Joined Jun 2004
412 Posts | 17+
australia
fork chrome corrosion
- Thread starter fe600racer
- Start date
Joined Dec 2005
184 Posts | 26+
Moab UT
Hey There
I just had my suspension serviced, and the guy also has a shop in Brazil. He said that they have some problems with this in certain areas of the country. He says it is due to a high acidic content in the local soil. They have had to replace some tubes. His advice was to wash the bike and not to use the neoprene fork booties.
cheeseberger
I just had my suspension serviced, and the guy also has a shop in Brazil. He said that they have some problems with this in certain areas of the country. He says it is due to a high acidic content in the local soil. They have had to replace some tubes. His advice was to wash the bike and not to use the neoprene fork booties.
cheeseberger
Joined Jun 2004
412 Posts | 17+
australia
thanks for the reply. The corrosion is strange because it is small bubbles from under the chrome behind the fork protectors. I was wondering if the thread at the bottom tube had some rust when installed that has come up under chrome. I would not have noticed it accept when changing the oil and removing the protectors to let the forks go down to do the oil hight? The other thought is that the form protectors wrap around so much that it does not allow that part to dry easily and the dampness stays longer and soaks down into the thread of the tube and then up under the chrome. I wonder how many others have actually taken the fork protectors off and had a look?
Quick corrosion toolbox talk by a corrosion science student for anyone that may find this of interest....
;
Chrome plated components can suffer an aggressive form of localised corrosion in locations of local coating break-down. As the vast majority of the surface area is protected by the chrome, this becomes the cathode in the electrochemical cell. The breakdown areas become the anodes (the anodic areas corrode, i.e. the bubbles), and because the cathodic/anodic reactions must be balanced to conserve electrical neutrality, the far greater cathodic surface area to anodic surface area results in accelerated anodic dissolution (corrosion). Chlorides (such as sodium chloride, i.e. salts from the roads/soils etc), are aggressive passive layer attackers, and within threaded components for example, can promote "crevice corrosion", where the corrosion by-products actually catalyses the ongoing corrosion, as it lowers the pH drastically (becomes very acidic) in the bubbles, due to hydrolysis of the metal ions in solution within the bubble, and the production of hydrogen ions (H+), (pH = -log[H+])
The bubbles you see are evidence that local breakdown has initiated, and anodic sites have become established.
The best thing to do in my opinion, is gently emery paper the bubbles (to remove these closed cells & halt the on-going corrosion), then apply a water resistant coating (clear varnish?) in that area. Try to always wash the bike down to remove wet spray/soil etc after each ride to avoid chloride ingress (& build up), within cavities such as threaded components etc, & of course the dryer the bike, the less corrosion takes place overall as you've removed the electrolyte, and ambient temp corrosion is impossible without an electrolyte. Hope this helps.
Cheers
Crispin
;Chrome plated components can suffer an aggressive form of localised corrosion in locations of local coating break-down. As the vast majority of the surface area is protected by the chrome, this becomes the cathode in the electrochemical cell. The breakdown areas become the anodes (the anodic areas corrode, i.e. the bubbles), and because the cathodic/anodic reactions must be balanced to conserve electrical neutrality, the far greater cathodic surface area to anodic surface area results in accelerated anodic dissolution (corrosion). Chlorides (such as sodium chloride, i.e. salts from the roads/soils etc), are aggressive passive layer attackers, and within threaded components for example, can promote "crevice corrosion", where the corrosion by-products actually catalyses the ongoing corrosion, as it lowers the pH drastically (becomes very acidic) in the bubbles, due to hydrolysis of the metal ions in solution within the bubble, and the production of hydrogen ions (H+), (pH = -log[H+])
The bubbles you see are evidence that local breakdown has initiated, and anodic sites have become established.
The best thing to do in my opinion, is gently emery paper the bubbles (to remove these closed cells & halt the on-going corrosion), then apply a water resistant coating (clear varnish?) in that area. Try to always wash the bike down to remove wet spray/soil etc after each ride to avoid chloride ingress (& build up), within cavities such as threaded components etc, & of course the dryer the bike, the less corrosion takes place overall as you've removed the electrolyte, and ambient temp corrosion is impossible without an electrolyte. Hope this helps.
Cheers
Crispin
Joined Jun 2004
412 Posts | 17+
australia
thanks .... I have used a small file and then emery and oiled the surface. The bubbles are at the bottom of the chromed tubes on the highest side of the tubes about 1cm from the bottom and the bubbles over a 2.5cm area. The fork protectors on the 08 model wrap around there keeping dust and mud off very well. It may tend to allow water to evaporate more slowly though. I was wondering.... if the thread compound used to secure the chrome tube in the aluminium axle base also seals the thread from moisture, then if not enough thread compound used.... moisture may linger around the thread and with the reaction advised by Crispin cause bubble up from under the chrome. It would be unusual for two tubes to be corroded or defective when first installed. On the other hand I have not seen fork tubes corrode before.... I wonder it the quality of WP is falling. I am considering drilling air holes in the fork protectors... that would allow dust and mud in a little.... but may assist drying. As it is on both tubes and I wash, dry,and WD 40 my bike regularly this one is a bit of a mystery. Not the biggest thing to cause concern just puzzling.
Hi, in answer to your question, yes the thread compound will seal the threads from water ingress, so use plenty & wipe off any excess. I see your point about drilling air holes, but would suggest this may make matters worse by allowing in more crap that will build up the chloride levels with time.
I'd still try using a clear varnish or another water resistant coating rather than just leaving an oiled surface, as this will halt any further deterioration in condition until it too finally breaks down (could last for years), after which you just renew the coating.
The oiled surface will soon be gone leaving the exposed corroded surfaces again.
Cheers
Crispin
I'd still try using a clear varnish or another water resistant coating rather than just leaving an oiled surface, as this will halt any further deterioration in condition until it too finally breaks down (could last for years), after which you just renew the coating.
The oiled surface will soon be gone leaving the exposed corroded surfaces again.
Cheers
Crispin
Joined Jun 2004
412 Posts | 17+
australia
cheeseburger, any chance of getting a contact email or phone number for the guy who has the shop in Brazil?
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