Metric bolts are not the same anymore

  • Thread starter Thread starter silvo
  • Start date Start date
sfcpiet said:
They never have been.  Lots of changes to the DIN norm has seen all sorts of hex heads mated to different thread diameters.  M5 used to be 9mm, now 8.  M8 used to be 14, now 13(normally). :D

The automotive industry changes standard bolt head and nut sizes to accomodate their needs.  Lots of M10 bolts currently used have a 15 or 16mm hex.  Find these very often on german cars, things are conconstantly getting tighter under car bodies...  Japanese standard for M8 is 12mm, M10 is 14mm.  Quite useful on a bike most times because of limited accessability.

What really pisses me off is that many imperial bolts require a 17/32" spanner, which is all but impossible to get over here!

piet
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Why don't you just use your 13.45mm spanner ?

  Keith
 
totally agree, if you work on bikes and cars full time you soon get to know that there is no actual standard
it is up to the manfacturer and their needs on that particular part

example, Dellorto float bowls went from 17mm spanner to 14mm spanner, or was that the other way round, never bothered to take notice seeing I refuse to touch the damn things, Mark will know
:D

there are normally 3 x 12mm hex head nuts x 8mm threads on a Laverda engine while the rest of the 8mm nuts are 13mm hex nuts, explain that one  :o
I say normally as quite often they have been long lost or changed

no prize for the first to identify which 3 nuts we are talking about


 
laverdakeith said:
Why don't you just use your 13.45mm spanner ?

  Keith
Click to expand...

I do! :D 

I have modded a 13mm open spanner to fit, but it seems it was a bit dodgy from the start, no real confidence in it.  And I prefer working with ring spanners when at all possible, not going to the trouble making one of those.

But it is stretching my luck a bit sometimes, always anticipating a seriously rounded head.  Not always possible to use a 6-point socket either.  Lack of imperial dies means I'll need to completely machine any bolts I knacker, makes a simple substitution a real pita.

Sorry, shifters are ok for anything over 40mm... but then they are rarely up to the job.

Red,

The 12mm hex at the front of the cam chain tunnel is used because of the limited space. Same at the starter motor, the 3rd. eludes me at the moment. :D

The Dellorto change from 14 to 17mm was probably a reaction to the millions of rounded 14mm nuts.  Lots more difficult to butcher the later 17mm nuts, but not impossible!  ::)

piet
 
Yep.

Lots of room there for a 13mm hex though. 

Probably easier for Luigi to grab into only 2 boxes instead of 3 for fitting the outer nuts.

piet
 
sfcpiet said:
The 12mm hex at the front of the cam chain tunnel is used because of the limited space. Same at the starter motor, the 3rd. eludes me at the moment. :D
The Dellorto change from 14 to 17mm was probably a reaction to the millions of rounded 14mm nuts.  Lots more difficult to butcher the later 17mm nuts, but not impossible!  ::)
piet
Click to expand...

I knew the answer and you were not supposed to reply, question was for the masses, not the experts  :(

 
I got a box of old imperial spanners originally used for adjusting machinery in a local paper mill.
Some of them have got striking pads on one end.
Incredibly hard material to grind to size but solid starting point for odd sizes.
 
silvo said:
I'm after high tensile but I wonder if stainless is the same?
Click to expand...

No, definately not. Stainless Steel is a lot weaker than HT so beware of St Stl in applications where it's important - brakes for example.
 
You could of coarse use HT Stainless. My bolt supplier does A2, A4 and HT in SS
 
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