steel plates for dropouts

boomn said:

I'm fixing up a junker aluminum SS frame that has pretty chewed up track ends. My plan is to not only file the dropouts smooth again but to also remove just enough material from the inside faces to add some steel plates. Dropouts are ~7mm thick and I would need to get them down to 6mm anyway to smooth out the deep indents, so I was thinking of using 20 gauge 304 stainless. Does 20 guage sound thick enough to last or should I use something thicker? Does 304 sound appropriate for this?

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While I cannot speak to the thickness question, however you have to be careful when combining two dissimilar metals like steel and aluminum it is possible you can get some pretty bad corrosion to the aluminum. Since you will be using stainless I cannot say if this will be an issue or not.

Thanks, I forgot about the galvanic corrosion issue. I can certainly add a thin layer of paint on the aluminum before installing the plates. I was planning to use countersunk screws, but if I wonder if using the right adhesive to bond the plates to the dropouts would be enough to prevent corrosion?

I'm certain that aluminum and stainless contact is fine corrosion-wise in exterior conditions.

jgerhardt said:

While I cannot speak to the thickness question, however you have to be careful when combining two dissimilar metals like steel and aluminum it is possible you can get some pretty bad corrosion to the aluminum. Since you will be using stainless I cannot say if this will be an issue or not.

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Given the ubiquity of various bike parts with steel screws threaded into aluminum parts, I doubt its an issue. See also aluminum seat posts and headset cups in steel frame.
Regarding stainless steel and aluminum, look no further than wheels with aluminum nipples and stainless steel spokes.

I think I just found a simpler solution that will finish this project quicker, one that would make Red Green proud: 3/8" ID stainless fender washers over the axle ends and sandwiched between the locknuts and inside of the dropouts. Chaintugs on both sides will protect the outside faces and hopefully make up for any potential decrease in bite that the hub might otherwise have on the dropout. Without any semblance of a machine shop i would have been stuck using a rotary tool and a vise to fabricate plates anyways

Fungazi said:

Given the ubiquity of various bike parts with steel screws threaded into aluminum parts, I doubt its an issue. See also aluminum seat posts and headset cups in steel frame.

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Once you've had an aluminum seat post stuck in a steel frame, you'll rethink this thread. I can assure you. It's not something that happens overnight, but after a few years, sometimes it doesn't matter how much grease was on the post when you installed it.

Blaster1200 said:

sometimes it doesn't matter how much grease was on the post when you installed it.

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that's what preventative maintenance is for.