Auto Union Aktiengesellschaft, Chemnitz
Auto Union 1934 ("A") (Grand Prix 750 kg)Starting off as the Porsche "P-wagen" the official name of the car was T 22 and it has later been called type A or type 1934.
The chassis composed of two 75mm diameter chrome nickel molybdenum steel tubes with upswept front ends interlinked ladder fashion by four tubular cross members.
The independent front suspension consisted of two trailing arms for each wheel, the lower one being connected to a 16mm torsion bar. The torsion bars were set laterally within the front cross tube, connecting to trailing links supporting the hub carriers. The rear suspension consisted of a swing axle with a transverse mounted leaf spring. The steering box was centrally mounted with the steering column being offset 2.5 deg to the right. The 42 cm steering wheel was detatchable. Brakes were drums type Lockheed on all four wheels.
The V16 engine was of a simple and straightforward design aimed to achieve the greatest possible power and torque per weight rather than per liter. The cylinders were arranged in two banks in a 45° angle. Each cylinder had two valves placed at 90° and a single plug, slightly offline from the center. The 45° concept made it possible to use a single camshaft in the middle of the vee for all 32 valves working straight on the inlet valves and on the exhaust valves with pushrods. Engine featured detachable cylinder heads and wet type cylinder liners.The pistons were light alloy. The one piece crankshaft ran in lead-bronze main bearings. The big ends too were plain. Lubrication was of dry sump type. A single Roots supercharger mounted vertically behind the block was gear driven off the camdrive. It delivered mixture drawn from two Solex carburettors at 1.66 ata boost. The V16 was slow reving but the mid range torque was an impressive 54 *9.81 = 530 Nm at 2700 rpm.
The gearbox was mounted behind the rear axle, a short shaft passing under the differential connected it with the cluch mounted behind the engine. The main fuel tank was mounted between the driver seat and the engine. The radiator was mounted in the front and included an oil cooler at the bottom. The frame was used to carry water to the radiator. That later proved to be a troublesome feature.
As a consequence of the mid engine design the driver was placed far forward, his feets being just behind the centre line of the front wheels. The lack of drive shaft made him to sit low. The 170 liter main tank was behind him and a 40 liter reserve tank was over his feet. The refuelling shaft was on the right side. Both tanks were well within the wheelbase and so minimized handling changes during a long race. The fuel capacity was selected to do even the longest GP with just one stop. The duralminum chassis weighed only 45 kg. The cockpit sides were actually of canvas.
The 58 % weight over the rear axle made the car oversteer. The combination of a low polar moment and the driver far forward made the car swing far from its axle before the driver was able to feel it, demanding very fast reflexes to get the most out of the car.
The car was ready for tests in November 1933. It made its first public appearance on 6 March 1934 at Avus when Hans Stuck broke three world records.
There have been lots of speculations about how many cars were built. It seems that the team went through the season with just five cars, three race cars, a T-car and a second reserve, which was later rebuilt to hill climb spec with a small fuel tank. There was also possibly a prototype. So chassis numbers of the race cars should have been 76001-76005 or possibly 76002-76006. The low rev engine made it possible to run it for two races in a row without any major overhaul and during the season the team made full use of the T-car, letting it actually take part in the races whenever possible. One 120 kg "speedlimousine" body existed and one more was built for 1935.
For 1935 season three cars (76002-76004) were upgraded with higher compression, improved gearbox and improved brakes. However, the old chassis did not allow installation of the new fuel tank. Chassis 76002 took part in Tripoli and 76003 and 76004 were raced as speedlimousines at Avus. The two other cars were meant to be used as spare parts, but see the B-type text. It is not known which car chassis was used for Varzi at Tunis 1935 but it was clearly a rebuilt A-type. After Avus there are no pictures of any cars with the front reserve tank, so it is possible that the old cars later were totally rebuilt with 105 mm chassis tubes.
Victories: 1934: 1 FELSBERGRENNEN (Mountainclimb) (Stuck) 1 KESSELBERGRENNEN (Mountainclimb) (Stuck) 1 GROßER PREIS VON DEUTSCHLAND (Stuck) 1 GROßER BERGPREIS (Moutainclimb) (Stuck) 1 GROßER PREIS DER SCHWEIZ (Stuck) 1 Mt. VENTROUX (Mountainclimb) (Stuck) 1 MASARYKUV OKRUH (Stuck) 1935: 1 GRAND PRIX DE TUNISIE (Varzi)
Auto Union 1935 ("B") (Grand Prix 750 kg)
Design: Porsche Engine: (V16 45° 68 * 75mm = 4358cc 2 valves/cyl) V16 45° 72.5 * 75mm = 4951cc 2 valves/cyl (V16 45° 72.5 * 85mm = 5610cc? 2 valves/cyl)?? Roots supercharger 375 bhp / 4800 rpm Transmission: 4 speed gearbox Chassis: tubular frame Suspension: Front: Independent with trailing links, torsion bars, friction dampers Rear: Longitudal torsion bars in frame side members, friction dampers Dimensions: wheelbase: 291 cm track: 142/142 cm weight: 805 kg dry Year: 1935 Cars built : 4 new + 3 type A rebuiltFor 1935 four new cars were built. Later known as the "B-type" the 1935 cars featured over 50 improvements including new longer 105 mm chassis tubes. The cooling system was totally rebuilt with the frame no longer carrying water to the radiator. The two tanks were replaced with a single 210 liter main tank behind the driver, meant to keep fuel for 320 km. The engine had bigger valves and new cylinders, increasing compression from 7 to 8.95. Also added were an improved brake system, an improved gear box and a new rear axle with torsion bars. At Avus new bigger engines with 72.5 mm bore were introduced. Some books have also mentioned that a 5.6 liter variant was tested at the French GP, but I have been unable to confirm this.
During the season there were several changes to the cars. The new cooling system heated up the pedals and driver's feet so at the end of the season the tubes were let out on the outside of the car on the right side of the cockpit.
It's my understanding that for 1935 cars recieved numbers with "1" as fourth digit (76011-76014 or 76012-76015) creating a gap in the numbering system and fooling some historians to believe there had existed a huge number of chassis.
At the end of the season the team had 7 cars (corresponding to the three "A" + four "B" mentioned earlier) plus a hill climb special. So where did the last one come from? Either a fifth "B" chassis was built during the season or then the fourth "A" was never scrapped as planned. For 1936 four old cars were retained (probably the "B" types), two to be rebuilt as reserve cars and two to hill climb cars.
Victories: 1935: 1 KESSELBERG (Mountainclimb) (Stuck) 1 COPPA ACERBO (Varzi) 1 GROßER BERGPREIS (Mountainclimb) (Stuck) 1 GRAN PREMIO D'ITALIA (Stuck) 1 MASARYKUV OKRUH (Rosemeyer) 1 FELDBERGRENNEN (Mountainclimb) (Stuck)
© 2010 Leif Snellman - Last updated: 10.01.2010|