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Author Topic: Speedo Clabration  (Read 2288 times)

Offline ljc19630

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Speedo Clabration
« on: October 28, 2019, 06:55:41 pm »
Evening fellow GTi-ers
Does anyone know the average MPH that the speedos are out by? I know that most, if not all are calibrated minus speed, i.e. speedo shows 70mph, but you're doing below that. Also does this change the faster you go? I am curious as I hit a certain speed today (on a private strip) thats somewhat surprised me :evilgrin:

Offline titchy

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Re: Speedo Clabration
« Reply #1 on: October 28, 2019, 08:28:38 pm »
Legally 2% accuracy if you have a sat nav check it against that

Offline rich83

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Re: Speedo Clabration
« Reply #2 on: October 28, 2019, 11:32:45 pm »
Mines about 10% out so 77 mph on the clocks gives 70 gps mph. 55mph clock gives 50 gps mph. Roughly.

Offline LC5F

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Re: Speedo Clabration
« Reply #3 on: November 05, 2019, 08:15:59 pm »
Legally 2% accuracy if you have a sat nav check it against that

That’s a very low margin for error, I heard it was 10%  -speed cameras are set to over 10% +a bit more to allow for this acceptable error

Mine is out by about 10% too - my first vag car to be out by so much

Offline titchy

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Re: Speedo Clabration
« Reply #4 on: November 05, 2019, 08:32:43 pm »
speed camera rules have changed tightened up 2 people I know got done 34mph in 30 north rd. cardiff

Offline Stupots

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Re: Speedo Clabration
« Reply #5 on: November 05, 2019, 08:58:16 pm »
speed camera rules have changed tightened up 2 people I know got done 34mph in 30 north rd. cardiff

So 10% + a bit then ;)
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Offline LC5F

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Re: Speedo Clabration
« Reply #6 on: November 05, 2019, 10:18:23 pm »
speed camera rules have changed tightened up 2 people I know got done 34mph in 30 north rd. cardiff

Cough...money grabbers

Offline pudding

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Re: Speedo Clabration
« Reply #7 on: November 08, 2019, 05:23:16 pm »
It's within 5% at urban speeds but the faster you go, the worse it gets.  I've seen an indicated 130 show as 120 on the GPS,  but that is probably deliberate for forum bragging rights! 

The only way to check it accurately is with a Racelogic GPS unit as it uses much, much better telemetry.  Phones and TomToms are rubbish.  That's why all the car reviewers and race teams use it.


2007 ED30 | 2009 TDI 140 | 2016 BMW 330D

Offline FJB

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Re: Speedo Clabration
« Reply #8 on: November 08, 2019, 06:45:29 pm »
You can change the coding to be more accurate. I did it with odbeleven, go to dashboard / coding / impulse, change the last 2 digits to 07 (which is maximum), my original coding was 0007403 and I changed it to 0007407. The coding is for changing wheel sizes, I'm on 17s, so it corrected the error. When I'm doing 40 on the gps its 40 on my speedo, 68 on my gps is 70 on my speedo.

Offline pudding

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Re: Speedo Clabration
« Reply #9 on: November 09, 2019, 11:52:48 am »
Good to know  :happy2:  If it's that accurate up to 70, I think I'm due a ticket in the post soon  :doh:


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Offline probedb

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Re: Speedo Clabration
« Reply #10 on: November 09, 2019, 09:38:22 pm »
Mine is the other way, the wheels should show minor differences but the speedo reads higher than that error according to the GPS speedo on google maps navigation.