Like all the Allies, the Soviet Union acquired technology and machinery from Germany after the Second World War. All technology was evaluated and reports circulated with its assessment. The Scientific Research Institute for Automobile technology (NAMI) received numerous vehicles for analysis. This partial (and poor condition) 1947 report analyzes a 1938 DKW Sonderklasse. By this time, the Sonderklasse was long out of production so the report did not make any particular recommendations, although we can't know for certain as many pages are messing. For comparison of a full report, check out this 1948 evaluation of a post-war Czechoslovakian Tatra T87. https://tatrat600.blogspot.com/2024/10/1948-nami-tatra-t87-review.html
1938 DKW Sonderklasse study by Ministry of Automotive and Tractor Quality Soviet SSR
State Order of the Red Banner of Labour
Scientific Research Automotive Institute
Introduction – Pg 1
Brief Specification – Pg 3
Test results:
1. Dimensions, low points and maneuverability - Pg 5
2. Weight data and centre of gravity height - Pg 7
3. Economy - Pg 8
4. Dynamic - Pg 10
5. Evaluation of body comfort, visibility and ease of control - Pg 13
6. Reliability of operation of individual units and vehicle equipment - Pg 14
Findings - Pg 16
General views of the DKW car
NAMI 1938 DKW Sonderklasse
ANNOTATION..
to the report on the testing of the DKW Sonderclass automobile, manufactured in 1938
The work covers laboratory and road tests to determine the dynamic, economic and other operational qualities of the automobile, as well as operational attempts with a mileage of 21,000 km.
In addition, the scope of the work performed included: drawing up technical characteristics, determining overall dimensions, clearances, maneuverability parameters, weight data, assessing the comfort of the body, visibility, ease of driving and reliability of the units.
The report provides comparative material on some small-capacity cars from other companies.
Based on the test results, conclusions were made about the operational qualities of the car and its reliability.
The technical characteristics given below almost completely correspond to the data published in 1937 in for the model “[blank]". Based on this, it can be assumed that this car model belongs to the production of 1937-1938.
The purpose of the tests was to determine the main design parameters, establish indicators for economy, aerodynamics, comfort and other driving and operational qualities of the car, as well as determine the reliability of its individual units during the tests.
The test car had a mileage of about 15,000 km before the tests (according to the kilometer counter).
By the time the laboratory and road tests (economy and dynamics) concluded, the total kilometers was 30,000 km.
In this regard, the results obtained for economy and dynamics are characteristic of a certain "average operational" rather than "parade" condition of the car, usually revealed during testing of new vehicles.
The DKW compact car has a 4-cylinder two-stroke V-type engine with two piston-type scavenging pumps, each of which is combined into a block with two working cylinders.
The working process in the engine takes place according to the scheme shown in Fig.4
Fig.4 Scheme of operation of the purge pump
The cylinder block is V-shaped, with the arrangement of cylinders at an angle of 90c, has a connector rod along the plane of the crankshaft. The left and right halves of the block are connected by bolts (figure 5).
Fig.5. Double block of cylinders. Bottom view
The design of the connecting rod and piston group and the crankshaft is shown in Fig.6. The shaft is located on two bearings. Bearing shells are made in the form of bushings. The crank of the connecting rods of the pistons of the scavenging cylinders is located at an angle of 90° to the cranks of the connecting rods of the working cylinders.
Fig. 6. Connecting rod and piston group
Note, the captions in the picture from left to right: Supercharger piston, supercharger seals, oil scoop, working piston.
Brief technical characteristics of the “DKW” passenger car
1. Engine type - gasoline, 2-stroke, with a scavenge pump V-shaped with an angle of 90 degrees
2. Number of working cylinders, diameter and stroke – 4 x 70 x 68.5
3. Working volume - 1054 cm3
4. The compression ratio in the working cylinders is 6:1
5. Power and speed - 32 hp at 3800 rpm.
6. Ignition - battery, 6 volts.
7. Ignition order - 1-2-3-4.
8. Power system - Carburetor "Solex", double, horizontal (Fig.7). Fuel supply by diaphragm mechanical pump.
9. Clutch - single disc, dry plate.
10. Gearbox - 4-speed with constant mesh on 3rd gear
Gear ratios:
1st gear - 4.06:1
2nd gear - 2.38:1
3rd gear - 1.47:1
4th gear - 1:1
Reverse - 5.28:1
11. Engine mounted at three points on rubber cushions.
12. Cardan shaft - tubular, open, with two soft semi-cardans.
13. Rear axle - type "Banjo". Gear ratio 4.88:1.
14. The front suspension is independent, having one transverse semi-elliptical spring below, and parallelogram levers with hydraulic shock absorbers on top (Fig. 8).
15. Rear suspension - one transverse semi-elliptical spring with two hydraulic shock absorbers.
16. Steering - installed on the left side of the steering mechanism is a worm with a sector.
17. Tires - 5.00-17
18. Brakes: Foot operated brake on hydraulic shoes acting on all 4 wheels. Hand brake centrally mounted, mechanical brakes acting on the cardan shaft.
Fig. 7. Carburetor "Solex" in section
1. Fuel filter mesh
2. Shut-off valve
3. Idle jet
4. Idle adjusting screw
5. Diffuser mount
6. Throttle stop vent
7. Diffuser
8. Main jet well
9. Main hitch
Fig. 8. Front suspension
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