Corrosion on swingarm

Discussion in 'Maintenance' started by Lock, Jan 5, 2020.

  1. Lock

    Lock Active Member

    Joined:
    Mar 7, 2011
    Messages:
    82
    Likes Received:
    14
    Was cleaning project bike yesterday and found corrosion under the rear hugger around the bolt holes, grrrr! Assuming this is acid corrosion likely to have pooled there during its apparently many cleaning/detailing episodes? Also found lots of white powdery residue in the swingarm - cleaned out the hole for the brake line clip and this residue was well packed in the hole - thought it was cleaner residue, but seems like loads of it - wonder if the swingarm has been shot blasted or chemically prepped as does seem shiny. Does the rr6/rr7 swingarm have some packing material inside? . Not sure if it's time for replacement!
     

    Attached Files:

  2. Lock

    Lock Active Member

    Joined:
    Mar 7, 2011
    Messages:
    82
    Likes Received:
    14
    Looks like this might be Galvanic corrosion:
    Galvanic corrosion is why you need a duplicate set of tools for aluminum work which are never used on steel. It exists when aluminum touches a dissimilar metal in the presence of a corrosive liquid and electrical current path. Commonly, this means that aluminum, steel and any trace of water which isn’t distilled starts corroding the aluminum. The rate of galvanic corrosion is very slow, requiring many hours of exposure to an electrolyte before visible corrosion is observed. So either make sure the two materials never touch, or use “sealers, such as adhesives, primers, and other paint coatings” to keep an electrolyte like salt water away from them.

    Not sure what the thick almost solid white powder/material is inside the swing arm, but found a similar residue on engine bolt spacer - is almost like poly-filler and is pretty tough stuff. Lots of cleaning and treating me thinks!
     
  3. Old_boy65

    Old_boy65 Active Member

    Joined:
    Oct 23, 2016
    Messages:
    169
    Likes Received:
    41
    .... or to put it another way... one part is acting as the sacrificial anode and corrodes in preference to the other.
     
    • Agree Agree x 1
  4. Jez

    Jez Active Member

    Joined:
    Jan 20, 2017
    Messages:
    521
    Likes Received:
    151
    It has probably been used when the roads have salt on, ACF50 has salt neutralisers which will greatly reduce the conductivity. salt being hygroscopic will naturally attract its own water to keep an electrolytic solution between the components. from my memory stainless is just as bad against alloy, I am not sure about titanium I shall have to look at galvanic tables
     
  5. Old_boy65

    Old_boy65 Active Member

    Joined:
    Oct 23, 2016
    Messages:
    169
    Likes Received:
    41
    Titanium - from recollection is inert
     
  6. Jez

    Jez Active Member

    Joined:
    Jan 20, 2017
    Messages:
    521
    Likes Received:
    151
    This is from the net
    Study of the Galvanic Series suggests that steel and aluminum are reasonably compatible; but, if titanium and aluminum contact, the aluminum, as the anode, will corrode. Fig. 1 illustrates an example. The bolt, where it contacts the aluminum, will not corrode because it is now the cathode. The aluminum plate in contact with the bolt may corrode,
    I must admit I would have thought It was inert and as such better than steel
    But This is just galvanic's and does not include steel etc corroding on its own
     
  7. NS400R

    NS400R New Member

    Joined:
    Mar 27, 2018
    Messages:
    58
    Likes Received:
    43
    The RR6 swinger is full of foam
     
  8. Lock

    Lock Active Member

    Joined:
    Mar 7, 2011
    Messages:
    82
    Likes Received:
    14
    Pretty much everything aluminium on the bike has furring on, too much salt and not enough cleaning! Bike is apart at the moment, red and exhaust headers off so Scottoiler F365 to neutralise salt, scrubbing, cleaning and then giving it a good oiling! Hopefully can keep it all at bay otherwise it will be a full strip out.

    Thanks for the confirmation NS400R - had seen a mention of foam in the swingarm on another forum - at least i should get away with the swingarm for a bit
     
  9. NS400R

    NS400R New Member

    Joined:
    Mar 27, 2018
    Messages:
    58
    Likes Received:
    43
    Yeah, I put a chain oiler on mine from new. On drilling and tapping the holes I discovered firstly that the metal was seriously thin and secondly that the swinger was full of foam. Never fitted an oiler to a modern bike again as a result
     
    • Like Like x 1
  10. nigelrb

    nigelrb Elite Member

    Joined:
    Nov 2, 2017
    Messages:
    9,771
    Likes Received:
    3,273
    Correct.

    I nick named my former wife 'Titanium'.:D
     

Share This Page