Chat 26
Tony Harris writes about his latest project where he transforms his Norton ES2 into a 4-valve special. Eddy
ES2 Development
First some
background stuff. Please
don’t nod off folks.
I started this project in the early 90’s. This
was a time when I was racing in various classes including modern
unlimited production class, CRMCC and Vintage racing, now call
British Historic Racing.
I have raced in many classes with the Vintage
club including 250, 350, Pre-War, Vintage Pre 1930, Post-War
Unlimited and Sidecar since the very early 70’s.
I hadn’t actually ridden in the 500 class,
although I had been racing for over 20 years with the club with a
reasonable success rate.
It would have been nice to have a Manx Norton but spreading myself
thin over many classes and bikes (not all of them mine) made
finances somewhat strained.
There were only a handful of proper cammy Nortons at that
time in the club unlike now.
The other thing was build a Triumph twin, but
the 50’s Triumph frames would be a disadvantage in the class so a
Norton it was. I always
admired the speed the Wright brothers, Colin Dally and Shane Lockley
and others got out of the pushrod ES2 and as I like singles and
already raced 650 and 750 Norton F/beds, a Norton it was.
Bits were still relatively inexpensive, and I
picked up an ex race motor and other ES2 bits fairly quickly. The
motor had steel flywheels a MUST if you want to increase power.
I put a motor together and it went quite well
but not fast enough to worry any front runners though.
My next job was to make the horrible combustion chamber more
efficient. The ES2
exhaust valve is way too big so most of the charge was lost down the
hole. A Model 50, 350 head is a good way to perk a road going 500 up
but I wanted a bit more than that.
I bolted a head onto a face plate on my lathe and bored the combustion chamber out until I almost had a stack of fins. Next, I machined a billet of HE30 T6 alloy and pushed this in with a slight interference fit then welded it in place. I then made a much shallower combustion chamber. I machined the inlet and exhaust ports, both at a much steeper angle than Norton made them and fitted Jaguar valve seats and valve.
After some welding I used Goldie modified
rockers with eccentric spindles.
This did away with the heavy tappet adjusters and the
geometry was about right.
I cut the inlet tract off and bored an offset
hole at a much steeper angle almost down to the valve head. This was
welded in too. I made
the drains from both rockers external and fed these onto the cams.
The original ones go through the barrels and usually leak anyway.
I had to alter the rocker box because the rocker pivots were
in the wrong place and the ends of the rockers over-shot the valve
tops by quite a margin.
I did some dyno testing with the motor.
I made the inlet port adjustable sleeves so I could test with 1½”, 1⅜
and 15/16” bores. (See
picture above.)
I also had different carbs set up and the changeover was very
quick. I also made a
couple of different exhausts to try.
After some swapping and changing I settled on 15/16”
bore. This gave the most usable power and torque.
I think it was almost 40 BHP, about 10 down on a good Manx
but a lot more than a std ES2 and up with the Goldies.
I think if I had experimented with better cams and set up I
could have got a little more but it was just a play thing for
another ride.
In this configuration I raced the bike and it
was a lot quicker and would get in the top 4.
It needed more development work. I made my own cams running
on roller followers. All
the ingredients were there I feel, and it gave me a reasonably
competitive extra ride in the 500 class.
I had learned quite a lot with this motor, and
it started and ran very reliably.
I decided to try and make a bigger jump in performance and
see if I could improve engine breathing and power.
The VMCC also had rules which had to be abided by, anything I
did had to look as much like a Norton engine as possible.
With this in mind I decided to alter another
head. I had to see if I could make it 4 valves.
Left:
Standard 2-valve Model 50 head + ES2 87 mm alloy barrel
for 2nd road engine. Right:
2018 road bottom end
The 4 Valve head.
First, I made
another bottom end with steel fly wheels, Weslake con rod,
strengthened cases and altered stud centres.
Crank on left and timing case with roller followers
4-valve bottom end showing modified Suzuki 4-valve piston
I did the same with this second head as I did
with the first, boring the combustion chamber out on my lathe and
inserted and welded a block of alloy in its place.
I looked at quite a lot of engines with 4 valve
layouts and decided on a Weslake\Godden type speedway design.
I used Godden valves, springs and valve seats and a straight
downdraft induction tract.
This took quite a bit of working out to make sure the holes came out in the right place. I also had to make all the rockers and rockerbox, as you do.
4-valve inlet ports
One of the problems I encountered was that the
valves were at a steep angle and at the time I couldn’t see how best
to open them. If the
cams were on the same shaft like a Velo or unit BSA motors it would
have been easier, but the ES2 cams are on different shafts and wide
apart. The pushrods came
into the head level with the tops of the valves.
What I decided was to use the exhaust cam to
control the inlet valves and the inlet cam for the exhaust valves.
To do this the rocker arms had to cross. In hindsight I now would
have done this differently.
It’s always clever to be wise in hindsight.
After I’d made all this, I never actually
fitted the head and ran this motor.
I retired from racing and got involved with other things.
The motor sat under my bench for another 26 years until 2018
when I decided to put the bottom end of the motor back in my old
race frame which at this time housed a 650 Triumph motor.
I built this up using a standard M50 head and used it through
2018/19.
Back in road trim for for 2018/19 with a standard 350 head fitted
Due to the lockdown I decided to dig all the 4
valve head bits out and see if I could make it work. Of course, some
parts had been lost and I had to re manufacture them.
The 4-valve and 2-valve heads side by side for comparison
As said, I did a couple of summers with the 350
std M50 head on before taking it off and fitting the 4-valve one
while in Covid 19 lockdown.
It all went together quite well.
A new head steady was made along with altering an exhaust to
fit. The exhaust port I
modified to fit a bolt on flange as most modern bikes have so no
more dodgy threads to come undone.
Checking valve timing
The cams had to be changed for others I had
made to go with the head and a few oil drains were altered.
The carb I wanted to use was a 15/16”
GP. This, along with
about 50 others I made some years ago, most 1 ½”.
Unfortunately, I had sold the one off, 15/16”
unit sometime in the past quarter century and the only one I had
left was a 1 ½” bore. I
made a tapered sleeve to fit the inlet tract that went from 1 ½” to
just under 13/8” just before the inlets split
to go down to the inlet valves.
I found a small SU remote float chamber and set this up to
the carb. I have one of
my own ignitions on from when I made the BT-H electronic units.
These are self-generating with built in adv/retard. This was
set to about 28º BTDC as a starting point. There’s no books to look
in and I have to start somewhere.
4-valve head top view
4-valve head with rockers fitted
The only fuel I had was about 10-month-old
rubbish from the supermarket in a jerry can in the shed so that went
into my dummy tank. I
figured its only just over 9:1 cr and with the modern combustion
chamber should burn it OK.
My old 650SS would never run on fuel more than
about 8 weeks old. I
flooded the carb the best I could as there was no tickler and gave
it a kick, nothing. So,
I gave it a push down the drive and still nothing.
I then put some carpet tape over most of the inlet bell-mouth
and pushed again and it started instantly.
When warmed up it ran OK but had a tick over of about
2500rpm. Considering the carb slide was bottoming out and GP’s have
no way of holding the slide up I assumed I had an air leak.
Eventually I discovered the throttle cable I
made, which screws into the top of the slide on the GP was
protruding to far through and hitting the top of the throttle
housing, holding the carb up slightly. A quick file on the solder
and all was well.
However, a quick ride up the road revealed fuel
starvation when opened up.
I did think this might happen with the small SU float
chamber. To overcome
this I made a TT type remote float chamber from bits of material I
had in the workshop.
When fitted, this worked very well and the bike revved out through
the range, but there’s always a but.
I now felt the carb was over size so I think something about
34mm would be better. It
could also be the silencer holding it back higher up the rev range
or ignition timing.
At least it does start very easily, even with a
38mm GP carb on. Next I
tried an old 13/16” Monobloc and this gave me
a tickover. The motor
then had problems revving past about 4500rpm.
Back on the ramp I thought I would pop the top
of the rocker box off to see how things were going.
I found there was about 1/16” play in the inlet tappet and
about .040” in the exhaust.
Everything else looked good.
There was plenty of oil about and everything nice and free.
The tappet clearance I suspect is self-inflicted because when
I made the pushrods I was not 100% sure I had them fully inserted
into the ends and running the engine a few miles had seated them
down.
I adjusted both inlet and exhaust tappet and
changed the silencer for something a bit less noisy. I’m not 18
anymore (Really? Eddy) and it just
attracts attention to me and gets motorcyclist a bad name.
I also fitted a 32mm Concentric carb (1¼”) and
went for another test ride.
This breaks all my own rules of only altering one thing at a
time. The bike now felt
much better. The
acceleration is very good, far better than an average ES2. The 4-valve head gets a lot better filling
at
the initial smaller valve lifts and it shows
through
the bottom end of the rev range.
The top end, may be no better than a reasonably tuned two
valve motor but the way it accelerates makes it very frisky.
I am sure with different cams and exhaust
system there is a lot more power to extract from the motor. The
bottom end is very strong.
Now that it no longer has to conform to a race
series rules I have no restrictions on external appearance so it
wouldn’t take too much work to take the exhaust cam out and extend
the shaft through the timing cover and fit a toothed belt to drive a
overhead cam or two.
This would eliminate the pushrods.
Ducati have been using such a motor for years. No expensive
vertical shafts and oil flying everywhere.
Just a rubber band. Hummm.
Tony
Harris. 2020.
Racing a motorcycle can be trying at times with hours spent building and
developing a bike and also race prepping the bike before each meeting.
Sometimes there are long hours doing repairs or even longer hours rebuilding
after a major blow up! Once the work is finished you hope you are all
set and ready to go to the race meeting. You may think you are
finished and ready but sometimes the biggest challenge is actually
getting to the meeting! How do we get ourselves and the bike
or bikes
to the meeting?
The first time John and myself raced we actually rode the bikes up
to Cadwell Park, me on the 1926 500 Sunbeam and John on his mid-30's
350 Sunbeam. We got up there OK and in the paddock we removed
the silencers and fitted our "race kits", two bits of straight
exhaust pipe. This improved the noise if not the performance.
Once scrutineering was
done we ventured out onto the track for practice. In the races
I managed
some laps at the back of the field and John was probably
doing a lot better than me but retired with machine problems.
We were unable to fix John's bike in the paddock so how do we get it
back home? Someone with a big old Humber car offered to take it
home so after a bit of dismantling it disappeared into the Humber's
cavernous boot. I suppose that Humber must actually count as our
first race transport. I was left to ride my Model 9 home on my
own and after sorting out John' transport home. It was getting
late and my Sunbeam had no lights. I probably rode home faster that
evening than I'd done around the Cadwell circuit during the day! I
got home by twilight and fortunately didn't get stopped.
In 1969 or maybe it was 1970 I had bought a new Reliant Supervan 3
that was the race transport for our next foray to Cadwell. It was
just me entered so we took the passenger seat out of the Reliant and
the front wheel out of the Sunbeam and squeezed the bike into the
back diagonally. John then clambered into the back too. The
bike was maneuvered out at the circuit and we put the front wheel
back. We reversed the loading process to get home again.
The next race transport in a round about kind of way was an Isetta
bubble car. Hard to believe? Well here is how it worked out.
I decided that what we really needed to upgrade our race transport
was a trailer. I was at the time working at Briggs who were
then in New Street, Burton where I fabricated a few parts to make a
tow bar and folded up a channel section suitable for the length of a
bike. The Isetta was "dismantled" and the channel section was
bolted to the front sub-frame complete with the wheels to make an
instant bike trailer to be towed behind the Reliant.
Our next race transport upgrade was an old Austin Allegro that John
bought. It was an unusual colour, aconite, a fancy name for
bluish-purple. (Aconite is also poisonous, not sure that is
too relevant here but it might be useful if you're doing a quiz.)
You may remember that the Allegro got a bit of a bad press
because the
rear wheels could, and some did, fall off if the wheel bearing
collapsed. It also had a "quartic" steering wheel, which was
rectangular with rounded corners. It was a bit of a
gimmick but at least it didn't fall off, unlike the rear
wheels. (Speaking of wheels falling off; one time we were waiting in
the in the queue to get over the bridge at Snetterton circuit when
the driver behind came up and said the wheels on our trailer looked
a bit wobbly. They certainly were wobbly because some of the wheels
nuts were loose and some were completely missing!) Moving on,
we were part way to a race meeting at Staverton in the Allegro with
the Sunbeam and trailer in tow when there was scraping noise.
On investigation the cause of the scraping was a front brake
pad completely devoid of any friction material!
We drove on with John using just the handbrake and judging his
braking distances very carefully. I think this was the meeting
where we hit the big time as John got a third place in a mixed race
and 10 bob prize money. (For our younger reader I should
explain that 10 shillings in old money is the equivalent of 50p
today.) This was an aerodrome circuit with an interesting
feature, a bump where two runways crossed, very entertaining on a
rigid girder fork bike.���� We drove home carefully on the
handbrake no doubt buoyed by the thought of the unexpected riches
from the 3rd place prize money. (I think John still has the 10
shilling note.)
Around this time my memory of race transport gets a bit hazy but I
think both John and myself had cars without tow bars and maybe the
trailer said it didn't want to be towed any more. I think maybe John
had a BMW 323i and I was running an old XJ6 Jaguar. Whatever,
we didn't have our own race transport for the bike. Salvation was at
hand and at times like this you are reminded what a great group of
people were involved with vintage racing. John Parker
transported the Sunbeam to some meetings and Roger Allen added the
Sunbeam to his huge and already well loaded trailer. Can you
imagine racing rivals transporting the oppositions vehicles in, say
Formula 1, Hamilton's pit crew transporting Vettel's race car to a
meeting when the Ferrari* transporter was unavailable? (*
Insert Red Bull or whatever team Vettel will be driving for.)
At one Cadwell meeting when one of our friends transported the
bike to the circuit I transported our team of John, Julie and Gloria in
the Jaguar. I can't remember much a bout the meeting but the
return journey in the Jaguar was eventful. We hadn't been
driving very long through wildest Lincolnshire when the engine
signaled a problem by emitting a cloud of steam, one of the hoses
had blown apart. Finding a small pocket of civilisation we
were able to phone the RAC who sent a man with a big breakdown
truck. He winched the Jaguar up onto the platform and we piled
into the lorry cab. He took us through Lincoln and those who
remember Lincoln before the A46 bypass will know that there is an
extremely long steep hill. As we started to descend the hill I
could hear the chains securing the Jaguar to the flatbed creaking
and groaning. I had vision of 4000 lbs of jaguar breaking free
and joining us in the cab. With great relief we reached the
bottom safely. For whatever reason the driver didn't take us
straight home but stopped at some big old garage. It was
probably his tea break and didn't seem in much of a hurry to get a
move on. I had a bit of a wander around and found an area with
lots of old engines and parts. There was a Jaguar engine with
a hose. I got a screwdriver and "borrowed" the hose.
Once fitted and the radiator refilled we bade the RAC man goodnight
(because by then it was certainly night and late) and went on our
weary way. It is bad enough when you have to improvise repairs
to the race bike at the circuit without doing the same to your car
to get home!
There are more race transport stories to add but by now you may be
tired of reading or perhaps like me a bit traumatised by the
memories! Maybe I will continue with more race transport tales
another time. Eddy
Above: The Bedford H-EAP at Oulton Park Three Wheels on my Wagon by Pat Davy
The Motorcycle combination or outfit is
an engineering anathema or if you feel that is a little strong it is
most certainly an engineering compromise, but then so are the
majority of engineering solutions. I spent most of my time in
industry trying to find engineering solutions with the least amount
of compromise. Having said all that heavy stuff, outfits can be
tremendous FUN. They certainly require a much longer period of
adjustment for a rider to become proficient and the most dangerous
time is when you think you have got the knack. That's when it will
bite you just to put you in your place. I suppose because of the
long learning curve I find an outfit more involving than riding a
solo. One is constantly reading the road ahead as left handers are
usually taken in a gear lower than right handers and throttle
balance is crucial. There are many other aspects to riding an outfit
but this piece was intended to tell of just a few of the outfits in
my life so here we go:-
My first outfit appeared early in my motorcycling life and was
brought about by a need for a racing transporter, an extremely grand
title for what was a heap of junk. The Mill Room foreman Ted Jones
at the Andre Rubber Co where I was apprenticed had a 500cc Triumph
single and side car chassis rotting in his front garden. I cannot
remember the year or model but it was certainly pre-war and very
tired. £2.00, I recall, sealed the deal. I got it running and got
home, what a steep learning curve that was with no body on the
chassis and the first outfit I'd had ever ridden.
The side car wheel spent more time in the air than on terra
firma hence the saying 'more firmer, less terror!'
The poor Triumph gradually
lost the little power it possessed and on stripping the engine the
piston rings were found to comprise 1/8” cubes of shiny cast iron.
It went down the dump, but the chassis was salvaged.
The second bike to be harnessed to the chassis, which by now had
gained a layer of scaffold boards covered with rubber sheeting
courtesy of my employers, was a 350cc ex WD 350cc Ariel WNG with a
broken frame. The twit who had owned it had removed the engine and
gearbox then sat on it emulating George Formby in 'No Limit' by
bouncing up and down. The frame top tube waved a white flag at the
seat lug. I took the frame home in two pieces. Thank God he had not
got inside the engine! I did not pay any money for the bike this
time but swapped a model aeroplane for it, sound a good deal? Well
he probably got the better half of the deal as the model was (are
you paying attention John Goodall) a control line speed model
powered by an American McCoy19 glow plug motor that, at the time,
was very rare and highly prized in England. The fact was the bike
was largely dismantled so the opportunity was taken to 'do it up'.
One Saturday when on overtime I strapped the two halves of the frame
to my back and cycled into work where I braised a previously
prepared plug into the seat lug re-joining the frame halves. The
ride home with a now complete frame attached to my back was
perilous. The cycle parts were painted Post Office Red the signature
colour of all aspirant special builders who learnt better when they
matured. The engine was stripped and tuned, or so I thought. Not
knowing anything about cams at that time I did not realise that the
military WNG cam had about as much lift as a “30” “A” cup bra. The
outfit went quiet well up to 40 and from there on it suffered from
asthma. However, it served
quite well dragging me back and forth to Brands Hatch with
the 7R on the side, being used for daily transport with a sack of
gravel from the Hogsmill Brook nailed to the boards as ballast and
even taking me and my mate with camping gear to France for the Le
Mans 24 hour Race.
There was an interlude of solo only riding until I was courting Ann
when I bought a bargain priced Vincent Comet and Steib via an advert
in Exchange & Mart. It had been laid up unused for quite a few years
and on the way home down the Kingston By Pass I opened her up. The
wonderful stream of sparks, red hot carbon disturbed from its long
slumber, that trailed from the silencer had caused following traffic
to keep a safe distance. This did not go unnoticed by a speed cop
patrolling the A3 on his Triumph Sprung Hub Speed Twin with fire
extinguisher in the leg shields. He pulled me over and was
disappointed to find that when I stopped so had the pyrotechnics, so
his fire extinguisher was redundant. He let me off.
In six months, we had rattled the Vincent to bits the final straw
being when the large alloy idler wheel in the timing chest lost its
teeth. I came to the conclusion that the Comet was probably inferior
to a B33, Red Hunter, MSS or Big Bullet. Later experiences with
Vincent twins has led me to conclude that the twin is much more than
twice as good as a single Comet. I have had a Shadow both solo and
with a chair and a solo Rapide and I hold them in high regard. The
Comet went but I kept the Steib in stock propped vertically in a
corner of the garage it offered the storage space equal to a small
wardrobe and quickly filled with bits that will come in handy. We
now come to the magnum opus of my formative years discounting the
1932 Morgan Three-Wheeler with a 1100cc JAP which I super charged
and is a whole story of its own.
It had become my practice since the earliest time to have a best
bike and a ride to work bike. Ride to work bikes never cost more
than £5.00 and usually lasted until a year’s tax ran out and then
changed for something a little more reliable but never more than a
fiver. They ranged from a Bantam to
a bronze head Rudge Ulster which finally lost the intermediate
ratios in its needle roller gearbox. Not to worry it had so much
torque and flexibility that I carried on using it for work using
only first and top gear. These were the days before DVLA at Swansea
and MOT’s. I can remember the date I got pulled on the Rudge for no
Tax, November 3rd, 1957, the day the Soviet Union put a
dog named Laika into space. Like the dog the Rudge died in its
course of duty however unlike the dog that fried on the 4th
orbit the Rudge engine ended up in a 500cc Formula 3 Racing Car
project and the frame ended up in the skip, please don't tell my
friends in the Rudge Owners Club. Enough of this irrelevant stuff
let's get back to the three-wheel theme.
It became the time to change my best bike and an advert in Exchange
& Mart for a small fin BB34 Gold Star took my fancy. I had been
missing the 7R and racing and fancied something with some urge under
my right hand. It wasn't quite the latest DBD 34 Goldie that all Ace
Cafe boys aspired to, but it was a Goldie. But not for long! On a
trip down to Littlehampton with Ann on the back a slight knock
developed round about Ockley on the A24 then WALLOP, RATTLE, RATTLE,
SCREECH OF REAR TYRE and everything stopped going round. The Goldie
had stuck a leg out of bed. The con-rod let go just under the
gudgeon pin letting the daylight in the front of the barrel and
quite a bit of oil out.
When I got the bike home and stripped the motor it was a mess inside
so much so the question was is it worth rebuilding? Searching
through Exchange & Mart for a suitable replacement I could not
believe my luck when I happened upon an advert for a DBD34 complete
with carb & stripped for inspection. No time was lost in whizzing
round the North Circular, a route I knew well from my Brands visits,
to make the purchase. The opportunity to view it stripped was a
bonus and it all appeared in good condition, the crank cases were
new and had not been stamped with an engine number – an amusing
problem for later.
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Left: John in the
paddock on his Sunbeam350.
Right: Me folded up on the 500 somewhere around the circuit.
The Isetta was my first car. I ran it for a while and although
it was a bit decrepit it was a lot of fun. When I got married
my first wife and I lived with relations in Anstey near Leicester.
We later bought a new house in Markfield. The Isetta was on its
last legs but I managed to drive it the few miles from Anstey to our
new house and parked it up on the drive. 
The Isetta looking rather sad.
Wife Ruth looking rather happy with the new Reliant.
A photo taken at Oulton Park. John with his 600 G80TCS, the
Sunbeam front wheel to the left and the Allegro in the background.
The happy looking crew in the sun. Not sure about the
bloke in the daft hat, he looks a bit thoughtful, a premonition
maybe about the journey home?
The next race transport upgrade should perhaps be categorised as a
downgrade. I'll explain. I decided what we need was a
van.
In a yard behind where John lived was an old CF Bedford van that had
been abandoned by a builder. I contacted the builder and
bought the van. It wasn't too expensive as it wasn't too good.
It had a Perkins 108 diesel engine with one big end journal
shot and the body was rotten in places. I bought a
reconditioned bottom half engine that I spotted advertised in the
local newspaper and did quite a lot of patching and welding on
the bodywork, enough to get an M-o-T. I had salvaged two nice car
seats from a Jaguar for any "lucky" passengers.
It really was a bit of a wreck. The registration number was
EAP 807K. The condition and appearance can be summed up by
telling the reader that I painted a black "H" on the bumper to the
left of the front number plate so it read, HEAP! If we were
feeling charitable we called it the "van ordinaire".
(A bit of corrupted French for you wine drinkers.)
We had one or two "notable" journeys. On the way to Snetterton
the ill fitting rear doors were letting diesel fumes into the back
so we had to stop for "air" before our wives in the back became
diesel smoked kippers and suffocated.
Another exciting journey was to Brands Hatch. After working on
the bike until the early hours of Sunday morning we managed a couple
of hours sleep before setting off at dawn. Part way down the
M1 a diesel injector pipe broke. We removed an engine access
panel and used some spare petrol pipe to run the leaking diesel from
the broken pipe into a gallon container that John in the passenger
seat had wedged between his feet. We continue our journey and
rattled to Brands on three cylinders. At one point,
John who after the very late night was only half awake suddenly
shot up and shouted "FIRE". Through the removed engine
access panel you could see the road. We were driving over some
hatched yellow lines painted on the road. John, in his
semi-conscious state thought that the intermittent yellow flashes
were flames licking up from the engine. Don't panic Mr.
Mannering!
We did mange finally to get to Brands Hatch where the gate ticket
man was quite taken aback when when we wound down the window to give
him the passes and clouds of smoke billowed out.
This photograph of the Triumph race transport outfit was
taken over 60 years ago, somewhere in France.
British Racing Green was chosen as I still had some left over from the Morgan Three-Wheeler rebuild. The Steib ball and claw design of sidecar connections are in my view the best of any road going clamps short of solid welded connections used on racing outfits. I would improve Steib clamps even further by bronze welding gusset plates to the Goldie frame at the four chosen connection points then saw off the clamp element from the balls and weld the balls directly to the gusset plates. The wheels were the next consideration. A BMW twin leading shoe front brake was chosen mainly because it was about the only decent twin leader that was fairly easily obtained. It turned out to be well up to the job of stopping a quick outfit but had one fundamental design fault, more of that later. The standard BSA rear hub was used with the precaution of having those dreadful rivets welded up. The hubs were built into 16” Dunlop Racing Alloy Rim by Mr Nunn who was a very experienced and highly respected in Southern parts. He said 'first get your tyres and then I'll order the rims' thinking I would not be able to obtain sidecar racing tyres. So straight round to Comerfords just down the road, produce my ACU race licence and hey presto a tyre order was placed. Mr Nunn built the wheel but he did struggle with the BMW hub as with 16” rims which all sidecar racers were using at the time, the spoke length was only about 2 1/2” on both sides being a full width hub. Front forks were the next component to consider. Leading link of the Earls type were the obvious choice and BMW were favourite, but I could not find a second hand straight pair so settled for Douglas Dragonfly. These needed modifying to accept the BMW hub & spindle also the torque reaction for the brake (brake plate anchor). The BMW design reacts the braking torque via the unsprung component, i.e. the pivoting arm, the result being that on brake application the bike rises and eventually under heavy braking the top pulls out of the front suspension units. What fun! In hindsight I should have copied the Douglas design and contrived a torque arm from the brake back plate to the sprung component of the fork and parallel to the pivoting fork. I had owned an NSU Max with leading link forks and properly designed front brake torque reaction which stayed dead level under braking so should have known better.
Douglas Dragonfly forks and BMW twin leading shoe brake.
Notwithstanding all that I now had a solo rolling chassis so could attach and align the sidecar.
The Steib side-car
Moving on to the petrol tank I was lucky to find an alloy 5 gallon Lyta for just a fiver but I think somebody had played football with
it so off to Paramount Metals in Kingston upon Thames run by Ted
Friend, the ex-Works AJS rider who raced the Porcupine. Ted could
weld anything. He cut the
bottom out of the tank, knocked out all the dents and put the bottom
back in, a beautiful job. The fact that the outer surface was all
scratched up by our football friend did not matter as it was going
to be sprayed green anyway. The fairing was Greeves Silverstone
suitably adapted to accept a headlight the shell of which was fibre
glassed in. The single seat also served as an auxiliary fuel tank.
Apart from a bit of upholstery both bike & chair that's about it.
The completed outfit.
Being a fairly law-abiding young chap, I thought I had best inform
Surrey Licensing regarding the change from solo to sidecar and the
change of engine number to nothing at all. They sent my form back
having written in the engine number space 'All engines have numbers'
I wrote TOFFEE underneath and sent it back. In the fullness of time
I received a new logbook with the engine number TOFFEE.
Oh I nearly forgot,
a quiz question:- 'What is the donor source of
the bikes single seat?'
Pat Davy
To finish off a few pictures from Brian Slack:-
A Brough Superior and an interesting EMC-Puch engine. Below them, chalk and cheese, a Vincent Firefly and a Vincent Grey Flash racer.
puch_engine.jpeg)
