Smiths Chronometric

Morgy · Nov 14, 2019

Managed to pick up a set of Smiths Chronometric Speedo and rev counter a few days ago..

Sold in a non working state but have managed to clean them up and get them to work, OK, They were really dirty and the cases were scuffed up pretty bad, Chrome is ok but would need re-chroming to make 100%
I would like to know what bike or bike these actually came from.
SC 5301/09
1476 (ratio?)

Smiths Chronometric

F1568D3D-DCD1-430F-B8B4-D1EB6842B13F by mark morgan, on Flickr

Rev counter
RC1307/00
4-1
Smiths Chronometric

060CF308-95C8-4802-989D-B91FB79BA46F by mark morgan, on Flickr

Morgy · Nov 14, 2019

There are more photos if you click on the image and follow to my Triton Flickr account

Both gauges now work although there not smooth when connected to a Cable and drill... They climb and descend very notchy.. if that make sense? is this normal or do they need more work to free up slightly.. Speedo Main drive was completely seized in the drive port/body but is now 100% free.. Both a little sticky but i guess at 65 they would be?

Fast Eddie · Nov 14, 2019

Chronometric clocks do NOT go smoothly, they ‘tick’ in increments up and down.

texasSlick · Nov 14, 2019

Your description "notchy" fits the normal way Chronometric gauges operate, both up and down.

There is no way to make them operate as smoothly as magnetic instruments.

These instruments are mechanical marvels, prize them highly. Should you ever need service or recalibration on these, I would recommend Greg Poirer.

Oops, i see you are in the UK ..... Greg is in Washington state, USA.

I think the number 1476 is a calibration factor, and might be a clue to the bikes the instrument was intended for.

Slick

L.A.B. · Nov 14, 2019

Morgy said:
I would like to know what bike or bike these actually came from.
SC 5301/09
1476 (ratio?)

Various 1960-61 AJS, Matchless, T120 US Bonneville, Triumph TR6 and Trophy TR5A (Competition Export model).
1476 = Should be cable turns per mile.

Morgy said:
Rev counter
RC1307/00
4-1

1961 T120 US Bonneville and TR6 Trophy.
1962 TR6S

Morgy · Nov 14, 2019

Thanks.... I thought as much...

Thank LAB.. will look into them a bit more when i have some time..
Had a look on Evilbay Bloody expensive clocks and i thought old RD350lc clocks were expensive!

Matt Spencer · Nov 14, 2019

They go in 1 mph increments , working properly .
accurate & without the lag & swing of the cheaper later magnetic ones .

A lot of T 120s ran 140 mph speedos .

texasSlick · Nov 14, 2019

Matt Spencer said:
They go in 1 mph increments , working properly .
accurate & without the lag & swing of the cheaper later magnetic ones .
.

I bought my Atlas new. The Chronometric Speedo jumped by 10 - 15 mph when new, and still does so after a Greg Poirer rebuild, when hard acellerating in first gear. Hard braking results in a similar jumping lag, as the instrument tries to adjust to the decreasing speed.

The jump increments decrease as the instrument "catches up" with actual speed, either going up or down, and becomes rock steady at a steady speed.

This behavior is due to a mechanical interruptor that "cuts out" the cable drive by a clockwork type escapement, hence the name "chronometric". Reference: Smiths_Chronometric_Speedo.pdf

Slick

Triton Thrasher · Nov 15, 2019

Matt Spencer said:
They go in 1 mph increments .

No, they update the speed every 0.4 seconds (or somesuch time period).

Edit: it’s 3/4 of a second.

Bernhard · Nov 16, 2019

Here is a link you may find useful for starters.

Smiths Motor Cycle Equipment 1954-1958

Staytite · Nov 16, 2019

Hi Morgy
Looks like you live near father and son David and Philip Woods in Bognor who specialise in
servicing and repair of Chronometrics. They have done several for me over the years (decades!)

oldbeezer · Nov 16, 2019

Triton Thrasher said:
No, they update the speed every 0.4 seconds (or somesuch time period).

In other words you know how fast you were going about 0.4 seconds ago.

Triton Thrasher · Nov 16, 2019

oldbeezer said:
In other words you know how fast you were going about 0.4 seconds ago.

3/4 second (edited) is the most late that the reading can be.

Depends how long into the 3/4 second interval it is, when you look at the speedo.

texasSlick · Nov 16, 2019

oldbeezer said:
In other words you know how fast you were going about 0.4 seconds ago.

Actually, if one reads the pdf link i gave above, it is 0.75 seconds ago, which explains why, under hard acelleration or braking, there can be as much as a 10 mph jump when the instrument updates.

Slick

BTW ..... The soul of a British bike resides in these "clocks".

BTW, X2 .... There is a Law, the Heisenburg Uncertainty Principle, which says, anytime you try to measure anything, you change it! Therefore, it really doesn't matter.

Triton Thrasher · Nov 16, 2019

Thanks, I just now went and searched and learned (re-learned) that the interval is 3/4 second.

http://www.wdbsa.nl/Jaeger-Chronometric-Overhaul.pdf

oldbeezer · Nov 16, 2019

texasSlick said:
BTW, X2 .... There is a Law, the Heisenburg Uncertainty Principle, which says, anytime you try to measure anything, you change it! Therefore, it really doesn't matter.

THAT never occurred to me.

Morgy · Nov 20, 2019

What would these be worth? Not that i was or am selling but I have been offered some very low and some fairly high prices for the two clocks Via my Facebook Profile when i asked about what bikes these were fitted on.. It seem'd some were just after a sneaky bargain but others were fairly, I won't say desperate but very pushy...

Are these rather rare and valuable

baz · Nov 20, 2019

Morgy said:
What would these be worth? Not that i was or am selling but I have been offered some very low and some fairly high prices for the two clocks Via my Facebook Profile when i asked about what bikes these were fitted on.. It seem'd some were just after a sneaky bargain but others were fairly, I won't say desperate but very pushy...

Are these rather rare and valuable

I'd take a look at completed listings on evilbay to see what they actually sell for
At a guess I'd say £200 + for the Speedo and £300 + for the tachometer
The tachometer being the hardest one to obtain
To get my tachometer I bought a Speedo as a core unit and had it converted to a tachometer
But my guess at prices could be way out
Cheers

texasSlick · Nov 20, 2019

Agree that they are rare and valuable. +1 with baz above.

Slick

oldbeezer · Nov 20, 2019

Morgy said:
Are these rather rare and valuable

Yes

Smiths Chronometric

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