Moller skrev i meddelelsen
<451308e6$0$141$157c6196@dreader2.cybercity.dk>...
> Yeps, var det ik os ham som gav os ReedValven som MZ havde i
>laboratoriet inden de flygtede, eller var det dem som smuttede til
>yahama/kawazaki... ka aldrig huske det, mener ham kawazaki nuppede fra
>MZ var ham som gav drejeventilen liv i 2 takterne.
Du mangler at læse om Walter Kaaden, så ville Du ikke videregive den slags
rygter.
Kawazaki nuppede ikke MZ folk, der var ingen at nuppe. Yamaha's
hjælp kom fra Adler, såe....
Så jeg tager chancen og gengiver The Classic Motorcycle's interview med
Kaaden kort før Kaaden døde.
Stoker genius
Walter Kaaden, the man who unleashed the two-stroke engine, talks to lan
Johnson
For the last quarter of a century two-strokes have dominated Grand Prix
racing. Yet in the Fifties the idea of a two-stroke winning anything was
laughable. Villiers against MV? One man was responsible for chan-ging all
that: Walter Kaaden.
Kaaden became the man who unleashed the two-stroke thanks to a mixture of
training and being in the right place at the right time. From Zschopau in
Saxony, eastern Germany, he was apprenticed to the local DKW factory. DKW
built only two-stroke engines, and successfully raced a supercharged
twin-piston single in the late Thirties. Yet Kaaden had no predilection for
two-strokes, despite working for the world’s largest manufacturer of
two-stroke motorcycles. He finished his studies at the Technical Academy in
Chemnitz by building a four cylinder four-stroke. In WWII he worked on the
development of the first jet fighter, the Messerschmitt Me262.
Returning home after the war, Kaaden set up an engineering workshop in
nearby Waldkirchen. Here he built his own racing motor cycle, a 100cc
two-stroke single with a power output of 7 bhp, and raced it in national
events.
The end of the war meant significant political changes in central Europe.
Saxony became part of the new Communist state of East Germany (DDR). DKW had
departed to Ingoldstadt in the West, and their former factory was
nationalised by the state to form a small part of the East German motor
industry, IFA. It was impossible for Kaaden's small plant to operate under
such conditions, and in 1953 he was offered a contract by IFA to run the
racing department at Zschopau.
Although sanctioned by the government, and even supported with a modest
grant, the racing department was an empty shed attached to the end of the
main works. Kaaden filled it with his old equipment. Kaaden was given a
couple of IFA's 125cc roadster singles. The two-strokes suited Kaaden
because they were cheap to tune – his budget was miserly – and because they
were a legacy of DKW. Like BSA's Bantam, the IFA 125 was yet another version
of the DKW RT125. Kaaden had already found the first few extra horse-power
for the little engine, and from an unusual source. Local privateer Daniel
Zimmerman raced Formula 3 cars of his own design using a two-stroke engine
with a rotary disc inlet valve instead of traditional pistonport induction.
Kaaden adopted the system and power immediately rose from 9 to 11 bhp.
Over the next five years a series of engine developments transformed the
humble two-stroke from an ex-DKW with Bantam performance to an MZ producing
200 bhp/litre. The adoption of the rotary valve was a fundamental departure
from the RT125 layout. The valve was mounted on the timing side end of the
crankshaft, so the carburettor had to move from its traditional position
behind the cylinder barrel.
The advantage of the rotary valve over pistonport induction is that it
allows the inlet tract to open earlier and still close at the optimum point.
The design was simple and gave plenty of scope for development, but fine
tuning was critical. For more power to be obtained the timing of the opening
and closing of the valve had to be correct to the third decimal place of
degrees of crankshaft movement. The diameter and length of the inlet tract
were equally important. A flat throttle slide was used to keep the
carburettor as short as possible.
Kaaden had another possible clue to power up his sleeve. When racing his
own machine he had begun ex-perimenting with baffled exhaust systems in a
rudimentary way, to maintain the pressure in the cylinder. "When I started
with MZ I had a chief engineer who told me that racing MZs must look the
same as prewar DKW's, which had megaphone exhausts. These were retained
until 1955," he says. "And then I changed them, and the power came, higher
and higher."
Reflecting the exhaust gases back into the cylinder had the effect of
supercharging the engine without breaking any regulations. Yet the correct
shape and length of the expansion box – as the world now knows them –
combined with the timing of the exhaust port, was absolutely critical.
Working out the exact details meant years of painstaking experiment for
Kaaden and his team. With only basic facilities and no additional funds,
every change had to be assessed on the track. Fixing exhaust pipes with
spring clips was originally an MZ idea, a quick way of replacing any number
of variations of exhaust system.
"Later we had an oscilloscope for measuring the pressure of the wave going
down the exhaust and back," recalls Kaaden. "Earlier it might take 50 or 60
attempts before we arrived at the right answer. Afterwards it was only
necessary to have four or five attempts."
Kaaden and his team also developed the MZ factory’s ISDT machines. Later
the ISDT team had their own workshop, but in the early days they all had to
cram into Kaaden’s little shed. "At first I had only six or seven people
working for me," he says. "I designed all the things myself, often without
drawings, and I would say to the fitter: ‘please make this part in this way’
.. The fitters were very good. Sometimes, when we were very busy, I made the
parts myself."
The development that finally ensured international success for MZ’s racers
was the introduction of the third transfer port. "Before the war DKW and
Zündapp had this third port, so I built such a port into the MZ racing
engine," says Kaaden. "With the third port we could direct the gases through
the piston and the third port, which was good for piston cooling." And,
Kaaden was delighted to discover, it produced more power.
These three developments – the rotary valve, expansion chamber exhaust and
the third port – were the basis of the MZ's stunning performance. There were
other developments which helped keep the engines competitive and reliable,
but none were as fundamental as the original discoveries. The power rose
from 9 bhp at 7800 rpm to 13 bhp at 8000 rpm between 1953 and 1954. In 1961
it had reached 25 bhp at 10,800 rpm – 200 bhp per litre! In this form the
250cc MZ twin was capable of 155mph.Up to this time most of the team's
racing was done behind the Iron Curtain. This was partly because development
had not advanced far enough, but mainly because of the political mistrust
between West and East. In 1955 the state controlled motor industry in the
DDR was reorganised. Production motor cycles at Zschopau now came under the
Motorradwerk Zschopau (MZ) banner, though still remaining part of the
IFA-Kombinat organisation. Control of the race shop passed to the central
government's sporting department.
Kaaden and his team now had to compete for funds with all other sports,
which always seemed to take priority. The problem was compounded by the
chief of department, who was not interested in motor sport. "You must
remember that the top people in the Communist party were old and all came
from poor backgrounds,” says Kaaden. “They had no experience of motor racing
in their lives. In the past they probably didn’t have enough money to buy a
motor cycle or car, so they were not interested in motor sport."
Now Kaaden had to apply to Berlin, 180 miles away, for parts lying across
the courtyard. On a more serious level, it meant that the team ran into
political difficulties with decisions that a grand prix team needs to make
every day. Apart from working out the logistics of attending an event
abroad, permission had to be sought to leave the country, along with foreign
currency.
Permission then had to be granted by the host nation and every other
country in between. Speaking from personal experience, I can assure you that
many western governments were far more grudging with their permits than the
communists. Motor Cycling reported in June 1962 that NATO governments were
no longer issuing visas to East German nationals, as they did not recognise
the government, which is why the MZs made so many appearances in Finland.
Finland was not part of NATO. When Kaaden applied to take the MZ's in a van
to the Spanish GP, the French (not a NATO power) refused him a transit
permit. And when racer Alan Shepherd tried to ring Walter from Daytona in
1964, he found that it was illegal to telephone East Germany from the USA!
Money gained from sponsorship deals with western companies had to be handed
over to the central committee in Berlin for general distribution. At least
that was the theory. In fact the chief of the department, Sportskommissar
Hartmann, had siphoned off such funds into his Swiss bank account. He
defected in 1083,but died in Switzerland that year, either by committing
suicide or at the hands of DDR's secret police, the Stasi.
In the pursuit of national prestige the East German authorities were
reluctant at first to allow their machines to sport foreign components.
However, start money could be used by Kaaden to buy high quality basic
products such as steel tubing and precious supplies of superior British
components and consumables, from carburettors to oil. As the development of
the MZ engine reached its peak, cycle parts were shown to be lacking. Thenew
duplex frame acquired Girling rear shock absorbers. The wheels gained Avon,
and later Dunlop, tyres. Amal carburettors, Lucas ignition, Lodge plugs,
Smiths instruments and Norton forks followed.Several stories surround those
front forks. One says that they came from Francis Beart in exchange for
front brakes. Another maintains that Joe Ehrlich supplied them in exchange
for an engine unit. Kaaden remembers it differently "At this time we had a
contract with BP, and they paid for us to have ten pairs of Norton forks –
only the forks legs, not the yokes. They came into West Berlin. I took the
fork legs through Checkpoint Charlie, one at a time, down my trousers."
By 1958 the MZs, the 125cc single and the 250cc parallel twin – virtually
two singles bolted together – were competitive enough to win international
races. Their experienced East German rider, Horst Fugner, won the factory’s
first Grand Prix on the 250 in Sweden, against a reduced field due to the
withdrawal of three Italian factories from racing. With the Italians back in
force at the TT in 1959, the 125 finished second, failing to win only
because rider Luigi Taveri was suffering the agony of a tight helmet.
So we come to the team's first memorable win, an experience Kaaden still
cherishes. At Monza that year the grid was littered with the best Italian
machines ridden by the top riders. They included Provini, Ubbiali, and now
Hocking – previously with MZ – on MVs, and Taveri on a Ducati. With Fugner
injured, the MZs were entrusted to Derek Minter and a young Ernst Degner.
Degner won to notch up MZ's first 125 GP victory and history's first ever
125 GP win by a two-stroke.
Next month: MZ's technology goes East to Japan with Degner.
Part two:
MZ's second place in the 1959 125 TT marked the beginning of the East
German team's greatest successes. Over the next few years both 250 and 125
machines won a succession of GPs in the hands of Ernst Degner, Alan Shepherd
and Mike Hailwood. With the better quality components housing the engine,
the machines remained competitive well after the Japanese onslaught began in
the early Sixties. Shepherd notched up a memorable victory at Daytona in
1964, and Heinz Rosner and Derek Woodman performed well throughout 1965 and
1966.
Engine development didn’t stand still. A squish band head, offset to
accommodate the ports, produced more power. Reliability increased with the
introduction of more robust needle roller big and small end bearings and
water cooling.
Kaaden says that to be fully effective the squish band on the cylinder head
should have no clearance. Otherwise it creates what he calls ‘dead space’.
But he found that "at high revs the dynamics of the piston pushes the crown
beyond the original limit. So you must have clearance."
By this time it was obvious that the Mz’s didn't suffer piston seizure
nearly as much as many other two-strokes. In the Fifties Kaaden had found
that at higher revs the piston distorted. MZ's third transfer port helped to
prevent distortion, as did the rear facing exhaust pipes. Originally this
layout was thought to be a cause of overheating. In fact the opposite was
the case because of the slower dissipation of cool air at the rear of the
cylinder.
Pistons were grooved above and below the single piston ring to reduced
carbon build-up. The extra weight of water cooling had to be matched by an
increase of power. A simple unpumped thermosiphon system was used on the
grounds of cost. Initially only the cylinder barrel was water cooled to
allow for rapid removal of the head. Kaaden’s original tests proved that the
air cooled engine produced more power at low speed, due to the efficiency of
the water jacket. The engine wasn't running hot enough. But there was no
doubt about the improved reliability on the long, fast GP circuits.
Despite these improvements, MZ racers were notoriously difficult to ride.
Taveri's success at the 1959 TT pleased Kaadden most because by finishing so
far ahead of the other MZs Taveri had proved to the East German riders that
the machines were capable of beating the best – if ridden properly. Most
difficult to judge was the use of the handlebar mounted air lever which
adjusted the mixture during a race. If used correctly the air lever
maximised power along a straight, while removing the risk of flooding on a
slow bend.
"Alan Shepherd was the only rider who could work with the air lever," says
Kaaden. "At the start of the 250 GP at Sachsenring in 1968 Mike Hailwood
said to me, "Walter, please put that air lever in the right position. I
don't want to have anything to do with it."" Shepherd shot into what
appeared an unassailable lead in that race, only to be overhauled by
Hailwood near the end, and had to be content with second place.
"Alan told me, "Walter I think Mike Hailwood is a little bit better than
me." But the next day I dismantled the engines, and I found that Alan’s had
a fault with the piston rings which was costing him five bhp," says Kaaden.
Shepherd altered the gearing on his machines to increase speed at the
expense of acceleration. "Alan would have a top speed of 230 kph (144 mph)
compared to the East German riders 200 kph (125 mph)," says Kaaden. "They
had the acceleration, but that was not good for the engine. You cannot ride
smoothly with such an overgeared transmission. Alan cornered faster, which
meant he did not need so much acceleration out of a corner, nor was he so
heavy on the brakes. The East German riders always complained about the
brakes, but Alan never did."
Ignition systems remained unreliable. The original East German IKA magnetos
proved incapable of coping with increased revs and heat under racing
conditions. Experiments in the early Sixties with Lucas electronic ignition
proved that the design was in its infancy. MZ's 250cc twin had a splined
crankshaft with enough whip in it at race speeds to upset the timing on one
of the cylinders. Eventually a one piece crank was fitted, but by then the
competition had caught up.
Full time participation in international events meant more exposure to the
West. This gave MZ’s race team access to high quality components, but there
were disadvantages. With the cement still wet on the Berlin wall, many were
jealous that a world beater could emerge from behind the Iron Curtain. Alan
Shepherd was given poor quality fuel at Daytona in 1964, a handicap he
managed to overcome, and he encountered the same problem on the Isle of Man.
Joe Ehrlich, who had manufactured 350cc EMC split single two-strokes in
England born 1947 to 1950, and later campaigned 250cc EMC-Puch racers in the
lightweight TT, provided another sort of annoyance. The paddock gossip,
repeated many times, that Kaaden supplied Ehrlich with a 125cc MZ engine
that was transformed into the 1960 125cc EMC in exchange for a set of Norton
front forks cannot stand up to Kaaden’s revelations. He says that the Norton
fork parts were supplied by MZ’s sponsors BP. Kaaden is adamant that he did
not supply an engine, but cannot say who did.
In May 1960 Ehrlich became chief engineer in charge of small engine
development at the de Havilland Engine company. De Havilland was neither
interested in making nor marketing roadster or racing motor cycles, but
provided Ehrlich with the facilities to carry on racing under the EMC
banner.
The engineer who drew up the EMC copy of MZ’s single in 1960, Phil Irving,
put the record straight before he died in 1992. "When the racing season was
ended Joe Ehrlich got in touch with me about designing a new EMC engine for
next year," wrote Irving in his autobiography. "As previously agreed, he
produced all the components of an MZ engine on loan for a limited period,
and with all the fruits of years of development in front of me, I only
needed to make drawings of all the MZ parts except for the cylinder jacket
which would be water cooled...Joe handed out 521 for my work, and we took
the drawings and the MZ parts to the de Havilland Engine Co...where all the
casting and machining could be carried out during the winter...On one of
several visits to the de Havilland factory, I saw the 125cc EMC in action
when it was listed to give 26 bhp at 10,800 rpm...I was pleased with the
appearance of the engine which did not noticeably betray its MZ origin".
A win by Shepherd or Hailwood on an MZ was regarded by the communist
hierarchy as a win for Britain, not East Germany. Consequently, although he
was allowed to employ overseas riders, Kaaden knew he would never get the
funding which would enable him to keep one. The fact that this cost the
factory a world championship more than once was beside the point.
Many top foreign riders tumed out for MZ when they had no 125 or 250cc
mount, either out of respect for Walter Kaaden, or because they were happy
for a free ride on what was quite simply the fastest lightweight available.
Some, like Gary Hocking, Alan Shepherd and Derek Woodman, sustained their
support over several seasons. But then Italian or Japanese factories tempted
them away with offers Kaaden couldn’t hope to match.
Championship winning talent doesn’t necessarily follow engineering
progress. Of the many competent riders available in East Germany only one at
any one time was capable of winning a world championship. First there was
Horst Fugner, but for most of his career MZs were under development. Then
came Ernst Degner: handsome, self-assured, talented.
Degner was East Germany’s one real hope. His best years as a rider
coincided with the emergence of the MZ racers in their fully developed form,
before the opposition caught up. From 1958 Degner’s race results improved
steadily until he superseded Fugner as the factory’s top rider. He strung
together impressive sets of finishes throughout 1959 and 1960, rarely
finishing outside the top six. Third place in the 1960 125 world
championship promised much for the coming season.
During 1961 Degner’s star continued to rise. First places at Hockenheim,
Sachsenring and Monza, backed up by seconds at Montjuich, Clermont Ferrand
and the Ulster, left him two points clear of Tom Phillis in the 125
championship with two races to go. The first of these was at Kristianstad in
Sweden.
"Right from the first flag-fall Degner was in business," reported The Motor
Cycle. "He was leaving them all behind within a mile. His screeching MZ had
never sounded better. ... Then suddenly the MZ scream died. With only about
10 miles covered the internals had had enough and Degner was pushing in."
In fact it was Degner who had had enough, not his engine. After
deliberately over-revving his engine, Degner dumped his MZ and hopped into a
waiting car. With his wife and family already safely out of East Germany, he
was about to defect. Degner had no mount for the last round in Argentina,
despite deciding to race a 125cc EMC there. The championship went to Tom
Phillis and Honda.
"Degner will be back in the saddle in 1962 – never fear," said The Motor
Cycle in October 1961. He was riding a Suzuki revitalized to such an
unrecognizable extent that the Japanese factory was able to claim the 125
world championship in 1963. Degner had taken his riding skill, his
mechanical knowledge, and a carrier bag crammed with parts to Japan.
Kaaden's humiliation could not have been more complete. In one stroke he
had lost his best East German rider, and with him the 125 world
championship. The technical superiority gained over a decade of hard graft
had been handed to the opposition on a plate.
Suzuki's copy of the MZ was exact. A few years later, Kaaden accompanied
Mike Hailwood to Suzuka, only to find that his toolbox had been mislaid in
transit. Suzuki were kind enough to lend him some of theirs. All were an
exact fit on the MZ right down to the special tools for the rotary valve and
ignition timing.
Yet Kaaden has nothing but praise for Japanese engineering and production
techniques. He reasons that they would have caught up with MZ within two
years without Degner’s help. Even so, you can't escape the twinkle in his
eye when he recalls their annoyance at Hailwood’s second place that day at
Suzuka.
He's not particularly bitter about Degner, either. Kaaden first saw him
again during the following season in Finland, but it was impossible for the
two men to talk to each other. When Degner wasn't sitting in the Suzuki van
he was surrounded by bodyguards. Many years later, when Degner was working
for the West German oil company Aral, Kaaden bumped into him at Hockenheim.
Degner wasn't happy with the changes in his life. His wife had left him, and
he'd had a crash at Suzuka which had finished his racing career, permanently
scarring his face. He committed suicide in 1968.
The political implications of Degner's defection reverberated around the
world's race paddocks and newsrooms. At Zschopau the shock waves of Degner's
departure made an immediate and lasting impact. Funds dried up, and the team
was not allowed to race abroad. Future successes were either limited to the
Eastern bloc, or relied on the likes of Alan Shepherd, who more than once
collected his racing machines at the East German border.
Instead, emphasis was placed on the ISDT team. The East Germans had a
handful of world class riders, and the ISDT engine was based on the MZ
roadster unit. Kaaden had been working on the ISDT engine since the early
Fifties. At one point he experimented with a rotary valve version. But the
advantages it gave on the track weren't matched in the rough. The standard
engine was altered in a number of subtle ways to increase performance and
improve reliability. Carburation and the length of the inlet tract were
modified. The cylinder head had deeper finning, and a squish band was
machined into it to increase the compression ratio from 7.5:1 to nearly
10:1.
The two-stroke single was easy to work on. To speed maintenance in
competition a second plug hole was tapped into the cylinder head. In a
crisis the plug lead could be swapped over immediately. A spare coil and
condenser were also fitted. Standard features, such as the fully enclosed
final drive chain, naturally lent themselves to off-road use, and were
supplemented by nice touches like the long butterfly carburettor bolt.
The one drawback of the engine design was its crankshaft-mounted clutch.
Originally designed to increase flywheel effect, the enginespeed clutch
needed careful balancing. Gearchanging was tricky. The other concern was
weight.
Even so, MZ was extremely successful, dominating the International Six Days
Trial in 1964, 1965 and 1966. The toughest of them all was the 1965 ISDT,
held in the Isle of Man. In atrocious weather conditions, only two out of 29
national teams entered finished without breakdowns – the East German Trophy
team and the East German Vase team! All the time Kaaden was pushing MZ's
hierarchy for the resources to produce a completely new, lighter off-road
engine. "The original engine was designed in 1953-54, and it was a good
engine for many years, but too heavy," he says. "This was the standard
engine as well, and was produced without change for all those years. When
other factories – Zündapp and the Italians – started producing more powerful
engines, I was allowed to make a lighter engine."
Yet this advance was ignored by the main factory. "The constructors of the
road bikes were not interested in the expertise of the sports department,"
says Kaaden. "At MZ the sports department and the production department did
not have a good relationship. With a better relationship maybe we would have
had a better road bike." It was their, and our, loss. The new engine weighed
a mere 25kg (55lb), 15kg (33lb) less than its predecessor. It incorporated
all Kaaden's experience of port design, and was produced in two versions - a
six speed 250 and a five speed 500. Significantly, the crankshaft mounted
clutch had been ditched in favour of a countershaft unit. A lighter engine
meant lighter cycle parts. Weight was down, power was up. A string of
successes followed during the Seventies and Eighties. Kaaden had not given
up on the road racing engines. One problem he attemped to overcome in the
late Sixties was the unwieldy width of the twin cylinder version. In 1969 he
produced a twin in which the cylinders were arranged in line, nicknamed the
tandem twin. Yet although frontal area was reduced, the tandem twin did not
match the old engine's power. Without the resources to redevelop it, the new
motor had to be abandoned.
The earlier engine designs, now fully developed, were still returning some
interesting results. Peter Williams won the 350 race at the Ulster GP on a
301cc MZ in 1971. And Italian rider Silvio Grassetti, who first raced for MZ
in 1970, continued to fly the flag. But the race department was being
starved of resources, and in 1972 all development was stopped.
Kaaden continued to work at the factory until his retirement in 19%, and had
to put in a further two years as Sportskommissar in Berlin after Hartmann's
defection. He and his wife still live in Zschopau, a stone’s throw from the
now deserted factory. His son lives nearby.
I couldn't resist asking Walter Kaaden if he had ever considered defecting,
like Ernst Degner. "No. I'm happy about my life and the work I have done
over the years," he replied. "As a member of the FIM for 82 years I have
been able to see most parts of the world. You must understand that I had my
wife, my parents and her parents here, and my son was at school"
"I started working here with a team, and the people in the team supported
me. I felt that if I left them it would be disloyal I was approached by the
Japanese on the boat from Belfast to Liverpool in 1961 about leaving East
Germany to work in Japan. I told them I couldn’t – it would be disloyal."
mvh
Orla
http://home20.inet.tele.dk/tfv/vtr