Bingo, all these more cathodic fasteners turn the lovely alloy you're screwing them into into an anode, i.e. it will preferentially corrode. There are guidelines available for the use of dissimilar metal fasteners & the prevention / elimination of such anodic corrosion if one want's to be anal / if one is an aircraft mechanic, however; in a dry environment / garage queen or for a race bike that's apart a lot and subject to regular inspections I'd not be worried, but I'd think twice about replacing the standard zinc plated fasteners on my tourer / daily beater with anodes.
I think that corrosion mechanisms are a speciality that most engineers aren't aware of, never mind 'normal' people! Knowledge is useful but needs to be interpreted case by case, so yes - it's not all doom & gloom, merely science that needs to be respected. I'm in the @West Cork Paul school of maintenenace - I try to help the next person along the chain have an easier time and quietly thank me for it.
Grease is the word! Or stainless steel bolts. I got the chills, they're multiplying! Chick flick film.
Nuh uh uh... minimum voltage difference is around 0.5V for "active" but realistically that's trying to repassivate itself so one could argue that thr delta V is closer to 1 volt... One could always argue that the SS will repassivate itself pretty quicky to be more inert to galvanic corrosion so there's that but on yer daily beater, covered in winter salt, nah, I'll still take the zinc plated fastener & replace / replate them regularly.
Ill grease stuff where it needs it...not sure what your getting at...personally id rather have maybe a stainless fitting that might be a bit chalky rather than rusty oem bolts that are made out of chocolate where you have to use a dremmel to get them off. All my bikes as i said where ever possible are replaced with fittings as ive stated. My zed goes through every winter in all weathers and its fine, cos ive been over it. Ironically just for the record....the manufacturer with the best quality fittings for me has been aprilia....where ever possible theve used stainless and alloy when they can and to that end its in near perfect condition (59 plate RSV4) - that being said im not sure what aprilia are currently doing in the coatings and fittings department.!
When I was an apprentice mechanic, ( motor cars) 50 years ago I remember copaslip was a new product to the trade, it was expensive. The main dealer I trained at used it primarily to silence noisy/squealing disc brakes, by applying sparingly to the back and sides of the metal backing of the friction material. Occasionally it was used on exhaust manifold studs, but it burnt off there in time. It was not used for anything else on vehicles as far as I remember.
Totally understandable. The exterior part of the bolt, be it Ti or s/steel doesn’t corrode with exposure to weather. However, the unseen sections where the Ti or s/steel is in contact with an Alu alloy, with the presence of water (moisture from the air) creates a little battery (the voltages of which can be seen in the table above) and ions start to flow. It’s this galvanic corrosion which can cause issues if not prevented or regularly cleaned off. This type of corrosion can be as bad as the regular rusting of ferrous materials. I don’t doubt for one moment it’s an issue on your bikes as you maintain them well as you say.
A famous corrosion problem for early airliners was on-board toilets. The urine played havoc with Aluminium alloys...
