Speedometer

[mirafiori76]

Recently i bought a Tomtom, or navigation if you like. I need it because of my work as a lorry driver.
But here it comes: I used it in my 1600 CL as well and guess what? Up to 50 Km's the speedometer and the navigation have the same reading. But when i go faster, the two don't share anymore. Most freeways here in Holland have a speed limit of 120 km/h. When i read the navigation at exactly 120 km/h the speedometer reads 133 km/h. Now, that seems a very large difference. When i speed up the gap gets even bigger. Soeme freeways allow 130. Then the gauge reads almost 150!
I know that almost all gauges do have a certain "loss", but this is ridiculous.

I concidered larger tyres, but then i have a similair problem. But the reverse way. The speedometer will read too high when driving slower than 50/60.

Is there anybody who has a low budget solution for this?

[jasonh131]

No thats about right ,, cannon balling across germany on 3ma13 my  max was 140kmh on the tomtom  about 163kph or 102mph  on the   speedo  

[mirafiori76]

Right? I think not. Why such a big difference? Why is it so difficult to make a speedo that reads the right speed? Makes me want to use the tomtom al the time and forget the speedometer...

[stathe174]

Well mine goes  10 km faster at all times...

[strada]

all mechanical speedos are a compromise and cannot be 100%accurate,

in england,anyway, the majority of speeding tickets are issued for exxeding 30 miles an hour or around 48-50kph so this is where the manufacturers concentrate thier efforts, legally a speedo can only overread NOT UNDER READ, so thanks to our friends in brussells, at higher speeds accuracy is not considered a priority.