Anybody ever seen this?!

[Ew83]

So I was doing a tire change and noticed this on the inside of my rim. The outside looks fine and the rim sidewall is perfect. What is going on with the inside of the rim? It looks like it's exploding inside out?

 

[crypto666]

That does not look like aluminum.  I would remove it and have it biopsied.

[G.P.]

Yup, seen it real bad on a used 2006 KTM 250xcw. It was much worse than that, but it never broke.  I watched it carefully though. The seam started to become visible from all of the swelling, so I changed it out at that point. 

 

edit: on mine it was internal aluminum corrosion. Ford Expeditions have a similar corrosion issue on their aluminum lift gates.  On those it’s cause from impurities (iron and dissimilar metals) getting in during the smelting process. Might be a similar issue causing this. 

Edited August 19, 2020 by G.P.

[eastreich]

I've seen that lots of times, usually on older bikes like early 80s Honda XRs that have been sitting outside some farmer's barn for a few years, but occasionally something newer.

Can be caused by contamination in the original casting, long term corrosion from dissimilar metals (rots out by steel spoke nipples), from an external chemical contact, or a defect in the anodizing process that got contamination in the aluminum or allowed something to get to the aluminum if the anodizing was damaged.

[Scrammer]

YUP "Have seen worse"  to the point the spoke nipple would not hold torque (did not even try to use it)., and I am currently using one that had a bigger area of corrossion than your pic.  My theory is  a "Hard Water" condition that gets inside the rim at the spoke nipples during a Powerwash sesson, add a break or scratch in the anodizing  . . . .  Seen it on original D.I.D rims and the Moose rim I am using now.  

This is what I did. I sanded the alien growth down clean. Then I used a strong 2 part Polyuretane to coat the sanded area and seal it. I then dribbled some of the polyurethane sealer onto the spoke nipple heads in their hole ,, let all of that dry before I added the rim tape.... I am running "Outex" tubeless tape system. "I do not know the results yet", as the tires are still new Dunlop 404's on the street. So it will be a while with this good quality tire before I have to dismount them. Although I was confident of the Polyurethane application atleast prolonging the life of my rim !!

Edited August 19, 2020 by Scrammer

[Drop-Bear]

Had the same problem when using Tu-Bliss. I put it down to the spoke nipples rusting after using soapy water to seal the tires. Haven't had the same problem on any wheels using alloy spoke nipples.

Wait until you take the tape off. BTW, they've changed to a different type of tape now. Maybe it was the glue 

Edited August 19, 2020 by Drop-Bear

[Trailryder42]

Both rims of my 2013 300 are eat up with corrosion like that. It bubbles up under the plating. I scrape and use a wire wheel and brush, then spray paint on every tire change.

[Drop-Bear]

4 minutes ago, Trailryder42 said:

Both rims of my 2013 300 are eat up with corrosion like that. It bubbles up under the plating. I scrape and use a wire wheel and brush, then spray paint on every tire change.

Yeah, wire wheel, paint and electrical tape here 

I sold them, buyer didn't seem fussed, but did get them pretty cheap.

I think they were the SM Pro wheels, the cheaper ones.

Edited August 20, 2020 by Drop-Bear

[hondaxr650rrrr]

I had this happen on a 1986 CR250 that I was first owner of. I blamed changing tires with dish soap. I have seen the havoc of its reaction with aluminum. The corrosion got below the gold anodizing and went rampant.

[Drop-Bear]

19 hours ago, hondaxr650rrrr said:

I had this happen on a 1986 CR250 that I was first owner of. I blamed changing tires with dish soap. I have seen the havoc of its reaction with aluminum. The corrosion got below the gold anodizing and went rampant.

Yeah, It can't be good IMO. I changed to Armour All.

[hondaxr650rrrr]

I use any cheap spray lube from the dollar store.

 

[mxwiz]

Search for Exfoliation Corrosion very common in the aviation industry due to the amount of aluminum alloys used in the industry.

[Ew83]

On 8/19/2020 at 7:10 PM, hondaxr650rrrr said:

I had this happen on a 1986 CR250 that I was first owner of. I blamed changing tires with dish soap. I have seen the havoc of its reaction with aluminum. The corrosion got below the gold anodizing and went rampant.

I use dish soap for setting up tubliss. Interesting. Might use armorall from now on. And the water I'm using is well water. Damn, didn't know this was a thing. Might need to lace a new wheel. Ugh.

[Drop-Bear]

5 hours ago, Ew83 said:

I use dish soap for setting up tubliss. Interesting. Might use armorall from now on. And the water I'm using is well water. Damn, didn't know this was a thing. Might need to lace a new wheel. Ugh.

Was only an Issue for me on wheels with steel spoke nipples. Most of my wheels have alloy nipples, never had an issue with those wheels.

[edlithgow]

Something similar-looking on crankcase I was cleaning yesterday. Powdery, quite deep, under flaking black paint which may not be original, on a Yamaha RZR that's been sat for some time.
 

I just applied my standard corrosion band aid since I havn't dealt with corroded (aluminium?) alloy before and didn't know what the SOP's were.

Hand wire brushed, then toothbrushed sunflower oil (linseed better but cant get any here in Taiwan) on and rubbed it in with an empty pill blister pack, (which has an embossed foil surface) as a "sanding" pad.

On rust I would abrade with crumpled up foil (by hand) or beercan (in a power tool) but thought I probably didn't need that much abrasion or extra aluminium on alloy. Might try foiling by hand for a second treatment, or on the other side, which has less corrosion

Surface is smoothed out and hopefully protected, and residual paint is ground up some and dispersed to give an approach to the original colour, though it isn't quite uniform.

This treatment might not be such a great idea inside a wheel, where the oil might attack the tube, oxygen to polymerise it might be limited, and it might grow mould. OTOH it wont attract dust inside a wheel.  

Edited February 28 by edlithgow