Whitworth or SAE?

radiofun · Jul 1, 2012

Is it true that the Commando engine and transmission were built with Whitworth fasteners while the rest of the bike the fasteners are SAE? Or are some fasteners British Standard?

Rohan · Jul 1, 2012

Yes, the engine and gearbox use whitworth fasteners - most are actually cycle thread (26 tpi, also called CEI). Require whitworth wrenches.
And the cycleparts are all (?) SAE.

But at some point, some of the engine fasteners at least bacame SAE - shown by the two little circles stamped into them.

L.A.B. · Jul 1, 2012

radiofun said:
Is it true that the Commando engine and transmission were built with Whitworth fasteners while the rest of the bike the fasteners are SAE? Or are some fasteners British Standard?

Some SAE (actually Unified) threads were also used in the engine from the outset, more being introduced 1972-on (barrel base studs and nuts changed to SAE [Unified], for instance) and some cycle part threads remained BS (not necessarily Whitworth) so each particular fastener's thread type has to be identified.

radiofun · Jul 1, 2012

Sounds like the use of all different thread types on the bike is a reflection of the disorganization occurring at the corporate level. 40+ years later it sure makes it interesting.

lbridges · Jul 1, 2012

Not to mention the 2BA threads in the points section, or perhaps the metric parts for brakes.

I've used more variety of tools on my Norton than any other vehicle I've worked on.

pete.v · Jul 1, 2012

I have one whitworth wrench (3/16 BSW) for the center rear head nut. Usage of 6 rather than 12 point sae and metric wrenches and sockets enable me to do absolutely everthing alse.

Rohan · Jul 2, 2012

L.A.B. said:
Some SAE threads were also used in the engine from the outset,

Name an SAE thread location in an early Commando's engine ??

Rohan · Jul 2, 2012

lbridges said:
Not to mention the 2BA threads in the points section, or perhaps the metric parts for brakes.
I've used more variety of tools on my Norton than any other vehicle I've worked on.

I wouldn't dispute that, for a minute.

But have a GM car that was transitional in converting from SAE to metric - the engine is all SAE, and the chassis is all metric. Two wholly different tool sets...

marston rhode · Jul 2, 2012

Rohan said:
L.A.B. said:

Some SAE threads were also used in the engine from the outset,

Click to expand...

Name an SAE thread location in an early Commando's engine ??

Primary chaincase screw, to name but three. 1/4" UNC

Rohan · Jul 2, 2012

L.A.B. said:
Some SAE threads were also used in the engine from the outset,

Rohan said:
Name an SAE thread location in an early Commando's engine ??

marston rhode said:
Primary chaincase screw, to name but three. 1/4" UNC

How do you know its UNC (SAE), and its not whitworth threadform 1/4". ??
Like the timing cover screws.
Neither of which would then be SAE in any respect....

Rohan · Jul 2, 2012

P.S. Atlas engines have 3 screws in behind the primary case for the alternator housing bizzo, which are 1/4" whitworth (I think, at least 1/4 whitworth fits), So does 1/4" UNC, but Atlas engines weren't made with Unified Threads, at all, ever (??).

L.A.B. · Jul 2, 2012

Rohan said:
L.A.B. said:

Some SAE threads were also used in the engine from the outset,

Click to expand...

Name an SAE thread location in an early Commando's engine ??

Clutch pushrod adjuster and nut, for one (or is that two? or three if you count the spring centre thread?) = 1/2" UNF.

Rohan · Jul 2, 2012

Fair enough - the clutch was a new component for the Commando, so would not have had any cycle thread ancestors to carry over with.

The fancy nut in the centre, holding the alloy primary chaincase on is AF too ?
(The alloy primary chaincase is also new for the Commando, although the P11 etc had a similar but different chaincase...)

L.A.B. · Jul 2, 2012

The stator retaining nuts were 060700 '68-on which is 5/16" UNF (therefore the corresponding 060386 stud thread must be UNF).

"060700 NUT 5/16"UNF - STATOR STUD"

'68-on chaincase centre stud nut - 060397

"060397 NUT 3/8"UNF (NYLOC)"

http://www.nortonmotors.de/ANIL/Norton% ... e-list.php

Engine sprocket extractor threads - 5/16" UNF

marston rhode · Jul 2, 2012

Rohan said:
How do you know its UNC (SAE), and its not whitworth threadform 1/4". ??
....

I just KNOW, is all

And the early (pre 200000) timing cover screws are whit form.
Any thread specific to the Commando engine when it was converted from an Atlas is UNC or UNF; design office rule.

dynodave · Jul 2, 2012

:mrgreen:

marston rhode · Jul 2, 2012

dynodave said:
but the 1/4-20 rocker cover screw on the unchanged head...whitworth threads use a whit wrench not 7/16. Yes the 850 head was "new" but the machine it was machined on was probably the original, and didn't warrant a new tap size.
Significant changes on the engine got new sae hardware such as the cylinder base studs/nuts. and 72/73 combat got 3/8-16 drain screws with 9/16 wrench.

The 750 head was not a good example to choose - because it really was new for the Commando. The three cap head screws for the head steady had 5/16" UNF threads, the head drawing was new, so it has an 06-.... number. The 850 head had a new number because it had machining differences but not thread-type changes from the 750.
The 200000-on crankcases (the ones with the cast breather elbow at the back) were completely different to the previous version; new drawings, new castings and new machining with UNC/UNF threads throughout.
There was a certain logic to it all, but difficult to support these days.

L.A.B. · Jul 2, 2012

marston rhode said:
The 750 head was not a good example to choose - because it really was new for the Commando. The three cap head screws for the head steady had 5/16" UNF threads, the head drawing was new, so it has an 06-.... number.

The original part number for the three 5/16" head steady screws was NM19437.

The later part number was 06-7745, however the screws were always 5/16" - 22 BSF.

Andover Norton - CAP SCREW - 5/16

CAP SCREW - 5/16

andover-norton.co.uk

"SCREW NM19437
Part Number: 067745"

http://www.norvilmotorcycle.co.uk/cylhead.htm
" 067745 - SCREW - HEAD STEADY - SOCKET - SET OF THREE - 5/16" x 3/4" BSF"

dynodave · Jul 2, 2012

marston rhode · Jul 2, 2012

L.A.B said:
The later part number was 06-7745, however the screws were always 5/16" - 22 BSF.

I bow to your superior knowledge

Whitworth or SAE?

radiofun

Rohan

L.A.B.

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radiofun

lbridges

pete.v

Rohan

Rohan

marston rhode

Rohan

Rohan

L.A.B.

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Rohan

L.A.B.

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marston rhode

dynodave

marston rhode

L.A.B.

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Andover Norton - CAP SCREW - 5/16

dynodave

marston rhode

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