The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => Frame => Topic started by: roadrocket on 13.12. 2015 21:32
-
Hello
I have learned that the right tacho for a Road Rocket is RC 83 (RC 1302/00) 2:1 Clockwise. Will a Goldie 1:1 drive be right for that? I take that the mag turns at half engine speed.
Otto in DK
-
HI Otto,
Both bikes run anticlock magnetos so the drive unit should be correct,
A fact about goldies is that they wear out the revcounter mechanism rapidly *sad2*
This is because of the high cable speed, = 1/2 engine speed
My plan is to use a 2:1 drive box and a suitable rev counter with a "correctly" marked dial (Shhhh!!!)
HTH
John
-
If you looking for 2:1 tach drive, l can offer you one. Only used one year in a racer.
cheers Klaus
-
Thanks folks, can my information about the instrument be correct RC 83 (RC 1302/00) 2:1 clockwise be correct if the mag runs anticlockwise? The things is that I have an excellent place to buy both the instrument and the drive, but the drive is black, and I would so much prefer to get one of Phil Pearsons beautiful brass drives for Goldies. If the mag runs the same way on A 10s and Goldies, I would at least suspect they could use the same tachometer, given the gearing is the same. Klaus how odes your drive look?
Cheers, Otto
-
Hi Otto,
A link to the application chart, http://www.chronometrics.co.uk/Tachometers/tachometers.html
As the drive unit has gears the output is reverse to input *conf2*
HTH
John
-
I know you can get drives that either keep the direction of the mag (or other prime mover), or reverse it. My question is: for a clockwise instrument, do I need a drive that keep or reverse the rotation? I would think that if an instrument is designated clockwise, it should get a clockwise rotating cable. But now I must say I am totally confused.
Cheers, Otto
-
HI Otto,
The magneto "direction" is defined looking at it from the drive end
So looking at the inner end of the drive box it will rotate clockwise
(maybe I stand corrected on the direction change as it will depend on which way the worm gear is cut *????*
this is an extract of the fitment list I have on the pc
John.
Smiths Chronometeric
Model Information
Model Speedometer Tachometer Speedometer Gear Box Tachometer Gear Box
BSA
D1 -1958 S.630/L
D1 Bantam 123cc SC 1102/07 BG5331/247
D3 150cc S.630/L
D5 175cc SC 1102/L
C10 250cc S.630/L
C11 S.433/1/L
C12 S.433/1
C15 Starfire Roadster 250cc SC 5301/03 BG5331/247
C15 Sunbeam 250cc ↑ BG5330/847
C15 Trials SC 1102/14 ↑
C15 Scrambler SC 5301/03 ↑
B31 -1957 S.608/9/L
B31 1958- SC 3305/04
B32 Triail & Scrambler -1957 S.525/3/L
B32 Comp S.608/11/L
B33 -1957 ↑
B33 1958- SC 3305/04
B32/34 Goldstar 1954-1956 S.546/3/L RC.83
B32/34 Goldstar 1957 S.608/11/L ↑
B32/34 Goldstar 1958- SC 5301/23 RC 1302/00 BG 5331/247
B32/34 Goldstar Scrambler SC 5301/07 ↑
B32/34 Clubmans SC 5301/23 ↑ BG 1508/04
M20 -1954 S.608/9/L
M20 1955- S.608/11/L
M21 -1957 S.608/3/L
M21 1958- S.433/3/N
M33 S.608/3/L
A50 SC 5313/00
A50 Star SC 3313/00
A65 SC 3313/02
A7 -1957 S.608/19/L
A7 1958- SC 3305/04
A10 -1957 S.608/11/L
A10 Super Rocket 1958-1962 SC 5301/22 RC 1303/03
A10 Super Rocket 1963- SC 5301/06 RC 1303/00
A10 Golden Flash SC 3305/04
A10 Spitfire Scrambler SC 5301/24
A10 Rocket Goldstar U.S.A. SC 5301/23 RC 1303/03
A10 Rocket Goldstar SC 5031/03 RC 1303/00
-
I have done some more research, and found that the Goldie tach drive will be correct for a RC83 instrument as specified for a Road Rocket. This is because: the BSA p/n 65-9164 (Smiths 1508/05) is a 1:1 reversing drive, and since the mag rotates at half engine speed in anticlockwise direction, it will be correct for the RC83 which is a 2:1 clockwise instrument. A nice chap dealing with Velocettes had a lot of Smiths information on his blog. Google the Velobanjoagent. At least this is what I could squeeze out of the combined web resorces of an evenings worth of surfing.
Cheers, Otto