H.H.Chinn

What I've understood POR15 is that once applied to a rusted spot of metal it reacts and renders the rust inert stopping the continuing process. The shop that painted my SC used POR15 on the 356s and other restoration cars that had minor rust spots. Real bad spots were cut out completely and the metal replaced. I would think any rust or suspected rust areas would need to be treated, followed by a few coats of a two part epoxy primer, with a few coats of the color coat, finished off with several clear coats and allowed to harden thoroughly before any windshield reinstallation take place. The glass installation process shouldn't involve the use of sharp implements. Damage occurs when the old glass and seals are removed where wooden wedges should be used instead of screwdrivers.

gonzilla

So if I'm reading you right, if my car has original paint and the original windshield, I needn't worry about rust in there?

GC96

Could you get the same effect by using Butyl rubber tape like this rather than the Wurh urethane? I've been considering following Bruce7's DIY since I recently had my windshield replaced and rust repaired but am concerned about the possibility that it might make replacing the glass in the future more difficult. I'm wondering if the butyl rubber tape might provide a good seal while still being easier to remove at a later date if a windshield replacement becomes necessary.

GC

Mike J

One issue I have with using sealers is the bond - if its not perfect, then you are making it actually worse, since water can wick into a gap and stay there, since there is little surface area to promote evaporation.

Tricky stuff. A good friend of mine owns a high end body shop, and some of the examples he has show me showed what can happen with bad bonding...

Cheers,

Mike

geolab

POR15 is not to be used on any windshield pinch weld , and strongly avoided.
993 relies on the windshield bonding strength for airbag proper operation. On a 356 'maybe' but the 993 has airbags.
POR15 gets harder than a 2K paint system, but does not bond on primed bare clean metal better than a 2K process. It will Peel.
POR15 will bond stronger than 2K paint, on rusted areas.
To fully understand why, check the preparation process ' do's and don'ts' on their site.
The best I could get with this is the process I followed in pictures:

products used:

Phosphoric etch diluted 70% ,
1 coat - 24hrs wait - sanding - 1 coat etc for 4 days or until no rust was left.
with the Phosphoric etch, when you apply a coat and leave for 24hrs, the rust inside the metal that you do not see, will make a black tiny pinhead spot, so you could dremel this out and restart.

PPG products used for prep:

D831 + D832
D834 + D835

Paul902

Oi, this is so scaring me...I had a 12 year old VW GTi. There was rust showing around the windshield in a few spots, but the car was on its last legs, so I let it go. When I needed to get the windsheild replaced, over two thirds of the ledge it sat in was rusted through. The guy used 3 tubes of sealant to get the new windshield in where he would normally use part of a single tube.

If installing windsheilds on these cars was easy, I'd almost think it wise to have it out for a peek.

Mike J

Hmmmm - I did not mean do the entire opening in POR15, what I was getting at is, if the windshield is in place, what would be a preventive measure you could take? Reading back I was not clear. One option is to fill the channel with Urethane. Don't really like that given you need perfect bonding or you will actually create problems. So I thought, if there was a bit of surface rust in place, would POR 15 be an option for additional protection in the exposed channel? ... but I agree, it's not an option for the entire opening since urethane will not adhere to it very well.

Nice pictures George!

Cheers,

Mike

Knight

I'm incline to believe this too, based on the cars I've seen locally go in for windshield repairs, removing the original windshield. And we do live here in like a rainforest. Maybe others will comment if they have seen differently?

I will say if your getting your windshield removed, ensure they know what they are doing to not damage/remove any surrounding paint.

Bill Verburg

There's no reason for the window to be a PIA job, just do what they did on the Cups and use the 964 seal, no fuss no muss and the window npo longer is destroyed to get it out.

JPP

Bill .. what's the difference between the seals and what's the advantage? Does the 964 seal keep water from accumulating?

JPP

I thought this as well, but in other recent threads on this subject, several folks posted that when they replaced their original factory installed windshields, they found rust in the usual places.

Paul902

Yes, Bill, could you expound on that a bit? I have not replaced a 993 windsheild yet, but reading on RL over the years it seems that you need an experienced guy to do it or else you will get creaking, etc.

CaptainGSR

A good front strut brace can take care of any creaking of the windshield.
Mine did.

nine9six

Johan,
Maybe so, but it does not speak to the real root cause of window creaking.

If the window does not creak prior to replacement with no strut brace in place; it should not creak after replacement if done proprely.

Personally speaking, I would not be happy tossing another 3 bills at a strut brace, after paying a professional installer to install glass that now creaks. I'd have him redo it.

Bill Verburg

all 911, 964 and 993Cups used an old style press in seal(964.541.225.00), the 993 was the first to glue them in so that the window acted as a structural member(hence the creaking complaints). This practice has been continued for 996,997, 991. The old style seals seems to work fine.

For some reason on 993 both the front and rear windows seem to collect water then rust at their lower edges