1970s Bi-Metal stainless trim - '76/'79 Sevilles & others

[Seville Life]

You may be aware that the '76/''79 Sevilles (and others into the early 1980s) had some stainless trim that was called bi-metal, stainless steel bonded to aluminium?

The aluminium was 99.999% pure and the stainless looked like kitchen foil as it was bonded to the aluminium? The idea was weight reduction. See picture.

Great plan -sadly it bubbles and if polished harshly you can polish right through it?

I just wondered if anyone had succeeded in polishing it well? I wondered about jewellers' rouge? Paul

[Seville Life]

I'll try again with the picture.

[Eric DeVirgilis CLC# 8621]

I have never seen stainless trim "bubble", even on cars after sitting in junkyards for decades. However, it's common for it to develop "road rash". Years ago I was told that trim was "flash coated" with chrome, which I think is what becomes worn.   

[Seville Life]

NO not solid stainless steel. Bi-metal is stainless steel (like kitchen foil) being bonded/laminated to 99.999% pure aluminium.

It started I believe with the '76/'79 Sevilles. It was a weight saving device.

Sadly as the years go by it bubbles, ie, comes away from the aluminium.

[smokuspollutus]

Can you show a picture of what is bubbling? I can't recall ever seeing any factory trim bubble even on some real rust buckets.

[Seville Life]

No because the car is stored just now. You'll only have come across this if you have cars with bi-metal trim, so windshield surrounds and the sill trim running along the bottom of the body and doors.

Started with Sevilles in May 1975 and is still talked about in the brochures in '81, possibly '82.

[Eric DeVirgilis CLC# 8621]

Please post some pictures whenever you can.

[Seville Life]

Haven't got the time, I think you either don't believe me or don't understand.

I discussed this very process with Bob Templin, Cadillac's Chief Engineer.

I had wondered if anyone else had tried to remedy this, pals in Europe have and if jeweler's rouge was of use.

No worries.

[Clewisiii]

I can picture what you are saying. Aluminum does corrode and I can see that causing separation.

I don't see it causing to much of a weight savings since aluminum often must be thicker to provide stability. Picture would be nice. Are these straight trims, or did they layer this over a die casting? Interior or exterior?

[dn010]

Read the 77 seville brochure. The "idea" was corrosion resistance, nothing to do with weight reduction. They don't even identify where they've used it. Later brochures say moldings. Aluminum corrodes but in 1970-80+ the thinking may have more been leaning towards cost savings (recession period? the whole Oldsmobile debacle?) and as a benefit that they could promote anti-corrosion knowing there would be no corrosion during the anticipated usable lifespan of the car. Either way, I have no suggestion that will help you with your bubbling trim.



81 Brochure
https://www.lov2xlr8.no/brochures/cadillac/80cad/bilder/13.jpg