Gradually ive been replacing a few of the fastners on me gsa for stainless, front engine cover, cylinder guards etc., which i thought was a gud idea, but ive just been flicking through a few postings on google etc. And it appears some people think stainless fastners on a motorbike are a bad idea due to corrosion, strength etc. etc., so what do peeps think on ere then, gud idea or bad?????
Stainless fastners
- Thread starter ghost-rider
- Start date
ihandyman247
Registered user
What
stainless still do not corrode ! , never happened to me
St/st can and does corrode, depending on the grade.
...but on a bike, in practice, i've never seen it.
use copperslip on the threads, and don't fit them in high stress applications and you will be absolutely fine.
use copperslip on the threads, and don't fit them in high stress applications and you will be absolutely fine.
technotony007
Registered user
grade
a2 is 304 stainless steel ( is slightly magentic and does corrode eventually)
A4 is 316 stainless steel ( does not corrode in my experienec ever on bike.)
becareful to replace the front brake caliper bolts in stainlessas they need to be a specail grade stainless steel , as they are a 10.9 grade zinc plated high tensile bolts in carbin steel.
regards
Tony
a2 is 304 stainless steel ( is slightly magentic and does corrode eventually)
A4 is 316 stainless steel ( does not corrode in my experienec ever on bike.)
becareful to replace the front brake caliper bolts in stainlessas they need to be a specail grade stainless steel , as they are a 10.9 grade zinc plated high tensile bolts in carbin steel.
regards
Tony
Just as i thought lads
, to be fare alot of the negative information i read tonite was from our american cousins over the pond
, to be fare alot of the negative information i read tonite was from our american cousins over the pond
Sooty09
Registered user
Unlubricated st steel can weld solid when screwing into other stainless steel. At work I have sheared M16 studs while screwing on st nuts using hand tools, usulally due to thread damage. A paste such as glook will prevent this. Stainless steel into alloy should not cause a problem. Stainless to stainless will not guarantee no corrosion.
Bendy toy
Registered user
Carbon steel threads will spring and they get up to the correct torque tightness. This locks the threads together. Stainless threads have virtually no "spring" so they suddenly go tight and can shake loose. Not to mention the threads galling. They are better if a carbon steel nut is used on a stainless bolt and they don't gall (usually).
Threads into aluminium alloy dont spring very much so stainless bolts are ok. Use a decent high solids anti seize paste.
I have used stainless fasteners on solid brake discs and calliper mounting points for years with no problems. I have taken out many carbon steel fasteners from the same places that were corroded and had to be greatly weaker than when new.
I reasoned the loads are perpendicular to the bolts (not to trying to pull them out) so as stainless being very tough would easily take the loads. It also wont degrade over time.
I would not use stainless on bolted together brake callipers as these are using the fastener's tensile strength. Stainless had poor tensile strength. It would equally be hopeless for something like a wheel bolt.
Threads into aluminium alloy dont spring very much so stainless bolts are ok. Use a decent high solids anti seize paste.
I have used stainless fasteners on solid brake discs and calliper mounting points for years with no problems. I have taken out many carbon steel fasteners from the same places that were corroded and had to be greatly weaker than when new.
I reasoned the loads are perpendicular to the bolts (not to trying to pull them out) so as stainless being very tough would easily take the loads. It also wont degrade over time.
I would not use stainless on bolted together brake callipers as these are using the fastener's tensile strength. Stainless had poor tensile strength. It would equally be hopeless for something like a wheel bolt.
ihandyman247
Registered user
Correct !
Stainless fasterners are mostly fairly low tensile but then so are mild steel bolts. So I wouldnt worry about the strength of stainless in cosmetic applications but I'd be a bit more nervous about replacing brake caliper bolts with stainless. These are likely to be high tensile cdarbon steel. You can get high tensile stainless but not likely in an ebay cheepo bolt set.
A more real problem is electrolytic corrosion where the stainless passes through and into ally. To avoid that coat the threads of the stainless with Duralac or similar zinc chromate paste. If you dont there is a real risk of the corrosion of the ally making the fastener either very difficult to remove or impossible to remove.
Help yourself by using 316 grade or A4
P.S. The above is based on years working in the stainless steel manufacturing industry plus 20 years of dealing with the same issue ( worse actually) on sailing boats.
diver1
Registered user
This may help :-
www.rocol.com/products/anti-seize-stainless-steel
www.rocol.com/products/anti-seize-stainless-steel
Bendy toy
Registered user
I have often found some quite severe corrosion of carbon steel fasteners into aluminium. I have not seen the same issue with stainless but I don't work with boats.
However, If I read this right, http://en.wikipedia.org/wiki/Galvanic_corrosion carbon steel should cause loss of aluminium (not the steel) and stainless could be even worse.
Its not been my personal experience so I'm now well confused.
However, If I read this right, http://en.wikipedia.org/wiki/Galvanic_corrosion carbon steel should cause loss of aluminium (not the steel) and stainless could be even worse.
Its not been my personal experience so I'm now well confused.
That stuffs over 100quid a tin on ebay
Dunno wethervim more confused now or not, so how many of you for arguments sake changed your engine front cover bolts for stainless?? And have you noticed any corrosion issues after???
Yes - with both mild steel and stainless its the ally that corrodes through electrolytic action. Made worse by any salts inc that in washing up liquid. The problem is that the products of corrosion of ally take up much more space than the ally that has corroded plus they are abrasive ie very grippy. So the small gaps between the threads on the steel bolt and the threads in the ally casting fill up with bulky grippy ally oxides and before you know it the fastener is gripped tighter than a Yorkshiremans wallet.
You can sometimes shift them with heat from, for example, a kettle of boiling water but release fluids are a waste of time. But like applying oil to emery paper.
Use this to prevent problems. Its used for the same purpose on aircraft.
I found out the hard way some years ago stainless steel nuts and bolts do not tighten up to high torques, that's not scientific but electric nut runners don't normally produce very high torques. When erecting steel we always do the last bit of tightening with a breaker bar.
Not exactly the m8/10 bolts you will have on your average bike. I replace all the non critical smaller fixings with 316 stainless on my bikes. I would never consider it for frame/brake fixings as it frankly isn't worth the kind of trouble it could cause.
ACF grease on all threads except when loctite is required. ACF 50 spray or grease on the exposed nuts and heads.
I buy mine from industrial fixings suppliers as the cost is neglible compared with some of the prices you see on specialist sites.
Not exactly the m8/10 bolts you will have on your average bike. I replace all the non critical smaller fixings with 316 stainless on my bikes. I would never consider it for frame/brake fixings as it frankly isn't worth the kind of trouble it could cause.
ACF grease on all threads except when loctite is required. ACF 50 spray or grease on the exposed nuts and heads.
I buy mine from industrial fixings suppliers as the cost is neglible compared with some of the prices you see on specialist sites.
Bendy toy
Registered user
The brake disc bolts on my Yamaha were a mess and very tight. I arc welded on some to shock them free. The replacement (local fasteners factors) stainless came out easily after 2 winters. They did have thread lock which may have insulated the galvanic effect. Or maybe they were the better quality material.
Humbug
Registered user
What Cookie said. 
Bendy toy
Registered user
What did I just say about stainless being fine. Yeah well...
I have just taken my Adventure side case frame off the bike. One of the 8mm stainless bolts into the aluminium clamp on bike the seat frame tube was tight and creaking. I soaked both with WD40. One whizzed out. The other sheared off. D'Oh.
Hopefully some heat will break the seizure and at least its left me a stub to get some pipe pliers onto.
There's the other downside with stainless. Its tough so when the bolt is too tight you dont feel the metal yielding. One point where I should have got the torque wrench to avoid overdoing the force. D'Oh. D'Oh.
I have just taken my Adventure side case frame off the bike. One of the 8mm stainless bolts into the aluminium clamp on bike the seat frame tube was tight and creaking. I soaked both with WD40. One whizzed out. The other sheared off. D'Oh.
Hopefully some heat will break the seizure and at least its left me a stub to get some pipe pliers onto.
There's the other downside with stainless. Its tough so when the bolt is too tight you dont feel the metal yielding. One point where I should have got the torque wrench to avoid overdoing the force. D'Oh. D'Oh.
I know the theory about stainless not being as strong as high tensile steel bolts for applications such as mounting the brake calipers, but ...... can anyone confirm whether stainless bolts would be weaker than the mounting point of the cast alloy caliper?
I know of high stress applications using alloy wheel nuts which sort of blows away the theory about using the strongest product available.
I know of high stress applications using alloy wheel nuts which sort of blows away the theory about using the strongest product available.
Bendy toy
Registered user
I have used stainless fasteners for attaching brake callipers. I reasoned they are not under tensile stress (I mean the bolts are not stretched by the applied loads) and the stainless steel is also at least as strong the aluminium it's screwed into. Also the originals were corroded so had to be weaker than new.
I would not use stainless for the bolts that hold the actual calliper together. They are taking bending and tensile loads.
I would not use stainless for the bolts that hold the actual calliper together. They are taking bending and tensile loads.
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