Author Topic: Converting chrono tacho from 2:1 to 3:1, advice needed.  (Read 1316 times)

Online fringedweller

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Hi all,
My 1960 SR has the wrong tacho on it at the moment (1307/01) and I would like to changeover to the correct 1303/03 tacho, without spending hundreds of dollars.
Is this possible to do at home or a specialist job?
Thanks
Don
South Australia

Online chaterlea25

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Hi Don,
The 3:1 tacho for the late A10 models also has the letter "L"  which means it has the opposite rotation to "normal"
An extra gear is fitted between the cable input spindle and the chronometric mechanism to correct the rotation for the
dial, then it has to be recalibrated to the different ratio.

In reality it is not a home job, unlesss you have accesss to a stash of spares etc
Most good repairers would either convert your tacho or trade yours against the correct one

HTH
John
1961 Super Rocket
1963 RGS (ongoing)

Offline wilko

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A friend of mine has an RC184 reverse drive tacho he cant use. Its 4.1 though but would be easier to convert to 3.1  I imagine. He needs a normal 2.1 clockwise one to swap. This particular Tacho is for a Big twin Royal Enfield. Ring Otto Instruments to see what they think.

Online fringedweller

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Both the 1307/01 and the 1303/03 are anti clockwise tacho's , just the 1307 is 2:1 so reads a bit slow.
The best I have been quoted is around $260 for a new face and ratio change. Refurbished from The UK they are $520 pus freight.
Might put the 1307 up for sale and lash out on the refurbished one shortly, meantime I'll just do the calculation in my head as I ride along.
Thanks for the replies.
Don

Online Russ

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Don
I had a speedo completely refurbished by a guy in New Zealand. Excellent job, although I haven't used it yet, for $260. I thought that was cheap. I will attach his info but I seem to have lost his email. He would be worth contacting.
Andrew   Rackstraw. Andrew Rackstraw Instruments ltd.  2 Argyle Grove, Upper Hut. 5018  N.Z 0011 64 4 9703707   021 299 6788

Russ.
1951 A10 Plunger.
Australia

Online Brian

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Don send this guy a e-mail and explain what you want and he will give you a quote. I have used him and had excellent results.

http://www.chronometrics.co.uk/

Offline wilko

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Online fringedweller

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Ta, will check them out.

Offline terryg

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A vote from me for chronometrics.co.uk

Russell is very knowledgeable and helpful, with a good stock of parts to back him up. He's rebuilt two clocks for me this year and repaired a third, right on time as promised.
Terry
'57 'SR', '59 SR, '63 RGS

Online fringedweller

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Just an update and a query.
Tacho recalibrated by Lionel Otto Instruments for the price of a couple of cartons of decent beer. Only took 3 days. Good to see someone who is passionate about  what they do.
The question now is, what rev's should a 1960 SR with standard gearing be doing at 60mph?
Mine is now showing 3500 @60mph, seems low to me.

Don

Online chaterlea25

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Re: Converting chrono tacho from 2:1 to 3:1, advice needed.
« Reply #10 on: 15.03. 2013 20:33 »
Hi Don,
Whats "standard" gearing ???? , and how accurate is the speedo???
It sounds about right if a 21 tooth engine sprocket is fitted

HTH
John
1961 Super Rocket
1963 RGS (ongoing)

Online fringedweller

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Re: Converting chrono tacho from 2:1 to 3:1, advice needed.
« Reply #11 on: 16.03. 2013 00:37 »
Standard gearing by the book would be 21T engine sprocket, 19T gearbox sprocket. Which is what mine is.
Speedo error is what I am trying to ascertain.
Thought all you riders out there would be able to rattle off the numbers from the top of your head.

Don

Online metalflake11

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Re: Converting chrono tacho from 2:1 to 3:1, advice needed.
« Reply #12 on: 16.03. 2013 00:46 »
Borrow a Sat Nav, that will tell you the actual speed then compare it with your speedo. 3,500 @ 60mph sounds about right to me.
England N.W
1960 A10
England