Chapter Eight Front Wheel Drive Configurations.
layout of the main components of a front
wheel drive cars power train can be in many configurations. The
are the engine, gearbox and final drive assembly (differential and
shafts,). The FWD cars of the nineteen twenties and thirties
the engine well behind the front axle line, as was common practice
time. At first with the gearbox in front of it, with the final
the front wheels. Inline, as in the case of the "Tracta"," Cord",
"Alvis", "Audi", "Adler" and "Amilcar".
1932 BSA T9
Transverse across the car, connected
by chains or spur gears as in the DKW. This layout took up a lot
and didn't make full use of the possible advantages of FWD, a
train and good weight distribution. J.A.Gregoire stated in
"Front Wheel Drive", "Technical honesty obliges me, therefore, to
that one of the principle advantages of front wheel drive does not
from the system itself, but from of it's secondary consequences;
of front axle loading". Citroen made a small step forward
Avante", by locating the gearbox ahead of the final drive
a limited improvement in weight distribution and space utilization
picture in part three). The "DKW", F9 was the first car ready for
in 1939, but not produced until 1950, that had a layout that took
advantage of a front wheel drive configuration, with the engine in
ahead of the final drive assembly with the gearbox behind.
the layout that has been used in most of "DKW"/AUTO
DKW F-91 Power unit.
practical experience J.A. Gregiore
came to the conclusion that this was the way to go. His Aluminium
developed during the Second World War and produced in the form of
"Dyna", in 1946 and all his later FWD designs had the engine out
Citroen" 2CV", designers also adopted
this layout as it suited the installation of horizontally opposed,
engines perfectly. Citroen went on to produce the AMI 6/8, the
also the GS/GSA, and smallest of the VISA models with the same
transverse engine configuration had
not been forgotten. In 1946 a prototype of the first SAAB, the 92,
produced with a transversely mounted twin cylinder, two-stroke
the clutch and gearbox located inline with the crankshaft and
located ahead of the final drive assembly. The 92 went into
at the end of 1949,
their first post war model the F89, DKW
moved the engine to a position in front of the final drive, In
by 1950. This was the last of the two-stroke twins from DKW. The
engined vehicle from DKW was the three cylinder F-91/4 Munga, four
drive utility made for the German arm forces in 1955.
until the advent of the AUDI 50 in 1974
that they fitted a transverse engine again. The next innovation,
mounting of a four-cylinder engine transversely in a front wheel
car. This came with the MINI in 1959. The difficulty with the use
four-cylinder engine in this way was that it was longer than the
fitted previously, which wouldn't allow the final drive to be
equal distance between the driven wheels. As unequal length drive
cause transmission fluctuations. The answer to this problem
in the MINI by incorporating the gearbox into the engine sump. The
to this arrangement is that the engine/gearbox unit is tall, also
run in a lubricant that is not ideal. Almost 10 million cars with
arrangement were produced by the British Motor Corporation/BLMC.
Mini Power Unit.
The advantages of the
transverse engine arrangement
in improving the packaging of a car became apparent with the MINI,
means of using a four-cylinder engine with a separate gearbox
with it and overcoming the drawbacks of the MINI arrangement was
The answer was to find a way of using unequal length drive shafts
the associated drive problems. The solution was to make the
drive shafts of equal torsional stiffness, this was achieved by
of FIAT, first in the Autobianchi "Primula", of 1964 which was a
stone to his big breakthrough the FIAT 128.
A111 similar to the Primula.
The 128, was the first front wheel drive
FIAT. By incorporating features, not new but not used in
front wheel drive before, such as a transverse engine (utilizing
layout and drive shaft arrangement). Adding Mac-Pherson strut
and rack and pinion steering, he produced the layout that is
at the beginning of the this century.
Another configuration used by Triumph in
the 1300 and Saab in the 99. It consisted of the engine mounted
with a separate gearbox and final drive located underneath the
it's own lubrication system (As opposed to the shared lubrication
by Issigonis.). The advantages of this system were a compact
an inline engines and equal lenght drive shafts. The disadvantage
tall engine /gearbox assembly. To overcome this, the engine was
The Triumph 1300 was not a success, but the Saab went on to a long
99 Power unit.
The only other layout in use at this time
is that with the engine mounted inline ahead of the final drive
the gearbox behind, as used by AUDI and SAAB.
The earlier front wheel drive layouts didn't
fall into disuse with the advent of the more compact systems for a
time. Citroen with the DS and ID series (1955 to 1975) continued
cars with the engine inline behind the final drive and the gearbox
Renault used the same layout for their early front wheel drive
"4" (1961 to 1991) the first "5" (1972 to 1984) and the "6" (1968
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