Trailer Crossbeam Repair

[Newf]

The photos are of the rear crossmember on my EZ Loader trailer. The crossmember is aluminum and held in place between two galvanized brackets with stainless bolts. The left photo shows a salt/calcium buildup between the brackets and square tube that is collapsing the tube to a point where both sidewalls are cracked. My plan is to remove, straighten and repair cracked sidewalls and then install spacer pipe sleeves inside the tube for the bolts to slide through.

Question: Should I use aluminum pipe spacers/sleeves and tack weld them to the tube or use stainless pipe sleeves? There is no direct loading on this tube from the boat. It's a spreader beam between the two aluminum I-Beams.

Thanks in advance for your thoughts.

 

[Corey_lax]

Aluminum likes to crack if you bend it back. Also, it seems funky that it would bend in at all with those brackets bolted to the extrusions. It’s definitely carrying weight or it was bent from the beginning.

I’d pull it off and use it as a template to cut and weld some new aluminum tubing. And probably ditch the galvanized brackets and swap for aluminum that is thicker or weld the whole thing together

 

[Newf]

Aluminum likes to crack if you bend it back. Also, it seems funky that it would bend in at all with those brackets bolted to the extrusions. It’s definitely carrying weight or it was bent from the beginning.

I’d pull it off and use it as a template to cut and weld some new aluminum tubing. And probably ditch the galvanized brackets and swap for aluminum that is thicker or weld the whole thing together

Thanks for the reply and suggestion on replacing the tube as well as the brackets. Just as info,,I have owned the trailer since new in 2014. This bending of the sidewalls on the tube started around year two and has very slowly progressed to where it is now so I do not fear for it falling off tomorrow sort of thing. As the better view of the crossmember shows below, there is no loading on it from the boat, it is merely a spreader bar at the back end of the trailer. From what I've been able to read online, the deflection of the sidewalls of the tube is a result of the salt/calcium under the right conditions crystallizing, growing and creating pressure between the two mating surfaces. The growth is accelerated by the number of exposures to these conditions. The build-up at the centre of the deflection shown in the 2nd photo is now around 3/16" to 1/4" A little too much for my little brain to understand but I have watched this buildup between the bracket and tube grow over the years and given that I drop the trailer in the water over a 100 times a year it does make a bit of sense.

Regardless of the cause, thanks again for your reply and recommendation. I will check with a couple of shops and see what they can do fo me.

 

[Flashman]

Almost for sure corrosion not salt/calcium build up. If you use aluminum brackets or a plastic/rubber shim to keep the steel from touching the aluminum that should prevent the problem from repeating. I agree, replace the cracked piece instead of trying to repair it.

Interesting the problem is only on the crossmember and not also on the other leg of the bracket on the main frame rail. Maybe the crossmember and frame rail are different alloys?

 

[jayinsurrey]

I had my ez loader trailer axle replaced at G&M trailers in Langley. Good guy to deal with. Builds all kinds of custom trailers. John, 604-581-9304
19585 96 Ave, Surrey

 

[Newf]

Almost for sure corrosion not salt/calcium build up. If you use aluminum brackets or a plastic/rubber shim to keep the steel from touching the aluminum that should prevent the problem from repeating. I agree, replace the cracked piece instead of trying to repair it.

Interesting the problem is only on the crossmember and not also on the other leg of the bracket on the main frame rail. Maybe the crossmember and frame rail are different alloys?

I agree that it's strange that the corrosion or whatever it is, appears on the vertical leg of the bracket only. Could be a different alloy as you noted. After a closer inspection it looks like it's starting to show up in a couple of the other brackets although not to the same degree. I plan on taking the crossmember in question off next week to get repaired or replaced.

 

[Newf]

I had my ez loader trailer axle replaced at G&M trailers in Langley. Good guy to deal with. Builds all kinds of custom trailers. John, 604-581-9304
19585 96 Ave, Surrey

Was your axle a torsion axle? If it was, why the need for replacement? Mine is a 2014 trailer with a single torsion axle rated for 5500 lbs and have been wondering about the longevity of the rubber cords in the axle. Been told when they fail, they just fail without warning.

 

[Newf]

Just a follow-up: Took the crossmember off and found corrosion on the aluminum tube as shown below. The faces of the galvanized brackets were fine and no signs of corrosion on the connection to the aluminum I-Beam. Took the tube to a shop in town and they couldn't do anything for me for a few weeks. Needed the boat before that so for now I just straightened the sides on the tubing and reinstalled it with a layer of Sikaflex over the contact areas as well as non metallic shims between the bracket and tube.

A question for those in the "know". What is the normal practice when bolting on different materials to aluminum that are in the salt water environment, especially those that are submerged? Using plastic/rubber/teflon shims may help but if salt water seeps in the joint it will still crystallize and start corroding the aluminum will it not? Seems like an adhesive/sealant between the contact faces would be a better option to keep the salt out. I will have to address all the other connections on the trailer in the future so I'm looking for the best option upon reassembly.

 

[Flashman]

The issue isn't salt crystalizing. It's about keeping the mild steel away from the aluminum and possibly keeping salt water out of the connection.

The issue you are dealing with is galvanic corrosion. In simple terms, when you have two different metals in direct contact and they get wet or are submerged in water, you get more aggressive corrosion on the less corrosion resistant material. That's a simplification, but covers the important points. The less resistant material will corrode preferentially. The more resistant material will corrode more slowly than if it were in the same conditions by itself. This is why you put zincs on outboard engine legs etc. The zinc takes all the corrosion, protecting the aluminum leg. Another example would be the old stories of people accidentally/maliciously dropping a copper penny in the bilge of an aluminum boat and having it corrode a hole in the hull. The copper is the more resistant material and causes the aluminum to corrode at an accelerated rate where they are in contact. In the case of your trailer the cross tube is the least resistant to corrosion, the steel more resistant, and the main beams are probably a different aluminum alloy that is slightly more resistant than the cross tube. Keeping the mild steel from directly contacting the aluminum will significantly reduce the problem, hence the plastic shims.

It's possible there is another effect at play, crevice corrosion. That's where there is a very thin gap that salt water can get into, where the water gets depleted of oxygen (from reacting/corroding with the metal in the crevice) the difference in the oxygen content of the water in the crevice and the surrounding environment creates a galvanic cell (kind of like a battery, but not exactly). The chemistry of the galvanic cell creates a very strong corrosion effect in the crevice. This is not really a problem in fresh water, it needs an electrolyte, the salt in the case of ocean water. Your solution of applying sikaflex to the joint will really help reduce the risk of crevice corrosion.

As for bolting aluminum in salt water I'm not too familiar with best practice aside from no mild steel and nothing with copper in it, brass etc. Pretty sure stainless steel is the standard. Others on here will know more than me on that.

 

[Newf]

Thanks @Flashman for taking the time with the detailed response. I've been reading about aluminum corrosion online this morning and in one article there were 13 different types of corrosion listed for aluminum. The two that you describe above appear to be the logical explanation for what is occurring on my trailer. Looks like I will have some work to do with the other connections to clean them up and put in some preventative measure to prevent or reduce the corrosion.
Thanks Again.

 

[cuttlefish]

I was thinking the same as what @Flashman wrote. But in addition, if the steel brackets were galvanized then there is a third metal at play. The zinc galvanizing would go first, then the aluminum would begin to sacrifice next and the bare steel would begin oxidizing (rusting) which would cause it to expand and put inward pressure on the aluminum crossmember.
If, as you say the crossmember is not structural, I would eliminate the galvanized steel brackets and just bolt the aluminum crossmember to the aluminum frame. Or get some aluminum brackets made up.
Just my two cents. Good luck with your fix.