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What is the most effective abrassive disc to remove undercoating?

Discussion in 'The Hokey Ass Message Board' started by 55Thunderboy, Jan 5, 2013.

  1. 55Thunderboy
    Joined: Mar 27, 2009
    Posts: 358

    from NYC

    I am struggling with undercoating under my floorboards and i need to remove this before i weld up new sections. I have been using 36 grit 3 inch 3M roloc disc but they get gummed up very quickly and are not very efficient. I used a Propane torch and a scraper to get the thickest stuff off, its a freaking mess and a PITA job.

    I plan to hit the tool store to see if i can pick up a better disc or even a wire brush but i wanted to recommendations on what works best before i piss money away on stuff that wont work.
  2. F&J
    Joined: Apr 5, 2007
    Posts: 13,221


    let the car metal get cold, and it chips off.

    any abrasive disc will just heat it and smear it.

    try the cold deal; if you get a good quick push, it keeps going. Not just a tiny flake at a time.
  3. 55Thunderboy
    Joined: Mar 27, 2009
    Posts: 358

    from NYC

    how can i possibly get it cold? this material on here is like the nastiest i ever come across on any of my cars. it isnt thick enough to chip off its a very strong uniform coating almost like a bedliner in sections but its bonded to well.
  4. slddnmatt
    Joined: Mar 30, 2006
    Posts: 3,682


    Torch and a puddy knife is what I use, comes right off

  5. dubie
    Joined: Aug 17, 2004
    Posts: 698


    Eastwood sells a product in a spray can that removes under coating.
  6. F&J
    Joined: Apr 5, 2007
    Posts: 13,221


    oh, you must live in "southern" nyc, where it stays warm?:D

    Open the shop on a brutal cold day, or push it outside.

    I use various widths of plastic handle wood chisels. Find the right width that peels it good. Some thicker undercoats need a narrower one to get started.

    I have a 37 ply in the shop with nasty thick soundproofing tar crap, and if you set the blade tip right, and give it a good shove, it breaks off like glass.
  7. deeddude
    Joined: Aug 30, 2011
    Posts: 127


    I’ve used the surface conditioning or paint and rust removal disc with some success. They do wear rather quickly though. Maybe after you get the heavy stuff off you could go over it with those discs.
  8. 55Thunderboy
    Joined: Mar 27, 2009
    Posts: 358

    from NYC

    Now can i use lacquer thinner to remove the residue after scrapping it off? whats the deal with the Eastwood product has anyone used it to comment? does paint stripper offer any help?

    it would be awesome to find a chemical that will just eat this cap up and i can just clean it off

    my garage is like an ice box and trust me it isnt helping once bit.
  9. 55Thunderboy
    Joined: Mar 27, 2009
    Posts: 358

    from NYC

    yeah they work well but they wear quickly and are so expensive to buy. i went through a box of 25 already and really didnt get much accomplished considering how last of the area i need to clear.
  10. ntxcustoms
    Joined: Nov 10, 2005
    Posts: 910

    from dfw

    x2 on the torch and putty knife. Keep it moving and get it warm, scraps right off with most of the time only a little clean up needed after. We blast cars at our shop and this is by far the fastest most economical means.
  11. Air hammer with a wide flat chisel works great on the flatter areas. Any solvent will soften up the thin stuff.....still messy though
  12. hotrod40coupe
    Joined: Apr 8, 2007
    Posts: 2,562


    Squirt it with liquid nitrogen.
  13. 117harv
    Joined: Nov 12, 2009
    Posts: 6,590


    I have removed it from sheet metal/body parts when it's cold by using a rubber mallet. If you hit it with the mallet it makes a momentary arc in the metal and a shock wave. It will come off or atleast break the bond so it can be chipped off easier. For thicker steel and hard to reach areas, chisels or scrapers of different widths, make sure they have rounded corners so they dont leave gouge marks.

    I wonder if the nitrogen idea would work?
  14. Kerrynzl
    Joined: Jun 20, 2010
    Posts: 2,283


    Dry Ice Pellets works a treat. Leave it on for a few minutes and give it a sharp crack with a rubber mallet [ it scrapes off real easy ]

    Here's a Ewetube link I found .but with my experience with it ,I prefer to wait a little bit longer and go easier with the "hitting stick"

    After that drop a 6-pack in the dry ice [ no longer than 30 secs or it freezes ] and treat yourself to a cold one.

    Or have a cold one while waiting for the sound deadener to freeze :D
  15. I use one of these multi tools.
    Works a treat and real easy too.

  16. Get yourself one of these and zip that crap off in no time...........

  17. Cantstop
    Joined: Jul 11, 2005
    Posts: 239


    Flame is too dangerous, a friends car had that stuff under it and had to have a muffler clamp welded. The guy didn't scrape the goo away and it caught fire. Try a heat gun and putty knife.
  18. fastcar1953
    Joined: Oct 23, 2009
    Posts: 2,626


    bet your shop teacher likes this idea :D

    I use various widths of plastic handle wood chisels.
  19. I'd avoid anything to do with heat.
    WAY too messy.
  20. I have used a heat gun & putty knife, time consuming and not fun but it works, then use lacquer thinner to get the remainder.
  21. black 62
    Joined: Jul 12, 2012
    Posts: 1,895

    black 62
    from arkansas

    my heat gun has an attachment for just that purpose ---do some on line shopping
  22. sdluck
    Joined: Sep 19, 2006
    Posts: 2,795


    I heard stories about packing the areas with dry ice and it would come off.Drag racers used to do it to lighten cars tears ago
  23. If you are welding in new sections, exactly how much do you need to remove?
    I'd take just enough around the perimeter of the patch.
  24. 3 pedals
    Joined: Dec 29, 2012
    Posts: 52

    3 pedals
    from Ohio

    This has been the best method I've found too.
  25. Chevy Gasser
    Joined: Jan 23, 2007
    Posts: 701

    Chevy Gasser

    The easiest way to remove under coat is to cut the old floor pan out and weld new in....(;) LIFESTYLZ idea is a good one, So is Waddayacare's idea. This is one of those no easy solutions!
  26. nonobadog
    Joined: Jan 8, 2012
    Posts: 19


    There is a vid of the tool waddayacare posted in action. It looks pretty good. There are several different systems shown. The dri ice is a good one also.
  27. nonobadog
    Joined: Jan 8, 2012
    Posts: 19


    OOPs! I forgot to tell you where to look. youtube has quite a few vids.
  28. Hot Rods Ta Hell
    Joined: Apr 20, 2008
    Posts: 4,340

    Hot Rods Ta Hell

    A) Jackhammer

    B) Plastic explosives

    Seriously, there's no easy way to remove the stuff. It's just no good dirty, shitty work that you have to get through. Might be quicker and easier to sell the car and buy a duplicate that was never undercoated or already has good floors.
  29. Roger Walling
    Joined: Sep 26, 2010
    Posts: 1,149

    Roger Walling

    A torch and a putty knife work best. Be careful that you don’t get it hot enough to catch fire and drip off. It has an uncanny knack to land on your left arm.

    <O:pOf course, the first reaction is to wipe it off with your right hand.

    <O:pThe second reaction then is to wipe your right hand off with your left hand.

    <O:pBy that time, you realize that the trick with your right hand was not the most intelligent thing that you have ever done.
  30. Grudge
    Joined: Jun 26, 2008
    Posts: 435


    Dry ice works like magic. Break up chunks with a hammer and spread the powder around. In a minute or two you'll hear cracking, big chunks of that rubber shit will just lift off the floor.

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