trapped under it, it actually sped up rusting - my dad’s Mustang was rotten right through by about 1977.
Did it slow some rusting down? Probably.
We still sell a lot of it at CT stores in Canada, plus better-quality products that are just like bedliner, and dry hard.

My dad bought a Citroen DS for parts that had been Ziebart undercoated at some point and the **** thing broke in half from rust when he tried to tow it home, the roof was the only thing holding it together

 

[eljefino]

I think the plastic shield type is better as its removable, and you could repair any surface rust pretty easily at home, then put the shield back.

These plastic shields are typically held on with M6 fasteners, so I imagine them snapping at year ten when I want to take a peek at the "real" floorpan above.

That said, maybe the plastic will buy me ten more years before nasty stuff sprays up onto metal with any regularity.