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N-Trouble's avatar
N-Trouble
Explorer
May 15, 2018

Undercarriage rust

Trailer will be going on 4yrs this October. I make several trips a year over the Sierras and keep hearing how CalTrans is using more salt on the roads in recent years and it shows. What can anyone recommend on tackling this?

  • Interesting tidbit; the John Deere world HQ has exposed structural steel beams. The architects and engineers designed it this way and used a specific alloy steel so it =would= rust. It's only on the surface and is never painted. Saves them thousands a year in upkeep.

    Lyle
  • whatever you do DON'T remove the rust with a wire wheel/brush, etc. Rust is oxidation and once you expose bare metal to air it will oxidize again. Since I'm in So Cal and don't tow in the snow/salted roads I've never done anything to mine. Yes they rust but it's just surface rust and is strictly cosmetic. I've squirted a bit of Rustoleum on the visible frame for cosmetic reasons but that's it.
  • Diesel fuel, fluid film, wd40 etc. Powerwash the loose and apply 1 of the above. Frequently.
  • Every year just before the winter, i power wash the TT chassis to get all the crud off. Then I mix 1/2 gallon of Marvel Mysterhy Oil and 1/2 gallon of WD40 in a spray bottle.

    I liberally spray everything underneath. My last TT was 10 years old before I sold it - the chassis looked almost brand new. My current TT shows no signs of any surface rust.

    I do the same to a 54 year old classic car i own - underneath looks totally rust free. My motorcycles get the same treatment (just watch out for the brake discs!!)
  • X2 for fluid film. I buy a gallon and apply it with an undercoating gun attached to an air compressor. It needs to be re-applied/touched up every year for best protection. I can re-coat 3 vehicles with one gallon, the initial application uses more. It is also available in aerosol cans.
  • There are a lot of DIY undercoating products available if you are one to get your hands dirty or consider having it commercially done.
  • I had the same problem with mine quite a few years ago. I used Rust-Kutter from Tractor Supply. Just spray it on, let it sit, and then paint right over the top of it. No need to rinse it off. Just make sure you wear a good breathing mask when you apply it while under your rig as the fumes are quite strong and can be harmful. A mask used by spray painter works well. It converts the rust to a black preventive coating that is paintable.
    I have not had to re-do my trailer at all and it has been about 7 years since I used it.
    Barney