The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => Gearbox, Clutch, Primary => Topic started by: Lightningpower on 22.07. 2010 04:26
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I have a semi-unit gearbox with the letters R and W. What do these mean? I've attached a photo to help. Thanks!
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Thats where they stanp the type of box eg std, day, scr. R should mean close ratio, RR means extra close ratio. Don't know what the W is for.
It could have been a replacement part with no stamping and ron woods put his initials on it *smile*
Cheers
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I think, but I am not positive, that these letters are inspection marks.
Trev.
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Could be right Trevor. Just looked at my plunger, it's got M D stamped on it. My spare has 5 on it.
Cheers
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I have a B and B20 stamped on mine as well. Where are M and the D stamped, Muskrat?
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Same place as your RW but side by side.
Cheers
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That's interesting. I wonder if they were the worker's initials or something else. There's a lot of history recorded on our machines that we may never decode.
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Yep, do you think honda or yamaha would let their testers inital the work like that. *eek*
Cheers
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Most of those strange little stampings were either to mark sets ( like left & right case halves ) or clearences.
Remember A 7 & 10 predate modern machining tools so every time a part was machined the tool got shorter.
Semi automatic lathes moved a set distance unlike modern computer controlled machines that cut to a pre determined size.
Machined parts were tested with go no-go type gauges and stamped according to the results so that tollerances could be maintained within acceptable limits.
You notice this when you try to put a bitsa together where a part like say a mainshaft is a good fit in a box with a u/s layshaft but a really bad fit in the box that you are trying to rebuild.
I personally have had all sorts or grief with things like boxes that would not turn because these is no running clearences when they a re bolted together but the various bit worked well in their donor cases.
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The tolerances explain why one of mine says B and the other says B20. Maybe the 20 is thousands of an inch on the mainshaft of something some other part.