Ever Wondered What These Numbers Mean?

[moonpup]

Ok guys, after an exhaustive search in the Great Library of eBay I discovered another one of the elusive number stamps. This one dated 40.11.25 and was located in an nos wheel hub.

This prompted me to take on a potentially dangerous journey to the desolated hot & humid garage cave located in the north east corner of my ancestral lands, where in the hub of an ancient relic, I found the numbers 42.8.14! Unfortunately, I was unable to take any pictures as the extreme heat, humongous cockroaches and leaping lizards forced me to flee.  

I must rest now before any other expeditions are attempted!  

[coxy]

ok so why would one of mine have nothing ?  maybe it did not get inspected

[Mopar392]

I inspected 4 of my stones today, same find as coxy, but in my case no stamp on any of them?
DL

[dcr]

I bought the 200 motor that Richard listed for someone in the classifieds. Turned out to be a 175, but that worked out better for me and more on that later.

Here are the insides of the cases of that motor that was on a October 1966 built 175DT.

[moonpup]

...snip... My money would be on it being an inspection mark at some stage in the engine manufacturing process. A final check the engine was timed correctly, gears and kick start worked and everything was in place before the right side cover went on ??    The left crankcase side covers don't have any stamps, suggesting these are not production dating marks.
   Brian.

Wouldn't the inspection stamp on the nos wheel hub I found on eBay indicate it was placed there as an approval of the part itself vs. the assembly process?

As far as no stamps being found on the left covers or some of the other members right covers, wish I had an answer for that, but I'm clueless for the moment.  

On the Z cars, they're on a lot of electrical parts, on the backside of the dash, on top of the gas tank, gauge housings....ect. However on our bikes, at least for now, they seem to be relegated to aluminum parts only.  Hummmm?


EDIT: Been doing some more thinking Brian ( probably taxing the grey matter a bit much  ), and since the wheel hub I found on eBay is not a separate piece by itself but part of a complete wheel (hub/spokes/rim), the stamp could very well have been put there to approve the assembly of the total piece and not just the hub. Oh well, back to the drawing board....

[moonpup]

Here's something else to think about. These are the dates from 3 different pieces off the same engine.

The first is on the upper main crankcase (42.9.12), followed by the one on the lower main crankcase (?.8.28) and lastly, the number on the right crankcase cover (42.8.11).

They're all over the place (date wise). Did it really take over a month to put these engines together or does this suggest individual part dating? You'd think that if it was an assembly inspection, then the right cover would have the highest date.... right? 

[dcr]

Makes me think this isn't an assembly related stamping but either a manufacture date, manufacture batch date or manufacture inspection date. I'm not sure what the quality control measures were 50 years ago in an assembly area where these bikes were built.

It's great chewing gum for the mind Mike - keep it up.

[slawsonb]

Looks like (as dcr says) lot code, inspection code, or date of manufacture code for the specific part to me.
...bert

[srpackrat49]

do you think it would be to find a person that worked at the plant back in the day and interviue them???  i worked at a tool and die plant back in the 70s..... my job was to take 55 gal. barrles off the line...  see how much they weighted... looked up the parts # taged it... then stored it.... parts go  togeather by the ##s   we allso made the shells for the handgernades for nam...... i never saw were they went....

[Mopar392]

Nice DM, have to agree with dcr and "The Bertski", parts mass produced, dated, then shelved until needed for final assembly...DL

[moonpup]

do you think it would be to find a person that worked at the plant back in the day and interviue them???  ...snip....

I would love for that to happen and it could potentially provide some answers to a lot of interesting questions. However, that would need to happen soon, as those folks aren't getting any younger!

The Z car community was fortunate to have access to several key individuals involved in both the design & manufacturing end of things. If only we had the same access.....

[dcr]

Where would you even start to find a former Bridgestone motorcycle assembly plant worker? Craigslist?

[slawsonb]

Kotaro-san might have an idea.
...bert

[BRT-GTR]

Hi All,
           Mike, dcr, Bertski and DL, you've cracked it.     
    All the stamped alloy parts have extensive machining operations and other ancillary parts which had be fitted before they go on to an engine, such as the oil baffle plate in the upper crankcase and the oil pump drive bush/oil collector trough for rev counter drive in the right case side.
     You would think the left front case side should be stamped as it has the clutch operating screw fitted. Maybe its just worn or washed off over the years.
   Brian

[Mopar392]

Right On Brian, sounds like a perfect time to crack a cold one...Cheers
DL

[slawsonb]

Another case cracked by the BS archeology team. Nice!
...bert(ski)

[dcr]

Here is another "what does this mean" item I noticed but never really thought about. The left and right crank bearings on my 175DT have "C3" manually engraved in them. I know what the C3 means, but I wonder why they inscribe it on the actual bearing. These are the only 2 that have it - none of the transmission bearing have this marking. I have disassembled four 175 motors and they are all the same in this regard.

For those wondering, bearings have a rating of C1 thru C5 which indicates the internal clearance. Bearing internal clearance is defined as the total distance through which one bearing ring can be moved relative to the other in the radial direction (radial internal clearance) or in the axial direction (axial internal clearance).

Suffix     Radial internal clearance
C1     Less than C2
C2     Less than Normal
CN     Normal, only used in combination with letters indicating reduced or displaced clearance range
C3     Greater than Normal
C4     Greater than C3
C5     Greater than C4

[slawsonb]

Not sure I can explain the upper pic, but the 6304 designation is standard bearing interchange nomenclature. If you look at many BS bearing part numbers you will find a 4 digit 6xxx in the number. This indicates BS bought off the shelf bearings for that particular application. In the above case a 6304.
...bert

Some more info on bearing nomenclature.

Bearing Nomenclature

You can learn a lot about a bearing just from its part number.

A typical bearing is the 6203ZZ bearing. This part number can be divided into it's components:

    Type Code - 6
    Series       - 2
    Bore         - 03
    Suffix       - ZZ

For more google bearing nomenclature.

[OldSwartout]

Suffix     Radial internal clearance
C1     Less than C2
C2     Less than Normal
CN     Normal, only used in combination with letters indicating reduced or displaced clearance range
C3     Greater than Normal
C4     Greater than C3
C5     Greater than C4

C3 clearances are normal for electric motors due to the armature shaft and inner race normally running hotter than the surrounding housing and outer race, so the internal clearance is greater than normal at room temperature, but normal under operating conditions. I'm not certain if this is the reason for the crankshaft bearings being C3 clearance or if it is an alignment or axial thermal growth or   We do know the crankshaft flexes enough to fatigue and break the center pin, so it may be an alignment issue.  Another subject for speculation.

[moonpup]

Hey gang, I found these letters stamped behind the knee pad on the right side of a 350 gas tank . I don't recall ever having seen anything like them before and haven't a clue what their purpose/meaning is.