Threads – Or Nuts to you – and bolts –
INTRODUCTION
The Sunbeam S7 appeared in 1946 and was redesigned in 1949 to create models S7 de Luxe & S8, before the Unified or ISO Metric series of threads came into use in the UK. In line with widespread practice in the UK motorcycle industry at the time, the majority of screw threads on the Sunbeams conformed to one or other of three British specifications:
Whitworth, Cycle and British Association.
- Whitworth (55º thread form); coarse-pitched: British Standard
Whitworth (BSW, often referred to as ‘Whitworth’, ‘Whit’ or ‘W’), finepitched: British Standard Fine (BSF) and pipe threads: British Standard Pipe (BSP). Hexagonal BSW & BSF fasteners take the BSW/BSF series of wrenches; some BSP fasteners do the same but BSP does not always adhere to this standard.
Another Whitworth-form thread used on British machinery at the time was British Standard Brass (BSB), and this series was probably used on the Sunbeams on a few fittings. - Cycle (60º form): mostly finer pitches than BSF or BSW. May be referred to as Cycle Engineers’ Institute (CEI) or British Standard Cycle (BSC or BSCy). Hexagonal fasteners take the BSW/BSF series of
wrenches. - British Association (47.5º form) (BA). Thread dimensions are usually quoted in millimetres rather than inches. Hexagonal fasteners usually take the BA series of wrenches.
Whitworth Thread. The angle (55º) and the truncation (H/6 and the shape at r) define this as Whitworth form. r = 0.137p. The pitch (p) is often expressed as number of threads per inch (tpi). The major diameter on a male threaded component is measured from the thread crests, on a female component from the thread roots.
APPLICATION TO THE SUNBEAMS
When the S7 was designed there appears to have been a policy of standardising on Whitworth-form threads wherever possible, with a few exceptions including assemblies bought in from other manufacturers (carburettor, electrical equipment and speedometer).
The redesign of 1949 incorporated some parts adapted from the large BSA models, introducing more Cycle threads at a time when BSA made extensive use of them.
Engine & Transmission: Most threads in the engine and transmission were BSF where matching male & female components were steel or bronze. Threads in the aluminium alloy castings were BSW, with a few exceptions.
Frame Parts: Most threads on frame parts were BSF, but on models S7
de Luxe & S8 there were several Cycle threads, e.g. on the front forks and yokes.
BSP threads were used on fuel-line components.
BA threads were used on small electrical components and some carburettor fittings.
Metric threads were used only on the spark-plugs and speedometer. The Smiths Chronometric speedometer was based on a French design by Jaeger, though most of its metric threads are not in the modern ISO Metric series.
Unified threads were not originally used on these bikes.
Left-hand threads: there were five left-hand threads: the dynamo armature bolt, both the wheel spindles, and both the hub lock rings (plate 7/6 or 7A/29, & plate 8/6).
Self-tapping screws were used in a few cases, in electrical equipment.
Screw and bolt heads were slotted (for flat-bladed screwdrivers), hexagonal or special designs. There were no cross-headed (Phillips etc.) or socket-headed fasteners.
Nuts were mostly of standard hexagonal form, but there were various
non-standard hexagonal types and other special designs.
Locking devices included: spring washers, shakeproof (star) washers (majority externally-toothed; internally-toothed types were used on some small electrical parts), tab washers, split pins, interference-fit pins, soldering, lock-wiring, punch or chisel marks, lock nuts, all-metal selflocking nuts and fibre-insert self-locking nuts. There were no nyloninsert self-locking nuts.
Grease nipples had simple tapered or straight heads; there were no hydraulic nipples with ball-shaped heads of the type suitable for modern high-pressure grease guns.
Finish: various surface treatments including electroplating were used, but there were no stainless-steel components.
Torque: only one torque recommendation was given, for the big-end bolts (Plate 1/208): 25-28 lb.ft.
LIST OF THREADED COMPONENTS ON MODELS S7 de Luxe & S8
The accompanying list shows original threads on the above two models only; model S7 differs from these in a considerable number of components.
After all these years, of course, our bikes will have acquired modifications and repairs which vary from the original specification. The penultimate section lists some of the more frequently encountered Stewart Engineering modifications (only data which differ from the original specification are shown). These measurements are taken from early examples; the design of these modifications may of course have changed during production.
The penultimate section also lists the sidecar mounting points on the
frame.
The last section gives the widths of some BA and BSF/BSW hexagonal fastners (across the flats), to help in identifying wrenches for these fittings. Not all of these sizes are found on the Sunbeams.
Not included in the list: some components of the carburettor and its controls, internal components of some electrical equipment (CVC & horn), internal components of the speedometer.
KEY:
Part numbers are the reference numbers on the exploded diagram plates
in BSA’s mid-1950s parts list, as used in the Stewart Engineering parts catalogue. Each section of the list refers to a separate plate.
These reference numbers are not the original BSA part numbers; the latter can be found in BSA parts lists for the Sunbeams and, in the case of parts designed specifically or initially for the Sunbeams, are prefixed 89-.
In a few cases these 89-prefixed numbers can also be found cast, stamped or engraved on the components themselves.
Male threads only are listed in most cases, to save repetition. Female components which are not either standard hexagonal nuts or threaded holes in castings etc. are noted in the Remarks’ column.
The terms ‘bolt’, ‘screw’, ‘plug’ etc. are used as in the original BSA parts lists.
Heads of bolts, screws and plugs are hexagonal, except where noted in
the ‘Remarks’ column.
Where bolt heads, nuts etc. are non-standard, the size of the tool required is noted in most cases. The term ‘wrench’ is used throughout for what in UK English is usually a spanner, to avoid confusion with the North American use of spanner only for certain specialised tools.
Washers and a selection of associated fittings (brackets, mounting plates, spacers, springs etc.) are described in ‘Remarks’.
Materials: steel, except where stated.
Where not stated, dimensions are in inches.
Length: only a selection are listed.
Bolts and screws: nominal length (i.e. not including heads) except where stated.
Studs, threaded rods etc: overall length.
Diameter: nominal diameter of the threaded portion (usually the same as the major diameter of the thread). For pipe threads (e.g. BSP) the nominal diameter is the bore of the pipe and is smaller than the major diameter: in these cases the major diameter is shown in Remarks.
Thread type: treat the information in this column with caution. The original thread angles and truncation have not been measured nor has reference been made to factory drawings to provide entries in this column. Instead, assumptions have been made on the basis of the
diameter and pitch combination, and/or the application, to provide a likely form. Note that ¼ inch x 26 tpi threads are all assumed to be BSF, even though this combination is also found in Cycle series: there is evidence that ¼ BSF was usually specified for Sunbeams even when
otherwise identical fittings on BSA models were Cycle-threaded.
Where a single component has two or more threaded sections of different diameters and/or different pitches, two or more dimensions and/or thread types are given in each relevant column, e.g. ’22 x 18′ pitch, ‘BSF x BSW’ thread type, etc.
Where a component has two threaded sections of identical diameter, pitch and type, only one entry appears in each relevant column. Threads are right-hand, except where stated.
Additional abbreviations
AF: across the flats
c/s: countersunk
CVC: compensated voltage control unit (‘voltage regulator’)
dL: de Luxe
HT: high tension
in.: inches
ISO: International Organization for Standardization
kph: kilometres per hour
lb: pounds
lb.ft: pound-feet torque
LT: low tension
mm: millimetres
mph: miles per hour
no.: number
NPTF: (American) National Pipe Thread, Dryseal
s/c: sidecar
SE: Stewart Engineering
SWG: (British) Standard Wire Gauge
tpi: threads per inch
UNF: Unified Fine thread
Plate 1 part 1
Page 1
Plate 1: Engine, Clutch, Dynamo & Distributor
Part no. Description Quantity Length, in. Diameter, in. Pitch, tpi Thread type Remarks
11 Screw, breather cover 3 ¾ overall ¼ 20 BSW Raised c/s slotted head
14 Screw, rocker tappet 4 5/16 22 BSF
26 Stud, rear rocker bracket 1 ¼ 26 x 20 BSF x BSW Plain washer
27 Spark plug 2 14 mm 1.25 mm ISO metric fine
28 Stud, rocker cover/rocker bracket 3 26 x 22 x 18 BSF x BSF x BSW
29 Stud, front rocker bracket/oil bypass 1 22 x 12 BSF x BSW Drilled for oil feed to rocker shaft. Plain washer
31 Bolt, camshaft, front 1 11/16 ⅜ 20 BSF
32 Stud, camshaft front cover 2 ¼ 26 x 20 BSF x BSW No washer
34 Stud, carburettor 2 5/16 22 x 18 BSF x BSW Spring washer
44
Dynamo: screw, brush earth to yoke 2 9/16 3.2 mm 0.59 mm 5 BA Slotted cheese head. Spring washer
Dynamo: screw, terminal block to yoke 1 ⅝ 4.7 mm 0.81 mm 2 BA Slotted cheese head. Spring washer
Dynamo: screw, terminal in terminal block 2 3.6 mm 0.66 mm 4 BA Brass. Slotted grub screw
Dynamo: screw, ‘kidney piece’ to terminal block 1 4.7 mm 0.81 mm 2 BA Slotted flanged head(?)
Dynamo: screw, pole shoe to yoke 4 ¼ 26? BSF? Slotted c/s head
Screw, dynamo yoke/field coil assembly to crankcase 5/16 18 BSW Slotted c/s head
49 Screw, dynamo cover 2 ½ overall 4.7 mm 0.81mm 2 BA Raised c/s slotted head
59 Screw, air cleaner cover 3 ⅝ ¼ 26 BSF Slotted mushroom head. Plain washer
76 Stud, main, cylinder head 7 ⅜ 20 x 16 BSF x BSW
79 Stud, cylinder head, rear inner, tightening sequence 4 1 2 ⅜ 20 x 16 BSF x BSW Plain washer
80 Stud, cylinder head, rear outer, tightening sequence 9 1 5/16 22 x 18 BSF x BSW Plain washer
12 Screw, breather baffle plate 1 9/32 3/16 32 BSF Slotted fillister head (short). No washer. Plate encloses six gauzes
(50-60 wires per in., SWG 30) over three disk valves
11/16 overall Flatted end: 5/32 in. AF. Reduced locknut: takes ¼ BSF wrench
¼ x 5/16 x 5/16 Special nut (takes ⅜ BSF wrench) and fibre washer above cover
5/16 x 9/16
Special plain thrust washer, ⅛ in. thick, 1¾ in. diameter
37 Exhaust pipe elbow 2 1⅞ 16 Whitworth form? Aluminium alloy. Special coupling nut and split olive. Exhaust pipe
secured to the rear olive by a flanged pin (9/54): not now
regarded as necessary
35 Stud, exhaust elbow 4 5/16 22 x 18 BSF x BSW Brass tall nut, or brass pillar 218 (length 3 in.) for rear screw of air-cleaner cover. Plain washer
Dynamo (Lucas MC45L) (MC45 on some very early bikes): (see also 49 below)
Dynamo: screw, field coil earth to yoke 1 13/32 overall 3.2 mm 0.59 mm 5 BA Brass. Slotted c/s head. Reduced brass nut: takes 6 BA wrench.
Spring washer
17/32 overall
Bolt, dynamo armature to crankshaft 1 3⅞ ⅜ 20 BSF Left-hand thread Reduced flanged head: takes 5/16 BSF wrench.
Spring washer, right helix for left-hand thread
2 3⅜ overall
46 Stud on front engine mounting bracket (‘cobra’) 1 ⅜ 20 BSF Castle nut & split pin. Note flat steel brace plate (45) to front cylinder
head stud (7/64 in. thick)
2½ Tall nut (7/16 in. high), plain washer (except front: see 46)
111/16
Plate 1 part 2
Page 2
Plate 1: Engine, Clutch, Dynamo & Distributor (continued)
Part no. Description Quantity Length, in. Diameter, in. Thread type Remarks
94 Bolt, oil pressure indicator union (96) 1 7/16 14 BSW
99 Adaptor tube, thread to 96, for oil pressure indicator 1 7/16 14 BSW Copper/asbestos washer (not shown on Plate 1)
100 1 ⅜ 20 x 16 BSF x BSW
Pitch, tpi
82 Stud, chain inspection cover & damper plate 6 ¼ 26 x 20 BSF x BSW No washer. Damper plate (138) has horizontal slot with radiused
ends (⅝ in. high x 3⅜ in. overall length) for access to cylinder head
nuts & timing chain. Early engines did not have this slot
83 Stud, cylinder head, side lugs, tightening sequence
10 & 11
2 25/16 5/16 x ⅜ 22 x 16 BSF x BSW Plain washer
86 Bolt, swivel, retaining clip for oil filler cap/dipstick 1 ¾ overall ¼ 20 BSW Special hexagon head. Clip: two curved pieces of spring steel,
lower (longer) one with knob to engage with top of oil filler cap,
upper with dimple to engage in hole in lower piece. Soft leather
washer for cap to engine block. Some caps were extended
downwards with a finned boss to reduce oil splash, and some were
engraved on top with recommended oil brands
87 Stud, distributor & damper plate 2 5/16 22 x 18 BSF x BSW Plain washer. Details of damper plate (138): see 82 (above).
Distributor flange sealed to 138 by O-ring (not shown on Plate 1)
88/89 Bracket, front, short, plug cover support 1 ¼ 26 BSF Late engines only. Captive bolt (89) on bracket takes special plugcover nut (see 93, below)
92 Stud, for plug cover support bracket 2 1
(see Remarks)
5/16 22 x 18 BSF x BSW Shakeproof washer. Early engines had long studs in place of parts
88/89, 92 & 93 (front 21/16 in., rear 2¾ in. long): ¼ BSF x 5/16
BSW, with large plain captive ¼ in. washer, to take special plugcover nut (see 93, below)
93 Bracket, rear, long, plug cover support 1 ¼ 26 BSF Late engines only. Captive bolt on bracket takes special plugcover shouldered nut: slotted, raised & knurled (captive on cover
by swaging)
Takes ⅜ BSW wrench. Outer washer: fibre, inner: copper/asbestos Stud, bellhousing, top 211/16 Plain washer, reduced tall nut (⅜ in. high): takes 5/16 BSF wrench
101 Stud, long, 10 o’clock position, engine end cover (rear main bearing carrier) & chain tensioner blade clip (109)
1 17/16 5/16 22 x 18 BSF x BSW From rear: nut, spring washer, clip, nut, spring washer. Stud 105
used here on early engines with Weller self-adjusting tensioner
Plate 1 part 3
Page 3
Plate 1: Engine, Clutch, Dynamo & Distributor (continued)
Part no. Description Quantity Length, in. Diameter, in. Thread type Remarks
103
1 Brass
Oil pressure indicator, late: screw, electrical terminal 1 ¼ 3.6 mm 0.66 mm 4 BA Brass. Spring washer
1 24 ? Brass, slotted. Locked with split pin in one side of housing
125 Stud, for plug lead insulating block on plug cover 1 3/16 32 x 24? BSF x BSW? Spring washer
128 Bolt, for locking chain adjuster (late engines) 1 ½ ¼ 26 BSF Plain washer
134 Screw, chain adjuster cover (late engines) 2 ¾ ¼ 26 BSF Slotted cheese head. Fibre washer
136 Plug, rocker shaft 1 ¼ ⅜ 20 BSF Slotted end
Pitch, tpi
Oil pressure indicator (early: AC, late: Smiths X 76171-10):
Oil pressure indicator: thread to adaptor (99) or (early engines) direct to cylinder head
1 7/16 14 BSW Copper/asbestos washer. Early engines did not have parts nos 94, 96 & 99: switch was on cylinder head, behind early plug cover with small semicircular lower rebate (later cover has longer rebate, to
clear 99)
Oil pressure indicator, early: stud, electrical terminal
Oil pressure indicator, late: ring securing internals 11/16
Oil pressure indicator, late: adjuster screw 1 3/16 3.6 mm 0.66 mm 4 BA Brass, slotted at both ends, flange with groove for steel circlip (to resist movement). Flange bears on two concentric coil springs
(length approximately 0.3 in.); outer: diameter 0.225 in., 4 coils, SWG
20; inner: diameter 0.137 in., 7 coils, SWG 24
104 Stud, bellhousing, top left & bottom right 2 311/16 ⅜ 20 x 16 BSF x BSW BSW thread: ¾ in. long, with groove for pressure-relief.
Washer & nut as 100
105 Stud, short, engine end cover (rear main bearing carrier) see Remarks
1⅛ 5/16 22 x 18 BSF x BSW Spring washer. Late engines (adjustable slipper chain tensioner):
quantity 5; early (Weller self-adjusting tensioner): quantity 6
107 Pivot, blade, Weller self-adjusting chain tensioner (early engines)
1 15/16 overall
⅜ 16 BSW Tab washer. Pivot section (diameter 5/16 in., length 19/32 in.): plain with circumferential groove for spring, plain tip. Spring: external diameter ⅜ in., length: 213/16 in., length over swivel loops 4⅛ in.,
49 coils, SWG 17, 13 lb/in.
107 Pivot, blade, adjustable slipper chain tensioner (late engines)
1 1⅜ overall
⅜ 16 BSW Tab washer. Pivot section (diameter 5/16 in., length 21/32 in.): plain with flat for lubrication of bush (108), shouldered tip for clip (109)
124 Body, chain tensioner adjuster (late engines) 1 ⅞ 14 Whitworth form? Flats take 7/16 BSF wrench. Fibre washer. Cush spring (113):
external diameter 0.40 in., length 1.0 in., 7 coils, SWG 12. Adjuster
spring (122): external diameter 0.58 in., length 1.31 in., 5½ coils, SWG- Early engines (with Weller self-adjusting tensioner):
threaded plug (as 190) here, in place of adjustable slipper tensioner
Plate 1 part 4
Page 4
Plate 1: Engine, Clutch, Dynamo & Distributor (continued)
Part no. Description Quantity Length, in. Diameter, in. Thread type Remarks
148 Distributor (Lucas D1A2): Distributor: screw, points base plate to body 2 3.6 mm 0.66 mm 4 BA Slotted cheese head. Spring washer
Distributor: screw, rotor drive sleeve to shaft 1 3.6 mm 0.66 mm 4 BA Slotted cheese head. Spring washer
Distributor: screw, points to base plate 2 4.7 mm 0.81 mm 2 BA Slotted cheese head. Plain washer
Distributor: screw, condenser to base plate 1 4.1 mm 0.73 mm 3 BA Slotted cheese head. Spring washer
Distributor: condenser terminal 1 3.6 mm 0.66 mm 4 BA Spring washer
Distributor cap: screw for HT lead 3 ½ 3.6 mm 0.66 mm 4 BA Special slotted cheese head. Length includes spike to secure lead
152 Screw, crankcase cover plate 9 ½ ¼ 20 BSW Slotted cheese head. Spring washer
171 Bolt, camshaft sprocket 1 ⅞ ⅜ 20 BSF
178 Stud, oil pump 2 5/16 22 BSF Castle nut & split pin
184 Plug, oil gallery, end cover (rear main bearing carrier) 3 ¼ ⅜ 20 BSF Slotted end
190 Drain plug, sump 1 ⅞ 14 Whitworth form?
197 Stud, crankshaft 1 2 ⅝ 14 BSF Special short nut: takes 1 in. BSF wrench. Tab washer
202 Plug, crankshaft oil gallery 1 1 16 Whitworth form? Slotted end. Staked by chisel or punch marks
213 Stud, sump 12 5/16 22 x 18 BSF x BSW Plain washer
217 Set pin (screw), crankcase buffer pad 2 ¾ ¼ 26 BSF No washer Pitch, tpi
Distributor: points pillar on base plate 1 3.6 mm 0.66 mm 4 BA Components from base upwards: Bakelite ‘top-hat’ insulator, LT connector, points spring, condenser connector, Bakelite ‘top-hat’
insulator, plain washer, spring washer, nut
Distributor: screw, external LT terminal 1 4.7 mm 0.81 mm 2 BA Brass. Square head (11/32 in. AF). Components from outside
inwards: brass nut, spring washer, tag for coil LT lead, brass nut,
plain washer, Bakelite shouldered insulating washer, body, sheet of
fibre insulation, sheet brass connector to points pillar, screw head.
Distributor, screw, identification plate to body 2 ⅛ 0.115 self-tapping Slotted round head. Tip of screw is truncated, to be approximately flush with inner surface of body
150 Screw with chain stop pin, crankcase cover plate 1 1¼ ¼ 20 BSW Slotted cheese head. Length includes ¾ in. plain extension, diameter
0.175 in. Spring washer
160 Stud, clutch 6 23/32 overall 5/16 22 BSF Shakeproof washers both ends. Nut at flywheel end staked by punch or chisel marks on stud
Reduced flanged head: takes 5/16 BSF wrench
174 Plug, oil pressure release valve 1 ⅝ 14 BSF Takes ¼ BSF wrench. Valve: ⅜ in. ball & spring (diameter 0.32 in.,
length 2 in., 17 turns, wire diameter 0.030 in.)
Takes ⅜ BSF wrench. Fibre washer
208 Bolt, big-end bearing 4 5/16 22 BSF Special bolt and special flanged slotted nut with split pin. Torque:
25-28 lb.ft
27/16
214 Stud, bellhousing, top right & bottom left 2 3¾ ⅜ 20 x 16 BSF x BSW BSW thread: 9/16 in. long, with groove for pressure-relief.
Tubular dowel: external diameter 0.520 in., length 0.475 in. Washer
& nut as 100
Plate 2
Page 5
Plate 2: Gearbox
Part no. Description Quantity Length, in. Diameter, in. Thread type Remarks
8 8 5/16 18 BSW Raised c/s slotted head
10 Stud, detent housing mounting 2 5/16 22 x 18 BSF x BSW
19 Speedo drive body (sleeve) 1 ½ 26 BSB?
21 Screw, speedo drive 2 ½ ¼ 20 BSW Plain washer
27 Stud, inspection cover 2 ¼ 26 x 20 BSF x BSW Special shouldered nut, plain washer
43 Bolt, oil baffle 2 ¼ 26 BSF
53 Stud, gearbox front plate 8 5/16 22 x 18 BSF x BSW Nuts locked in pairs with tab washers
58 2 ½ ¼ 20 BSW Plain washer
66 1 5/16 22 BSF Short nut. Plain washer
71 Stud, kickstart spindle bearing 2 ⅞ ¼ 26 x 20 BSF x BSW Nuts locked together with a tab washer
74 Stop pin, kickstart quadrant 1 ⅜ 20 BSF Special slotted head. Spring washer
77 Bolt, ratchet release 1 ⅝ 5/16 22 BSF Spring washer, rectangular plate (75)
110 Bolt, gear pedal 1 ¾ 5/16 22 BSF
112 Bolt, kickstart pedal 1 5/16 22 BSF No washer
113 Plug, oil level 1 ⅜ 16 BSW
116 Stud, exhaust pipe stay 1 5/16 22 x18 BSF x BSW
120 Drain plug 1 ⅞ 14 Whitworth form?
122 Stud, rear mounting plate 2 ⅜ 20 x 16 BSF x BSW
Pitch, tpi Screw, gearbox sideplate 1⅛ overall
Slotted nut, lockwired. No washer
Brass. Drive-cable nut: non-ferrous, shouldered (takes ⅜ BSF wrench)
Slotted cheesehead, drilled and lockwired. No washer
Screw, bellhousing inspection plate
Stud, camplate
99 Layshaft 1 ½ 16 BSF Special flanged shouldered slotted nut with split pin. Note that the speedometer
driving worm gear (90) is to the rear of bearing 89 (not as shown on Plate 2)
Special reduced hexagon head: takes ¼ BSF wrench. No washer
1⅜
Head: reduced, takes 5/16 BSW wrench; engraved ‘OIL LEVEL’. Fibre washer
Shakeproof washer and two large plain washers
Takes ⅜ BSF wrench. Fibre washer
Two plain and one shakeproof washers. For details of mounting plate see 4/144
124 Stud, layshaft coupling 2 2 ⅜ 20 BSF Locked to coupling by punch marks on front end. Slotted nut and split pin,
spring washer. Late bikes had bolts: see plate 8/27
127 Fulcrum pin, clutch lever 1 1¼ ⅜ 16 BSW Slotted end. Length includes plain extension, length ⅝ in., diameter
0.275 in. Reduced short locknut: takes ¼ BSW wrench
Plate 3
Page 6
Plate 3: Frame & Fittings (boxes, rear suspension, centre stand, S8 saddle)
Part no. Description Quantity Length, in. Diameter, in. Thread type Remarks
7 Bolt, saddle nose, S8 1 ⅜ 26 Cycle
14 Bolt, tool box to frame lug 2 5/16 22 BSF Large plain washer
29 Bolt, battery box to lug on rear mudguard hinge 2 ⅞ 5/16 22 BSF
41 & 42 Battery carrier stud & hinge piece 1 of each ¼ 26 BSF
47 Cap, plunger carrier column 2 ⅞ 20 Cycle Slotted raised head
54 & 74 Grease nipple, straight 2 ¼ 26 BSF
55 Bolt, rear spindle pinch 1 7/16 18 BSF
57 Bolt, rear spindle clamp lug 1 ⅜ 20 BSF Domed nut. Plain washer
68 Bolt, rear suspension bottom clamp, left 1 ⅜ 20 BSF Plain washer
72 Bolt, rear suspension bottom clamp, right, S7dL 1 ⅜ 20 BSF Plain washer
72 Bolt, rear suspension bottom clamp, right, S8 1 ⅜ 20 BSF Plain washer
74 See 54 (above)
Pitch, tpi
4 Bolt, control box & battery box bridge piece to
frame lugs
2 ⅞ 5/16 22 BSF Shakeproof washer. Bridge piece (21): 5/32 in. thick. Note stiffening plate (8)
(3/32 in. thick) linking 4 & 19 inside control box
2½ Shakeproof washer
11 Screw, control box lid 1 1¼ overall ¼ 26 BSF Special c/s screw: head slotted, raised & knurled. Split pin & plain washer to
keep screw captive
15 Stud on inside of tool box wall, to fix lid 2 ¼ 26 BSF Special c/s nut: slotted, raised & knurled with groove for circlip to keep nut
captive (shown as part of tool box lid assembly, 20, on BSA version of Plate 3)
19 Bolt, control box to lug on rear mudguard hinge 1 ⅝ 5/16 22 BSF Reduced short nut: takes ¼ BSF wrench. Shakeproof washer, distance washer
(5/32 in. thick, external diameter ⅝ in.) and stiffening plate (8) (see 4, above)
25 Stud, saddle support lug, S8 2 5/16 22 BSF Two large plain washers. Main springs (SE replica): external diameter 1.95 in.,
length 6 in., 9 coils, SWG 5.
28 Screw, battery box lid 1 1⅝ overall ¼ 26 BSF Special c/s screw: head slotted, raised & knurled. Split pin & plain washer to
keep screw captive
Shakeproof washer and distance washer (5/32 in. thick, external diameter ⅝ in.)
34 Bolt, rear suspension top clamp & mudguard
stay
2 23/16 ⅜ 20 BSF Special head (takes round bar, diameter 5/16 in.) and special nut kept captive
by split pin
38 Screw, battery carrier 4 13/16 overall ¼ 26 BSF Slotted c/s head. Shakeproof washer. Threaded plate (⅛ in. thick, ⅞ in. square;
not shown on Plate 3) on some, between control-box wall and CVC or coil
Secures battery strap (46). Shakeproof washer
13/16 Special head: takes round bar, diameter 5/16 in.
1⅝
60 Bolt, plunger sleeve retaining 1 3½ 7/16 18 BSF Plain washer. Plunger main spring: external diameter 2 in., length 6¼ in.,
12½ coils, SWG 1/0; rebound spring: external diameter 1¾ in., length 6⅛ in.,
15½ coils, SWG 6
1⅝
1⅜
79 Cotter pin, centre stand 2 1⅞ overall ¼ 26 BSF Shank length 1½ in. Plain washer. Note that the cotter pins are inserted so that
their nuts and washers are below the raised stand (not as shown on Plate 3)
Plate 4 part 1
Page 7
Part no. Description Quantity Length, in. Diameter, in. Thread type Remarks
7 Bolt, exhaust pipe stay to exhaust pipe lug 1 ⅝ 5/16 22 BSF Spring washer
15 Bolt, engine mounting plate (top front) 2 ⅞ 5/16 22 BSF
18 Bolt, tank mounting bracket (to frame) 1 ⅞ ⅜ 20 BSF Spring washer
22 & 51 Grease nipple, straight 2 ¼ 26 BSF
51 See 22 (above)
52 Rear brake cross shaft 1 ⅜ 20 BSF Domed nut. Plain washer
54 Bolt, rear brake return spring collar 1 ½ ¼ 26 BSF No washer
57, 86, 90 Grease nipple, angled (90: S7dL only) 2 or 3 ¼ 26 BSF
58 Rear brake pedal fulcrum pin 1 ⅜ 20 BSF
72 See 10 (above)
83 Stud, saddle front bearing, S7dL 1 5/16 22 BSF No washer
86 & 90 See 57 (above)
91 Bolt, saddle fulcrum, S7dL 1 ⅜ 20 BSF Special bolt. Grease nipple (90) in head
94 Stud, saddle height adjusting, S7dL 1 5/16 22 BSF No washer
98 1 7/16 18 BSF
Plate 4: Frame & Fittings (engine mountings, rear brake linkage, propstand, footrests, S7dL saddle etc.)
Pitch, tpi
10 & 72 Bolt, tank support bracket 2 1⅛ ⅜ 20 BSF Special bolt : length comprises plain shank 11/16 in. (diameter 25/64 in.)
and thread 7/16 in. 10 has locknut. Two large plain washers & rubber
pad (7/16 in. thick) above brackets 19 & 39 (not as shown on Plate 4)
Shakeproof washer. See 33 (below) for details of mounting plate
26 Bolt, engine damper 1 1¾ 5/16 22 BSF Shakeproof washer, spring cover (71), conical spring (41) (diameters:
major 0.95 in., minor 0.68 in.; length 1.1 in.; 4½ turns; SWG 12),
special flanged washer (40), flanged tubular distance piece (38), Ferodo
plate (29, sandwiched between 77 and 1/138). Friction plate (77) is
cranked, not flat. Details of damper plate (1/138): see 1/82
33 Engine suspension unit (front mounting rubber),
as 144
1 2⅝ overall ⅜ 20 BSF Length comprises studs 1 in. & ⅝ in. and rubber/steel block 1 in.
(diameter 2 in.). Thick fibre washer (32) between 33 & 34 or between
33 & 31 (⅛ in. thick). Two shakeproof washers. Mounting plate (31)
has three slots, aligned along its long axis (compare 50: see 144 below)
37 Torque reaction buffer (on 1/138) 2 1 overall 5/16 22 BSF Length comprises stud ½ in & rubber/steel buffer ½ in.
Special nut, plain washer
42 Crankcase buffer, frame (front snubber) 2 2⅝ overall 7/16 18 BSF Length comprises stud 1½ in. & rubber/steel buffer 1⅛ in.
Special shouldered locknut, no washer
Flats on pin take ⅜ BSF wrench. Locknut. Shakeproof washer
80 Bolt, long, anchor bracket (damper bracket), top tube 2 1¾ 5/16 22 BSF Shakeproof washer. Two versions of anchor bracket (79/87) were used:
one with buffer plate welded to 87 and the other with the plate separate
85 Bolt, short, anchor bracket (damper bracket), top tube
2 1¼ 5/16 22 BSF Shakeproof washer, two rectangular strengthening plates (76/78, curved
to relieve stress on friction plate 77), distance washer (5/32 in. thick, external diameter ⅝ in.) between 78 and bracket 79 (not as shown on Plate 4). Some drawings show a shakeproof washer under bolt head Eyebolt, seat stay (rear mudguard hinge bolt) 10¾ Special nut (takes round bar, diameter 5/16 in.). Plain washer
Plate 4 part 2
Page 8
Part no. Description Quantity Length, in. Diameter, in. Thread type Remarks
101 Bolt, saddle suspension link, S7dL 1 5/16 22 BSF No washer
104 Spindle, saddle suspension link, S7dL 1 5/16 22 BSF Locknut, no washer
109 Bolt, saddle suspension pushrod, S7dL 1 5/16 22 BSF No washer
115 Bolt, pillion footrest 2 5/16 22 BSF No washer
116 Pillion footrest 2 ¾ 20 Cycle
134 Bolt, prop stand pivot 1 7/16 18 BSF Short head. Short locknut. No washer
142 Bolt, silencer clip to frame 1 ¾ 5/16 22 BSF
147 Bolt, footrest crank pinch 4 5/16 22 BSF Plain washer
151 Screw, brake cross-shaft lever (right) 1 ¾ ¼ 26 BSF
Plate 4: Frame & Fittings (engine mountings, rear brake linkage, propstand, footrests, S7dL saddle etc.) (continued)
Pitch, tpi
1⅜
1⅞
1⅛
Short locknut: takes ⅝ BSF wrench
122 Rear brake rod, short (left) 1 5⅛ ¼ 26 BSF Reduced short locknuts: take 3/16 BSF wrench. Shackle pins, diameter
7/32 in., overall lengths: front (65) ¾ in., rear (123) 1.70 in. (the latter to
provide anchorage for spring to brake light switch)
132 Rear brake rod, long (right) 1 16½ ¼ 26 BSF Length: perpendicular between ends (rod is double-cranked to clear rear of frame, offset approximately 7/16 in.). Locknuts: see 122 (above).
Shackle pins (130 & 151): as 65 (see 122, above)
1¼
136 Bolt, engine mounting bracket (lower rear, 138) to frame lug
2 1 ⅜ 20 BSF Spring washer. Bracket: round hole for mudguard bolt (9/80 or 9/82)
between vertical slots for 136; fore-and-aft slot for suspension unit (144)
Distance washer (5/32 in. thick, external diameter ⅝ in.)
144 Engine suspension unit (rear mounting rubber), as 33 1 2⅝ overall ⅜ 20 BSF Length: see 33. Two plain and two shakeproof washers. Mounting plate
(50) has two round holes and one slot in centre aligned along its long axis
(compare with 31: see 33 above)
1⅛
Reduced head: takes 3/16 BSF wrench. No washer
Plate 5
Page 9
Plate 5: S7dL Front Fork & Yokes
Part no. Description Quantity Length, in. Diameter, in. Thread type Remarks
1 & 37 Fork legs, left and right, stud for mudguard support bridge 4 5/16 22 BSF
8 Screw, fork shroud fixing 6 9/32 3/16 32 BSF
10 Plug, bottom of shaft (stanchion) 2 28 Cycle?
12 Shaft (stanchion), male thread 2
17 Bolt, yoke clip 1 ⅜ 26 Cycle Special head. Special nut. No washer
18 Handlebar bracket, male thread 2 ⅝ 14 BSF Special nut
20 Bolt, handlebar bracket cap 2 5/16 22 BSF Plain washer
25 Plug, fork shaft top 2 ⅞ 20 Cycle Special plain washer
27 Bolt, top yoke shaft clip 2 5/16 22 BSF Plain washer
35 Bottom yoke, thread for adjuster sleeve 1 24 Cycle?
37 See 1 (above)
38 Drain plug, fork leg 2 5/16 3/16 32 BSF
48 Bolt, steering damper anchor plate 1 ⅝ 5/16 22 BSF
50 Bolt, front spindle pinch 1 7/16 18 BSF
Pitch, tpi
1 & 37 Fork legs, left and right, male thread for oil-seal holder 2 1⅞ 28 Cycle? Springs: external diameter 1⅞ in., SWG 5. Solo: length 9½ in., 18
coils; s/c (as S8 solo): length 10¾-10⅞ in., 20½ coils, 30 lb/in.
Shakeproof washer
Slotted fillister head (short). No washer
1⅛ Takes ⅞ BSF wrench. Lower bush: as S8 (see Plate 6/8)
14 Nut, hexagonal, fork shaft: male thread 2 1¼ 18 Takes special round slotted nut (16). Hexagon takes 1 in. BSF
wrench (?)
1⅜
1⅛
22 Steering adjuster sleeve: male thread 1 15/16 24 Cycle? Cover (23) takes ½ BSF wrench. Steering head bearings: ¼ in. balls,
total 40 (not 41 as printed in some BSA parts lists)
1⅜
1⅛
Slotted fillister head (short). Fibre washer
44 Steering damper rod 1 5/16 26 Cycle Bakelite adjuster knob threaded onto top of rod and locked with brass
interference-fit pin. Thackery washer under knob. Special slotted nut
on bottom of rod
Shakeproof washer and two plain washers
13/16 Special head: takes round bar, diameter 5/16 in.(?)
Plate 6
Page 10
Plate 6: S8 Front Fork & Yokes
Part no. Description Quantity Length, in. Diameter, in. Thread type Remarks
11 Bolt, yoke clip 1 ⅜ 26 Cycle Special head. Special nut. No washer
16 Steering adjuster sleeve: male thread 1 24 Cycle?
19 Nut, fork top 2 20 Cycle
26 Bottom yoke, thread for adjuster sleeve 1 24 Cycle?
29 Bolt, bottom yoke pinch 2 5/16 26 Cycle
34 Bolt, steering damper anchor plate 1 ⅝ 5/16 22 BSF
39 See 1 (above)
41 Drain plug, fork leg 2 5/16 3/16 32 BSF
42 Bolt, wheel spindle pinch 1 ⅜ 26 Cycle Spring washer
Pitch, tpi
1 & 39 Fork legs, left and right, thread for oil-seal holder 2 1⅞ 28 Cycle? Springs: external diameter 1⅞ in., SWG 5. Solo: length 10¾-10⅞ in.,
20½ coils, 30 lb/in.; s/c: length 11½-11⅝ in., 19½ coils, 34 lb/in. The part
number of the s/c spring changed early in production, but it is not clear in what
way (if any) the early type differed from the above specification
8 Plug, bottom of shaft (stanchion) 2 1⅛ 28 Cycle? Takes ⅞ BSF wrench. Stanchion: overall length 22½ in., two oil holes. Bushes:
overall length: upper: 2⅛ in., lower: 1¼ in.
1⅜
13 Bolt, handlebar bracket 4 1⅛ 5/16 26 Cycle Reduced raised head: takes ¼ BSF wrench. Reduced plain washer, external diameter 9/16 in.
15/16 Cover (17) takes ½ BSF wrench. Steering head bearings: ¼ in. balls, total 40
11/16 Takes ⅞ BSF wrench. Special plain washer
1⅛
211/16 Shakeproof washer
30 Steering damper rod 1 5/16 26 Cycle Bakelite adjuster knob threaded onto top of rod and locked with brass
interference-fit pin. Thackery washer under knob. Special slotted nut on
bottom of rod
Shakeproof washer and two plain washers
Slotted fillister head (short). Fibre washer
15/16
Plates 7 & 7A
Page 11
Plate 7: S7dL Front Hub & Wheel
Part no. Description Quantity Length, in. Diameter, in. Thread type Remarks
2 Spindle, front wheel 1 ¾ 12 BSF Left hand thread
14 Grease nipple, angled 1 ¼ 26 BSF
17 Brake adjusting cone 1 ½ 16 BSF
21 Bolt, brake adjuster housing 2 1 ¼ 20 BSW
Plate 7A: S8 Front Hub & Wheel
Part no. Description Quantity Length, in. Diameter, in. Thread type Remarks
1 Wheel spindle 1 9/16 20 Cycle. Left hand thread
9 Hub spindle sleeve 1 ⅞ 20 Cycle
10 Grease nipple, angled 1 ¼ 26 BSF
13 Brake fulcrum pin 1 7/16 20 Cycle
25 Brake lever: screw for cable bracket 1 ¼ 26 BSF
27 Brake cam 1 7/16 20 Cycle
29 Bearing retaining ring 1 20 Cycle. Left hand thread
Pitch, tpi
11¼ Special head (takes round bar, diameter 7/16 in.)
6 Lock ring, hub 1 2¼ 16 Whitworth form?
Left hand thread
Locked by ‘C’ spring (SWG 16)
Square end: takes 3/16 BSF wrench
Reduced head: takes 3/16 BSW wrench. No washer
30 & 31 Spoke, short & long, front
& rear wheel
20 of each
per wheel
SWG 7
(see Remarks)
32 Cycle Spoke diameter: SWG 8 (the thread was produced by rolling, resulting in a thread of
larger diameter, SWG 7, taking SWG 7 nipple). Nipple: barrel diameter 0.30 in., flats
¼ in. AF. Rim: 3.00D x 16 in. Offset: ¼ in. from brake drum
Pitch, tpi
8¾ Special head (takes round bar, diameter ⅜ in.)
5¼ overall Shouldered nuts: take ¾ BSF wrench
Reduced short nut: takes ⅜ BSF wrench. Plain washer
Slotted fillister head, locknut (screw, locknut & bracket not shown on Plate 7A)
Reduced hexagon nut: takes ⅜ BSF wrench. Shakeproof & plain washer
21/16
33 & 35 Spoke, short & long 20 of each 7⅝ & 8¾
to inside
of bend
SWG 9
(see Remarks)
40 Cycle Spoke diameter: SWG 10 (the thread was produced by rolling, resulting in a
thread of larger diameter, SWG 9, taking SWG 9 nipple). Bend length (inside,
excluding head) ⅛ in. (short), 3/16 in. (long), angle 75º (all lengths & angle are
approximate). Nipple: barrel diameter ¼ in., flats 0.225 in. AF. Rim: WM2
x 19 in., offset: ⅞ in. from brake drum
Plate 8
Page 12
Plate 8: Worm Drive, Propeller Shaft, Rear Hub & Wheel
Part no. Description Quantity Length, in. Diameter, in. Thread type Remarks
21 4 0.85 5/16 22 BSF Nuts locked in pairs by tab washers
27 2 ⅜ 20 BSF Spring washer. Early bikes had studs and nuts here: see plate 2/124
30,37,81 Grease nipple, straight 3 ¼ 26 BSF
36 Bolt, front universal joint 2 ¾ ⅜ 20 BSF Special shouldered hexagon head. Spring washer
41 1 ½ 16 BSF Slotted nut and split pin
51 Stud, roller bearing housing 4 ⅞ ¼ 26 x 20 BSF x BSW Nuts locked in pairs by tab washers
53 Screw, inspection cover 2 ¾ ¼ 20 BSW
56 Spindle, rear wheel 1 ¾ 12 BSF Left hand thread
62 Brake adjusting cone 1 ½ 16 BSF
64 Bolt, brake adjuster housing 2 1 ¼ 20 BSW
66 6 ¾ ¼ 26 BSF Heads locked in pairs by tab washers
69 & 72 Spoke, S7dL: see Plate 7/30 & 31
71 Grease nipple, angled 1 ¼ 26 BSF
74 Rear brake cam 1 ⅜ 20 BSF Domed nut, plain washer
81 See 30 (above)
85 Stud, end cover 4 5/16 22 x 18 BSF x BSW
87 Drain plug 1 ⅞ 14 Whitworth form?
88 Stud, side cover plate 6 5/16 22 x 18 BSF x BSW All-metal self-locking nut. No washer
Pitch, tpi
6 Lock ring, hub 1 2¼ 16 Whitworth form?
Left hand thread.
Locked by ‘C’ spring (SWG 16)
Stud, wormshaft flange coupling
23 Thread on front of universal joint, for cap
(26)
1 1 26 Cycle? Cap encloses a cork washer and is retained by a special circlip (resembling
incomplete plain washer, thickness 1/32 in., external diameter 61/64 in., internal
diameter ⅝ in., approximately)
Bolt, layrub coupling 1⅝
41 Wormshaft, front thread 1 ⅝ 14 BSF Slotted flanged nut and split pin. Flats on wormshaft (to rear of front bearing)
take 15/16 AF wrench
Wormshaft, rear thread
Slotted fillister head. No washer
12¾ Special head (takes round bar, diameter 7/16 in.)
Square end: takes 3/16 BSF wrench
Special head: takes 3/16 BSW wrench. No washer
Bolt, inner ballrace carrier
69 & 72 Spoke, S8, short & long 20 of each 4¼ & 8
overall
SWG 7
(see Remarks)
32 Cycle Spoke diameter: SWG 8 (the thread was produced by rolling, resulting in a thread
of larger diameter, SWG 7, taking SWG 7 nipple). Bend length (inside, excluding
head): 3/16 in. (short), ⅛ in. (long), angle: 25º (short), 35º (long) (all lengths &
angles are approximate). Nipple: barrel diameter 0.30 in., flats ¼ in. AF. Rim:
WM3 x 18 in., offset: ¼ in. from brake drum
1⅝ Shakeproof washer
Takes ⅜ BSF wrench. Fibre washer
11/32
95 Plug, oil level (not provided on some very
early bikes)
1 1⅛ ⅜ 16 BSW Length includes ⅝ in. plain extension, diameter 9/32 in., to locate baffle 33. Head:
reduced, takes 5/16 BSW wrench; engraved ‘OIL LEVEL’. Fibre washer
Plate 9 part 1
Page 13
Plate 9: Exhaust, Mudguards, Handlebars, Petrol Tank etc.
Part no. Description Quantity Length, in. Diameter, in. Thread type Remarks
4 & 12 Bolt, silencer pinch, rear & front, S8 2 ¼ 26 BSF Plain washer
6 Bolt, clamp for exhaust flexible pipe 2 ⅝ ¼ 26 BSF Spring washer
11 Stud on silencer, to plunger column, S8 1 ⅜ 20 x 16 BSF x BSW Spring washer
12 See 4 (above)
14 Bolt, front stand pivot, S7dL 2 ¾ 5/16 22 BSF Spring washer
15 Bolt, front stand pivot, S8 2 ¾ 5/16 26 Cycle Short locknut. Spring washer
17 Bolt, front mudguard stay to fork leg, S7dL 2 5/16 22 BSF
24 Bolt, front mudguard stay to fork leg, S8 2 ¾ 5/16 26 Cycle Short locknut. Spring washer
32, 39 & 101 Screw, brake cable clip & mudguards to supports 7 ⅝ ¼ 26 BSF
36 Bolt, front mudguard support bridge to fork leg, S8 4 25/32 5/16 26 Cycle
38 Stud on rear of front mudguard for front stand 1 5/16 22 BSF
39 See 32 (above)
41 & 110 Front brake & clutch control levers: pinch bolts 2 ⅝ ¼ 26 BSF
41 & 110 Front brake & clutch control levers: pivot bolts 2 ⅝ ¼ 26 BSF
41 & 110 Front brake and clutch control levers: screws for switches 4 ¼ ⅛ 40 BSW or Cycle? Slotted round head; not shown on Plate 9
43 Adjuster, brake cable, on fork leg, S8 1 ⅜ 26 Cycle Knurled flange and knurled locknut
48 Screw, front numberplate 3 7/16 3/16 32 BSF
49 Screw, front mudguard to support bridge 2 ⅝ ¼ 26 BSF
57 Screw, petrol tank mounting rubber clip 2 ⅝ 3/16 32 BSF
65 2
Petrol tap: nipple, thread to 63 1 per tap ⅛ 28 BSP
Petrol tap: nipple, thread to petrol pipe 1 per tap 3/16 19 BSP
66 Petrol pipe: thread to flexible pipe 1 3/16 19 BSP
68 Petrol pipe, flexible, nut to nipple on float chamber 1 ¼ 19 BSP
Pitch, tpi
1¾
Plain & shakeproof washers
Slotted mushroom head. Shakeproof washer
Reduced head: takes ¼ BSF wrench. Spring washer
Special shouldered nut: takes ⅜ BSF wrench. No washer
Slotted fillister head
Slotted fillister head, fibre-insert short-form self-locking nut
Slotted fillister head (short). Plain washer
Slotted mushroom head. Shakeproof and plain washers
56 Bolt, petrol tank kneegrip plate 4 ½ ¼ 26 BSF Shakeproof washer. Distance washer (5/32 in. thick, external
diameter ⅝ in.) under plate. Washers not shown on Plate 9
Slotted fillister head. No washer
63 Adapter with filter, for tap to petrol tank, male thread 2 ⅜ 19 BSP Brass. Major diameter 0.656 in. Non-standard hexagon: 20 mm
AF wrench a satisfactory fit. Fibre washer
Petrol tap (Enots ‘Concentric’):
Brass. Major diameter 0.383 in. Fibre washer
Petrol tap: nipple, thread to tap body 2 per tap 9/16 26 BSB? Brass. Non-standard hexagon: ⅝ AF wrench a satisfactory fit.
Cork seal (2 per body): diameter (compressed): external
½ in., internal ⅛ in. Operating slide in body, hexagonal end:
‘PUSH ON’, round knurled end: ‘PUSH OFF’
Brass. Major diameter 0.428 in. Nut takes 5/16 BSF wrench
Brass. Major diameter 0.428 in. Nut takes 5/16 BSF wrench
Brass. Major diameter 0.518 in. Takes ⅜ BSF wrench
77 Bolt, silencer fixing, S7dL 1 ⅜ 20 BSF Plain washer and distance washer: 5/32 in. thick, external
diameter ⅝ in.(?)
Plate 9 part 2
Page 14
Plate 9: Exhaust, Mudguards, Handlebars, Petrol Tank etc. (continued)
Part no. Description Quantity Length, in. Diameter, in. Thread type Remarks
80 Bolt, bottom of rear mudguard, S8 1 ⅜ 20 BSF
82 Bolt, bottom of rear mudguard, S7dL 1 2 ⅜ 20 BSF
84 Bolt, rear mudguard stay 4 ¾ 5/16 22 BSF
86 Bolt, late-type fully-enclosed rear numberplate 4 ½ ¼ 26 BSF
94 Reflector, rear: see plate 12/28
101 See 32 (above)
109 1 5/16 22 BSF
110 See 41 (above)
Pitch, tpi
1⅝ Shakeproof washer. Spacer, length 7/16 in.
Shakeproof washer. Spacer, length 13/16 in.(?)
Plain and shakeproof washers
Plain and shakeproof washers
104 Stud, petrol tank 4 ⅞ 5/16 22 BSF Length of threaded section inserted to tank: ¼ in. Shakeproof
washer. Left studs carry brackets (105 & 107) for tyre inflator
Adjuster, clutch cable, on gearbox sideplate Adjuster & locknut take ¼ BSF wrench
114 Bolt, pillion seat 4 ¾ ¼ 26 BSF Plain washer. Main springs (SE replica): external diameter 1⅞ in.,
length 1¼ in., 4½ coils, wire diameter 0.20 in.
Plate 12 part 1
Page 15
Part no. Description Quantity Length Diameter Pitch Thread type Remarks
1 Ignition coil (Lucas Q6, CQ or CQ6):
Ignition coil: stud, LT terminal 2 4.7 mm 0.81 mm 2 BA
Ignition coil: screw securing end cap to body 1 ⅜ in. self-tapping
2
Speedometer: stud for mounting 2 6 mm 1.0 mm metric Nut: 11 mm AF. Spring washer
Speedometer: boss for lamp-holder nut 1 16 mm 1.0 mm metric Brass. Knurled brass nut, rubber washer
Speedometer: screw, angle drive to case 2 8 mm 3.5 mm 0.7 mm metric
Speedometer: angle drive, thread for drive-cable nut 1 12 mm 1.0 mm metric Zinc(?) alloy. Knurled non-ferrous nut
Speedometer: bezel 1 80 mm 0.9 mm metric Brass. Rubber washer
4 CVC (Lucas MCR2):
CVC: screw, small, cable clamp 1 3.6 mm 0.66 mm 4 BA Slotted cheese head
6 Dipper switch (Lucas 99, 31220) Cables soldered to terminals. For screws to clutch control lever see Plate 9/41
7 2 4.7 mm 0.81 mm 2 BA Brass. Two brass nuts, spring washer
9 Headlamp (Lucas MS142) & warning lamps (Lucas WL3/1):
Headlamp: screw, headlamp bulb clamp 1 ⅛ in. self-tapping
Headlamp: bolt to fork shroud 2 1 in. Cycle Raised hexagon head. Large plain washer, external diameter 0.8 in.
Plate 12: Electrical Equipment & Speedometer (except distributor, dynamo & oil pressure indicator switch: see Plate 1)
Brass. Shakeproof washer, brass nut
Ignition coil: screw, HT terminal 1 ½ in. 16 tpi BSF? Bakelite. Tubular with ridged end for hand-tightening. Secures core of
HT lead with brass split washer
21/32 in.
Speedometer (Smiths Chronometric 120 mph or 180 kph): (85 mph version may have been used on some very early bikes)
Slotted hexagon head (6.5 mm AF), shakeproof washer
CVC: screw, large, cable clamp 1 ½ in. 4.7 mm 0.81 mm 2 BA Length includes plain shank, diameter 7/32 in., length 3/16 in. Captive in clamp,
by swageing. Slotted cheese head
7/16 in.
Ammeter (Lucas CZ27 or CZU27): stud, terminal
5/16 in. 26 tpi
Warning lamp: bezel for lens 1 21/32 in. 26 tpi? BSB? Brass. Rubber washer. Lenses: red for dynamo charge (ignition) (left lamp);
green for oil pressure (right)
Warning lamp: screw, central terminal 1 ⅞ in.
overall
3/16 in. 40 tpi ? Brass. Hexagon (inside lamp body) takes 5 BA wrench. Components, from
body outwards: thin shaped fibre insulator, side terminal, fabric insulating disk,
Paxolin washer, brass nut, spring washer & brass nut for cable tag
Warning lamp: screw, side terminal 1 15/64 in. 3.2 mm 0.59 mm 5 BA Brass. Slotted fillister head. Spring washer. Some versions had no screw:
cable was soldered directly to side terminal
Plate 12 part 2
Page 16
Part no. Description Quantity Length Diameter Pitch Thread type Remarks
10
Horn: screw, terminal 2 4.7 mm 0.81 mm 2 BA Brass. Slotted hexagon head
Horn: screw, cable clamp 1 3.6 mm 0.66 mm 4 BA Slotted cheese head
Horn: stud, short, for clamping-ring (bezel) 4 ⅝ in. 5.3 mm 0.90 mm 1 BA
11 Ignition & lighting switch (Lucas PLC6, 34057):
Ignition & lighting switch: screw, terminal 5 4.7 mm 0.81 mm 2 BA Brass. Slotted grub screw
Ignition & lighting switch: screw, central pivot 1 3.2 mm 0.59 mm 5 BA Nut locked by soldering
17 1 3.6 mm 0.66 mm 4 BA Brass. For screws to front brake control lever see Plate 9/41
23 Bolt, stop-lamp switch & horn brackets to frame lug 2 ⅝ in. ¼ in. BSF
2 4.7 mm 0.81 mm 2 BA Brass. Slotted grub screw. Switch was fitted originally to late bikes only
27 Screw, stop-lamp switch to bracket 2 7/16 in. BSF
Rear lamp, Lucas 525 & 564: stud to numberplate 2 4.7 mm 0.81 mm 2 BA Shakeproof washer
Rear lamp, Lucas 525: screw for lens 2 ⅞ in. 4.7 mm 0.81 mm 2 BA Brass. Slotted round head. Thin plain Paxolin(?) washer and rubber washer
Plate 12: Electrical Equipment & Speedometer (except distributor, dynamo & oil pressure indicator switch: see Plate 1) (continued)
Horn (Lucas Altette HF1234):
Horn: stud, long, for clamping-ring (bezel) and
mounting to bracket
2 15/16 in. 6.0 mm 1.0 mm 0 BA Front: brass acorn nut, ⅜ in. AF. Rear: spring washer and nut (⅜ in. AF) to
bracket. Rear of stud is slotted
Brass acorn nut, ⅜ in. AF
Horn: nut, tone disc (front cover) 1 or 2 9/16 in. 32 tpi ? Domed brass nut and on most versions a shouldered brass locknut: both take
7/16 BSF wrench
Ignition & lighting switch: screw, spring clip for
mounting to control box lid
1 ⅜ in. 3.2 mm 0.59 mm 5 BA Slotted cheese head. Nut but no washer
Horn push (Lucas 4A, 76206): screw, terminal
26 tpi Shakeproof washer
25 Stop-lamp switch (Lucas 54C, 31281 or 22B,
031445): screw, terminal
3/16 in. 32 tpi Slotted fillister head (short). Spring washer
28 Rear lamp (Early S7dL: unbranded special. Early S8 and possibly some S7dL: Lucas MT211, 052304. Later bikes: Lucas 480 or 477 followed by 525 and finally 564. Lucas
477, 525 & 564 incorporated a stop lamp, and 564 an integral reflector. Where a separate reflector was provided, Lucas RER5 was used: plate 9/94. On most bikes a version,
probably 57048, was fitted in a hole at the bottom of the rear numberplate as a grommet. On very late bikes version 57052 was fitted by a conventional screw):
Carburettor
Page 17
Carburettor
4/241 Screw, body cap retaining spring 1 ¼ 3.2 mm 0.59 mm 5 BA Slotted fillister head
622/086 Screw, mixing chamber & float bowl 4 9/16 4.7 mm 0.81 mm 2 BA Pozidriv fillister head. Waisted, to hold spring washer captive
622/078 Bolt, banjo 1 ⅜ 26 BSB or Cycle?
372/4 Air lever:
Air lever: screw, handlebar clamp 2 9/16 5.3 mm 0.9 mm 1 BA Slotted fillister head
Burlen/Amal
part no.
Description Quantity Length, in. Diameter, in. Pitch, tpi Thread type Remarks
Original carburettor (Amal 276: DO/3A, 15/16 in. Main jet: 150. Needle jet: 107. Needle clip position: 2 from top. Slide: no. 3 cutaway)
1A Intake nipple, float chamber bottom 1 ¼ 19 BSP Brass. Major diameter 0.518 in. Brass locknut: takes ⅜ BSF
wrench. Fibre washer
Stewart Engineering Concentric carburettor (Amal 600 Mark 1: 624 R, 24 mm right-handed. Main jet: 140. Needle jet: 4-stroke, 105. Pilot jet: 0.016 in. fixed bush without a screw-in jet.
Needle: 4-stroke, 2 identifying grooves above clip grooves. Needle clip position: 2 of 3. Slide: no. 2.5 cutaway. Spray tube: standard 4-stroke, not angled or cut away. Some late versions
were stamped 622 R, but were bored out to 24 mm).
376/ Banjo, to float bowl 1 ¼ 19 BSP Zinc(?) alloy. Major diameter 0.518 in. Later versions
have spigot for flexible tubing instead of male thread
Takes 5/16 BSF wrench
4/035 Adjuster screw, cable 2 ½ 7/32 38 Hexagon head: 9/32 in. AF (takes 3 BA wrench). Locknut:
11/32 in. AF (later versions 5/16 in. AF)
Air lever: screw, pivot 1 15/32 5/16 26 Cycle Slotted fillister head (short). Components from top: cover, lever,
wave-spring washer, base
Modifications
Page 18
Modifications & Sidecar Mountings
Equivalent part no. Description Quantity Length, in. Diameter, in. Pitch, tpi Thread type Remarks
Some Stewart Engineering Modifications (for Stewart Engineering 600-series carburettor see previous sheet)
Plate 1/11 Screw, Stewart Engineering modified breather cover Slotted cheese head
1/190 Drain plug, Stewart Engineering finned sump ⅜ 19 BSP
1/213 Stud, Stewart Engineering sump extension
1/44 Dynamo: screw, field set to crankcase
Plate 2/8
2/- Bolt, Richard Turner’s modified clutch linkage (above) 1 5/16 22 BSF Plain copper washer
Plate 10/26 Dual seat base, female threads, Stewart Engineering kit 5 5/16 24 UNF
Sidecar Mountings
Rear upper 1 ⅜
1⅛
1/28 Stud, rocker cover/rocker bracket Washer of copper/asbestos (instead of fibre) was supplied by
Stewart Engineering for many years, for improved sealing
1/103 Adaptor, Stewart Engineering, for modern oil-pressure
indicator switch
7/16 14 BSW Female thread for switch: ⅛ NPTF (27 tpi, major diameter
0.407 in.)
1/188 Screw, strainer to baseplate, Stewart Engineering
modified sump strainer (filter)
42 mm 4 mm 0.7 mm ISO metric
coarse
Posidriv head, self-locking nut (nylon insert), plain washer
Major diameter 0.656 in. Takes ½ BSF wrench
3⅜ Extension thickness ⅞ in.
1/218 Pillar, exhaust-elbow stud to air-filter cover, Stewart
Engineering longer version for 624 carburettor
3½ overall Brass
Stewart Engineering socket-head screw: takes 7/32 Allen key
Screw, gearbox sideplate Stewart Engineering socket-head screw: takes 3/16 Allen key
2/- Adjuster rod, Richard Turner’s modified clutch linkage
(now Stewart Engineering part no. 2/140)
1 104 mm 6 mm 1.0 mm ISO metric
coarse
Three plain copper washers
1½
Plate 9/52 Exhaust pipe coupling nut, Stewart Engineering
hexagonal alternative
60º profile? Thread pitch as original, profile probably differs: 60º(?) rather
than original 55º Whitworth(?)
Front upper 1 ⅝ 20 Cycle Special eyebolt (eye diameter ⅞ in.) with 20º tapered shank
(major diameter 1⅛ in.) to lug under headstock . Some versions
of the bolt had a split clamp instead of an eye. Nut takes 9/16 BSF
wrench. Spring washer.
Front lower 1 Special nut (with eye: diameter ⅜ in.) replaces locknut on front
snubber (4/42). For a stronger alternative use a clamp to the
frame downtube (diameter 1¼ in.)
Bolt through head of seat stay (mudguard hinge) eyebolt (4/98)
Rear lower 1 ¾ 20 Cycle Stud, eyebolt or ball-and-socket joint, in pillion footrest lug.
Locknut required
7/16 18 BSF
Hexagon sizes
Page 19
Hexagon Fastener Dimensions
Nominal size
6 BA 0.193
5 BA 0.220
4 BA 0.248
3 BA
2 BA 0.324
1 BA
0 BA
0.344
0.445
0.525
0.600
0.710
0.820
1.01
1.20
1.30
1.48
Note: Wrenches for BA and Whitworth-form (BSF, BSW) hexagonal-headed fasteners are usually
marked with the nominal size or diameter of the fastener, not the dimensions of the hexagon.
Wrenches for Unified and ISO Metric fasteners are usually marked with the width across the flats (AF) of the hexagon
Width AF, in. (for clearance for wrench jaws add 1.0 ±0.3 %)
0.282†
0.365†
0.413†
†hexagon size not found on Sunbeam S7dL or S8
3/16 BSF, ⅛ BSW
¼ BSF, 3/16 BSW
5/16 BSF, ¼ BSW
⅜ BSF, 5/16 BSW
7/16 BSF, ⅜ BSW
½ BSF, 7/16 BSW
9/16 BSF, ½ BSW 0.920*
⅝ BSF, 9/16 BSW
11/16 BSF, ⅝ BSW 1.10*
¾ BSF, 11/16 BSW
⅞ BSF, ¾ BSW
1 BSF, ⅞ BSW
1⅛ BSF, 1 BSW 1.67*
1¼ BSF, 1⅛ BSW 1.86*
*hexagon size not found on Sunbeam S7dL or S8, but may be encountered on sidecar fitting
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