Roof & Sail Panel Blisters

[daytonajim]

Most all 4th Gen's have this issue. Black is worst color.

Info from Jeff Foster who painted a lot of GMMG's for Berger & Nickey.

4th Gen Roof Blistering

9/9/19 – visit with Jeff Foster – He’s @ Wentzel in MI with Dennis Barker.

Jeff Foster painted many GMMG’s for Berger Chevy & is the GMMG Paint Guru.

Every 4th Gen has this issue.

If you sand & print the roof it opens the pathways for the solvent. When repainted the blisters are worse.

Best fix short of a new top is……. sand & prime around blisters – fill holes up with primer & repaint.

Only correct fix is a new roof & sail panel BUT almost impossible to get the new top in the proper location. Window glass has to be out. Where do you put the new roof? Cost is over $3k.

Jeff’s advice is to sell it like it is & let the new owner deal with it.

The glue GM used was a one off for the fiberglass tops.

PRIMER:

Epoxy primer will not work – separates SMC Fiberglass.
Water based primer does not work

Suggestion from Jeff – don’t touch it – leave it alone – sand only blisters & fill with primer – DO NOT sand & prime entire roof. Black is the worst color.

From Jeff Foster – There is no way to stop the bleeding except to replace the roof. The glue is set in the SMC for good & will always wick out.

Jim,

This thread is very long, but here's a link to where I chimed in while doing Vince's car.

https://ls1tech.com/forums/paint-body-w ... es-97.html

My thoughts were that I had HOPED the reaction of the glue leaching through was over with age for the most part based on observations of my own car. In other words, give it enough time and it is done bubbling. But I don't think that is correct anymore. I still DO believe that if the top is subjected to enough heat for a prolonged period, you can get the reaction to slow down tremendously. Work it out of its system sort to say. My car has been outside a couple years in the sun to get it out and that's what I based my theory on. And I do believe at a certain point the leaching stops. So, my new theory is that if prolonged heat is thrown at the top for an extended period of time, you can get it to work its way out and stop at some point. What point that is will vary greatly as to the storage degree of most cars and how it has been shielded from the elements for the most part. Good for the car, but not for these tops. Hope this makes some sort of sense.

Jim Smith
GMMG Registry