the Rennsport BMW Rs 54 of 1954 – the Bevel Drive Boxer

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BMW RS 54 Rennsport
The Rennsport BMW RS 54 of
1954 – the Bevel Drive Boxer
Special thanks to BMW Group Archive in Munich for these fine
vintage images. And thanks to BMW Classic’s Fred Jacobs.
And thanks to Sothebys.com for the larger color images. Take
a look at their incredible auction fare online.
whose “Earles fork” design was just about the most advanced
available at the time.
T
It’s thought that only 24 were built between 1953 and 1954
though this number has been called into question. It isn’t
really known how many RS54s are still around today but most
estimates put the number at somewhere between 15 and 18.
The BMW Rennsport RS54 was a 286 lb DOHC racing machine
that produced 45hp from its boxer-twin. The front suspension
was made under license from the Englishman Ernie Earles,
While BMW had captured the world’s attention before
WWII by repeatedly capturing the World Land Speed Record
with its supercharged streamliners, winning the European
Championship in 1938 and the Isle of Man TT in ‘39, all
German factories (BMW, NSU, DKW, etc) were barred from
international competition immediately post-war. Yet each
he 1954 BMW Rennsport RS54 was one of the first racing
motorcycle designs to come out of Germany in the postwar period, the FIM had very recently re-allowed German
machines into their events and the engineers at BMW wasted
no time turning out some remarkable new two-wheelers.
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BMW RS 54 Rennsport
Notice the single bevel
drive shaft above the
cylinder, the unusual
front cover, and the
racing fuel take off
from tank to carb.
carried on developing their ‘old’ supercharged designs for
domestic championship honors, while retooling for renewed
civilian production. When Germany was again admitted to
worldwide FIM-sanctioned events, each factory focused with
renewed vigor. With the burgeoning German economy and
exploding sales of two-wheelers, the BMW factory invested
in upgrading their prewar RS255, built for supercharging, into
modern, normally-aspirated GP racers.
Their new engine retained much of the old Kompressor engine
design on paper, with twin gear-driven camshafts compactly
hidden in the cylinder heads, but the engine was nearly allnew, while the greatest change came to the now cutting-edge
chassis. The introduction of a full loop, all-welded lightweight
frame with a proper swingarm suspension and hydraulic damped
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shocks, plus the latest ultra-rigid Earles front fork design put
BMW back in the game.
What wasn’t expected was the announcement in 1953 that BMW
would offer well-heeled professionals a genuine production
racer, closely modeled on the Works (factory) machines. The RS
(‘Rennsport’) 54 could be found in black and white (and blue!) in
the factory catalog, although perhaps only a few were ultimately
built by BMW. What the factory offered was a 286 pound DOHC
dedicated racing machine producing a nominal 45hp, which on
paper compared well with its competition, the Norton ‘Manx’
with its all-welded Featherbed frame and DOHC engine, which
produced around 50hp, but was 22 pounds heavier. While the
BMW had theoretical advantages as a production racer over rival
Norton, with a lighter weight and a lower center of gravity, the
BMW never handled quite as well, but then again, it never leaked oil, as from Norton’s notorious
open cam box, over the rear tire!
The RS54 was introduced two years before BMW roadsters converted to swing arm suspension
front and rear in 1955, still using Earles forks and a far different frame than the RS54, with
extended loops holding upright hydraulic shocks. The new road-going motorcycles never looked
as rakish and fast, nor were they anywhere near as light, and the RS54 was the bike BMW
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BMW RS 54 Rennsport
The ‘works’ team that built the BMW RS 54: From left: Hans Ulrich
Schuhmacher, Sepp Eicher, Rudolf Schmalholz, Gustl Rettig, Project
Manager Max Klankermeier, Josef Achatz, Max Wolz, Hans Plessl, and
Hans Prütting, shown with two sidecar racers and two road racers in 1954.
enthusiasts really wanted. But with such small and selective
production, ownership was out of the question for all but a lucky
few professionals, as the machine was built by the highly skilled
works Rennsport division at quite a high cost.
crankcase bolting. The typical BMW engine-speed flywheel
clutch drove a four-speed gearbox, and the final driveshaft was
housed inside the right-hand swing arm tube, although unlike
the later production models, the swing arm did not hold oil.
The RS54 initially had bore and stroke dimensions of 68 x 68
mm, while the ‘works’ racing machines used a 70 x 64 mm bore
and stroke. The camshafts were driven by a shaft and bevel gear
system running on needle roller bearings throughout. To keep
the cylinder head short, the engine-driven exhaust cam was
geared directly to the inlet cam, and moved the valves by short,
flat rockers. Valves were set at a wide 82º angle in the semispherical heads, using duplex coil valve springs held by stepped
aluminum keepers.
For braking, an aluminum 200mm twin-leading shoe fullwidth drum brake hauled down the Earles forks, while a single
leading shoe drum controlled the rear swing arm. Hydraulic
drum brakes, as fitted to the later Works racers and sidecar
machines, sometimes found their way to the RS54 as well. Other
developments of the RS54 included a shorter-stroke engine, a
five-speed gearbox, higher compression pistons, larger Dell’Orto
SS1 carbs, and more. In the 1950s, the BMW factory produced
25 RS 54 type 253 and 8 Works type 256 racing machines.
30 mm Amal-Fischer TT carburetors (made under license in
Germany since the 1930s) were mounted at a 15º downdraught.
The crankshaft ran in three main bearings inside a one-piece
cast crankcase, at the front of which gears drove the oil pump
and magneto that sat atop the engine. The connecting rods used
a flat section, as tests showed cracking with a more typical ‘I’
section rod. Forged Mahle pistons of only 8:1 compression
ratio ran inside cast aluminum cylinders, with either a shrunkin iron liner, or chrome-plated plain barrel, with six stud
Walter Zeller, official BMW racer from ‘51 to ‘56, was German
500cc Champion in ‘51, ‘54 and ‘55. Second place in ‘56
behind Englishman John Surtees on the MV Agusta. Walter
Zeller stopped professional competition in 1957. He participated
in historic races in Europe from 1979 to 1988 with his loyal
mechanic Gustl Lachermeier, who accompanied him throughout
his career at BMW racing. Gustl restored and prepared two
marvelous bikes: a 1946 RS Kompressor and a Rennsport type
256 with an over square engine from 1968.
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The head and valve
gear are seen. The
bevel tube gear-drives
the valve mechanism,
and the twin cams are
shown along with the
valve lifters. There’s
beauty and mystery in
this image, and a very
rare glimpse inside a
piece of BMW history.
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Start of the International Solitude Race of 1955. Faust/
Remmert (53), Schneider/Strauss (34), and Noll/Cron (43)
on fully fared BMW Works RS54 sidecar combinations.
Thanks to Sotheby’s
for this image of a
machine recently
sold at auction.
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Rennsport
Rennsport –
BMW
Racing
in the
1950s
The 1954 RS
254 machine
sold at auction
by Sotheby’s.
E
arly on, racing bikes based on road-going machines quickly
appeared. Many of these racing machines were assembled
by owners who literally transformed their BMW road bikes into
production-based club racers. By the end of the 1930s, BMW had
become more involved with every aspect of two-wheel racing
with great success. And there was more success on the horizon in
the form of the Rennsport racing machines RS 53 and RS 54
Post WWII, the Fédération Internationale de Motocyclisme
(FIM) was formed. One of the first tasks of this global ruling
body for motorcycling was to ban the use of supercharged
machinery. This effectively ended any hope of the famous and
successful BMW RS 500 Rennsport Kompressors returning
to the international stage. This decision was a harsh blow to
BMW’s resurrection and was impacted further still with another
FIM rule that forbade any German riders, teams or motorcycles
to compete at international level.
Finally, in 1950, following pressure from BMW and several
European nations who realized BMW machinery production was
central to raising the ailing European economy, the FIM cancelled
the ban and allowed BMW full integration into international
motorcycle sport. But BMW now had a problem with the lack
of competitive machinery. Removal of supercharger-induced
power meant existing RS 500 machines were robbed of 2530HP. Not only were the BMW machines down on power, but
the competitors had the advantage of four years of unrivalled
engine and chassis development, and development and data
translates into success, as we’ve all learned from BMW’s recent
WSBK project.
Salvation for BMW racing department came from an enthusiastic
team of designers and engineers. In 1950, Alfred Böning,
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Eberhard Wolff, Leonard Ischinger and Rudolph Schleicher
set to work on improving the neutered RS 500 engine in order
to gain more performance from the now normally-aspirated
(carbureted) Boxer engine. The resulting machine was nearly at
the same pace as the competition, but it required the skill of a
young German rider to show the result of the team’s hard work.
Twenty year old Walter Zeller won the 1951 German National
(motorcycle) Championship. Considering the class of his
opponents – including team mate legendary Georg Meier – this
was a remarkable feat. Impressed with the young rider’s talent,
Meier became Zeller’s mentor and this stood the young German
in good stead in the years to come as a professional factory rider
and then manager of BMW racing projects.
Walter Zeller on the RS 54 at Salzburg in 1954.
Meanwhile, BMW was laying out its future racing plans, which
included not competing in the 1952 season of the recentlyformed world championship racing class entitled ‘Grand Prix’,
which was set to replace the old international 500cc class.
During this time, BMW continued developing the RS 500 into a
new racing machine known as RS 53. The RS 53 was essentially
a hand-built factory racing (ex-works) machine which employed
interesting chassis and engine developments tested by Zeller and
Meier, one of which was the first use of a rear swing arm on a
BMW machine.
The pivoting rear arm featured new rear twin dual shock
absorbers – in the same vein as hydraulically damped telescopic
forks – and was monumental in aiding traction at high speeds.
Not only did the ‘swinging arm’, or ‘swing arm’ for short, assist
the rear wheel to move over road deflections without interfering
with chassis stability, the rear suspension units could, unlike the
previous plunger-type units, accurately control the amount and
speed of the rear wheel’s vertical movement.
The swing arm consisted of two ‘arms’ holding the rear wheel
hub while pivoting from the rear of the main frame. The right side
of the swing arm also provided an enclosed space for the drive
shaft. The engine had extensive porting work for more power,
48-52HP. Of course, factory riders were given all available
technical assistance, but even so, the 1953 privateer customer
Rennsport machines were never far behind the Works machines
of Zeller and his fellow factory riders.
Towards the end of 1953, a revised version of the RS 53 was
shown. This new Rennsport model was designated RS 54 and was
to be made available to customers even though it was claimed
to be the closest thing to a works racing machine that BMW had
built to date. Because of the cost of materials and the time spent
to hand-fabricate each RS 54, only about 25 machines were
made to supply ‘preferred customers’ – teams with the finances
and ability to win major championships. It’s rumoured the BMW
factory riders were also meant to have access to purchase these
25 bikes, but would not continual development have meant
‘additional’ machines being produced?
Rear wheel and
swingarm of the RS 54.
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Rennsport
Dieburger Triangular Race 1955: start
of the solo class up to 500 cc. The
first starting line-up shows: Ernst
Riedelbauch (no. 1), W. Zeller (no. 21)
and J. Forrest (no. 13), all on 500 cc
BMW racing motorcycles.
The RS 54 Boxer engine wasn’t much further developed than
the original Kompressor engines of the late 1930s, and the recent
RS 53, but did incorporate the latest components for reliability
and increased power. The bore and stroke of 66 x 72mm gave
a capacity of 492cc. Compression was given as 8:1 and fuel
was delivered by two Amal-Fischer 30mm carburetors. Inside
the engine it was a tuner’s delight - shot-peened and polished
components, connecting rods of special shape, needle roller
bearings for the cam followers, and bevel gear-driven double
overhead camshafts in each cylinder head.. Power output for
the RS 54 was reported as 55 hp in ‘stock’ trim.
Racing of course meant that severe lean angles would be
encountered at every circuit. Because of the Boxer engine
design with the bulging cylinder heads, the cylinders were
the only restriction to cornering angles. Previous experience
ensured BMW engineers had gained as much clearance as
possible by building a compact cylinder head with optional
chamfered covers if required. Adding fuel to the fire that the
factory team had their own ‘special machines’ unavailable to
the privateers, came the acknowledgement the Works bikes
were running higher compression figures and a shorter stroke
engine of 68 x 68mm, which changed again later in its model
life to 70 x 64mm.
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BMW privateers Faust
and Remmert take the
checkered flag on their
series production RS 54.
Other technical steps for the factory machines came in late 1954
with the advent of a new five-speed gearbox, hydraulic rear
brake, and mechanical fuel injection. BMW was no stranger to
the power-enhancing property of fuel injection but it was difficult
to fully make use of it on tighter circuits where throttle action
was constant on-off and in-between. Some riders would swap
between traditional carbs and injection, especially at longer,
flowing circuits.
What the RS 54 did arrive with in 1954 was the adoption of
an anti-dive front suspension system consisting of a leadinglink front fork. The fact that the RS 54 weighed in at a mere
286 pounds dry was superb, but it could have been lighter still
through the use of ‘normal’ telescopic forks – which BMW
originally championed. Although the strut-front suspension did
a fantastic job of neutralising the inherent dive that comes with
telescopic forks, the weight, stability and rising front end that
came with the Earles-type set-up caused problems in tight, slow
speed turns. This was compounded by heavy flywheel torque
reaction from the engine on closed throttle and made even worse
with fuel injection when used. Quite a few racers relished the
prospect of riding such a revered machine as the RS 54, but
most couldn’t adapt their riding styles to accommodate the RS
54’s riding quirks and failed to benefit from its light weight and
performance.
The RS 54 proved to be a superb racing motorcycle in national
races throughout the next decade but never won the premier
and growing 500cc Grand Prix World Championship despite
the likes of Zeller riding superbly. But where the RS 54 failed
to secure world championship status as a solo machine, in the
ever-popular sidecar class it became the most successful sidecar
competition machine in the history of motorcycling sport.
It started in 1954, when Wilhelm Noll and Fritz Cron partnered
onboard a RS 54 sidecar outfit and won that year’s World Sidecar
Championship; a feat they repeated in 1956. BMW also took the
winning cup in 1955 but with Willi Faust and Karl Remmert. It
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Rennsport
seemed then, that the RS 54 had found its true vocation in life.
The Boxer engine’s low center of gravity and the fact sidecar
outfits do not lean so the engine width had no bearing on corner
speed, and tractable midrange power was a recipe for success.
Between 1954 and 1974, RS 54-powered sidecars secured 19
World Sidecar Championships. This amazing feat has not been
beaten to date. We’d see these machines in AHRMA races, no
doubt, but for their rarity, hence very high value. At a recent
sale, of one of these sidecar outfits sold for over $160,000!
The surviving few carried on being raced in national
championships and won many of them. Unfortunately, the RS
54 never saw the same level of success in international premier
classes. Around 1957, BMW cars had become affordable
and the ‘in thing’ for personal transport. Motorcycle sales fell
dramatically and caused major policy shifts within BMW in an
effort to stem the fall in sales and, therefore, profits. One such
measure was the end of the official factory racing team. The
entire motorrad division almost became history but for a Board
While the success of the RS 54 as a BMW racing machine
was being written into the history books as a beautiful and rare
example of BMW racing technology, it was also going into
the record books as the most prolific sidecar championshipwinning machine. But what became of the RS 54 as a solo racing
machine?
of Directors successful vote to stay the two-wheeled course,
thankfully. Imagine what moto life would be like today without
our beloved class-leading BMW motorcycles!
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So, BMW withdrew from international and major national
championships. It wasn’t just BMW who chose this route; many
other European motorcycle manufacturers adopted the same
position before moving on towards bankruptcy. Once again
BMW had to draw up survival plans and the company prepared
to hold back a tide of uncertainty with an all new model range.
The rest is history. The period poster is from yet another racing
triumph in 1966.
Tina Doggett
Doggett Insurance Agency LLC
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