I may be asking the 64,000 dollar question here, but anyway here I go. Can anyone tell me why GM rust out so bad around the backglass and windshield so BAD, compare to FORD and MOPAR products. I was in heaven[[ JUNKYARD]] the other day and just about every firebird,chevelle and ,gto, and other GM,s were totally rusted out in these 2 areas.On the other hand the FORD,s and other cars were in great shape in these areas. Could it be the sealer or what?? It has become a big topic around at CRUISE-IN,s and shows. Any ideas??

IMO, these cars rust at the points you stated because of poor design. There is nowhere for water to go so it just sits under the trim. After some time, the channel rusts and allows water to leak into the trunk and the firewall/cowl area. Eventually these areas rust as well. Anybody else have an idea?

In doing the many (make that MANY ) repairs of rusted Gm windows and vinyl tops I came up with the what I think is the definitive answer to why the these cars rust so bad.
It is not so much that the water gets trapped, if the metal was protected it wouldn't have any way to start the rusting process.

I have looked at many on the verge of rusting and I feel that the stud that GM welded in to hold the clips works like a little umbrella and "shields" the base of the stud from the paint and primer that was sprayed into these areas.

If you look real close at the studs up on the sides or top where it has not rusted you can see that the base of the stud has no paint on it.

This and the fact that the metal clips scratch the paint when being installed also is a factor.

I found that if you spot blasted the studs, etch primed, epoxy primed and painted it would last.
This of course after first installing drains just as insurance. I put little tubes in the corners with a rubber hose going to the bottoms of the quarters, that did the trick.

I agree with MARTINSR - the area is not well protected from the factory and over the years dirt and debris collect here to hold water and the under-protected metal begins to rust.
As we all know to well - rust begats more rust, and so on - and so on - and so on ...

As for Furds and others not rusting out - I would quess you've not spent to much time around Ranchero's, and Falcon's and Mushtang fast-backs have you?
I'm not sure who first coined the word 'Rustang' - but it fits! :D
Dodge/chrysler stuff does tend to rust from the frame up - Very Rapidly! tongue.gif

Have any of you guys ever used an electric leaf blower after a wash? I like to hit the moulding area with the leaf blower to get the majority of the water out of the channel. I don't know if it helps much but it sure makes me feel better knowing all that water is out of there.

-Mark.

I use the leaf blower every time, but aim the exhaust away from the car, the oil/smoke can dirty the glass and trim. graemlins/thumbsup.gif