Re: 91 Spider windshield distortion

["John Hertzman" <johnhertzman@xxxxxxxxxxxxx>]

Karl Robrock mentioned optical distortion right in front of his field of view,
towards the left side, on both of two replacement windshields from Pilkington
glass, a huge, well-known glass manufacturer for OEM replacement glass,
("Passenger side is fine"); got unsatisfactory replies from the manufacturer,
(Alfa's design fault, they all do that) and asked "Anyone have any insight on
this issue?" Beatle Bayly replied "I've noticed this on both replacement
windshields and on new vehicles. Must be something modern drivers just put up
with?". Evidently both noticed it in front of the driver, not the passenger,
although one drives LHD cars and the other RHD cars.

I don't know, but - - US windshields are normally laminated glass, (I thought
by mandatory specs) and most other markets get tempered glass windshields
(also, I thought, mandatory). Tempered glass, when stoned, usually hits the
floor in a shower of small fragments without sharp edges (surfaces in tension,
core in compression) BUT can also just crack along those multitudes of
fracture lines, going instantly opaque without falling out. To allow for this
contingency tempered glass windshield manufacturers usually (if not always)
resort to differential tempering so that an area directly ahead of the
driver's view either remains clear or cracks on a much larger scale, staying
relatively clear, or falls out in a relatively large smooth-edged piece. The
chronic objection when differential tempering was introduced was that it
usually, if not always, produced distortion such as that which Karl and Beatle
experienced. My guess is that Pilkington may have foisted some tempered glass
upon Karl, perhaps by accident, or perhaps the rules have changed.

The tempered versus laminated issue is why you will never, ever, see a cracked
rear window in a GT Veloce, and why methods that get GTV rears out in one
piece so often produce an oops-it-cracked on the windshield. Usually auto
glass carries a small etched ID in a corner; the Saint-Gobain (sounds French)
rear window in wife's 164 says "Sekurit" (sounds German) while the windshield
adds, below Sekurit, "Verbund" which to my very limited German sounds like
bonded or laminated. Karl might try a different manufacturer, or an OEM
windshield, perhaps from Alfa, or an old one from APE. Or my guess could be as
wrong as any.

Good luck,

John H.
--
to be removed from alfa, see /bin/digest-subs.cgi
or email "unsubscribe alfa" to majordomo@domain.elided