Galvanic corrosion at tub overflow

[JohnnyCom]

Several years ago, I replaced a 1995-era lever-operated tub drain with a foot-lock drain. The kit included an aluminum adapter bracket to convert the original two-screw overflow cover and lever to a single-screw plain cover.

Now I have found that the adapter bracket has corroded away to the extent that the ABS tub overflow fitting is no longer secured the two large screws. The bottom legs of the slots in the adapter bracket have basically dissolved where they overlapped a copper plate that was attached with two small screws of its own as part of the original installation. This appears to be a classic case of galvanic corrosion.

I've seen youtube videos of people doing this exact replacement install over the copper plate but it seems doomed to fail. What can I do to avoid having the same failure again? Wondering what is the function of the copper plate? Can I simply remove it - does it serve any purpose with my new setup? Would the adapter and two large screws on their own provide enough force to pull the ABS fitting snug against the gasket at the back of the tub? Or should I leave it in place and use an insulator between the copper and steel? Electrical tape maybe?

Also, is there any point in replacing the overflow gasket at the back of the tub? I'm sure this has been leaking with it not being securely attached for who knows how long. Thanks!

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John

 

[JohnnyCom]

Well, I found a double-screw plain cover plate that makes my question moot. However, I wonder how many failures of this type occur because the kit maker saved a couple pennies using aluminum instead of stainless steel...

 

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[hj]

Yours is the first one I have ever heard of. The brass strap is to hold the overflow in place whtn the cover is removed. Few drains have that feature, and if your overflow riser was rigid when the cover was removed, you did not need it.

 

[Kreemoweet]

I wonder how many failures of this type occur because the kit maker saved a couple pennies using aluminum instead of stainless steel...

Stainless is nice, no doubt, but there was no need to have two clamp bars on that overflow, the "copper" one (more likely dezincified brass) should have been removed.