Corrosion on nuts and bolts? R1200GS 2007

horudis82

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Hi guys,

After leaving the bike exposed a little bit too much last winter I have now almost each and every bolt rusty. The front cover has alittle bit of it as well as the engine paint flaking but I know this is fixed by sanding and repainting, but what about the bolts? I have used ACF50 profusely and it has stopped the process, but now I want to get it all cleaned up.

The bolts holding the disc brakes (front and rear), the 4 ones on the handlebar, the tubular axle holding the front wheel, or the bolts holding the break calippers... all are affected.

I thought about 2 options:

1. Replace with new ones, but I heard inox is a no go as it might accelerate aluminium corrosion through electrolysis - any ideas for that?
2. Take apart, sand, clean, and put back with a layer or wax or similar.

What do you think?

Thanks!
 
I brought a kit of bolts including proper disc bolts but the first one I put in rounded off so I didn't use any more. Replaced a couple of cosmetic bolts from the kit but for my caliper and pinch bolts I took off and sanded back and then sprayed with silver Hammerite. If you don't protect them with something they'll corrode in no time.

The results looks great and saved a packet on BMW bolts. Still need to do the discs but they are getting thin so I'll wait until I replace them.

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I used a few stainless fasteners but they are not a panacea for stopping the rot.
You could also send your bolts and brackets to a platers and have them bright zinc plated. Chrome plate is costly but zinc is very reasonable.
 
Thanks for the advice!

The previous owner did exactly that: sanded and repainted the bolts with hammerite. Now a few years later the paint is flaky and looks really ugly. I would like to have to avoid re-making this every couple of years; I will look into getting the lot zinc plated.
 
Looking at the bolt kits on Ebay. Dam they mark them up so much for a few bolts.

50 quid for a few stainless bolts! 80 quid for 10 Titanium bolts.

https://www.ebay.co.uk/itm/BMW-R120...351167?hash=item466d78e8bf:g:HPsAAOSwVohZ3gsX

https://www.ebay.co.uk/itm/BMW-R120...350996?hash=item466d78e814:g:-YMAAOSwXhZZ3gsL

Maybe we could do a bit of research on size and strength together and find what is needed and buy them for a few pound instead.



https://www.aliexpress.com/item/3-P...rch0204.8.75.409e21eazW9q5U&priceBeautifyAB=0
 
Titanium into aluminium is really not a good idea. The ally will evaporate and seize the screw solid. Good luck drilling that out.

These were bright zinc plated by http://www.kmfinishing.co.uk/ total cost was £30 cash.

IMG_20180329_131326.jpg
 
Just use stainless......as meat of Copaslip on thevthreads and they won’t gall, zinc will last for a while, but stainless is for ever.


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Just use stainless......as meat of Copaslip on thevthreads and they won’t gall, zinc will last for a while, but stainless is for ever.

Stainless is fine but the aluminium it screws into corrodes badly.
Insulated washers help but are not available in small sizes. As you say copper grease helps but it’s only part of the story.
Stainless has no spring so shakes loose it’s useless for frame fasteners and has poor tensile strength.
But it does look nice.
 
As Bendy suggests... find a marine supplier near you and ask them about getting parts re-plated.
I've had a bucket full of assorted parts done for £20.... better than new!

Make a list though...they always lose something.

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If you use stainless, coat the threads in duralac - expressly developed for stainless into aluminium fasteners in marine environments. Much better than coppaslip.
 
I have done marine grade high dielectric stuff. It’s far to slippery and the bolts just shook loose.
Action Can CS-90 has not shaken loose and to date the treated aluminium has not corroded. It’s copper with carbon and I have no clue how it stops the battery cell effect but so far it’s been great.
 
Well you've used the wrong stuff, or used the right stuff wrong.
Decades of boat builders know more than the average DIY bike mechanic (or indeed you) about stainless to aluminium fasteners.
Duralac isn't 'slippery', it is formulated to do exactly one job and doesn't affect torque settings.
 
You could try washing the bike in winter, a la Micky. But he’s very old and knows nothing of the modern habits of bikermates.
 
Well you've used the wrong stuff, or used the right stuff wrong.
Decades of boat builders know more than the average DIY bike mechanic (or indeed you) about stainless to aluminium fasteners.
Duralac isn't 'slippery', it is formulated to do exactly one job and doesn't affect torque settings.

It was certainly the wrong stuff but sold to me by a chandlers. The copper/carbon paste isn't marine grade but has done ok against road salt weathering. I don't live right on the coast or I'm sure it would not be so cool.

The fashion is aluminium with stainless screws, but using noble metal fasteners into aluminium simply because they look pretty is asking for trouble. We have stainless handrails on the harbour fixed with stainless bolts. No worries. Elsewhere, the reproduction cast iron posts are fixed with stainless fasteners and non conductive washers. Where aluminium is used it always has non conductive washers and no doubt the likes of Duralac as well.

If a bike must have stainless fasteners, the easiest option is to have them zinc plated. Then again carbon steels are better for the job so just scrap the stainless phase. Zinc plate is cheap. On tubular stuff (like carrier racks) and brackets, stainless should be fine, but use carbon steel fasteners and watch them rust before your eyes.

Even Touratech with their stainless fetish can't get it right with stainless fasteners into aluminium. Their luggage made for BMW is a good example. If its not been polished every week there will be rings of oxide around every stainless washer/rivet. What was so wrong with aluminium rivets?
 
Hand rails and stuff around the harbours here are stainless with stainless bolts or other metals with insulated washers and stainless bolts. Anything aluminium is always insulated. Aluminium that is not protected from electrolytic damage soon rots out.
Anyone with OEM BMW Adventure luggage will get a frosting of oxidation on the aluminium around the stainless rivets. It cleans off but shows stuff is going on. I don’t know why Touratech (who made them for BMW) did not use aluminium rivets.
 
Lots of useful feedback here guys thanks!!

So, is it possible to use stainless steel washers with an insulating product, without the bike falling into pieces?? Is Duralac the solution?

BTW I wash it a lot and always reapply ACF50 :)
 
Gave up using Coppaslip a good while ago and now use Molyslip ALUMSLIP, better at higher temps ( up to 1100 degrees) and suitable for stainless fixings into aluminium ............... never had a case bolt or a stainless spindle seize into an aluminium spacer to date.
 
Just to add to the conversation, I found this online:

galvanicchart.gif


Seems that the type of stainless steel needs to be very specific, and they also recommend using non-metal washers, such as nylon.

Austenitic Stainless Steel + Alumslip + Nylon washers??
 
https://www.graphskill.com/grades-of-stainless-steel-a2-a4-in-relation-to-fasteners

Tensile strength and stretch of stainless steels varies. The spring effect locks the threads together. Carbon steels are good for that but corrode. Stainless tends to tighten solid with no spring as the threads take up. These will shear if taken much further and prone to shaking loose.

A2 bolts with A2 nuts (or A4-A4) are more likely to gall (self weld) so ideally use A2 with A4. Nyloc nuts are a must-have. A good threadlock might help but once it looses - that’s it.

Carbon steel nut on stainless bolt works quite well but the carbon steel will corrode even faster than usual.
 
Zinc-Carbon batteries use elements at the opposite ends of the galvanic scale to make power for toys etc

I believe that copper reduces corrosion between stainless and aluminium because it’s between them on the galvanic scale so reduces the battery voltage.
However if that was the whole story copaslip would turn green over time. It never does. It must always be used along the whole bolt not just on the threads.
Nickel however is even more cathodic so simplistically should make matters worse. But copper/carbon paste works better than copper alone. Work that one out.

https://www.bssa.org.uk/topics.php?article=89
 


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