Re: metric fasteners

["Jacob Haagerup" <alfakroehl@domain.elided>]

John Hertzman quoth:
>
I had made a cavalier assertion that "There are very few 8 x 1.25 mm nuts on
an Alfa or in an Alfa parts-pile - at my last count about a dozen, with four
different part numbers, on a 2000", and Dana countered with (other than the
engine) "Elsewhere on the car, however, most nuts, bolts and studs use
standard metric threads--1.25 thread pitch for 8 mm fasteners.  This size is
readily available from hardware stores and import-oriented parts vendors.". 
I
assume he is right, and I undercounted both on the absolute number and the
number of different ones. Skipping one which is probably a typo (listed in
different places as an 8 x 1 and as an 8 x 1.25) I count thirty-nine 8 x 
1.25
mm nuts on a 2000 with seven different part numbers - 2120.15046, 
2120.15104,
2120.20054, 2120.20149, 2120.92874, 2125.15046, and 2125.20078. One is
probably an elastic stopnut, another is in the exhaust system and may be
corrosion-resistance-oriented, and probably the hardware store generic 8 x
1.25 would do for all in a pinch, but the implication of nuanced design
rationales goads my curiosity. It is probably less rational than the Spica
injector interference case.
<snip>

One very notable exception to the standard metric fasteners are the bolts 
which connect the rear drive shaft section to the front section and the 
diff. (well - notable if you have ever tried to obtain any of those).

My then drive-shaft shop tried convincing me that they were in fact SAE 
bolts (or at least imperial in measurement) while I kept maintaining that I 
saw absolutely no reason why Alfa Romeo should use non-metric fasteners on 
their cars in 1975.

Turns out that those bolts aren't exactly DIN either since they are 9 mm (on 
the GTV 2000 and contemporaries at least) with a fine pitched thread.

Thing is that within the DIN system there is no such thing as a 9 mm bolt.

That's the reason why you have to order those bolts through your friendly 
Alfa Romeo parts supplier - at significant cost as bolts go.

Regards

Jacob Haagerup,
'75 GT 1600 Junior 'M'
Rotterdam, Netherlands


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