The Gerhard Macher Bi-Motor Special - Oldtimer Markt 11/1997

"All-wheel drive at DKW, before the Munga was thought of.

Gerhard Macher, born in 1905, was operations manager of the large DKW agency Bittrich on Schloßplatz in Berlin in the early 1930s. With a healthy sporting ambition, he was the top driver of the DKW factory team at the time. When preparing the DKW racing and sports cars, he proved himself to be a creative inventor and an excellent technician with various rather unusual vehicles.

Macher, an outspoken all-rounder (as it is so nicely called in New German), came from the test department in Zschopau and cleverly used his connections to the DKW car factory in Spandau in Berlin. He had an influence on the development of racing vehicles, and his advice was always sought after in the various designs. As a result, he received benevolent support from the factory in the construction of his competition cars. However, he also operated at his own initiative.

At the Monte Carlo Rally in 1929 he tried his hand with Gustav Menz as a co-driver. From Königsberg he was less than happy with a DKW "P 15" cabriolet with rear-wheel drive in ice and snow. The unsatisfactory result gave Macher reason to think about how rallies could be approached better in the future.

But it was a streamlined coupe designed by DKW in 1933 with a 600cc rear engine (probably intended as a prototype of a ‘Volkswagen’ that was being discussed everywhere at the time, but discarded due to serious defects) that gave him the inspiration for his planned "GM" competition car. This is probably how he came up with the idea of a streamlined coupe with two engines and all-wheel drive. In the optional combination of front, rear or all-wheel drive, he saw an opportunity to be able to deal with the difficult weather and road conditions more successfully. 1935 Macher appeared again at the start of the Monte Carlo Rally, but now with his "GM" special, a mixture of DKW "master class" and said [rear engine] prototype, with a similar drive unit rotated by 180 degrees installed in the rear. The conversion of the starter and alternator caused this engine to rotate in the opposite direction. The functions of the clutch, shift and throttle linkages had been so skilfully modified that both engines could be operated simultaneously and in the same way. The fact that the "ear coolers" protruding from the body on both sides in front of the rear fenders disturbed the overall impression of the coupe (rather clumsy despite some flowing lines) was something Macher was happy to accept because of the efficient cooling effect. When accelerating, the front engine kicked in first, which of course required a great deal of finesse on the part of Macher when setting it up and fine-tuning. The two engines together delivered about 50 hp, which combined with the relatively light structure of the body (made of plywood covered with imitation leather) for a total weight of 1100 kg - including cooling water and 120 (!) liters of fuel - resulted in a top speed of 125 to 130 km/h.

In 1937 a certain senior engineer, Max C!aus, from Reinsdorf near Zwickau, followed in Macher's footsteps. Based on Macher’s model, he converted a "master class" into a "bimotor". The second complete drive unit (600 ccm) for the rear-wheel drive was installed in the trunk, behind the typical DKW high-lying transverse leaf spring. A second radiator was not used. The coolant for both engines circulated in two large-diameter metal hoses through the radiator of the front 700 cc unit by means of a water pump.

Both clutches were actuated with a foot pedal and the two gearboxes were actuated via a common shift lever. However, a separate accelerator pedal was provided for each engine; they could also be served together. Since both engines were freewheeling, one or the other engine could be operated off-road as required while idling at the same time.

With its 38 hp, the car managed a comfortable 120 km/h. Claus praised the relatively low fuel consumption, the high cross-country mobility and the excellent mountaineering qualities of his all-wheel drive vehicle.

At DKW, no practical consequences were drawn from these experiments at the time. That was probably a good thing, considering the unresolvable difficulties other German manufacturers experienced during the Second World War with their complicated and immature all-wheel drive vehicles demanded by the theorists of the Army Weapons Office. It was not until twenty years later that the four-wheel drive automobile was given the go-ahead and the Munga was offered. And they still remained true to the two-stroke engine."

The Gerhard Macher Bi-Motor: https://dkwautounionproject.blogspot.com/2020/12/the-gerhard-macher-dkw-bi-motor.html