Galvanic Corrosion, OR, I think I have been screwed and not in a good way!!

[MikeT]

I have been outside doing some pre-season checkups on my 2015 21RBS and found a few items that caused me concern.

1.  I gave the brake breakaway switch a tug and the whole mechanism came off the trailer.  The head of the screw attaching it to the trailer broke free leaving the rest of the screw in the frame.  The screw used to mount it to the trailer was a thin flat headed screw.  It broke due to corrosion.  The placement of the switch, in my opinion, was poor in the first place so this now gives me the opportunity to mount it in a better spot.  I don't even want to think what would have happened had it come off whilst on the highway!

2.  While cleaning the factory installed awning (Dometic 8273000.401U - Sunchaser) I noticed that the awning appeared lifted on the left side (back of trailer).  Upon closer inspection,  the mounting bracket was bending outwards and upwards due to some friction in the sliding mechanisms of the awning.  I believe, this in turn was putting stress on the mounting screws and may have caused them to bend slightly. After aligning things I checked the screws to see if they were loose by tightening them slightly.  SNAP, and out popped one of the screws.  The attached picture shows it broke at 1-3/8 inches from the head and was corroded at the breaking point.  According to the installation instructions, that screw should be a #14-10x3" screw.  I suspect a shorter one was used and not of good quality. Investigation ongoing!  Again, this could have had a disastrous outcome on the road.

3.  My toilet was wobbling.  Upon investigation, I determined the floor flange was broken.  Finding a replacement flange proved difficult.  I did find one, but the alignment was off due to the poor installation of the original. Also, the new flange only had 4 mounting holes. Normally, that would be enough....but, because the aluminum decking planks that form the floor are relatively thin and have an I-beam type (for lack of a better term) construction for strength, when self tapping screws are driven into the floor to secure the flange, and by chance, hit the "I" portion of the beam, they deflect and go in crooked.  Needless to say, two screws were crooked (during construction) and one of them was broken, probably due to too much torque.  An additional two screws had been driven in to the point of shredding the aluminum floor.   In the end, I had to re-use the old flange by rotating it 90 degrees.  In the meantime I will think about how to address the issue should it break a second time.

4.  I am worried as to what I will find next!!

So, this was a long story of frustration.  Due to the potential dangerous outcomes that could have occurred (Items 1 and 2) I thought it important to share.  I have been researching types of screws and bolts, stainless, aluminum, etc. as well as strengths and coatings to prevent corrosion but this is proving to be rather arduous.  If anyone has experienced these problems and can provide solutions or ideas it would be greatly appreciated.   Merlin, you had mentioned a coating that may assist in preventing corrosion (Tough Gel?)  Can you provide a picture of the product? 

Cheers everyone.

[Merlin]

Wow, thanks so much for taking the time to post this. Looks like inspections need to include critical fasteners. For any time aluminum comes in contact with other metals, any good anti-seize will help prevent corrosion. I use Versa-Chem Anti-Seize Thread Lubricant Type 13. Don't use it on lug nuts, but for anything else it's fine (messy!)

With the fasteners issues you had, some of them come from over-torquing the screws. LL was infamous for that, especially where SS screws went into aluminum. They tend to bind.

I'm going to take a close look at corrosion in my spring fit-out next month.

[Pinstriper]

SS fasteners are famously soft, too.

[tt2retire]

I use Tef-Gel where my SS come in contact with aluminum in areas like the tongue where there is any moisture.

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[dlb53151]

In my opinion, Fluid Film is the best anti-corrosion lubricant on the market.  It's even used on the space shuttle.  I buy it by the case and usually end up giving a can away here and there when RV'ing when someone mentions an application they need a product like this for.  (I don't work for Fluid Film nor have any personal benefit from this recommendation.  Just a great product!)

[Merlin]

In my opinion, Fluid Film is the best anti-corrosion lubricant on the market.  It's even used on the space shuttle.  I buy it by the case and usually end up giving a can away here and there when RV'ing when someone mentions an application they need a product like this for.  (I don't work for Fluid Film nor have any personal benefit from this recommendation.  Just a great product!)

Agreed! I use FF all the time as a rust preventative.