"The Harley and the Bantam had a race..." - to the Milky Bar Ad tune

The subject of the Allies taking possession of German patents and technology as reparations in 1945 came up in the Chaffee Hybrid thread...

Just after the war, Harley-Davidson and BSA both brought out versions of the DKW RT125 two-stroke (or two-cycle for our American audience) single-cylinder motorcycle; and on first glance, the two engines are remarkably similar...






NOTICE ANYTHING???

 

There was HUGE competition between the Allies in 1945, with their Technical Missions wandering all over Germany grabbing industrial processes, patents, blueprints etc. And just by chance - the Americans got the most and the best of them; the british came away almost empty-handed in comparison...

But ONE British technical mission came across a large collection of German automotive blueprints in a schloss they had been evacuated to for safekeeping. Among them were the blueprints for the quite amazing (for its day) DKW RT125 motorcycle and its engine - a very simple but very robust piston-ported two-stroke 125cc machine. Apparently BOTH the British AND the Americans had been searching for these...

The British basically had to smuggle these out of Occupied Germany past the Americans! But once they became aware the British had them in their possession - the Americans demanded them under the terms of the Reverse Lend Lease agreement! So just like the cavity magnetron, the Miles jet-powered supersonic fighter, the Bren Gun Carrier, and a huge amount of foodstuff etc. from Australia and New Zealand during the Pacific campaign - the British government was forced to hand over the plans of the DKW RT125 into the outstretched hand of our American allies....

...who promptly handed it to Harley-Davidson, the country's largest motorcycle producer (Indian still existed in those days, but the Springfield "Wigwam" was a much smaller operation...) - and a few years' later the original Harley Hummer appeared, the black-and-white picture you can see above....

AND THEN - in 1948 the BSA Bantam D1 - beloved of GPO Telegraph boys for a generation! - appeared....

Looks closely at the two bikes - what do you see?

 

Well.......

You've got a RIGHT hand view of the Harley...

But a LEFT hand view of the BSA Bantam...

And yet the side of the engine you can see is exactly the same!!!

One engine is an exact MIRROR IMAGE of the other!

So how did THAT happen???

It seems that in a panic....and somewhat of a hurry!... a couple of civil servants were told to take pictures of the DKW blueprints before they were handed over, in such a scale that they could be blown up to size and "new" blueprints made from them!

However - the average civil servant is NOT overly au fait with the internal workings of the two-stroke motorcycle - and didn't notice that they'd hung up the semi-transparent blueprints....BACK TO FRONT!

So once the original plans were handed over, and new blueprints made from the blown-up photographs - and the new items handed over to BSA in Birmingham...BSA gt to work on constructing a replica DKW RT125...

Only ONE minor problem...

 

Motorcycle - and car! - engines can run "backwards" or "forwards"....depending WHAT way the crankshaft needs to turn to have the GEARBOX turn in the right direction to provide drive!

Now - in a car engine it's not THAT difficult to achieve, with the gearbox bolted onto the end of the crankshaft

But a motorcyle is different, because in the VAST majority of motorcycles - the crankshaft runs ACROSS the frame, and thus there has to be a separate connection to the gearbox that is "behind" the engine or crank...a "primary drive".

These can be by chain - old British bikes or modern Harleys, that big chancase on the lefthand side of the bikes??? - or by matched gears, like Japanese bikes under the engine covers - but in THAT case, because of the two-wheel gear drive, unless there's an extra idler gear in there making the whole plot overly long - the engine/crank has to run "backwards" I.E. the OTHER way to the direction the rear wheel has to turn...

BSA were presented with a MIRROR IMAGE set of plans - which meant that if built EXACTLY like the plans said...the engine would run "backwards"....but that motion wouldn't be flipped by the reverse in a gear primary...for the DKW design had a CHAIN primary drive!!! So the bike would come off the production line with, in effect - THREE REVERSE GEARS!

BSA achieved the technically-impossible; they sat down and re-engineered whatever they neded to make the "backwards" design run "forwards"...quite an amazing engineering challenge....for they ALSO had to flip over ALL the piston transfer ports etc...that SHOULD have been impossible. And the little Bantam grew into a legend through the next 23 years until the death of BSA, and beyond.

When the engineers at BSA were asked HOW they managed to do it....their answer was along the lines of -

We knew the bike ran. When we got the blueprints - noone told us about the mistake that had been made! We couldn't see WHAT was wrong, for we KNEW the RT125 ran, and these were the plans for it, weren't they?...so we sat down and just did whatever we had to do to make it work! WE all thought the DKW engineers had made mistakes!



What else can you say, except - "We shall not see their like again"

 

Finally - here's the original DKW RT125 in all its wartime glory - look down at the rider's foot...




And you'll see the "timing" side of the DKW engine is the RIGHT HAND side! Just like the Harley Hummer below - the TRUE copy

 

Seems the British like to do everything in mirror opposites, like driving on the wrong... oh never mind. Great article. Its amazing what little mistakes, given patience and a will to make things work, will actually turn out for the better. So I take it the Bantam did well, but I have never personally heard of the Harley "Hummer". They must have done something right that the American competition did not.

 

I have never personally heard of the Harley "Hummer"


Oh, haven't you??? Take a close look at the PETROL TANK...

In 1957, when H-D wanted a new, stylish petrol tank for their overhead-valve replacement for the Model K....they looked back in the catalogues, and put the Hummer's tank on the -

Sportster

 

also based on the DKW. I had one of these, bloody brilliant.

http://www.amicalemzmotosdelest.fr/index.php?part=8&cib=1&rub=1