Speedo reading

[Craigy]

Hi guys,

I have a 1952 Golden Flash which has just been restored. The speedo reading is way out, reading more like kph instead of mph.

Is the any adjustment on the cable? Looking at the part list, it lists 67-3175, but it doesn’t list any other parts which makes me think it must be adjustment not the wrong part/gearing.

Thanks Craig

[Bsareg]

Is it an original chronometric speedo ?  The drive cable is offset at the back on chronos. On the later magnetic type types, the cable is central. There is no adjustment on either types without expert expertise. There are many replicas (some of dubious quality) coming from India. The are often marked as chronos but are cheap magnetics, but they do satisfy the the law. If yours is a chrono with a screw on bezel, mph faceplates are available on ebay and are easy to change.

[Craigy]

Thanks for the info. Not sure if I’ve got the wrong end of the stick here, but here goes….. the speedo faceplate(?)/dial is original and in mph.

When the bike is travelling, what feels around 30mph is reading as 50mph etc. The odometer which is in miles is putting on more distance than I’m travelling.

I’ve only done a couple of miles on the bike as I’ve been sorting a clutch cable problem out, but it’s not reading speed/distance correctly.

If there is no adjustment/calibration, do you have any idea how to remedy?

Thanks Craig

[limeyrob]

The odometer is driven from the speedo cable and if that it running fast then you need a different gear ratio in the speedo drive or speedo head.  Its not an adjustable thing, its all fixed by gears.
A Chronometric is very accurate - it works by having a clock mechanism - hence "Chrono" - and dividing distance from the odometer by time from the clock mechanism.  Adjustment to the clock part are possible but a minefield.  If you odometer is wrong then you must get the drive ratio right first.  My bet is when you do that the speed will be correct.

[Bsareg]

The only adjustment possible is at the drive end. I've never heard of alternative gearing for an A series gearbox. Perhaps it is a kilometre speedo with a mph face on it. Have you checked if odometer is accurate in kilos? Ebay sells replacement kilometre face plates. Isn't Oz all metric now?

[muskrat]

G'day Craig.
I think Reg (yes Oz has been metric since the mid 70's) may have sussed it out. 30mph is close to 50kph.
The speedo on my plunger is badly in need of a refurb, the needle bounces around like a pogostick.
Cheers

[limeyrob]

I'm thinking the same, or its not the correct one for an A or B series?  What final drive ratio do you have, if you have a small gear box sprocket it will read fast but only 19:17 which is about 10%

[Craigy]

Hi guys thanks for the replies.

The bike was refurbished in the UK, so definitely in miles not km’s, and I’d prefer to keep it in miles.

I’ll have a look at the gearing at the front end.

I also have a 1959, where the speedo is correct until 60th then it jumps around

[limeyrob]

Don't what ever you do use any solvent to clean teh face.  I did this many years ago and the white numbers melted

[Rex]

And try not to touch them either, as they smudge and leave fingerprints.

[RichardL]

What are the numbers on the faceplate?

Richard L.

[Craigy]

Hi Richard,

Can you point me in the right direction, photo etc

Cheers

[Rex]

What are the numbers on the faceplate?

0 to 120?

[Swarfcut]

 These original instruments are an absolute nightmare. The number you're looking for is on the dial, below the word CHRONOMETRIC. The usual format starts with  S, then the speedo model number? along with is a number which is the key to the whole ensemble and relates the number of turns of "something" per mile." * Plenty of images on the web. Forum members with accurate speedos will hopefully respond with what's out there. M A  represented "Motor Accessories", hence SMITHS M A.

 Something per mile as urban myths range from the number of turns of the cable, the number of turns of the back wheel or now  more closely the number of £££'s for a good example. Those in the know, know, and this is why a genuine unit costs a lot.

 The drive is from the gearbox, so any change in gearbox speedo drive pinion (unlikely) or final drive ratio (possible) affects the reading. But with another unit to hand a comparison is simple, and will show if the problem lies within your present speedo. It is definitely a job for an expert, warnings already on this thread include the fragility of the original dial printing, and you need guile and skill to get the bezel off without damage, then inside there is more precision chaos. And yes, there are EXPERTS and experts. So don't even consider a backyard fix. Indian versions look the part, but the one you have is probably more accurate......

 Later models (A65) took the drive from the rear wheel and use magnetic type instruments. A whole lot simpler. Japanese bikes used shorter cable, saved costs, speedo drive from front wheel, genius!!

 Swarfy.

 *I'm no authority, just what I've picked up over time. Hope this helps.

[Craigy]

The dial reads to 150 mph