I INTERNATIONALES AVUS-RENNEN
AVUS - Berlin (D), 2 August 1931.
15 laps x 19.573 km (12.162 mi) + 831m (0.516 mi) starting straight = 294.43 km (182.95 mi)
Caracciola victorious at Avus tire race
by Hans Etzrodt
From 12 starters only five finished at the Avusrennen, which was now the fastest race in Europe. Severe tire problems were encountered during practice but were only solved in part, leaving most of the large
cars with inferior tires. A tense duel, between Caracciola (Mercedes-Benz) and von Morgen (Bugatti) who was glued to the Mercedes' rear wheels, lasted until three quarters of the race when the Bugatti driver
had to replace one of his rear tires. This gave Caracciola a gifted advantage and the Mercedes driver was able to cruise home uncontested without ever changing his tires. Von Brauchitsch finished third in
another Mercedes after one stop for tires, while Stuck, who held third place in the early laps, lost much time changing tires and then succumbed to a broken engine due to a water leak on his Mercedes.
Broschek, Burggaller, zu Leiningen and Hartmann, all in Bugattis, raced in midfield, while Kotte, Winter, Wälti, and Zichy were not fast enough to challenge the front runners. Caracciola scored a popular
victory, followed by von Morgen, von Brauchitsch, Broschek, Hartmann and Count Zichy, who was last.
The Avusrennen, held just two weeks after the July German Grand Prix on the Nürbugring, was a minor event. After an interruption of five years, the ADAC (Allgemeiner Deutscher Automobil-Club) decided in December 1930
to hold another automobile race on the Avus in Berlin, despite the poor economic situation and high unemployment in Germany. The date was set for June 21, two weeks after the Eifelrennen. But then in June, when the
various improvements to the Avus could not be completed in time, the ADAC postponed the event until August 2 in the interest of both drivers and spectators.
One lap of the Avus was19.573 km and for the first lap 831 meters had to be added from the start line to the finish. The circuit served both as an automobile test track and as a connecting road between Berlin and
Potsdam, comprising two 9.5 km long parallel straights joined at the Potsdam end by the slightly banked South Loop and at the Berlin end in the North by a 180-degree slightly banked bend. Only at these two turns did the
drivers have to slow to about 90 km/h, otherwise they could go at maximum speed on the two very long straights.
The ADAC reported that about eight km of new tarred surface was laid to the latest technique. A stretch of nearly 2 km of tarred macadam was replaced by a concrete layer, and the entire Nordschleife (North Turn) was
resurfaced with especially hardened "Klinker" bricks. The large starting area was resurfaced with Askalit special asphalt. Double chain-linked fences to catch stray racecars were erected in front of the grandstands to
protect the spectators. Likewise grandstands C and D had received barricades made out of tree trunks to act as a bumper for wheels from off-track racecars.
The event was split into three separate races. Race I for Class I-H up to 750 cc, which had to complete 5 laps or 98.696 km. Race II comprised Class F & G cars over750-1500 cc, which had to do 10 laps equal to 196.561 km.
Race III was for Class A-E over 1500 cc, which had to do 15 laps equal to 294.426 km. Race cars as well as sports cars were allowed.
Race I awarded a first prize of 1500 RM, second 1000 RM and third 500 RM. In Race II the first prize was 2000 RM, second 1000 RM and third 500 RM. In Race III the winner would receive 5000 RM, second 3000 RM, third 2000,
fourth 1500, 5th 1000, 6th 500, and 7th 300 RM. The prizes were given to the entrants of the cars concerned. All drivers who started would receive a memorial medal. The entrance fee was 50 RM, primarily to cover the
limited insurance for each driver. Official practice took place on Friday from 10:00 AM to 4:00 PM, when the track was blocked off to public traffic. Scrutinizing was on Saturday from 2:00 PM to 5:00 PM.
The ADAC had received a total of 40 entries, 12 for the tiny cars up to 750 cc, 15 for the voiturette class up to 1500 cc, and 13 for cars over 1500 cc. The German Bugatti Team headed the entry list, with Ernst-Günther
Burggaller in a 2.3-liter T35B, Heinrich-Joachim von Morgen with the latest 2.3-liter twin-cam Bugatti, capable of 230 km/h top speed and Hermann Prinz zu Leiningen with an older 2-liter T35C. Max Wälti, a Swiss journalist
living in Berlin, showed up with his 4-seater stripped T43 Bugatti, which carried a spare wheel on the right side and had a mechanic in the passenger seat. Count Eberhard von Kalnein entered a T35C and Albert Broschek his
T35B. Two Bugatti entries arrived from Hungary, László Hartmann in a T35B and Count Tivadar Zichy with a T35C.
These eight Bugattis were opposed by four white Mercedes-Benz SSK, stripped 7.1-liter sports cars. Rudolf Caracciola, and Hans Stuck enjoyed limited factory support, both driving an SSKL, the lightened version of the SSK.
Daimler-Benz team manager Alfred Neubauer and technical director Hans Nibel were present. As the leading driver for the Stuttgart factory, Caracciola usually drove the best prepared SSKL with the strongest engine and special
supercharger. The privately sponsored Manfred von Brauchitsch arrived with another SSKL but also enjoyed factory support at this event. The independent Dr. Eugen Winter drove an SSK and carried as passenger, his wife.
As a result of an accident, his right arm was crippled, likewise his hand, which was just barely sufficient to shift gears. When in difficulties, there was always his wife who accompanied her husband in every race.
Finally, there was a single white Maserati 26M entered by Ernst Kotte, which carried a spare wheel on the right side. Several magazines reported entries by the Italians Ernesto Maserati and Tazio Nuvolari but these drivers
did not appear since they took part in the race for the Coppa Ciano which was held on the same day.
Official practice took place on Friday from 10:00 AM to 4:00 PM. The track was blocked off from public traffic. Due to the high speeds that were expected, great demands would be made on the tires. The tire problem was
not restricted to the heavy Mercedes. Von Morgen in his new Bugatti returned after three laps, driving on the bare canvas and a left front flat tire. The tire technicians stood there with red faces and gaping mouths.
The result of the tire tests were at one time so discouraging that the Mercedes team considered withdrawing from the race.
Daimler-Benz team manager Alfred Neubauer wrote an internal tire protocol, here abbreviated, stating that in June 1931 Rudolf Caracciola ordered special tires for the Avusrennen from Continental. They expressed their
willingness to manufacture special tires for higher speeds. On Thursday evening before the race, three sets of tires for the three cars of Caracciola, Stuck and von Brauchitsch were mounted.
On Friday, the only practice day, practice started at 10:00 AM with the tires. Stuck began the tests. On the second lap he went missing and arrived later at the pits with a large thread section thrown from his left rear
tire. The flying tire thread had hit him on his left elbow and his arm was already bandaged when he arrived.
Von Brauchitsch who was on his first lap was immediately stopped. His left rear tire (same as Stuck's left rear tire) had begun to become loose from its lining. Due to these circumstances Caracciola was held at the pits
while four 32 x 6.50 Mille Miglia type Dunlop tires were quickly mounted. After four and a half laps, the tire thread of the Dunlops also separated. The same day at 3:00 PM, Dr. Weber of Continental called Dr. Bobetz at
the Hannover factory. In view of the situation they initially wanted to retreat from the race.
The general opinion was that Continental had chosen too strong a cover of 16 mm. Continental had again given preference to the two-groove-record-thread. Thereupon Continental decided immediately to reduce the thread from
16 mm to 6 mm running thickness. This happened during the night from Friday to Saturday. On Saturday morning 8:00 AM the tires arrived by plane from Hannover. On these special 7.00 - 21 Avus tires the entire thread had
been milled away.
Additionally Continental had sent two very similar tires, except that these were produced with a 6 mm thick cover which was completely smooth. Dr. Weber said that these tires should not be tested because such tires would
not be available for the race and that the tires had given manufacturing difficulties. These two tires were put aside.
Through the intervention of the ADAC an additional practice session from 1:00 - 3:00 PM on Saturday was secured with race management. At this practice a set of special 7.00 - 21 tires were first mounted to Stuck's car.
After two laps the car had bearing problems. The tires, still in warm condition, were quickly mounted to von Brauchitsch's car, which did a further six laps. Thereupon the tires were quickly handed over to the car of
Caracciola, who covered another four laps with them; altogether there were 12 test laps with that set. After a further slower lap the tire surface was slightly worn through; the white connecting places between the cover
and canvas appeared.
Despite the fact that the tires had held up relatively well, Continental urged not to use this special 7.00 - 21 tire but instead use their proven 7.50 - 19 Nürburgring tire. Nevertheless, the profile of this good and
well-seasoned tire was supposed to be milled down likewise to 6 mm rubber strength. Dr. Weber declared that the tires would be cooler and guaranteed their durability. We were against these tires because their diameter was
less and therefore we feared for higher engine revs. Dr. Weber explained to us that the practical circumference would amount to not more than 2%, thus Dr. Nibel [technical director Hans Nibel] and I [Alfred Neubauer] agreed
to drive with the 7.50 - 19 Nürburgring tires, which evidently had not been tested. Decisive for that decision was also the consideration that it would be possible with this tire to drive without a change. This however
was solely concluded out of the fact that the smaller 7.00 - 21 tires had lasted 12 laps.
Accordingly, on Saturday evening Dr. Weber ordered the 7.50 - 19 tires and on my request had also manufactured several 7.00 - 21 tires. These changes were carried out during the night from Saturday to Sunday and the tires
arrived Sunday morning at 7:00 AM at the Avus. When measuring the tires once again the difference between both types was not 2% but 5.6%. For this reason I feared too high engine revs and against the wishes of Continental
decided now for the 7.00 - 21 tires. However, Continental had sent only eight of those tires. I had to anticipate for each of the three cars a single change and therefore I would have needed 12 tires. For this reason,
I returned to the two completely smooth 7.00 - 21 tires that had been put aside.
I inquired with Dr. Bobetz, who had now arrived, about both tires of the 7.00 - 21 dimensions if there was no difference in the rubber cover, which Dr. Bobetz confirmed. However he once more pointed out that both tires
had a flaw in manufacture.
My consideration was now that the smooth manufactured tire had to be slightly harder than the changed special tire, where the hard layer had been milled away. Since there were only two such tires and I considered them
somewhat better than the special tires, I gave them naturally to Caracciola. However it was a great risk involved by doing so, and Caracciola was informed about this, to be prepared for a possible tire defect already in
the first laps. By comparison the tires received by Stuck and von Brauchitsch were absolutely assumed to last half the distance. This ended the tire protocol during practice.
After piston failure first on von Brauchitsch's car then on Stuck's car, the technical director Hans Nibel decided to lower the engine rev limit from 3200 to 3000 rpm. After practice, the general opinion was that the
winner would be Caracciola, von Morgen or Stuck. The lighter Bugatti had the higher top speed, but the larger-engined SSKL could reach its maximum revs faster.
The Avusrennen was a major event for Berlin and grandstand tickets were sold out days before the race. Despite the severe economic situation in Germany, an estimated crowd of 150 000 to 200 000 spectators showed up on Sunday with wonderful, sunny summer weather. Several prominent dignitaries from the worlds of government, police, embassies, theater and cinema, appeared. Even the former Crown Prince attended the event.
The start for the small car class up to 750 cc had to be delayed over half an hour because the crowd had pushed through the barriers at several places. A great part of the standing room spectators had pushed through the Avus barriers to gain free access. Constantly more people arrived and pushed eagerly to the front, so that the first rows could not hold their ground and spilled on the track. Finally after the police had made sure that the roads were completely secured, the small class of ten cars was started. After five laps Gerhard Macher (DKW) won this race in 49m14.4s at 120.24 km/h.
There was another delay until the police had cleared the track by once more pushing the crowd behind the barriers. In the second race for cars up to 1500 cc there were 11 starters to do ten laps or 196.56 km. This race turned into a farce since only two cars finished. Hans Lewy (Bugatti) won the race in 1h18m26.0s at 150.38 km/h, five minutes ahead of the only other finisher, Decaroli (Salmson).
After these curtain-raisers, it was time for the 12 large cars to assemble on the grid with the third row cars lined up unusually close next to each other, while the police again cleared spectators from the track.
Count Kalnein (Bugatti) did not start. It was a tremendously hot summer day with a scorching sun. Following a delay of one hour, the large cars finally took off. Stuck had the best start from the first row.
Von Morgen who was glued to his rear wheels, overtook Stuck. These two were followed by von Brauchitsch and Caracciola who then overtook the Mercedes in front of him. When Stuck slowed and went off line in the
South Turn, Caracciola went past him. After the first lap the three favorites to win had already detached themselves from the field with a gap to von Brauchitsch in the following order:
|1.||von Morgen (Bugatti)|
|4.||von Brauchitsch (Mercedes-Benz)|
|7.||zu Leiningen (Bugatti)|
After the second lap the order of the first five remained the same. Burggaller in sixth position stopped at his pit with engine trouble and retired. Dr. Winter passed Kotte's Maserati. On the third lap
Caracciola overtook von Morgen in the North Turn. The Berliner had not resigned himself to give in and stayed firmly on the Mercedes' tail. At the same time Stuck arrived at the pits with two flat rear tires,
which took 75 seconds to change from Continental 7.00 - 21 tires to 7.50 - 19 Continental Nürburgring type tires. The spectators believed that Stuck was the first to fall foul of the tire problem, but it was not
his fault, he was merely a victim of bad luck, they thought. Kotte and Count Zichy both stopped at the pits to change spark plugs. After three laps the order was:
|2.||von Morgen (Bugatti)|
|3.||von Brauchitsch (Mercedes-Benz)|
|6.||zu Leiningen (Bugatti)|
On the fourth lap von Morgen followed one or two seconds behind or at times was right next to Caracciola. Von Brauchitsch had both rear tires replaced in 56 seconds, from Continentals 7.00 - 21 to 7.50 - 19 Nürburgring
type tires. Dr. Winter also stopped for tires. After four laps Leiningen passed Brauchitsch in the pits. On lap five, Stuck passed von Brauchitsch and zu Leiningen for third place. Kotte again changed plugs while
Broschek stopped to have oil refilled and fell to ninth place. On lap six Kotte and Wälti both passed Broschek. Dr.Winter again arrived in the pits with a flat tire. After six laps the order was:
|2.||von Morgen (Bugatti)|
|4.||zu Leiningen (Bugatti)|
|5.||von Brauchitsch (Mercedes-Benz)|
On lap seven there was no change in the order. Stuck stopped once more to replace the left rear with another 7.50 - 19 tire. The field shrank to eight cars, after Leiningen retired with a broken magneto somewhere
away from the pits, Kotte and Dr. Winter with their tires finished, were also stranded out on the circuit. On lap eight the order remained the same, except that Broschek went past Wälti. Caracciola had slightly
extended his lead over von Morgen and at the end of lap eight Stuck retired at the pits with an overheating engine and piston damage due to a burst hose between the radiator and the engine block. Von Brauchitsch
took over third place once again. After nine laps the field was down to seven cars.
|2.||von Morgen (Bugatti)|
|3.||von Brauchitsch (Mercedes-Benz)|
During the tenth lap Caracciola still maintained first place but with von Morgen laying in ambush, driving most of the time close behind in the Mercedes' slipstream. The speeds attained were over 190 km/h per lap and
on the straights the leading duo drove well above 200 km/h. It was noteworthy that Caracciola drove the long straights of the Avus almost all the time without using the supercharger. This way he always had a reserve
of power, which might have been equal to what von Morgen might have had in reserve in his Bugatti. However, after the race the honest von Morgen admitted candidly that he had driven flat out. Hartman fell to last
place due to plugged jets of his Bugatti. After 11 laps Max Wälti retired but the reason was unknown. There were now only six cars left in the race. On lap 12, von Morgen, who had clung to Caracciola's rear wheels
for 11 laps, came slowly to the pits with a bad left rear tire, which robbed him of any chance of victory. He only changed the left rear wheel and lost 1m50s. With his strongest opponent now gone, Caracciola could
take it easy. But he carried on at only slightly reduced pace, unchallenged, lap after lap without tire trouble. The twelfth lap had brought the big change in the race, when the general opinion had been that von Morgen
followed Caracciola like a shadow to wait until the last lap and then risk everything with a final spurt. After 12 laps the order was:
|2.||von Morgen (Bugatti)|
|3.||von Brauchitsch (Mercedes-Benz)|
On lap 13, the order remained the same, even after von Morgen stopped once more to change the other rear wheel. Count Zichy stopped at the pits to change plugs on his Bugatti and by lap 14 he had fallen to last place.
On the 15th lap von Morgen again stopped for tires. To great applause from the immense crowd Caracciola finished the race after 1h35m07.3s at an average speed of 185.7 km/h. Von Morgen followed after a gap of 3m42.2s
and von Brauchitsch in third place was a further 3m42.7s behind when he passed the finish line. Then thousands of enthusiastic spectators began flooding across the race track so that Broschek, Hartmann and Count Zichy,
who were all one lap down, had to be flagged off after only 14 laps.
A lot was written about the tire situation affecting the fastest cars, the Mercedes-Benz and von Morgen's new Bugatti. These tire reports unfortunately were not well researched and wrong statements were published
causing great confusion. For this reason we will not show extracts of those accounts but trust the preceding practice report. ADAC-Motorwelt summarized the tire situation after the race but got the facts wrong,
causing confusion. Allgemeine Automobile-Zeitung reported that until Saturday afternoon the start of the Mercedes cars was uncertain, which was true. Their account was more detailed but contrary to their statement,
Mercedes tested only two tires on Saturday, not four. Their version contained other misinformation and as a result is also a confusing story.
Motor und Sport reported that Hans Stuck sent a letter to a leading Daimler-Benz personality [managing director Wilhelm Kissel], which had been published in a Berlin midday paper. In the letter the tire question
was the main issue because the drivers had been left in the belief that everyone had the same good tires for the race. Instead, Stuck explained, all the Mercedes drivers should have been informed that Caracciola
was the only one to start with the two special tires while the three other Mercedes drivers had to use the old style tires. They would then have changed the way they had driven in the race. Stuck explained later
that the letter had been published without his knowledge or consent. Daimler-Benz in return issued a public answer because since Stuck's letter had been publicized, they felt compelled to inform the public likewise.
Primary sources researched for this article:|
ADAC Motorwelt, München
Allgemeine Automobil-Zeitung, Berlin
Allgemeine Automobil-Zeitung, Wien
A-Z Motorwelt, Brno
Europa Motor, Austria
Mercedes-Benz Archiv, Stuttgart
Motor Sport, London
MOTOR UND SPORT, Pössneck
The Autocar, London