Technical Seicento speedo wrong

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Technical Seicento speedo wrong

hobbsy555

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:bang:

Has anyone got any idea why my sons 1998 sei sx speedo shows a higher speed than the car is actually going? :confused:

The error gets larger the quicker you go.:shrug::cry::shakehead:

dont know much about the car yet so may not have answers to any questions you have.

Cheers !:)
 
is it running oversize wheels?most speedos are slightly out but running the wrong profile tyre or oversized wheels are the main causes.ad
 
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undersize wheels will give a higher reading than what your actually doing.

also there ment to overread slightly so you dont have a excuse for speeding as to be doing 45mph the speedo would be reading 47 or even more!
 
when you say the speedo is getting worse the faster you go is the needle bouncing around?

The speedo cable maybe on the way out?
 
How much of a difference are we talking about?

My car did this until I fitted slightly larger wheels/tyres which corrected the error.

Most cars over-read the speed by 5-10% depending on the exact tyre size (don't forget tyres wear out which means it is constantly changing).

My explorer overreads by roughly 7% and annoyingly that means the speed limiter cuts in early...
My sei reads accurately to within 1%
My abarth 500 overreads by roughly 3%
My old X1/9 (not the current one as it doesnt even have a speedo) used to overread by a huge 15%
 
Thanks for all the suggestions!!

The car is running on 155/65 13's which I assume is the correct size from new.

The speedo cable seems to be fine as the needle is nice and steady when you travel.

And finally, to get about the correct speed, it would seem if you take the reading in km/h and half it you get a more accurate idea of your true speed!!!???

Any more suggestions , please.
 
Mine does the same thing. Its a 2000 Sporting.

Its not too bad at low speed but when the clock says 80mph its acutally only doing about 70mph.

Again mine has standard wheels and the needle doesnt bounce about.
 
mine is well out the other day I had 120mph but my gps was showing 108 I was over impressed by that from a standard car, how correct that was I dont know I thought these things only pushed 100.
 
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