Stainless bolts into alloy seizing

[ian parkes]

I remember reading a thread here some time ago on this subject , first was a reason why copper grease was not the right assembly lube and second was a reason why threads can suddenly lock up solid when age and corrosion isn't the cause thread galling I think it's called .
Any links or info could help , I have had a search without any luck

Reason is Iam having a problem on an almost new motorbike that's under warranty .

[spartacus]

http://www.rib.net/forum/f8/what-the...his-54420.html

Stainless steel should be tightened by hand. Power-tools are a no-no as stainless steel is prone to galling, which as I understand it can be caused by the roughness of the thread and increased friction effectively cold weld the two. Just watched a youtube video where some guy had to cut the fuel filter out of his boat (fibreglass) using a Dremel after the nut and bolt seized.

[Pikey Dave]

Stainless seizing into alloy is dissimilar corrosion, in non-marine applications use copperslip to prevent this.

Stainless seizing into stainless is galling or "pickup", likewise in non-marine applications use Copperslip.

In marine applications it gets a bit fuzzy, there's a school of thought that says copperslip is ok, another says that is exacerbates electrolytic corrosion (big word day today) I have a nickel based anti-seize that's approved for seawater applications on nuclear installations, so I reckon it will do for my bote Failing that I'd use a marine grease such as the thick blue grease that Evinrude sell, can't remember it's name off hand, good stuff though

[ian parkes]

Thanks for the replies and that link , it has made clear what was kind of in my head .
Problem I have is a siezed chain adjuster bolt on a nearly new ktm motorbike . The thread literally siezed so solid I broke the bolt trying to free it despite heat and coating it with copaslip when it was new . Hoping spark erosion will remove the broken bolt

[Trimix]

Ive also got a couple of KTM's. I use copperslip. If you look at this forum you will find answers specific to your KTM issue: Orange Crush - ADVrider

I also drilled a tiny hole at the end of the swingarm to allow for any trapped water to drain out.

[two stroke mick]

can you use stainless and alumimun together?

[Trimix]

Galling:

Thread galling seems to be the most prevalent with fasteners made of stainless steel, aluminum, titanium, and other alloys which self-generate an oxide surface film for corrosion protection. During fastener tightening, as pressure builds between the contacting and sliding thread surfaces, protective oxides are broken, possibly wiped off, and interface metal high points shear or lock together. This cumulative clogging-shearing-locking action causes increasing adhesion. In the extreme, galling leads to seizing - the actual freezing together of the threads. If tightening is continued, the fastener can be twisted off or its threads ripped out.

Solution:

Use Nuts and Bolts of the same material, so one does not wear faster than the other.

Also use a lubricant like molybdenum disulfide (moly)

[NSS]

Used to be a big problem with Lotus Mk1 Cortina - Steel bolts into alloy head. Spark eroder was always how we got them out so should do the trick if you have access to one. Erode the core and then peel out the thread.

[ian parkes]

Originally Posted by Trimix

Ive also got a couple of KTM's. I use copperslip. If you look at this forum you will find answers specific to your KTM issue: Orange Crush - ADVrider

I also drilled a tiny hole at the end of the swingarm to allow for any trapped water to drain out.

Yes I know it's a common problem reported on the forums , I have also drilled a drain hole and used copaslip from new
Problem is my bike is nearly new and no corrosion or water etc has ever got in the swingarm .
I have had two of these now and Iam fastidious with maintenance That's why I was looking for the reason the thread had locked up . Ist thing the dealer said was that ktm would tell me I hadn't washed it and it was corroded and refuse warranty . I was actually winding the bolt in when it locked up then it would only undo half a turn and nothing would move it furthar iether way .

[jyasaki]

Originally Posted by NSS

Used to be a big problem with Lotus Mk1 Cortina - Steel bolts into alloy head. Spark eroder was always how we got them out so should do the trick if you have access to one. Erode the core and then peel out the thread.

Seems to me that a lot of auto/truck engines these days are aluminum, and I haven't heard of anyone using aluminum hardware to bolt them up - it's all steel hardware. So why is the issue you referenced not still a problem? Worded differently, why was it a problem in that instance?


jky

[Trimix]

Ouch, that shite. I lubed mine with copperslip from new. Not sure what you can do now given the position in the swingarm, its not like you can get a drill in there to tap it for an extractor stud.

Before you spend loads of money and time, see how much a secondhand swing arm is first. You never know, it may be quicker and cheaper than trying to sort it.

What bike is it?

[Searider]

1. If it's under warranty - get on to the supplier.

2. Teff gel is what's often used when assembling components onto an aluminium mast with stainless steel fastenings.

3. Copper grease in a marine environment will be more noble than aluminium - meaning that the aluminium will corrode in preference to the copper. Which should prevent seizing - but will probably weaken the connection leading to a whole other level of trouble!

[NSS]

Originally Posted by jyasaki

Seems to me that a lot of auto/truck engines these days are aluminum, and I haven't heard of anyone using aluminum hardware to bolt them up - it's all steel hardware. So why is the issue you referenced not still a problem? Worded differently, why was it a problem in that instance?


jky

No idea, but, as someone else mentioned, direct contact between such dissimilar metals was always a problem. As for nowadays, perhaps the surface treatments are more advanced. Perhaps they sleeve the bolt holes. Perhaps they are machined to a much more accurate tolerance. Perhaps it's a combination of several factors

[SIBRider]

Regular (non-stainless) steel and aluminum have very close galvanic numbers. In atmospheric environment would mean virtually no galvanic corrosion. Stainless is much more noble than aluminum and will corrode aluminum especially in marine salt water environment.

[m chappelow]

Graphite dust is a good thread lubricant for stopping Galling on stainless threads .
Other dry lubricants or dust such as Mica or even french chalk is supposed to be ok too though i have only ever used Graphite .