Corrosion starting

[ShadowsPapa]

The hinge's zinc shims are insulated from the hinge itself, there is no electrical contact between the hinge and the shim. The shims are only sacrificial for the door and only when installed against bare aluminum. When my dealer does the corrosion repair, since both the door and shim get painted, I doubt that the shims are sacrificial at all.

The shims are not available as a separate part and because they are adhered to the hinge, they will have to be replaced with the hinge.

Random thoughts.......

that fits with the idea that the issue is the bare aluminum being exposed to air and moisture if there's any break in the paint surface between the parts. Ideally, the paint seals that sandwich and there's never a chance of any problem. However, there are many aluminum parts, like the bumpers on my cars, that aren't problematic even if the paint is chipped or nicked.
But the bubbling on the hinge is another thing altogether.

How is the zinc insulated from the hinge? a plastic gasket of some sort?
The adhesive? Which would have to be a bit special in itself to act as insulation, and be absolutely complete coverage, never allowing the two to touch or close to it.

Zinc is a soft metal - I can see it being a gasket of sorts all by itself, helping to seal the aluminum surface if the surface of the zinc was very smooth. If properly painted where the paint sealed the edge of the zinc, then there is no chance of a problem. If the paint seal at the edge was broken, then the zinc would become sacrificial.

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[jebiruph]

Random thoughts.......

that fits with the idea that the issue is the bare aluminum being exposed to air and moisture if there's any break in the paint surface between the parts. Ideally, the paint seals that sandwich and there's never a chance of any problem. However, there are many aluminum parts, like the bumpers on my cars, that aren't problematic even if the paint is chipped or nicked.
But the bubbling on the hinge is another thing altogether.

How is the zinc insulated from the hinge? a plastic gasket of some sort?
The adhesive? Which would have to be a bit special in itself to act as insulation, and be absolutely complete coverage, never allowing the two to touch or close to it.

Zinc is a soft metal - I can see it being a gasket of sorts all by itself, helping to seal the aluminum surface if the surface of the zinc was very smooth. If properly painted where the paint sealed the edge of the zinc, then there is no chance of a problem. If the paint seal at the edge was broken, then the zinc would become sacrificial.

The black coating on the hinge is not conductive, I suspect the adhesive isn't either.

 

[ShadowsPapa]

The black coating on the hinge is not conductive, I suspect the adhesive isn't either.

So they've put a dielectric or insulating layer on the back....

Interesting in that talking to one of the guys who does these repairs at the shop, he didn't call it zinc - I mentioned zinc and he had another word for it. I really wish I had written down what he said. I know Jeep calls it zinc and it appears to be, but he was more like it wasn't actually zinc but was something else.

That picture doesn't resemble the raw zinc metal I have.

 

[jac04]

That picture doesn't resemble the raw zinc metal I have.

Agreed. It looks like Remflex graphite exhaust gasket material.
https://catalog.remflex.com/default.asp

 

[RhinoJT]

Interesting. TSB specifically states a zinc spacer. Maybe there is more they did to, states a newer hinge in TSB as well. Again, hopefully the shop does a good job at prep and sealing.
Just as ShadowsPapa said, the manger at the collision center I’m dealing with said they have not had one return after the new process and brand new replacement parts vice spot repairing.

 

[ShadowsPapa]

Agreed. It looks like Remflex graphite exhaust gasket material.
https://catalog.remflex.com/default.asp

Maybe they are doing like humans do - abusing the word "zinc" when maybe there's zinc in it or it acts like zinc or an alloy or whatever............ but having bought half a pallet of pure certified 99.98% zinc, cut it on my band saw, and used 99% pure zinc strips for other purposes, it's just not quite right. Of course, have to be honest - my eyes are old and I'm looking at that FCA part on a computer screen, not in person.

(anyone need some pure zinc bars for anything? I'll probably die with 1/4 of a pallet of zinc since it lasts so long in my plating tank!)

 

[93civej1]

Interesting. TSB specifically states a zinc spacer. Maybe there is more they did to, states a newer hinge in TSB as well. Again, hopefully the shop does a good job at prep and sealing.
Just as ShadowsPapa said, the manger at the collision center I’m dealing with said they have not had one return after the new process and brand new replacement parts vice spot repairing.

so based on this, us 24 and 25 guys shouldnt have to worry about the usual bubblig corrosion? Guess time will tell.

 

[Gvsukids]

so based on this, us 24 and 25 guys shouldnt have to worry about the usual bubblig corrosion? Guess time will tell.

Five years in, and I haven't had any corrosion and I live in a salt state. Maybe washing often in the winter helps, or the frequent mud baths.

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