Size of nut

I've never found any difference between Japanese and European metric threads. As far as I know they all comply with the same standard thread form.
Click to expand...

Then your in a different part of the world other then Canada where all European Metric thread profiles are different from Japanese Metric thread profiles.

Not saying Metric is NOT Metric.

I've noticed that STD Japanese Metric Treads are coarser then STD  European Metric Threads.

Just compare Lucas Bar Contol bolt threads to Japanese Bar Control fittings or any Breganzie 10mm Engine Cover Plates.

The Metric Threads DO NOT match.
 
Ron.....im in Winnipeg ...8 hours west of you. If you go to a local hardware store or have some Japanese bike bolts laying around many of the thread pitches will be different than same size diameter  Laverda bolts.  My local specialty shop has many  but not all metric fasteners used on Laverdas in different pitches needed. The good news is Wolfgang  has all the right bolts etc for Laverdas and he is  just  a few days by  mail if I need something I can't get local.  Good old imperial fasteners used  on our  Noorth American built older vehicles...either fine or course thread ...simple and available anywhere back in the day.
 
Yes, metric is metric.  There is metric coarse and metric fine, both are metric but it's no different to UNC vs UNF, they are members of the same system used for different purposes.  Japanese and Europeans might tend to use one or the other for a particular purpose but they're all to the same standard.  There is also metric extra-fine, just as there is UNEF in the ANSI standard as one example of many.

Where they do differ (and it IS bloody annoying!) is things like bolt head sizes, but that is because the bolts are made to differing DIN, ISO, ANSI, JIS, etc standards.  The thread form is the same, but for example an M10 hex head is most commonly a 17mm hex but can also be 16mm and it's quite common to find 14mm hex M10's (particularly flanged head bolts) on Japanese bikes and probably other sizes too.  But a DIN931 will always be 17mm, as will JIS1180, but a JIS1189 will be flanged with a 14mm hex.

These different bolt styles are used for various reasons, the most common is possibly designers humour/schadenfreude thinking of the joy they will bring to home mechanics the world over.  :LOL:
 
I think the 'Japanese Thread' lore simply comes from the fact that Japanese Engineers are (were?) generally more willing to specifying metric-fine when it would be the preferred solution. Thus we see more of a thread mixture on Japanese stuff. Others would avoid fine where possible and spec the ubiquitous coarse.
 
my engineer son tells me that course or fine is not used to identify thread forms, it should always be identified by the pitch.
ie
M10x1.50
M10x1.25
M10x1.00
M10x  .75
so which one is course or fine?

M18 can have seven different pitches.

commonly used, he admits, understood by most, he says, but actually not correct
CLEM
 
Who would have thought that 40 year old Lucas switchgear screws were metric....
 
CLEMTOG said:
my engineer son tells me that course or fine is not used to identify thread forms, it should always be identified by the pitch.
ie
M10x1.50
M10x1.25
M10x1.00
M10x  .75
so which one is course or fine?
Click to expand...
M10x1.50 is ISO Metric coarse.
The other three are ISO Metric fine.

As your son says Clem, just measure the pitch with a thread guage if there is any doubt.
 
Brake systems on Japanese bikes tend to have M10 x 1.25 threads on the banjo bolts etc. European (eg. Brembo) are more likely to be M10 x 1.0.  Both are standard metric threads though.
 
Grant said:
Who would have thought that 40 year old Lucas switchgear screws were metric....
Click to expand...

Don't think so.  Several imperial and metric threads "overlap", some with ease, some with a little "persuasion". :D  The ones I have are a quite coarse imperial thread, BA?  Maybe the Sparx repros have metric threads. ???

After securing the french Jaeger patents sometime in the 1920/30's, Smiths instruments used metric throughout.

piet
 
You must log in or register to reply here.
Back
Top