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back_marker · #16 Post by **back_marker** » Sat Apr 21, 2012 9:28 am

HowardQ wrote:
paddyz1 wrote:Thanks for the replies guys
Nooj I will be placing an order for ally bolts with the screw on collars you have suggested. I will also want screen bolts in black too. Will pm you later tonight.

As for corrosion between dissimilar metals i do believe copper-slip is a no no between stainless and anything. I am not 100% sure on this because i use dry moly on my bolts with red locktite. The dry moly i have costs £16 and it is only a standard sized aerosol can.
You've got me thinking now Paddy and I am not now sure about Copper-slip,
and think the silicone grease mentioned by Keith might be the one to go for.
I'd been using Blue Loctight, advised by a bike shop, but certainly not sure about that anymore.

Can either of you expand on this at all? I have always been under the impression that this was the way to stop the problem, and at the risk of sounding like "I've been doing it for years and had no problems blah blah blah", it seems to have been working ok for me, especially in the cam cover bolts on the Falco lump.

stivesvelo · #17 Post by **stivesvelo** » Sat Apr 21, 2012 9:59 am

fwiw, boats/yachts use a lot of alloy & stainless in a pretty hostile environment & they use some special sort of grease/coating in rigging (a lot of stuff is rivetted) to help with this.

Don't know what it is, I've just seen people using it in a boat yard about 10 yrs ago asked what it was for (yellow stuff) so try a boat chandler or rigger, I've meant to follow this up but never seem to get around to it...

rob

paddyz1 · #18 Post by **paddyz1** » Sat Apr 21, 2012 12:21 pm

stivesvelo wrote:fwiw, boats/yachts use a lot of alloy & stainless in a pretty hostile environment & they use some special sort of grease/coating in rigging (a lot of stuff is rivetted) to help with this.

Don't know what it is, I've just seen people using it in a boat yard about 10 yrs ago asked what it was for (yellow stuff) so try a boat chandler or rigger, I've meant to follow this up but never seem to get around to it...

rob

I can't, i can only tell you my experience and what the engineers demand at work.

We use dry moly on everything stainless.and copper slip on everything carbon. The bolts are unlikely to be removed for years .
I use the same procedure on my car and bike without problem.

irich · #19 Post by **irich** » Sat Apr 21, 2012 12:29 pm

Pick two metals. The one higher in the table is the sacrifical anode (it will corrode). The bigger the difference in potential (the farther apart they are in the table) the faster the corrosion.

Also related to size. Small zinc and big steel means the zinc corrodes very fast. However big mild steel and small stainless steel means slow corrosion in the mild steel.

Metals need to be electrically in contact, and in the presence of an electrolyte.

HowardQ · #20 Post by **HowardQ** » Sat Apr 21, 2012 4:34 pm

Well I think that confirms the stainless and Alloy (or magnesiun) problem.
Same for chrome plated (or nickel also in stainless).

Doesn't look good for copperslip either with it being right at the bottom.

But zinc or cadium plating looks OK

Titanium

Wonder what Pro Bolt think?