Re: Alfa front suspension.erversions, torsionbars and origins

["John Hertzman" <johnhertzman@domain.elided>]

in AD8-0196 Tamme Kramer asks about the origins and development of Alfa IFS
(the 116 type) with the longitudinal torsion bars, later in the same post
writing "So I would appreciate it very much if someone could point me to
literature/webmaterial where I can find out more about this subject. I would
also like to know who else used this type of front suspension".

 I can't say about literature, webmaterial, or the ultimate origins, but
Citroen was using a front suspension with longitudinal torsion bars acting
through the lower of upper and lower wishbones (along with rack-and-pinion
steering) by the mid thirties- certainly by 1936, and I believe a year or two
earlier. Mercedes was using double wishbones, but with coil springs, at about
the same time, perhaps slightly earlier, and I have an impression that
Mercedes was the first major manufacturer to use the wishbones on a
significant production car, and that Citroen was similarly the first major
manufacturer to use the wishbones with longitudinal torsion bars on a
significant production car.

 In the middle of his post Tamme, after discussing Ricart's Pegaso Z-102,
writes "Also I remember that the Ricart designed 1940 512 racecar (1490cc and
some 335 HP at 8600RPM! in 1940) and the 6C2000 prototype (aka Gazelle, by
Trevisan) had the same suspension system." I believe the part about the
Gazella needs reconsideration; Fusi's description of the suspension is perhaps
ambiguous ("indipend. parallel. longit. barre tors. travers, anteriore e
poster,") but my reading of it in conjunction with the chassis drawings is
that both the front and rear torsion bars were transverse, (the "barre tors.
travers" part), that the rear suspension was by swing axles (as all Alfa road
cars from 1935 on had been) and that the front suspension was pure Porsche
with parallel upper and lower trailing arms (the "parallel longit." part of
Fusi's description), which is not at all like Ricart's 512.

 The suspension format which Jano adopted for the 6C 2300 B in 1935 had swing
axles at the rear with longitudinal torsion bars (which were replaced by
transverse leaf springs on the 2900 and on the GP cars) and modified
Porsche-type trailing arms at the front, the modification being the addition
of a rocker arm actuating an enclosed coil spring in place of Porsche's
torsion bars.

 I don't know how early in Ferdinand Porsche's long career (Austro-Daimler
1906-1923, Mercedes 1924 -??, Auto Union from 1934) he first use the twin
trailing arms for the front suspension, but it was being referred to as
"Porsche-type" when it appeared on the Auto-Union in 1934, a year before Jano
adopted it for the Alfa. The Auto-Union's rear swing axle originally had a
transverse leaf spring in 1934 a year before it appeared on Alfa's 1935 Tipo C
GP car, but in 1935 Auto Union replaced the leaf spring with longitudinal
torsion bars in the same year that Alfa adopted longitudinal torsion bars for
the 6C 2300 B. In 1938 Auto-Union replaced the swing axles with a De Dion, a
year after Mercedes went to a De Dion on the 1937 W 125 GP car. The Mercedes
application had two radius rods running forward to the frame rails, and a
rotating joint in the middle of the De Dion tube to prevent the tube from
acting as a massive tubular anti-roll bar. Ricart's reversal, bringing the two
radius rods to a single point behind the axle, eliminated this problem. Was
this original? It may depend on how strictly analogous a case one needs for
'originality'; Henry Ford had been using similarly joined radius rods on the
front axles of his cars from the Model 'T' on.

 Alfa's excellent 116 layout combines a chassis-mounted transaxle (commonplace
in turn-of-the-century chain-drive cars) with Charles Trepardoux' axle layout
(patented by de Dion in 1894) and the Model T Ford's radius rods (integrated
by Ricart in 1940, in the 512) along with Citroen's wishbones-and-torsion-bars
from about 1934, all brought together under Satta with perhaps some input from
Rodolfo Hruska, who had been with Porsche from 1938. It would be both
difficult and futile to precisely distribute credit among the various parties,
but my opinion is that the special talent of Alfa, as a corporate culture with
modest finances, lay in building on well-understood systems with minimum
compromise rather than in innovating. It didn't always work, but it did
produce several very satisfying cars over the years.

A sidebar trivia note: the first competition appearance of a De Dion rear axle
that I know of was on the semi-trailer ( a four-wheeled tractor pulling a
two-wheeled passenger trailer) which finished first in the 1894 Paris-Rouen
road-race with an average speed of 18.7 km/h (11.6 mph) but was disqualified
because it required a two-man crew (steersman and stoker) and the organizers
of the event felt that one should suffice. That same year the engineer
Trepardoux quit the firm, because de Dion was becoming interested in gasoline
engines, and Trepardoux didn't think there was any future in that.

Cheers,

John H.

Raleigh, N.C.

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