BladesGrant Posted June 3, 2009 Share Posted June 3, 2009 My Z has been converted from KPh to MPH but appears to be out. I know they say they are approximately 10% but mine seems to be a constant 10MPH out rather than 10%. Is there any way of closer calibrating the speedo or do I just have live with it? I just feel a little nervous going down the motorway and seeing the needle getting close to 3 figures even though I know I am not going that fast!!! Any suggestions welcome. Quote Link to comment Share on other sites More sharing options...
H5 Posted June 4, 2009 Share Posted June 4, 2009 Who did the work and what are you comparing it against to know you're out? Quote Link to comment Share on other sites More sharing options...
dcash5 Posted June 4, 2009 Share Posted June 4, 2009 reposition the needle Quote Link to comment Share on other sites More sharing options...
BladesGrant Posted June 4, 2009 Author Share Posted June 4, 2009 It was already converted when I bought it. I have used my Sat nav and my iPhone to verify it. They are not 100% accurate but they seemed to be closer then my speedo!!! Plus going down the motorway in Mondeo at 80 I don't get sped past by everything, where as in the Z I seem to. Maybe people just want to speed past me in more!!!!!!!!! Quote Link to comment Share on other sites More sharing options...
H5 Posted June 4, 2009 Share Posted June 4, 2009 The sat nav will be lower than the speedo, but you say the speedo is always 10mph ahead? Unless the speedo starts at 10mph there must be points where you are seeing less than that. What's the difference at 30mph on the sat nav? Quote Link to comment Share on other sites More sharing options...
martinmac Posted June 4, 2009 Share Posted June 4, 2009 75 on my uk speedo = 70 on my sat nav. Quote Link to comment Share on other sites More sharing options...
BladesGrant Posted June 4, 2009 Author Share Posted June 4, 2009 Not really checked it at low speeds. just noticed it more around the 70 - 90mph mark. It definitely doesn't start at 10mph. Its no big deal at the end of the day, shouldn't ever get done for speeding even if I go a little of the limit on my speedo!!!!! Quote Link to comment Share on other sites More sharing options...
paddy0d Posted June 4, 2009 Share Posted June 4, 2009 speedo's can be conservative compared to sat nav, as they have to run on tyres that have different amounts of tread, which chnages the rolling radius. How worn are your tyres? If they are close to the end, your speedo will be over reading more... Cheers Quote Link to comment Share on other sites More sharing options...
BladesGrant Posted June 5, 2009 Author Share Posted June 5, 2009 My tires are fine, tried it at lower speeds and its a lot closer. Maybe it is just the usual percentage out but it just seemed a big difference when I was on the motorway. Quote Link to comment Share on other sites More sharing options...
Rob_Quads Posted June 5, 2009 Share Posted June 5, 2009 Be safe in the knowledge that manufacturers normall ship cars which under read the speed sometimes by up to 10%. The reason is its illegal for them to sell a car that under-reads. Quote Link to comment Share on other sites More sharing options...
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