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Author Topic: Speedo over reading  (Read 1975 times)

Offline wilson

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Speedo over reading
« on: 15 May 2009, 19:25 »
Is there any particular reason why my speedo would over read, I've got used to what speed is what but would like to sort it at some point...  at around 70-80 mph, it is reading 14-16 mph over the speed of sat nav,  My standard 1990 16v does 150 mph !!! :grin:

I know must speedos over read slightly, my mums vectra is only 2-3 more than sat nav, and the old merc is reading 4-5 over.

I am of course assuming that sat nav is a correct reading

Thanks
Wilson

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Offline Dan34

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Re: Speedo over reading
« Reply #1 on: 15 May 2009, 19:49 »
what size wheels and tyres are you running?

Dan
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Offline wilson

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Re: Speedo over reading
« Reply #2 on: 15 May 2009, 20:07 »
16's with 205/45's
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Offline Dan34

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Re: Speedo over reading
« Reply #3 on: 15 May 2009, 20:27 »
on mine when i put on 45 profile on 15's it messes up the speedo and gearing but i would have though a 16 inch wheel wouldnt be as bad to be honest, there's a calcutor thingy on the internet somewhere to work it out

Dan
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Offline wilson

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Re: Speedo over reading
« Reply #4 on: 15 May 2009, 20:49 »
Actually, didnt think about it when I answered your question, but I've had 15's with 195/50's on and it was same.

Thanks
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Offline Dan34

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Re: Speedo over reading
« Reply #5 on: 15 May 2009, 20:56 »
hmmm the 195 50's should be ok with the speedo reading, i think you have a problem else where i think  :sad: hopefully someone else should shed some more light im not too sure

Dan
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Offline Ben Lessani

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Re: Speedo over reading
« Reply #6 on: 16 May 2009, 03:03 »
Wrong clocks or wrong gear on the end of the speedo cable.

... or just the fact its a 20 odd year old car :D
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Offline JC

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Re: Speedo over reading
« Reply #7 on: 16 May 2009, 05:00 »
Quote from: Dan34 on 15 May 2009, 20:27
on mine when i put on 45 profile on 15's it messes up the speedo and gearing but i would have though a 16 inch wheel wouldnt be as bad to be honest, there's a calcutor thingy on the internet somewhere to work it out

Dan

http://www.alloywheels.com/tyrecalc.asp

i run 195/50/15s, and mine is 5 - 7 mph over across the speedo according to satnav.  :wink:
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Offline wilson

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Re: Speedo over reading
« Reply #8 on: 16 May 2009, 10:05 »
Quote from: Ben Lessani on 16 May 2009, 03:03
Wrong clocks or wrong gear on the end of the speedo cable.

... or just the fact its a 20 odd year old car :D

I dont think they are the wrong clocks, everything else is fine, all the MFA works correctly etc,  what is the gear at end of cable and how do i find out if its wrong / replace it ?

Thanks
Wilson
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Offline Grazy

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Re: Speedo over reading
« Reply #9 on: 16 May 2009, 11:25 »
I have same problem on mine Wilson maybe its a Suffolk thing lol , Previous owner changed clocks maybe this contributed , interested to see answer on this  :cool:
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