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Thread: Speedo is about 10% over

  1. Default

    At 200km/h your more likeley to have a judgemental or a paralax error while reading.

    Which brings me to another point... gen2 clusters are extremely bad for paralax errors due to curved nature of the indicator strip and the angled front perspecs

  2. #42

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    Knew you'd say maths is a science :-P depends who you ask.
    As someone who's studied maths and physics at uni, I say they are different. Science is applied mathematics but that's beside the point.

    Evenly spaced. Hmm luke what's the next excuse? :-P


    Sent from my LG-P880 using Tapatalk 4

  3. #43
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    Quote Originally Posted by GibbA View Post
    Knew you'd say maths is a science :-P depends who you ask.
    As someone who's studied maths and physics at uni, I say they are different. Science is applied mathematics but that's beside the point.

    Evenly spaced. Hmm luke what's the next excuse? :-P


    Sent from my LG-P880 using Tapatalk 4
    If it was square all sides would be equal and would be mathematically a quad equation . So if you were doing 70 or 140 of 210 or 280 your needle would have to be longer to reach the numbers

    Stop feeding the troll lol
    Many want Power not many hold it long.........

  4. Default

    on my ultra gauge with stock everything the faster i went the more it was out. at 110 ultraguage
    the speedo needle is at 119 in gen 2

  5. #45
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    Quote Originally Posted by shaneski View Post
    on my ultra gauge with stock everything the faster i went the more it was out. at 110 ultraguage
    the speedo needle is at 119 in gen 2
    In all seriousness mine gets closer to being correct. My gen1 was heaps out, my gen 2 a 100ph is only 2-3kph faster reading
    Many want Power not many hold it long.........

  6. #46

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    Sorry to say it luke but I think you must have alcams speedo. It's superior than everyone else's and works better the faster you go

    Sent from my LG-P880 using Tapatalk 4

  7. #47
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    Quote Originally Posted by GibbA View Post
    Sorry to say it luke but I think you must have alcams speedo. It's superior than everyone else's and works better the faster you go

    Sent from my LG-P880 using Tapatalk 4
    I have no come back .... Just that Alcam tis nevar wong!
    Many want Power not many hold it long.........

  8. Default

    I think I may buy an Ultragauge or one of these Elm327 WIFI Wirless OBD2 Car Diagnostic Reader Scanner Scan Tool for Iphone iPad iOS PC : Amazon.com : Automotive and hook it up to my iPhone.

    Thoughts?

  9. #49
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    Quote Originally Posted by peterm3150 View Post
    I think I may buy an Ultragauge or one of these Elm327 WIFI Wirless OBD2 Car Diagnostic Reader Scanner Scan Tool for Iphone iPad iOS PC : Amazon.com : Automotive and hook it up to my iPhone.

    Thoughts?
    Connecting via iPhone and wifi is crap and laggy. Only good for logging no point watching it. You need an android, Bluetooth and torque to be able to watch live with accuracy. I've tried everything with the iPhone, all types of wifi adapters suck. Some are better than others but in the end to be able to do it optimally you want to go the android route.

  10. #50

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    Ultragauges are great, but as soon as you change you wheel size, it makes them both go out

    This is what happened with my car

    18" stock rims
    Actual Speed - 100
    Speedo - 109
    Ultragauge/Cobb AP - 101

    19" rims
    Actual Speed - 100
    Speedo - 105
    Ultragauge/Cobb AP - 97

    Cobb told me there isn't any way to recalibrate the ECU to compensate wheel size

    I'd have to recalibrate to speedo or my brain to get any accuracy

  11. Default

    Quote Originally Posted by slixx View Post

    Cobb told me there isn't any way to recalibrate the ECU to compensate wheel size

    I'd have to recalibrate to speedo or my brain to get any accuracy
    correct, without doing something nasty and molesting the ecu... you can only recalibrate what you see (the speedo dial).

  12. Default

    came across this...

    Direct from the Mazda Australia FAQ page

    Why is the speed nominated on my GPS different from my vehicle's speedometer?

    Mazda Corporation goes to great lengths to ensure all its components comply with both Mazda product performance guidelines and the Australian Design Rules. The current Australian Design Rule (ADR 18/03) indicates the speed shown on the speedometer must always be equal to or greater than the actual vehicle speed. ADR 18/03 allows approximately 10% variation at 100 km/h. For more information refer to the Australian Government, Department of Infrastructure and Transport website.
    Whenever a speedometer is tested and found to conform to the relevant ADR, it is deemed to be within specification and not subject to any further rectification. For speedometers components operating correctly, there is no further calibration adjustment available.


  13. #53

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    Quote Originally Posted by AzzA SP20 View Post
    came across this...

    Direct from the Mazda Australia FAQ page
    /thread

  14. #54
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    Almost. It's 10% + 6kph.

    2. Requirements

    The production shall be deemed to conform to this Regulation if the following relationship between the speed indicated on the display of the speedometer (V1) and the actual speed (V2) is observed:
    In the case of vehicles of categories M and N:

    0 = (V1 – V2) = 0.1 V2 + 6 km/h;

  15. #55
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    Default

    Quote Originally Posted by AzzA SP20 View Post
    errr... hate to break it to you... It is a percentage thing!

    our speedo's are controlledby variable reluctance magnetic sensor, which reads the speed of the passing teeth on a gear in the diff (works from electro-magnetic pulses). The sine-wave signal generated is converted to a certain amplitude of pulse depending on your speed. This is done via your computer, and this signal is sent to a stepper motor which moves the needle with digital accuracy.

    when you have such multiplication processes, your accuracy will be based upon a percentage.

    even old school eddy current needles have a percentage of error using your speedo/ ring gear system.
    anything that uses some form or ratio's or multiplication of another dependent value will have a percentage of error.



    your theory is severeley flawed as Gibba pointed out.

    at 200km/h you are travelling at 3333.3' m/min

    if you are on stock size rim (225/40/18) your tyre has a circumference of 2.0018m.

    meaning per revolution of your tyre your car has travelled 2m (unless wheel spin )
    anyway... your wheel is now doing 1666.6' rpm.

    by the time you factor in your rotational mass variances at such high speeds aswell as the mass ammount of extra heat generated... your tyre has now expanded (and by a fair bit).

    once your tyre expand... Its now travelling slower than it would be if it was cold (due to diameter increase).
    which your speedo which was reading 106km/h at an actual velocity of 11km/h is now reading slower than it was when cold... mking your speedo reading say... 101km/h at an actual velocity of 100km/h.

    BOOM! SIENCE BITCH! rofl
    sounds good. last bit made me laugh.

    although the whole lot is correct. it doesn't take into account the heat incease, pressure increase and circumference increase that happens at higher speeds. which is probably why someone may see less percentage varience at higher speeds.

  16. Default

    Quote Originally Posted by projectrracing View Post
    sounds good. last bit made me laugh.

    although the whole lot is correct. it doesn't take into account the heat incease, pressure increase and circumference increase that happens at higher speeds. which is probably why someone may see less percentage varience at higher speeds.
    Please read the middle to last section of the quoted text you just posted... already on that like a rash matey!

  17. #57
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    haha how'd i miss that the first time.

  18. Default

    Quote Originally Posted by projectrracing View Post
    haha how'd i miss that the first time.
    Probably due to the many typo's and auto corrects lol

  19. #59
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    This thread... Makes me giggle lol

  20. #60

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    maths not science? Ha! Bahahaha. Ha! Oooh that made me laugh.

    Sent from my HTC Velocity 4G using Tapatalk 4

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