Hi guys, looking for little guidance in my trailer project. I have removed the bunks with the mounting brackets attached. Where the brackets were fastened to the I beam aluminium trailer (6000 lb.Road King) has left quite a salt deposit with some corrosion where the dissimilar metals join. I have cleaned up the corrosion which has left a shallow davit in the material (aluminium) cross member. Installing new u bolts but think it might be an idea to sandwich a 1/4 inch piece of starboard between the steel bunk bracket and the alundum cross member to stall the reaction between the two metals. Good idea? or can you suggest a better way to separate the two metal. Ideally have aluminium bunk brackets made but, I have got 17 years out of this arrangement and really do not want to disassemble the bunk and have custom made bunk brackets. Ideas are welcome.
aluminium trailer corrosion
- Thread starter trapper
- Start date
I have a Boatmaster trailer that was built about 6 years ago. They use a "tape" between dissimilar metals that is made by 3M. Don't know what it is called but a search for the 3M product may get you to the right product.
I can't imagine how that would hurt. However, I suspect you're still going to get that same corrosion effect as it's also caused by water being trapped between the two things. Aluminum does a great job at protecting itself from corrosion, but only when it has access to oxygen. When "dead" water stays in contact with the aluminum, it can no longer self protect itself.
I would be inclined to use butyl rubber tape between the HDPE and trailer frame - or maybe just between the frame and bracket.
I would be inclined to use butyl rubber tape between the HDPE and trailer frame - or maybe just between the frame and bracket.
The trailer is 17 years old. Things will corrode. I think it is a bit late to worry about the mounting pads
That said, as long as it is apart, you can clean the frame areas and apply an etching metal primer made for aluminum, followed by something like the butyl tape that Dennis suggested or a bed of 4200. That may slow down the corrosion as long as the 4200 completely covers the mounting pad contact surface
That said, as long as it is apart, you can clean the frame areas and apply an etching metal primer made for aluminum, followed by something like the butyl tape that Dennis suggested or a bed of 4200. That may slow down the corrosion as long as the 4200 completely covers the mounting pad contact surface
Parthery
GreatGrady Captain
Thanks guys., will proceed as suggested butyl tape or 4200. Yes it does sound like a better block as Denis mention "caused by water being trapped" would still occur still with starboard.....although are we trying separate the metal or also keep salt water from being trapped agains the aluminium. I always though dissimilar metals was the issue.
Dissimilar alloys are the issue but in addition to the anode and cathode, you need an electrolyte. The moisture in the air can be enough especially if the air is near the briny.
Thanks seasick, Talked to a outfit here that sells Highliner trailers and does repairs to boat trailers. On picking up new u-bolts from them they suggested putting an anti static (grounding strap)strap as they said that some of the corrosion on the trailer is from electrolysis, I guess caused while towing???
You're right that dissimilar metals can cause an issue. The stronger the "electrolyte" between them, the stronger the galvanic corrosion. Air is an electrolyte (well, maybe not in the desert!), although fresh water is a stronger electrolyte... and salt water is stronger still. Salt water "air" is stronger than inland "air", too.
I think I just said the same thing that Seasick did - but wanted to respond to your question so you didn't think I had disappeared
The other side to this is the "dead water" that eluded to - and if you want to read up on this, search for "crevice corrosion". In the end, you have two factors that could be at play.
Buy THE right tape. Dis similar metal corrosion is disastrous. Do it right. Don’t guess with proper materials to save $10 on a specialty product.
Maybe so but if one does a job thoughtlessly, then the trailer owner probably won’t see that second 17 years he was hoping for. Corrosion can be a really embarrassing thing.
Any 'ol HDPE will work. Starboard is a brand name for HDPE but there's no reason someone HAS to use Starboard (and pay more than they need to). McMaster Carr has an extensive selection of this stuff and it is available in smaller sizes than Starboard is typically available in.
Heck... a plastic cutting board (which is typically HDPE) from the dollar store would work!
The reason I suggested starboard is because I have left overs from other projects. Yes seasick a 17 year old trailer, but in good shape (aluminium I beam ) The question I proposed re the trailer with corrosion received a much bigger responce the I expected. I guess that is a good thing. Anyway we will give the subject a rest as I have completed the "renew" with a double layers of Interna Bond that I have used before on rv repair, placed between the frame and the bunk brackets with all new U-bolts. Yes another 17 years.........done. Fortunately billbass I was able to completely overcome the embarrassment of corrosion.
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