How to use and decode Nissan part numbers for hardware (fasteners, etc.)

richiep

richiep

Club Member
This is a “How To” thread based on a journey I’ve been undergoing recently as I begin organising my parts pile for the rebuild of my project car once exterior paint is done (I’ve already made a start underneath and inside the shell).

You may find yourself, if doing a full or partial resto or refresh with a big pile of bolts, washers, nuts, etc., with various subtle variations in lengths, heads, and markings, leaving you at a loss as what is supposed to go where and attach what. This is especially the case if you’ve had everything replated in bulk. Now I was fairly diligent in making a file of faster/hardware specs and locations as I dismantled Project Dixie, given it was a very tatty, but very original CA car. Still, I had a lot of extra hardware replated in addition to what came off the car (thanks to inheriting a large crate full from Pmac when he powered down his Z angle grinder…). Some bits and bobs also don’t get fully accounted for, so I had to get researching.

If you want to build a Z with the correct fasteners in the correct locations there are two resources on the web you need (unless you have hard copy equivalents available).

1) The S30 parts manual/s. The best online option for this is here:
www.carpartsmanual.com

Datsun 240Z/260Z/280Z (S30) Parts Manual

Exploding parts diagrams and listings for the 1969-1978 Datsun 240Z, 260Z & 280Z model S30 series.
www.carpartsmanual.com
This allows you to search all the exploded diagrams and gives you all part numbers. However, it doesn’t tell you specifics of, say, a particular bolt, e.g., M8x16, medium tensile strength, zinc plated, etc.

However, Nissan’s part numbers can be decoded to tell you exactly that. Leading me to resource..
2) http://datsun1200.com/modules/mediawiki/index.php?title=NES_Part_Numbers

The section relevant to Z cars begins at the section headed Metric.
The part numbers as presented in the parts manual break down into specific bits of information, allowing you to work out what fasteners are needed where.

EXAMPLE: 08120-61210 BOLT
0 standardization digit (starting ~1968)
8 Nissan Engineering Section prefix
1 Bolt
2 bolt type: Hexagon bolt, #Medium carbon steel
06 #Dimension Digits: =6mm (M6)
12 #Length Digits: 12mm
10 #Suffix digits: no special finishing

One of the other interesting bits is under the heading Strength. You may have noticed that many of the bolts used on Zs having ‘4’, ‘7’, or ‘9’ on the heads. These relate to the JIS (Japanese Industrial Standard) strength classification from low carbon steel (4 or blank), medium carbon steel (7) of high carbon steel (9). The table on the 1200 website gives the MPa for each. It basically allows you to work out torque specs without needing the service manual, Haynes manual, etc.

So, for that bolt example above, the code reveals it to be an M6x12mm hex bolt with a ‘7’ on the head (zinc plated).

Read through the Datsun 1200 site write-up as it is valuable if wanting to build things correctly rather than just slap a load of nuts and bolts from Screwfix on your cars!
 
I

Ian Patmore

Well-Known Forum User
Mr Tenno said:
They're almost always JIS/Metric fine
Click to expand...

No. On the S30 its a mixture, partly where the bolt/nut/threaded screw goes on the car leads you. A bolt on the suspension is likely to be a 1.5 or 1.75 pitch, whilst a bolt holding a inner wing on is probbaly a M6 x1.0. Probbaly on the carbs even finer threads, say 0.75.

Courser threads usually for meater jobs (e.g. holding suspension, gearbox to engine bolts), bolts that require tight, with some less likely to require a torque setting , say the M6, whilst finer on fixing that a lot of turns means something (say the likes of a idle adjustment screw.)

No doubt you will find a M10 x1.5/1.75, but you aren't going to find a M10 x 0.7 on a S30. Thread pitch usually correlates to diameter. Usually larger the dia larger the pitch, unless required for a specific reason.

For me, anything x1.0/1.25 and larger is course, below x1.0 is fine. Those fines come in the likes of 0.8, 0.75, 0.7, 0.6 and 0.5
 
yellowz

yellowz

Club Member
I've got a pitch gauge, my problem is usually 'what goes in that hole?', that's where a tap and die set comes in! :conf2:
 
I

Ian Patmore

Well-Known Forum User
jonbills said:
I think designation as fine/coarse pitch depends on the thickness of the fastener.
Click to expand...
As I said.

Using the link, most fastners on the S30 are going to be M4-M12, and most of those sizes are course. Some are fine, but the statement almost all fine doesn't fit.
 
jonbills

jonbills

Membership Secretary
Site Administrator
Ian Patmore said:
As I said.

Using the link, most fastners on the S30 are going to be M4-M12, and most of those sizes are course. Some are fine, but the statement almost all fine doesn't fit.
Click to expand...
Yes, I was merely correcting the suggestion that e.g. 0.7 is always fine and 1.25 is always coarse.
Ian Patmore said:
anything x1.0/1.25 and larger is coarse, below x1.0 is fine. Those fines come in the likes of 0.8, 0.75, 0.7, 0.6 and 0.5
Click to expand...
 
jonbills

jonbills

Membership Secretary
Site Administrator
MCBladeRun said:
Is it a case that a combination of metric size and tensile strength determines the pitch?
Click to expand...
No, the manufacturer is free to make the fastener in any allowed pitch they like, for their own reasons.
The wiki article suggests that e.g. fitting a thin wall pipe might be a reason to use a fine thread (because I think the finer thread is shallower as well as tighter)
 
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