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One returning
question is: what are the differences between the 16H and B4.
On the civilian M/C's it was really only the engine and transmission.
All the rolling chassis parts were identical.
There is not much more to
say about it.
The
military B4 versus the military 16H is however another story.
Based on the spare parts lists, a number of differences are clear but
looking at the actual parts they are not always clear.
Study of front forks using 3 B4 forks and one 16H fork revealed that
they were basically identical castings and tubings. The actual
flat milling (spot facing) on the bottom part was identical but the cut
out to hold the front axle was smaller on the 16H. This is in line with
the fact that the front axle of a 16H is 12 mm diameter and the front axle of a
B4 is 16 mm diameter.
All the available top and bottom links were identical, leading to the
conclusion that Norton did not specially change the camber of the front
fork for sidecar use.
The military
Big 4 did indeed have stronger springs, which is clear from the
different part number of it.
This may then be the cause for some confusion.
Below a
list giving a number of details differences between 16H and B4 military
bikes between 1938 and 1942 (Big 4 production stopped in late 1942).
This is not definitive and probably not
complete but based on the
best information available to me at the moment. (With great help from
Lex Schmidt).
Norton Model years went from October to October so that e.g.
enclosed valves engines were built and sold starting in the last months
of 1937!
|
PART |
16H |
B4 |
|
Max. power |
12 BHP at 4800 RPM |
14,5 BHP at 4000 RPM |
|
Solid handlebar clamps |
X |
- |
|
Rubber cushioned handlebar
clamp introduced in 1935 on civilian machines |
- |
X |
|
Open valve cover
|
X |
- |
|
Enclosed valves |
-*1 C |
X |
|
Oil tell tale |
M |
M |
|
No oil tell tale |
M*1 C |
M*1 C |
|
Ricardo turbulent principle cylinder head |
- |
M |
|
Front brake plate/drum left hand
side *2 |
M C |
M |
|
Front brake plate/drum right hand
side *2 |
- |
C |
|
Saddle spring studs vertical |
M |
M |
|
Saddle spring studs
horizontal |
M*11 C |
M*11 C |
|
Gear position indicator
small |
M C |
M C |
|
Nut front fork shock
absorber |
M |
M |
|
Footrest tubes
interchangeable |
M |
M |
|
Serrated foot hanger short |
M C*4 |
M C*4 |
|
Rear brake pedal short |
C |
C |
|
Side stand |
M |
M |
|
Diamond frame |
M C |
M C |
|
Petrol tank with only Spark
plug dome |
M |
M |
|
Additional mudguard stay
between halfway rear upper mudguard stay to rear lower mudguard stay/bottom
portion of mudguard |
M |
- |
|
Pillion foot rest lugs on left
and right lower chain stay short version |
M |
- |
|
Sidestand lug on left rear
chain stay and pillion footrest lug on right rear chain stay and “bolt-on”
pillion foot rest lug on left rear chain stay |
M |
M |
|
Sidestand and pillion foot
rest lug on
left rear chain stay and pillion foot rest lug on right rear chain stay |
- |
- |
Notes:
*1
only on non-British Military bikes (NIZAM India contract for instance),
*2 Different front fork to accommodate righthand brake
plate reaction arm,
*3 BSA type headlamp supports (two
strips in V shape on its side), so no lugs for the
headlamp “prongs”,
*4 also used on civil Trials versions,
*5
steel tubular footrests introduced around 1942 to preserve rubber,
*6 to go with short serrated footrest
hangers on civil Trials versions,
*7 in
1946 a completely new design toolbox was introduced,
*8 Longer
pillion footrest lugs required to cater for the "Cows Udder" silencer,
*9 introduction
of dedicated left hand pillion footrest lug approximately second half of
1940.
*10 Separate footrest tubes and engine plates introduced from
20th August 1936
*11 1938 model WD16H destined for India Storeds Dept were
provided with the civilian horizontal studs
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