Classic cars forum & vehicle restoration.

[TonyBrooks]

My present speedo reads some 20% fast - I have got round this by sticking a piece of paper over the printed figures showing the 'true' speeds. However it would be nice to get something more accurate.
I know I can get the instrument recailbrated by the likes of Speedy Cables etc but I thought I would first see if there is a generic speedo which would be suitable.
My present model has the following on it SN 6144 2685 1280 and I assume the final 4 figures are the revs per mile. One web site I have found suggests that the 1280 should be increased by 20% equating to 1536 - do the experts here agree?
If so has anyone got a database of 100cm wide (4 inches) speedos that have a relevent ref no nearer to my ideal?
Thanks
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Dinalpin Berlinette (Alpine Renault A110)

[peter scott]

Hi Tony,

This might help:
http://tidentenn.com/pdf/Speedometer%20Repairs.pdf

You can do minor re-calibrations by driving through these "Your Speed" signs and noting your current speedo reading. Then turn your speedo pointer to the same speed that it was showing, restrain the aluminium disc and twist the pointer to the "Your Speed" position.

If you have a rev counter and know your gear ratios and rolling radius you can do the same thing at a known speed. Or a third possibility is to read your speed from a sat nav.

Peter
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http://www.nostalgiatech.co.uk
1939 SS Jaguar 2 1/2 litre saloon

[Jim.Walker]

I had such a problem when I changed the wheel size on my Gentry.
The final numbers are the turns per mile.
I measured out the longest straight and level distance I could as a known fraction of a mile and marked out the start and finish. With a piece of card on the detached cable as a flag and on the new wheels and tyres carefully inflated I rolled the car over the known distance and counted the cable turns. It was easy then to calculate my requirement. e.g. 176 yards (1/10th of a mile) means the required figure is the resulting turns x 10.
I was able to find a suitably marked speedometer of the same dimensions as my original in a local scrap yard. Though the original was a Smiths and the "find" was a Jaegar the internals were easily interchangeable (identical in fact) to retain a matching dial though curiously the speedo cable threads on the back are different and I had to modify the cable end.
Don't be tempted to compare your speed with the "your speed" devices. they can be, and often are, way off. And can be influenced by other traffic.
Jim.
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Quote from my late Dad:- You only need a woman and a car and you have all the problems you
are ever likely to want". Computers had not been invented then!

[MVPeters]

There have been several threads on this topic recently. Here's just one, but if you Search the forum for "Calibration" or "Speedo" you'll find the others.

http://www.oldclassiccar.co.uk/forum/phpbb/phpBB2/viewtopic.php?p=54896&sid=9ccad49568e02ab7d720aace1397cbb1

I'll just comment that I thought the turns-per-mile number was under the odometer - I don't know if it is also part of what looks more like a serial or part number.
You might check with the other(!) Talisman owner & see if he also has a 1280 speedo or not. I imagine there were variations in axles etc, so this may not be much help.

Send me your e-mail address & I'll send some files that have more detailed information.

MVPeters@comcast.net
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Mike - MVPeters at comcast.net
2002 MINI Cooper 'S'

[MVPeters]

I just came across this book about repairing & calibrating speedos on eBay:

http://www.ebay.co.uk/itm/Smiths-Speedo-Speedometer-Tach-Tachometer-Repair-save-/320850606505?pt=UK_CarParts_Vehicles_Manuals_Litterature_ET&hash=item4ab42fb9a9

If it's any good it might be a worthwhile purchase.
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Mike - MVPeters at comcast.net
2002 MINI Cooper 'S'