Bonded screens, rust, and obligatory 'Sud content

[JHertzman@domain.elided]

The Torinese quarterly "Style Auto- Architettura della Carrozzeria" issue 
#33, April-May-June 1973 had an extensive article on the styling, engineering 
and production of the Alfetta berlina (along with a similar article on the 
Opel Record and shorter articles on several lower production cars and styling 
exercises).. There are 24 illustrations of the styling development, 17 on 
aerodynamics and crash-testing, 24 on body assembly, and another dozen 
assorted. The text, written in Italian and "translated" for the 
English-language edition, has a passage on the bonded windshield which may be 
of interest to some. It says:

"Windshield and backlight bonding to the body 

"In the Alfetta's production planning, the three main advantages leading to 
the abandonment of the old glass-fixing by rubber gasket method and to the 
adoption of the new technological process have been: 1) better appearance, 2) 
greater body torsional stiffness and 3) greater economy.

"1) Rubber gaskets were born with the automobile. The black fascia (at most 
lightened by a bright trimming) would always represent a big anachronism as 
compared to the requirements of utmost visibility and to the evolution toward 
an ever the more clean and essential styling. 

"Every attempt to reduce to the minimum the gasket cross dimensions turns out 
to be compromised by the requirements of its fastening to the sheet metal 
outjutting edge wnich does influence its shape too, while the bonding of the 
glass directly to the sheet metal - eliminating the gasket - does blend the 
two outer surfaces with obvious aesthetic, aerodynamic and visibility 
advantages. A simple brightwork, contouring the glass, provides lightness and 
new 'dimension' to the windshield and backlight openings.

"2) As is known, the two glasses mounted in their housings 'contribute' to 
stiffen the whole body and their fixing to the sheet metal is essential to 
establish on statically and dynamically testing the body prototype whether 
the parameters measured are within acceptable values or whether a further 
stiffening is required. This glass-gasket torsional rigidity contribution 
averages a 10 per cent, while the ejection thrust is about 0.7 kg per linear 
cm. The bonding products examined by Alfa Romeo's engineers were limited to 
three main categories: butylic, neoprenic and polysulphuric rubber adhesives.

"The butylic adhesive was immediately rejected as the bonding was physical, 
that is based on the principle of fats; while it could stand the ejection 
test, it would neatly give in not so much because of the torsional 
contribution which resulted to be slightly higher than the usual rubber's, 
but when subjected to the endurance dynamic test which would engender severe 
tightness inconveniences.

"The neoprenic adhesive proposed resulted to be most satisfactory as to 
torsional contribution (twice as much as the traditional fixing method) and 
to ejection test, but most toilsome was the polymerization method based on 
electrical heating by extrusion-buried wire.

"The polysulphuric adhesive obtained by mixing 2 components (in a facility 
next to the trimming line) and humidity-polymerizing, would finally give most 
favorable results: about three times the value of natural rubber gasket as to 
torsional contribution, and around 2.5 kg per linear cm as to ejection 
thrust. To the above must be added the enormous advantage of bonding the 
glass by filling in its housing following the irregularities of the sheet 
metal bearing lip and checking the filling perfection by visual inspection 
through the glass.

"3) To the cost analysis, already preestablished on early product planning, 
the new technology resulted to be more economical also in consideration of 
the old gasket wastes and the cost of car's revisions due to water seepage 
during buy-off testing (water test) and to that much heavier at the stage of 
customers' service. During these revisions, disassembly of the old gaskets 
would almost always require the replacement of the relevant anodized aluminum 
trimming. In this respect, we remind that the holdfast springs of the new 
trimming - due to their particular glass-selfhitching shape - guarantee its 
positioning toward the housing outer edge and its adherence to the glass 
surface itself."

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 

The "holdfast springs of the new trimming - due to their particular 
glass-selfhitching shape" are part #11608.59520.02, a strange-looking little 
winged insect which positions the glass in relation to the steel flange; the 
part which engages the steel flange has sharp little teeth which scratch 
though the paint film at several dozen points around the perimeter, giving 
the rust an unfair advantage from the git-go. The earlier bonded screens on 
the USA-spec 105/115 cars did not have this pro-rust feature, instead 
supporting the glass on rubber spacers during installation.

With the 1978 cars, the Sprint Veloce and the Sport Sedan in the USA and the 
GTV and Alfetta 2000 in Europe, reverted to a gasketed windshield, but with 
what seems to be a harder synthetic rubber gasket and a more involved 
cross-section which is retained by four clips which are pop-riveted to the 
inside of the windshield posts.

On the Milano, the perimeter of the glass has a fine texture of black dots 
fused to the glass, probably to give a "tooth" for the adhesive. I am 
reasonably sure, from the survival rate of the cars, that they do not have 
anything like the Alfetta's "glass-selfhitching holdfast springs". The 
chronology and technical evolution of glass-fitting on the Giulietta Nuova, 
90, and European 75s is out of my realm.

Back to 'Suds. The quarterly "Style Auto" ceased publication after issue 37 
which should have been April-May-June 1974. That issue 37 (which I have not 
seen) had articles on the Alfasud Sprint, Lancia Beta Montecarlo, Alfa 33 
Navajo Bertone, as well as the Porsche 924, Volvo City Taxi, Bertone-bodied 
Jaguar Ascot, Seat Sport Inducar, Renault 14, Opel GT2, and Ferrari Dino 308 
GT4B.  Issue 30 had an article on Italdesign's Alfasud Caimano, as well as on 
the Montreal, Fiat 128 Berlina, Rally, and Sport Coupe. Alfasud partisans 
might find either or both interesting. In the recent past back issues, mostly 
in Italian, were available from the Libreria dell'Automobile for L.12,000 and 
also from Chater's, probably mostly in English, for about 6 GBP. The Libreria 
dell'Automobile also has a few full runs, price on request, probably between 
$300 and $400, which could be tempting; lots of good stuff scattered, Canguru 
in #4, Giulia GT in #5, Sprint Speciale in #7, Giulia Berlina in #9, etc.

John H.
Raleigh, N.C.

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End of alfa-digest V7 #796
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