Windshields

[aston@ultrasw.c]

Does anybody know if the later windshield will fit an early car?

If so, what year part # etc.

I have a 1979 and I would like use the later bond-in type.

I know I will probably need to add an aluminum strip to the pinchweld to increase bond area and raise the finished height of the glass flush to the body.

BTW this is a race car and aesthetics are not so important.

Cheers

[stepson]

Yes, the windshields are interchangeable.
That said, do not use a windshield that has an built-in antenna in your race car.
Buy a new windshield and sell the built-in antenna one to help fund your race car.

Selling a built-in antenna windshield will help you make friends in the 928 world.

[aston@ultrasw.c]

Interesting, thanks.

So if the windshields are the same, did the aperture size (pinchweld) change?

Bare with me. It is my understanding that, in older cars (not porsche necessarily, any old crate,)
the glass would fall through the opening, it was the function of the rubber molding and trim strips to bridge the gap and hold the glass in place.

On newer cars there is an overlap between the glass and the pinch weld which acts as the bonding surface.

The reason why I am so interested is the car is new to me and it has a scratched up piece of lexan for a windshield. All trim/molding/glass etc is long gone.

I wish to change to a bonded glass part. So there are two issues to resolve.

1. creating a suitable bond surface, or verifying one exists

2. ensuring the finished height is flush with the surround

Sorry I don't have an antenna windshield - I will have to find some other way to ingratiate myself with the 928 world.

[stepson]

I think I saw that the windshields are 25#. I'm sure the Lexan was installed for weight savings and safety sake.


I do not believe that the windshield will fall through the opening. I have only seen one actually installed, but as I remember it, the installer put a bead of some type of butyl-type adhesive/sealer type stuff down, laid the windshield on top of it, filled in where he thought he needed additional sealer, then installed the trim.


Good Luck

[Mal81]

To be sure, a bonded windshield makes the whole car stiffer and stronger, and can help prevent people from flying out of the car in a frontal collision. It allows the use of curved glass that is better at deflecting road debris.

But the windshields are engineered with the design of the car. As you noted, there will likely be differences, to both the glass and mounting surfaces, and you’d need to to examine the car with the bonded windshield carefully - there are often clips in addition to the adhesive holding it down.

Windshields are pretty cheap. Probably less expensive than the lexan you have in there now. Which makes me wonder about why it might be there. Was it already a track car? Maybe it’s there to adhere to a rule?

[aston@ultrasw.c]

It is a race car and the lexan was for weight reduction but it scratches so easily and when the sun is low in the sky the reflections are horrible.

So I'm going back to glass and I can save weight in other areas if needed.

I race in a power/weight series and I have a little room to play with.

[Opelotus]

I've had the windshield in my '84 replaced twice. The original unit was held in by butyl strip adhesive. The two new units I had installed were put in place with the newer urethane sealant which is stronger than the old butyl stuff (although it's also much harder to remove than the butyl sealant). If I were to do it myself, I'd use the butyl. There were no additional clips holding the windshield in place, aside from two rubber pads at the base of the windshield channel which act as spacers. Make sure you achieve sufficient installation depth: both replacement windshields in my car were not seated far enough into the chassis along the bottom edge, which causes the cowl panel to sit too high, and the wiper arms rub on it slightly. Do a test fit to determine where the glass should sit before you apply any sealant.

[stepson]

Thanks for chiming in Opelotus. I did not remember any clips or anything like that, but didn't want to say so in case my memory was faulty. My windshield was installed with the urethane also. I could not get butyl off my mind, but it was urethane.

[honerboys]

hey - i also had the windshield replaced in my 84 - while i don't believe there are clips to hold the windshield in there are clips to hold the trim pieces in place - i think these are somewhat embedded in the sealant - at least that's how i remembered it

[stepson]

Originally Posted by honerboys

hey - i also had the windshield replaced in my 84 - while i don't believe there are clips to hold the windshield in there are clips to hold the trim pieces in place - i think these are somewhat embedded in the sealant - at least that's how i remembered it

Yep, that's true. There are clips that hold the trim in place. They are mounted independent of the windshield though. I did not want to confuse the issue. The clips do not hold the windshield, only the trim.

[Opelotus]

You guys are correct about the trim clips. There are at least 5 of them that the top trim piece presses in to. They are held onto the windshield channel by rivets. I had to replace mine because the windshield channel paint was flaking behind them. I might have pictures handy if needed.