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General => General discussion => Topic started by: boldy147 on 07 April 2008, 06:42

Title: speedo calibration help pls
Post by: boldy147 on 07 April 2008, 06:42

i have just bought a mk2 golf gti and i have noticed that because it has 17" wheels on it the  sppedo is not calibrated for these wheels  , can someone please tell me how i go about calibrating the speedo thanks  jason

Title: Re: speedo calibration help pls
Post by: jv on 07 April 2008, 13:48

if it has the correct size tyres on the 17's then nothing needs doing :afro:

Title: Re: speedo calibration help pls
Post by: boldy147 on 07 April 2008, 17:52

hi

IT has 205/40 ZR17 84W on it , i know the speedo is out because there is no way i am going as fast as it reads , any other ideas pls

thanks

Title: Re: speedo calibration help pls
Post by: MowatGTI on 07 April 2008, 18:01

I am probably wrong in saying this, but surely with the bigger wheels, the speedo would show a slower speed than what you are actually doing?

40 profile too, so surely the diameter is just larger than standard.

Im probably wrong mind.......

Title: Re: speedo calibration help pls
Post by: jv on 07 April 2008, 19:06

bigger wheels, correct lower profile tyres equals same(ish) overall rolling radius.

they are the right size tyres for 17's so if the speedo is miles out the problem is elsewhere me thinks.

Title: Re: speedo calibration help pls
Post by: Uruk Hai on 07 April 2008, 19:08

Have a look at this, might help ?

http://www.miata.net/garage/tirecalcold.html

Title: Re: speedo calibration help pls
Post by: DarnPB on 07 April 2008, 19:23

If in doubt, contact speedy cables. They have a website so do a google on it. They do calibration for speedo's fitted to kitcars and can issue a calibration certificate that is recognised by the ministery of transport as if required.

Title: Re: speedo calibration help pls
Post by: raferackstraw on 07 April 2008, 23:26

hi mate i would check you have the correct speedo drive gear on the end of the cable first

does the speedo needle move back and forth when at high speed as this could indicate that the spring in the back of the dial is fooked

try borrowing a sat nav as this will show your true speed

Title: Re: speedo calibration help pls
Post by: boldy147 on 08 April 2008, 06:43

hi

thanks all for your suggestions , just one more thing i have noticed  . the speedo in my golf is a 140 mph speedo but shouldnt the speedo in a 8v 1990 gti be a 120mph speedo . Is it possible that this is the problem

thanks again

jason

Title: Re: speedo calibration help pls
Post by: boldy147 on 08 April 2008, 06:47

sorry i have just discovered there was a 140 mph speedo on the 8v gti , what concerns me is that from the look of the 120mph speed and the way my speedo goes up the separation of 120 mph speedo looks as if it would be correct