Speedometer Off

B

B121

Member
Hi All,

I had 2 GPS readers active in my car, and both seemed to confirm the speedometer is 2-4 MPH too high. Only thing I'm thinking is that I'm not running original wheels (put on by a previous owner). Note, I've only had the car for a month. :)

Anyone have any ideas? Is this something I could/should recallibrate? Thanks!
 
B121 said:
Hi All,

I had 2 GPS readers active in my car, and both seemed to confirm the speedometer is 2-4 MPH too high. Only thing I'm thinking is that I'm not running original wheels (put on by a previous owner). Note, I've only had the car for a month. :)

Anyone have any ideas? Is this something I could/should recallibrate? Thanks!
Click to expand...

Hi, it’s normal but you can bring it closer by fitting higher profile tyres or using Carly or similar to code the speedo to display the correct speed.
You will lose your safety buffer when it comes to speeding offences though! :o
Rob
 
The official specs for a factory speedo are +10% -0% so they always err on the side of reading high (as much as 77mph at a true 70mph). Most over-read by around 2-3%.
 
ph001 said:
The official specs for a factory speedo are +10% -0% so they always err on the side of reading high (as much as 77mph at a true 70mph). Most over-read by around 2-3%.
Click to expand...
Thank Goodness they do.
 
Come to think of it, though ...

I use the cruise control in my 18"-wheel E89 on average speed camera roads. Limit 50 - set at 50. My GPS-based speed camera locator screams at the same points + 1 mph.

(The the cruise control indicator can be fixed exactly on the speedometer and is easier to read than a wandering speedometer hand.)

So, my speedometer seems to have no margin for error at all.
 
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