While the boat is stuck at the dock, I’m replacing as many of the old rusted bolts holding together my aluminum trailer. The new bolts are zinc plated with galvanized washers… the question: how should I clean the old rust stains on the aluminum trailer with before I install the new bolts? Quick sand or wire brush or solvent?
Trailer Bolt Replacement
- Thread starter DuroBoat
- Start date
Reel Gone
Well-Known Member
This is what you want to do
Alex_c
Well-Known Member
If it was engineered to use grade 8 bolts, I’d replace them with grade 8 bolts. Stainless bolts are weaker in comparison. Spray some fluid film on them a couple times a season to inhibit corrosion
Foxsea
Well-Known Member
As structural connections, I will agree that grade 8 bolts make good sense. I would use a corrosion inhibitor before and after assembly. Slightly oversize holes and insulating washers at the interface also help reduce galvanic corrosion.
Corey_lax
Crew Member
WTH? I work with aluminum and our fasteners are all stainless. And our work doesn’t even see water. I’d think that zinc bolts, galvanized washers, and aluminum trailer is like the worst way to do this. Zinc bolts rust as quick as anything. And you’re mixing a bunch of stuff into the electrolysis soup. I’d use stainless. Highest grade you can get. Or weld whatever is holding it on and get rid of the bolts.
Maybe my brain is foggy right now after spending 3 hours trying to get my 2 year old to bed. But this doesn’t seem right to me. Zinc bolts will rust in the first few months
Maybe my brain is foggy right now after spending 3 hours trying to get my 2 year old to bed. But this doesn’t seem right to me. Zinc bolts will rust in the first few months
Alex_c
Well-Known Member
There’s nothing wrong with stainless fasteners, it’s just that they aren’t as strong as grade 8, so need to be sized appropriately. If the trailer was
engineered and built with grade 8 fasteners, that’s what I would replace them with. Or drill everything out and install stainless fasteners with the same strength ratings.
Here’s an article explaining it:
High Tensile Steel vs Stainless Steel Bolts in Marine Engine Restoration - Boat Renovation People
Confused on whether or not you should use stainless steel bolts in your engine restoration? Don't worry, Boat Renovation People has you covered! Read now.
www.boat-renovation.com
Good info as always guys. Correct the bolts are grade 5 and I understand zinc has less reaction to aluminum than stainless. Further, the trailer came with zinc fasteners. I agree, it’s not clear and I’ve done a bunch of research and still get a lot of different opinions..
SpringVelocity
Crew Member
I would only use zinc myself but that's just me.
Corey_lax
Crew Member
My extrusions are aluminum, and any fastener that is exposed to outside air is always stainless steel. We can't use zinc outside. So there's another conflicting opinion lol
turbomack
Well-Known Member
You pretty much are the research. Ask yourself why you are replacing the fasteners on your trailer, those galvanized bolts are what some people refer to as cheese bolts. They are known for low tensile strength and short life in a marine environment. To me, stainless hardware is the only way to go for that application. My aluminum I-beam trailer has 100% stainless hardware holding it together, just be sure to lube the threads when you install to prevent galling on initial tightening.
Clint r
Well-Known Member
12 years in a stainless shop and fasteners were stainless. Always stainless. Just to throw another opinion in the mix
Last edited:
Captain PartyMarty
Crew Member
If using stainless beware that you might face galling while installing them, either use different grades for nut and bolt, lubricate threads, and install slowly. I would replace fasteners with similar parts to what was provided by the OEM, just incase somethings happens and you have to explain why stainless was used instead of the OEM's recommendation. Just a thought as I am always thinking liability with on road stuff...
good point Marty - I went to fastener force yesterday to exchange my zinc bolts for ss and they said ss only comes in grade 2 (orig bolts are grade 5) so I went with the grade 5 zinc plated bolts… I’ll monitor them and if they rust excessively, I’ll find a suitable replacement.
On a more exciting note, heading back to Winter Harbour tomorrow for one more last sunny weekend at the cottage. What a great summer it was up there.. there is never enough time off in the summers sigh..
gunnerlove
Well-Known Member
I might have taken a couple aircraft structures courses and pulled a few wrenches for the navy over the years. My advice is to replace it with what you removed or one size larger in a properly sized hole, it lasted this long and grade 5 bolts are cheap. Movement destroys fasteners and causes more movement so sloppy bolt holes are bad unless you are counting on pins to take the loads ( think legs, heads and bell housings). Cover the fasteners in Mastinox and a constant film of LPS-3 and move on.
I have never broken a new 1/4" grade 5 bolt while tightening it but have galled and snapped many SS ones often with very little force. I don't trust stainless because so much of it is now stainresss
I have never broken a new 1/4" grade 5 bolt while tightening it but have galled and snapped many SS ones often with very little force. I don't trust stainless because so much of it is now stainresss
gunnerlove
Well-Known Member
And in my monosyllabic ways
"No"
"No"
Fritz
Active Member
I just put in a stack of grievances in about your touching wrenches!
Shouldn’t you stick to putting gutters and dryer ducting in gender neutral bathrooms?
Take it from a real blog reader!
Titanium bolt + copper washers + wasp alloy castle nuts + bronze cotter pins = Your gear on the cover of overpriced boating monthly!
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