Misc: Everything Else Smith rev counter

[MichaelOrgzey]

Hello everybody,I have a question:
I have a new Smith's Chronometric rev counter that was installed but not connected due to lack of a gearbox on my B Rapide.
Am I right in assuming that it would be running clockwise with a 2 to 1 ratio? It doesn't have any serial number on it.
Cheers for your input, Michael

 

[oexing]

Try the instrument with a hand drill to find out the sense. But it is another case about gearboxes to go with it. I cannot tell how to find out which gearbox would suit. I guess these can rotate in any sense depending on gears inside ??

Vic

 

[MichaelOrgzey]

Hi Vic, cheers for the fast reply. I will try it out.

 

[davidd]

The original tach was an RC103 (RC1303/01 in the more modern number), which would be an anticlockwise 4:1 head ratio.

I would recommend a BG1507/02 gearbox. This is a 2-1 reversing gearbox that has bearings instead of bushings. The 1508 series is a pot metal housing with bronze bushings of the same orientation.

If your tach ratio is 2:1, then you can use a 1-1 reversing gearbox.

If you use a Smiths mechanic, he can set you up with what you want. The Factory used the 4:1 head ratio and the 2-1 reversing gearbox.

David

 

[MichaelOrgzey]

Hello David, thank you for the input. I'm not actually planning on installing it to my Rapide but somebody is interested in buying it.
He wants to use it on a Triton with a T140 engine and needs an anti clockwise with a 2:1ratio apparently. Could I damage it by trying it with a hand drill and it's running in the wrong direction?

 

[oexing]

No problem if you got wrong sense when finger spinning. You should see a bit of reading with a small drill when finger spinning. With wrong sense nothing.

Vic

 

[MichaelOrgzey]

Just been in contact with Russell,"Chronometrics" in Nottingham, they have done a complete overhaul of the instrument in 2014. It is actually a Vincent instrument with a 4:1 ratio, clockwise. I will put it up for sale here soon with quite a few other rev counter parts.
Thanks a lot for your input!
Michael

 

[davidd]

It is actually a Vincent instrument with a 4:1 ratio, clockwise. I will put it up for sale here soon with quite a few other rev counter parts.

This is always a bit confusing, so I hope there is some adult supervision watching this thread, but the Vincent tach head is 4:1 anti-clockwise. If you have a clockwise head, it will not work correctly with the gearbox.

The anti-clockwise direction is not an obvious thing, such as the needle direction. The direction of the tach head is based on the "point of drive", which in this case is the output on the end of the tach gearbox. That output on the gearbox happens to be anti-clockwise, so the tach head has to be anti-clockwise also.

I hope this makes sense.

David

 

[Simon Dinsdale]

Here is the Smiths equipment sheet for Black Lightnings 1954. Shows the rev counter was RC115 and in the lower box says 8000 Revs, 4:1 anti clockwise rotation. Note as David says above the rotation is refering to the rotation of the drive cable and not the instrument needle.
The gearbox that goes onto the engine at that time was X70549/1 which was 2:1 ratio reversing and was the bronze body type. Same rev vounter gearbox is listed against the Grey Flash along with gearbox 36362/1 . I have a NOS X70549/1 gearbox here that came with a bike I bought a few years ago.

 

[MichaelOrgzey]

Hi David, hi Simon,
all a bit confusing indead, I was actually assuming it is the direction of cable rotation that defines the rotation and not the needle direction. I assume Russell at "Chronometrics UK" knows what he's talking about, giving me the information that the instrument is clockwise rotation. What's puzzling to me that the rev counter was actually mounted on my Rapide, but as I said before, wasn't connected. The magneto was converted to manual advance with all the rev counter drive parts present except the actual gearbox.
Since the last owner in the US,before the bike went to Germany with the former owner, was Sid Biberman I assumed the parts would work together. So I will try the direction of rotation myself ones I'm back home.
Thanks again to everyone helping to clear things up.
Best regards,Michael