Copaslip on aluminium

[MSeries]

Is Copaslip Ok to use on an aluminium frame ? for BB, and titanium seatpin ?

[Biggsy]

Finish Line on their version of the product (also containing copper) say:

"Use on all metals; aluminum, titanium, carbon steel, magnesium"

[iakobski]

Depends -  Shimano or Campag? Helmet?  

[MSeries]

Depends -  Shimano or Campag? Helmet? 

Shimano UN74 BB, Campag Record seatpin. No helmet.

[iakobski]

Depends -  Shimano or Campag? Helmet? 

Shimano UN74 BB, Campag Record seatpin. No helmet.

That'll be fine, then.


Chis Juden (CTC tech answers bloke) says:

I find recommendations for Loctite Krytox RFE, Molyslip and the ubiquitous Copaslip (often mis-spelled as copperslip). Since a lot of bicycle parts also involve aluminium, I'd prefer Alumslip, and this is confirmed by the manufacturer,

But the link to the manufacturer says nothing of the sort. I think it's an urban myth, some may disagree.

[MSeries]

I know. I have CopaSlip, the real stuff from Molyslip. It talks about AlumSlip where there is a prejudice against copper. My question I suppose is Aluminium + steel and aluminium+titanium prejudiced against copper ?

[Rhys W]

Where can you buy Copaslip btw? I've got some brake anti-seize stuff from Halfords, but it doesn't have that bright coppery lustre that I see when I have parts fitted at the LBS.

[MSeries]

got mine on ebay in a squeezy toothpaste type tube which is ideal

here

[philip]

What you want to avoid is galvanic corrosion.  Aluminium/copper is more susceptible than aluminium/steel, so adding copaslip between steel and aluminium doesn't seem like a good idea. Aluminium/titanium is even worse than aluminium/copper so in that case I suppose the copaslip won't make things worse.

I thought copaslip was intended for high temperatures, why would you use it on a bicycle? An non-conductive grease would seem to be better.

Disclaimer: I did physics and maths, not engineering.

[MSeries]

I thought copaslip was intended for high temperatures, why would you use it on a bicycle? An non-conductive grease would seem to be better.

is it better ? copaslip has prevented seizing so far on cars and bikes so how is it better ? All I want is it not to seize. Not seizing is not seizing. It can't not seize any better !!!!!

So are you saying grease will be better on titanium+aluminium than copaslip ?

[philip]

I thought copaslip was intended for high temperatures, why would you use it on a bicycle? An non-conductive grease would seem to be better.

is it better ? copaslip has prevented seizing so far on cars and bikes so how is it better ? All I want is it not to seize. Not seizing is not seizing. It can't not seize any better !!!!!

So are you saying grease will be better on titanium+aluminium than copaslip ?

If you are worried about corrosion caused by the difference between the metals I can't see how copper helps. I suppose it will last longer than plain grease, but I would expect the grease in the bottom bracket to fail before the installation grease.  A zinc anti-seize would be more likely to prevent galvanic corrosion of aluminium. I've used copaslip on motorcycle brake pads, but I've never used anything other than plain grease on bicycles (but I've never used titanium either).

[Biggsy]

Copaslip and all similar anti-seize compounds contain loose flakes of copper mixed with grease.  Unlike some plain greases that might dry up or disperse, these metal flakes are guaranteed to stay put until it comes to disassembly, when they help the two components slide apart.  In other words, it prevents seizure.  This is something you may need on bicycle parts that are left a long time before removal - and this can include bottom brackets.

EDIT: Copper also may make galvanic corrosion less likely (depending on the metals), and the grease in the product keeps out electrolytes anyway.

I don't think a reputable company like Finish Line would claim it was suitable for all metals if that was blatently untrue.  It's common practice to use it for aluminium and steel components in titanium frames, so it should be equally good the other way round, etc.  Anyone in doubt, however, can use an aluminium-based anti-seize product instead of a copper one.

"Prevents cold-welding, galling, and seizing of metal to metal contact parts, especially those subject to extreme pressures and moist conditions such as bolt threads, seatposts, pedals, bottom brackets, etc. For all metals, but essential when attaching reactive metals like titanium, aluminum, and specialty alloys and magnesium"

- http://www.finishlineusa.com/products/ti-prep.htm

[Biggsy]

What you want to avoid is galvanic corrosion.  Aluminium/copper is more susceptible than aluminium/steel

I'm finding conflicting information on this, and it depends on the type of steel as well.  Notice that aluminium and steel (non stainless) are in the same group in this table, meaning that aluminium/copper is less susceptible than aluminium/steel according to that info.  It's different for stainless steel.

[nmcgann]

I use it on everything metalic that might sieze, although I haven't got any titanium bits on any of my bikes so I can't comment on that. It know it works well for steel-ally and ally-ally.

I got my last tube from a discount car parts shop.

Neil

[Biggsy]

Another thought:

Galvanic corrosion requires an electrolyte, like salt water.  So how is that going to get in when you've sealed the threads with durable grease and metal flakes (Copaslip)?

Ordinary grease may do the same thing for a while, but I would expect Copaslip to last longer.

Threadlocker prevents galvanic corrosion in the same way if you use enough to completely seal the threads.

[iakobski]

I know. I have CopaSlip, the real stuff from Molyslip. It talks about AlumSlip where there is a prejudice against copper. My question I suppose is Aluminium + steel and aluminium+titanium prejudiced against copper ?

Yes, that's a very strange phrasing used by the manufacturer. Digging a little deeper, what they mean is: is it in contact with chemicals which will react with copper? Nitric acid being the obvious one. Copper is in general not particularly reactive - perhaps that's why it was chosen for this application? 

By all means use standard grease, the point of using grease with copper in is the grease will dry out or be washed out over time but the copper particles will still be there when you come to undo it.

[Rhys W]

Isn't it something to do with the high electrical conductivity of copper as well? Having a good conductor in the interface between two different metals as opposed to an electrolyte (dirty water) preventing galvanic corrosion?