Union started the new season under a cloud. Professor Ferdinand Porsche's contract was not
renewed after the 1937 season in a strange case of economics and was
snapped up by Mercedes who fed his company several lucrative contracts.
Just after the beginning
of the year they lost their greatest driver when Bernd Rosemeyer was killed during a speed
attempt. While Robert Eberan von Eberhorst assumed most of Porsche's duties
there could be no replacement of the beloved Rosemeyer. Only the talents Nuvolari
could lessen the loss to the team's success if not to their heart. With
all of the turmoil including the threat by some board members to shut down the racing
team, Auto Union was still able to create a new car in 18 months.
For the new 3 liter formula, Auto
Union, like Mercedes chose to use a V12 engine. Built along the same lines of their V16
the engine would later incorporate a two-stage Roots supercharger. The engine could rev at over 10,000 rpm but
usually never exceeded 7,000 rpm while racing. The main change in the chassis department
saw the replacement of the swing axles with a De Dion rear suspension. The handling
of the Auto
Union was very much improved but they still trailed Mercedes in shock absorber design.
Rather than use hydraulic dampers, Auto Union still relied on rotary friction dampers.
Later they would replace their front dampers with hydraulic units while retaining the
friction models at the rear. The body was a further refinement of their Type C model and
sported horizontal tail-fins at the rear. True to the new formula the Auto Union weighed
exactly 850 kg dry and 1220 kg in racing trim including driver. Under Eberan no detail was
too small. When wheel covers were deemed necessary for ultra fast circuits he had fenders
with Plexiglas windows made so that the drivers could monitor tire wear by watching for
the white breaker strip.
Without anyone at Auto Union comparable to Mercedes' chief
engineer, Rudolf Uhlenhaut who could drive his cars at race speeds, Eberan adopted a
trucker's 24-hour tachograph to monitor the cars performance while it was being driven by
one of the works drivers. "Isidor" as the drivers dubbed it, was called a
cockpit spy. The device, heavily modified by Eberan and an associate by the name of
Kienzle, could record revs, speeds, shift points, brake pressures and
acceleration/deceleration all on a paper disk. For security the device could not be opened
without a key; of which Eberan von Eberhorst had the sole copy!
In 1938 the weak link in the Auto Union pits were the team drivers and early season mishaps forced them to re-sign Hans Stuck who
they had unceremoniously fired a short time ago. Stuck promptly
continued his mastery of the mountains, winning at La Turbie and at the
fearsome Grossglockner which earned him the German Mountain Championship. The
regular season started with a stunning upset when Rene Dreyfus won at
Pau driving a Delahaye Type 145. While Nuvolari was getting familiar
with the rear-engined Auto Union, Mercedes were winning races. Nuvolari
would go on to win the Italian Grand Prix as well as at Donington but
this was too little and too late and Caracciola became European Champion
for the third time.
It should also be remembered that Auto Union was operating with a budget a fraction of what was being spent at Mercedes Benz.