Author Topic: Gearbox Question  (Read 1180 times)

Offline Lightningpower

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Gearbox Question
« on: 22.07. 2010 04:26 »
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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1953 Star Twin - Racing
1956 Road Rocket
1958 Super Rocket
1959 Spitfire Scrambler
1967 Hornet

Online muskrat

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Re: Gearbox Question
« Reply #1 on: 22.07. 2010 10:54 »
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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Offline trevinoz

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Re: Gearbox Question
« Reply #2 on: 22.07. 2010 22:29 »
I think, but I am not positive, that these letters are inspection marks.
Trev.
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Online muskrat

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Re: Gearbox Question
« Reply #3 on: 23.07. 2010 09:22 »
Could be right Trevor. Just looked at my plunger, it's got M D stamped on it. My spare has 5 on it.
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'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
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Offline Lightningpower

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Re: Gearbox Question
« Reply #4 on: 23.07. 2010 16:03 »
I have a B and B20 stamped on mine as well.  Where are M and the D stamped, Muskrat?
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Re: Gearbox Question
« Reply #5 on: 23.07. 2010 21:44 »
Same place as your RW but side by side.
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Offline Lightningpower

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Re: Gearbox Question
« Reply #6 on: 24.07. 2010 05:16 »
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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1967 Hornet

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Re: Gearbox Question
« Reply #7 on: 24.07. 2010 08:35 »
 Yep, do you think honda or yamaha would let their testers inital the work like that. *eek*
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Offline BSA_54A10

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Re: Gearbox Question
« Reply #8 on: 24.07. 2010 11:16 »
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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Offline Lightningpower

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Re: Gearbox Question
« Reply #9 on: 24.07. 2010 18:09 »
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.
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1953 Star Twin - Racing
1956 Road Rocket
1958 Super Rocket
1959 Spitfire Scrambler
1967 Hornet