Adjust speedometer from miles to km/hour

wkuehnis

wkuehnis

Member
Hi, is it possible, do adjust the round speedometer of my 1931 A from miles to km/ hour ?
I tried it, but its not very exact.

Thanks gor help
Willi
 
Maybe I'm wrong, but isn't it just a scale of the measurement that is different? just like on a ruler that has both inches & mm. The wheels turn the same speed regardless. I would think you'll need a speedometer sticker made for your specific speedometer but printed in km instead of mph
 
These old speedo's are usually not very accurate, and, adjusting them to take up the 58% difference may be asking too much from it.

One of the speedo rebuilders will probably know.
 
I recently installed a "rebuilt" speedometer from one of the "rebuilders" and it is way off. I expected better. Farther off than the speedometer that I replaced. The only reason I switched them was because of the numbers.

If your odometer is relatively close, I would not be too concerned.
 
Just a diffferent scale transfer for KPH speedo ...... BUT getting the trip into kms rather than miles is a different kettle of fish altogether! ( now then you guys have you ever come across that expression before or it is purely British ? :) )
 
johnbuckley said:
Just a diffferent scale transfer for KPH speedo ...... BUT getting the trip into kms rather than miles is a different kettle of fish altogether! ( now then you guys have you ever come across that expression before or it is purely British ? :) )
Click to expand...

John, we have kettles of fish over here too.
Do the vendors sell metric speedo stickers? In a land stuck in imperial antiquity, I doubt it.
To the OP, a fairly accurate conversion is 1 km = 5/8 mile and a half decent conversion you can do quickly in your head is multiply or divide by 6. I've seen a sticky note on the dash with metric/imperial equivalents at every 10km or so. It doesn't take long and you don't even have to think about it but I am lucky enough that I was familiar with imperial before we converted (in the 1960s) so bot come easily. My work as a Land Surveyor also made conversion easy.
 
When we converted, all of the cars already on the road were calibrated in miles. We could buy a small gearbox that went either in the speedo cable or behind the speedo that did a reasonable conversion. 8 teeth drove 5 so both speedo and odometer were near enough.
 
since the distance of a mile and Kilometer are different I would think that the gears inside the unit on the odometer might be different as well.
 
Simple but near to good as you can get: divide your miles per hr by 5 and then multiply by 8. Simple mental maths.
 
thanks for pointing out it's a round speedo .. I should read the question always. Change my word "trip " to "odometer"or "mileometer" to bring it into line! ...yes when touring europe I always estimate at kms miles at 2/3... I find the sum easier than 5/8- sure, not accurate but quicker in my head.... in my model As the mileometer have seldom worked anyway ... I always fit a bicycle speedo now... BUT in true Fordbarn style we have strayed completey from what the OP #1 wanted to know.... he wanted to know if poss to convert thespeedo .. not arithmetic or other options ....:)
 
Try the 4.55 rear axle speedo drive cap .I think but not sure the spiral gear on the drive shaft is the same I will check the parts book .I will look in the "stores"to see if I have a 14.9 HP car speedo drive cap . It would be easy to spot as the gear in the cap is larger and the ratio marked on the bottom of the cap . The larger gear diameter will make the speedo read slower and if you are lucky could be a closer match .

John in snow bound and locked down Suffolk County England
 
One of the guys here went to set a 1932 Convertible and found it to be a 1931 Cabriolet. There were several things odd about it and he inquired of the owner. Seems the current owner bought it in Finland and brought it here. Had a Russian GAZ engine in it and the speedo was in KM.
 
JAK is correct. It's not just a matter of different decals. The internal drive gears are different. I have worked on both USA and Metric Speedos and they are indeed different.

Bob bader
 
you will have to change the speed wheel from miles to kilo reading. Then set the speed to read in kilo's not miles. let me know if you need my help. papanick.
jrnichols642@yahoo.com
 
Hi Guys,
Kilometres speedos are out there. I found one for my Ford as well as my Chevy. Argentina went metric many years ago.
 
Our open road speed limit (Australia) is 100kph (and 110kph in few selected locations) which equates to 60mph (without splitting hairs). Since my A’s won’t comfortably exceed 100kph it is not important for me to know what speed I make. Our town limits are 60 kph (36mph) and I need only lift my foot just a little and I am compliant.

So to summarise the above, I don’t look at the odometer and I don’t care what it reads. It's purpose is to fill a hole in my dash.

Yes, I know that doesn't answer your question does it.
 
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