Zundapp KS750

Zundapp KS750

With an impressive specification that includes hydraulic brakes, shaft drive, off-road and reverse gear, plus heating elements to rider’s hands, feet and sidecar, the Zündapp KS750 was equipped to cope in the harshest of conditions – none more so than those experienced on the German/Soviet Eastern front in WWII. A grim place where not only did the fighting men have to endure the horrors of war, but also combat cold and biting winds which frequently forced temperatures to 40C below zero.

When Nazi Germany embarked on Operation Barbarossa in June 1941, Hitler was confident it would be accomplished in little more than six weeks. However, as history would record, this was not the case and, as winter fell, the offensive ground to a halt. Many of the vehicles and planes were ill-equipped to deal with the severe weather; carburettor icing was a common problem. With its pre-heater mounted in the air cleaner this was not something to trouble the KS750, a bike built to deal with Arctic cold and Sahara sand alike.

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Zundapp military threee wheelerIt proved to be a very versatile machine and in eight years of production 18,695 KSs would roll out of the Nuremburg factory gates. Our test bike is one of 7228 made in 1942, the model’s peak year of production, and has recently been restored by Wiltshire enthusiast Bill Northcote.

The records show that, in the hands of the SS 1st Panzer division, it saw active service until April 1942 when it ‘disappeared’, probably captured by the Red Army on the Eastern Front. What happened to it for the next 60 years is anyone’s guess but, when it emerged through the Czech Republic in 2005, Bill needed little in the way of encouragement to buy it. In his ‘day job’ Bill’s no stranger to unusual sidecars; the Zündapp’s ‘bed mates’ in its new Wiltshire home are a brace of Ural outfits. It was one of these, a 1975 model referred to irreverently (but affectionately) by Bill as ‘the old nail’ which more than 20 years ago introduced him to the idiosyncrasies of sidecars, and it has since seen a lot of service.  

'Green Elephant'
Having never previously ridden an outfit with the chair mounted on the right, I was eager to sample Bill’s ‘Green Elephant’, but first we’ll look back at the evolution of this rare V-twin. You might get strange looks if you turned up at a V-twin rally on the Zündapp but, with its cylinders set at 170 degrees, it does qualify. It might seem odd that each cylinder is only five degrees off the horizontal but it achieved some all-important extra ground clearance over the boxer engine it replaced.

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Zundapp military three wheelerThroughout the 1930s Zündapp had delivered many K500, K600 and K800 models to the Reichswehr but these were little more than thinly disguised civilian machines. When at the end of 1937 the army arms unit in Berlin demanded an outfit capable of meeting a new criterion, Zündapp had to return to the drawing board and a new machine.

Berlin insisted that the bike should carry a payload of 500kg, which corresponded to three soldiers with arms, ammunition and full equipment. Fully loaded it must be able to maintain a permanent speed of 80kph on the autobahn, possess a top speed of 95kph and, to accompany marching troops, be capable of maintaining a minimum of 4kph. Cross-country 4.5 x 16 tyres must be used (interchangeable with those on VW’s Kubelwagen), minimum ground clearance had to be 150mm and, in addition, the mudguards should have sufficient clearance to allow for the fitment of snow chains.

By 1939 Zündapp had built two 700cc prototypes that went to the OKH for testing. Incidentally BMW had also been asked to develop a similar bike but, after testing both, the Zündapp was found to be superior to the R75. BMW were asked if they would build the KS – which by then had grown by an additional 50cc – under licence but, not surprisingly, they refused, although later they did adopt the two-wheel drive and hydraulic brake system. The KS750 might have been technically perfect but they were expensive to build. At that time costs were of secondary consideration but it’s interesting to note that two VW Kubelwagens could be made for the same work and material as a KS750.

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Iron Curtain
No doubt it was this excellent build quality, allied to some clever repair and improvisation behind the Iron Curtain, that saw Bill’s bike survive more than 60 years from capture in 1942 to the present day.

Zundapp military three wheeler“I’d hankered after a Zündapp for a long time but they’re quite rare so, when this one turned up, it was too good an opportunity to miss. It had been partially restored in the Czech Republic but, although it both looked and sounded pretty good, it would only pull about 35mph in top gear. I stripped the engine and discovered that, sometime during its life, it had been fitted with a pressed-up crank and low compression pistons; in addition the heads were in a bit of a sorry state with several broken fins and pitted valve seats.”

You might think that acquiring spares for a machine that went out of production in 1948 would be a nightmare but, as Bill discovered, they were readily available online.

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“Both AP Hommes in Germany and Oldtimer Garage in Poland (www.oldtimergarage.eu) have been extremely helpful and I managed to source everything I needed to rebuild the engine.”

Although the war ended in 1945, small-scale production of the KS750 continued under Soviet control for the next three years, many examples of which would later disappear behind the Iron Curtain. Austerity called for improvisation and, with little or no access to spare parts, the Zündapps were kept running using whatever was available; the Russian pressed-up cranks a common replacement for the Split shell needle-bearing originals.

Courtesy of AP Hommes, Bill has replaced the rather crude Soviet offering with one that utilises white metal big end bearings, the all-important lube supplied by a high-output oil pump and filtered through a modern spin-off canister.

“I managed to get the broken head fins repaired and, while this was being done, new valve seats were fitted; these now allow it to run on unleaded fuel. I overhauled the gearbox, although this needed little in the way of attention, and also the final drive. This is supported by numerous needle roller bearings, one of which had been knocked out and gone through the crown and pinion, but thankfully without causing serious damage.”

The tinware
Cosmetically the outfit was tidy but, while the engine was out of the frame, Bill treated the tinware to a facelift and it’s now finished in the paint referred to by military aficionados as ‘European beige’. This colour was introduced, along with white for the cold Eastern Front and a lighter African sand beige, in 1942 – the authorities in Berlin reasoning that it offered better camouflage than the previously standard dark grey.

Zundapp military three wheelerMost Zündapps produced prior to June 1942 returned to Nuremburg for a refit and, out of recognition for their battle services, were awarded crescents to go around the company insignia. By then, of course, Bill’s had been captured by the Soviets and still sports the old garlanded battle shield on its nameplate. Another alteration that occurred at the refit, and on all subsequent KSs, was the fitment of 10mm longer forks, this simple modification preventing snow from building up under the mudguards and jamming the front wheel on the harsh Russian front.

By 1944 the tide had turned against Nazi Germany and commodities like aluminium became increasingly scarcer; this was reflected in post-1944 Zündapps, which were fitted with cast iron drive shafts and pressed-up steel head covers.

Our photo shoot on Salisbury Plain was interrupted by the sound of small arms fire; photographer Nick scurried for cover but thankfully the targets on the adjacent ranges were pointing in the other direction. Certainly it would not have been the first time that the Zündapp had come under fire; on stripping the paint Bill discovered filler in the tank, masking punctures in the metal that looked very much like they were caused by bullets!

With Bill’s confident words of, ‘it’ll start first kick’ fresh in my ears, it was time to fire up the Zündapp.

A 6v, 50W Noris generator sits on front of the crankshaft and an automatic advance and retard magneto from the same manufacturer takes care of the sparks. In harsh use the Noris unit was sometimes found wanting and later replaced by one from Bosch; however, with the aid of a hidden modern electronic regulator, Bill’s has proven to be extremely reliable and, as promised, started first swing of the pedal. As previously mentioned, to combat extreme cold the bike was originally provided with various heating elements, all of which ran from pipes off the exhaust manifold. However, MoT examiners tend to have an aversion to holes in exhaust pipes, so they have now been blanked off.

Prodigious use of bearings
Once under way, the bike sounded like a tram, probably a legacy of the manufacturer’s prodigious use of bearings and straight-cut gears. Somewhat surprisingly – given its workhorse role – the clutch was extremely light and progressive with a take-up equal to that of a modern road bike. This in turn married up to a sweet-selecting four-speed gearbox, which can be operated by both foot and tank-mounted hand levers. Of course, if the terrain gets too tough, then a set of off-road ratios can be dialled in which, along with the handy reverse and diff lock, makes the Zündapp such a highly manoeuvrable piece of equipment. Accidental selection of low ratio and reverse is prevented by a lock on the shifting gate and, if all else fails and it does get bogged down, then there’s a useful extension to the end of the front spindle to support an extra ‘helper’.

Zundapp military vehicleThe wheel on the Steib BW43 sidecar is in constant drive with a diff ratio of approximately 60/40 in favour to that of the KS, this chair replacing the earlier type 40 produced by Zündapp. For ‘passenger comfort’ the sidecar wheel is suspended by a simple spring inside a tube while the ‘boat’ is hung on two outside leaf springs.

The bike features a rigid rear end and, while this negates the need for a universal joint, it does mean that the rear gets spattered with liberal quantities of grease and oil from the exposed drive shaft. Despite its lack of rear suspension the single-sprung seat was pleasantly comfortable.

Sadly my ride on the Zündapp was limited to a short ride round (and over) Salisbury Plain, but such was its easy handling, sure-footed nature, my earlier concerns about riding an outfit with a right-handed chair were soon forgotten. No doubt the constant drive differential made things easier, but it’s no good having an outfit that handles well if it doesn’t brake and, for a 60-year-old bike, these can only be described as superb.

Zündapp claimed that the KS750 was the first production machine to feature a hydraulic brake and during the planning stages put a lot of research and development into the application of asymmetric braking forces to overcome the earlier problem of the bike ‘overtaking’ the sidecar. The net result (which gave the required balance) was that the rear wheel got a 22mm brake cylinder while the sidecar sported one of 19mm. At first the front stopper gives the impression of being a single leading shoe but a cover belies the fact that it’s a twin with a cleverly designed automatic centralising device hidden out of sight; and, like the rear, it’s excellent.

Certainly with the combined weight of Bill, Mary, the outfit and attendant ‘ammo’ trailer it needs them, especially when jostling with modern car drivers on the M25.

Thanks to Bill and Mary for their time, enthusiasm and help with the background history. bike

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