Removing underbody asphault from the car...

[dotorg]

Anyone know any tips/tricks to make this job unpleasant and difficult instead of hell-on-earth?

We've been using scrapers and a heat gun, which has worked but has been very slow.

Anyone know any good solvents that can soften it up without damaging the metal?

[Tim Walsh]

The pvcish rubbery goop? A wirewheel on a grinder does a good job going down to the bare metal.

A more expensive way but it leaves the paint is brake cleaner. Yesterday I helped dtw on his undercoated wiring harness and brake cleaner did wonders on it.

[jpnovak]

HMM I tried brake cleaner on the fender wells with no luck.

Not just any wire cup crush. Get one of the braided twist brushed. Much more aggresive and will work much faster. It will not damage the sheet metal.

btw, this is a nasty job and there is no easy way. Most stippers will just make it goey and not remove it. Expect to find the bits everywhere. Wear eye and ear protection.

[targa80]

I have been stripping the Wurth Body Shultz undercoating from my car for the past several months. It is slow going, I used an air die grinder and many wire wheels to get a lot of it off. I have also used the heat gun and razor blade scraper. For the hard to get at places I use aircraft paint stripper and let it sit over night. the stripper attacks the primer underneath and lifts the edges up so I could scrape the undercoating away. I am now using a Dremel with the cable attachment and a grinding tip to get into the really tight areas to get the remnants of the undercoating off. I wished there was a magic solution to getting rid of this stuff other than an full acid dip or using a sandblaster.

[dotorg]

Yeah, I'm just trying to get it close enough that the POR will stick adequately to the underbelly.

99% is enough for that...

[john70t]

Although this is probably not recommended because of carpet/fuel lines etc, I used a propane torch in some areas. If you wave it over the surface and quickly scrape it, only the top surface gets hot. Work quickly or it will harden. Smells great too

[Tim Walsh]

Jamie,
We use Brake cleanter that was 100% tetrocloroetholene (sp) Nasty stuff but was suprised it worked so well on Jekyll's undercoating. Pics should be in the mail sometime

[RickM]

Targa,
I'm not thinking that it can be removed with sandblasing. The rubber material will absorb the impact of the media and render it useless. I think I know this because I tried once.

Perhaps an email to Wurth to see what they say.

[Mattias Hellore]

I used a twisted wire wheel on a angle grinder and lots of patience and it´s messy but leaves shiny metal after each run.

I just did whole front end, interior and engine compartment.
But not the underpan, it´s not necessary.

[Randy Webb]

How much wt. do you save? Then if you put on a thick "paint" coating (like POR), don't you gain wuite a bit of the wt. back?

[dotorg]

This stuff is thick and heavy... I can't imagine POR weighs anything close to what it weighs. I didn't get a weight on the car before, though, so I can't tell you what its going to be after...

[RickM]

6-7 lbs (?) and ALOT of protection.

[dotorg]

Originally posted by RickM
6-7 lbs (?) and ALOT of protection.

Huh?

[RallyJon]

Anyone tried the Harbor Freight "Air Gasket Scraper"? It reciprocates the blade back and forth but is much less hard-core than an air chisel. I used it on the tar stuff on the interior side of the floor panels. Worked pretty well.



Another trick the rally prep shops use is a big bottle of liquid nitrogen. Freeze the undercoating and it chisels off in nice big sheets.

Edit: I knew I had this pic somewhere...

[RickM]

Originally posted by RickM
6-7 lbs (?) and ALOT of protection.
--------------------------------------------------------------------------------



Huh?


My comment was that the Body Schutz that you're removing is probably about 6-7 lbs. Additionally, this product provides alot of protection to the underside of the car.

[RickM]

I like that liquid Nitrogen idea! Off to Pep Girls to get some.

[dotorg]

Originally posted by RickM
Additionally, this product provides alot of protection to the underside of the car.

I don't know what they use on newer Porsches but the stuff on the old cars is basically a layer of asphault... its tar and some sort of filler. And its clearly bad to have on the car. It dries out, cracks for, water gets in there, and it rusts the floorboards out without you even knowing there's water trapped there.

Modern stuff is 100x better, thats why as much of this crap as possible is being stripped off and POR-15 is going on in its place, offering MUCH more protection than a 40 year old layer of tar could.

And on the LN response, I've heard the same thing... freeze it and it comes off in big flakes.

[RickM]

I don't know what year your car is but as far back as the SC Porsche used Wurth Body Schutz (aka SKS Stonegaurd). Here's an article on its use by noted PCA product specialist and detailer Larry Reynolds.... http://www.dgi.net/914/maintenance/Undercoating.html

I would not use POR in place of the Schutz but would remove the old layer of crud and replace with a new coat of the Wurth product. POR may crack and / or chip from the normal abuse and leave the underside of your 911 exposed to the elements.

[RickM]

BTW this is the response from Wurth.....

Rick

The easiest way (to remove the undercoating) is with a wire wheel,either air, or electric it will clean down to the

Metal and you are ready for the new application

Thanks

eric



Eric LaPorta
Customer Support/Technical Support

WURTH USA Inc.
Distribution Center Northeast
93 Grant Street, Ramsey, NJ 07446

Phone: +1 (201) 825 2710 ext.2255

Fax: +1 (877) 871 7787

www.wurthusa.com

[kenrinc]

On the early cars a thick coating of bituminous (?) asphault like tar was used, manufactured by National Chemical or Toroson. It's nasty. Anyone who has ever been through the process of removing this stuff knows that a wire wheel in a grinder does next to nothing but smear the stuff around and create a bigger problem. The only way to remove it within any reasonable time frame is to get a propane torch and a putty knife. You heat a section about 12" square and watch the suface as you do. You will see it begin to let go. Then wait about 5 seconds and hit it with your putty knife. It will just fall right off in long strips. Make sure you wait the 5 seconds. There is a fine line between melting the undercoating and creating a bigger mess and losening the coating in order to get a blade under it. We just did the entire underside of a car like this last week. Trust me, it is the only way. Once you've got all the coating off, wipe the area with a rag soaked in lacquer thinner (please wear gloves) and then hit the area with a 3M 4" green bristle disc in a buffer/grinder and the metal will shine. Perfect substrate for epoxy, Por15., ZeroRust ... anything. Once' you've primed / painted it shoot Wurth SKS or 3M body shutz.

$.02

Kenr-
PCA Zone7
GGR