Ohlins fork leg corrosion

[Chuck]

G'day guys. I think you'll find the problem has more to do with using stainless bolts in alloy forks , ie it'll happen even without the carbon fibre bits. IN the boating world we use duralac between dissimilar metals to try and reduce the problem. Some genius put a stainless bolt into the alloy end of my yachts boom and it's never coming out! I've tried all the usual things- soaking with wd 40, heating and freezing it, impact driver...it's there to stay.

 

 

 

And off topic, since this is my first post, this site is an amazing resource! I'm up to page 40 so far and getting just a little paraniod about all the problems I'll be having in the next few weeks - having just picked up an 02 lemans with 5000 km on the clock. Surprisingly I've added 1000 km and nothing has happened in the last couple of weeks, so perhaps it's the honeymoon period?

Well, nobody posts, "Well, I put 16K on the 02 LeMans this year, and all I did was change oil. " People post stuff when they have a problem..

[belfastguzzi]

G'day guys. I think you'll find the problem has more to do with using stainless bolts in alloy forks , ie it'll happen even without the carbon fibre bits.

For sure, but the interesting thing that the original post added was about the effect that carbon fibre itself can have. While we're very aware of the curse of metal to metal reactions, particularly in damp climates with added water and salts, I hadn't thought about cf in the same way. It's not dramatic, but it's interesting.

 

Congrats on the V11 acquisition: enjoy! Which model? Oh, looking at your info, it's the LeMans, with fairing..?

[PDoz]

G'day guys. I think you'll find the problem has more to do with using stainless bolts in alloy forks , ie it'll happen even without the carbon fibre bits.

For sure, but the interesting thing that the original post added was about the effect that carbon fibre itself can have. While we're very aware of the curse of metal to metal reactions, particularly in damp climates with added water and salts, I hadn't thought about cf in the same way. It's not dramatic, but it's interesting.

 

Congrats on the V11 acquisition: enjoy! Which model? Oh, looking at your info, it's the LeMans, with fairing..?

 

 

 

Sorry, I didn't mean to pull a know it all type first post.

 

Mine is a late 02 lemans in black, it seems to have the 03 upgrades- eg cross over pipes, fuel pump in the tank etc. Pretty much standard apart from some madaz mufflers (custom built stainless pipes- VERY nice note). I'd had a weekend lined up to look at a high milage 02 a few thousand km away when this one came up down the road as part of a deceased estate! We're still getting to know each other- I haven't had a real road bike for over 20 years (dirt background- hence lots of experience with rusted bits of metal). Anyway, sorry to get off topic.

[Baldini]

...

Mine is a late 02 lemans in black, it seems to have the 03 upgrades- eg cross over pipes, fuel pump in the tank etc. ..

 

Hi PDoz, Welcome! Guzzi model years are pretty haphazard but sounds like yours is 03/04 model - unless those are owner mods. There's 3 distinguishable models: 99/00, 01/02, 03/04. The 03/04 is usually regarded as best sorted. They're a lovely bike to ride & most of the issues you might encounter have been discussed somewhere here.

 

KB

[68C]

Hi PDOZ,

 

Thanks for following my thread. My original point was to hi-lite the unexpected nature of carbon fibre, in that allthough not a metal is does conduct electricity and so causes problems akin to the disimilar metal corrosion you referred too. The corrosion does not take place on or within the CF itself, it happens to the metal it is contact with. As an aircraft maintenance engineer I spend a lot of time grinding and polishing out corrosion, treating it chemicaly and ensuring the metal is reprotected adequately. Apart from the loss of metal caused by corrosion it is the rough uneven surface that act as stress raisers and can cause premature failure that is the biggest problem - hence the polishing. Although I had a basic knowledge that CF can cause these problems I had not seen it myself, mainly because I work on older aircraft that do not have CF, I was thus suprised at the damage to the forks on a bike made in 2004. I thought it worth raising the issue. I mentioned this corrosion to a friend who told me of similar problems with a carbon fibre hugger he fitted to the alloy swinging arm of a modern Triumph, his had corroded within a year.It may be wise to look at any CF parts such as alternater covers which are very exposed.

 

Have fun.

[docc]

Great stuff! I threw the Ohm meter on the cf canisters and am really amazed at the conductivity!

 

Never heard this come up before. Thanks for the posts!

[68C]

In hindsight I now realise I should have posted this as "Carbon Fibre rots metal", rather than refer to Ohlins forks as it not a specifically Ohlins problem.

 

Moderator, please ammend as you think fit.

[belfastguzzi]

In hindsight I now realise I should have posted this as "Carbon Fibre rots metal", rather than refer to Ohlins forks as it not a specifically Ohlins problem.

 

Moderator, please ammend as you think fit.

 

I don't think it needs amended. You noticed it on the forks, so fair comment.

Good to have new info/discussion subject!

[madridpunch]

Hi Guys,

Been following this thread with interest, on my sailing boat I have a carbon mast with mainly stainless fittings, on my bikes some carbon parts in contact with aluminium.

 

I knew about the problems between stainless and aluminium, but I never considered carbon/metal mix. The carbon fibres in carbon fibre are always held in an epoxy matrix. This should act as an insulator and so stop the corrosion - but I guess the mounting holes are drilled through after molding, so exposing the carbon. We should be able to remove the bolts and then coat either the bolt or the inside of the hole with epoxy, and there should be no problem. You could use duralac also although it can be a bit messy. The other solution is to make sure that all the salt is washed off. Pure water won't act as an electrolyte and so will not cause the problem. Even rainwater and spray off the road shouldn't cause a big problem, it needs the salt (or something similar) to form a galvanic cell.

 

Cheers

David