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Thread: Speedo, Tyres and Correction

  1. #31
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    Quote Originally Posted by trout1105 View Post
    There is absolutely Nothing wrong with the build of my D2a and I am very fussy about its maintenance But I have No interest in altering the electronics by adding a non genuine part just to have my speedo read 100% accurate when it doesn't make any difference whatsoever to the truck reliability and performance.
    From what I have read these speedo correctors actually can cause the speedo to fail anyway.
    I have spent about $20k on my D2a getting it up to scratch over the last few years of ownership So I'm not stingy, I just cant see the point or any value in doing the speedo mod.
    I really don’t know much about your build, I do know about my build. A part of having my vehicle done properly was having the speedo corrected so that it complied and then having it all engineer certified. I can almost guarantee there are no D2’s on this forum that have had a speedo correction unit longer than mine, and mine has been 100% reliable. I actually don’t think they make anything fail. Valuing making it comply and actually making it comply are totally different things. If its done properly, it will comply.
    Cheers
    Slunnie


    ~ Discovery II Td5 ~ Discovery 3dr V8 ~ Series IIa 6cyl ute ~ Series II V8 ute ~

  2. #32
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    Quote Originally Posted by donh54 View Post
    The vehicle should have a plate stating that it met the ADRs required at the time of importing. Unless you have replaced the speedo with a non-genuine one, it's still certified.

    If you are willing to go through the process of getting an engineer to re-certify your speedo, you would be one of probably only a handful of vehicle owners that have ever done so.

    Will it affect the reliability or driving experience of your vehicle? Will it affect the insurance premiums you pay? Is there any potential for cost recovery?
    The certification relates to the reading on the speedo, rather than the speedo itself. Quite a few do engineer certify, but quite a lot don’t.

    Good questions, but really you need to just do what the modification guidelines say to do.
    Cheers
    Slunnie


    ~ Discovery II Td5 ~ Discovery 3dr V8 ~ Series IIa 6cyl ute ~ Series II V8 ute ~

  3. #33
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    Quote Originally Posted by trout1105 View Post
    I am running 245/70/16's and my speedo is out 8kph at 100kph
    Apparently my D2a is unroadworthy at 8kph over what the speedo is saying, Maybe I should mention that to all the people I see broken down or bogged in my travels
    Not sure how your speedo can be out that much on 245/70/16, I'm running 235/85/16 which puts mine out by about that much. The standard tyre size is 235/70/16 which is 29" and from the information I have gathered a 245/70/16 is only 29.5" an increase of only 1.7%.

    235/70/16 (29") to a 235/85/16 (31.7") is an increase of 9.3%, my speed isn't over quite that much but it is close. So at 100 Km/h your speed should only be over by < 2 Km/h.

    Please someone correct me if I'm wrong.
    There is no eraser on the pencil of life.

    Now - 2008 D3 SE 4.0l V6
    Was - 2000 D2 TD5 with much fruit.

    Ray

  4. #34
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    Quote Originally Posted by ChookD2 View Post
    Not sure how your speedo can be out that much on 245/70/16, I'm running 235/85/16 which puts mine out by about that much. ....

    Please someone correct me if I'm wrong.
    Interesting point!

    Brother is running 245/75 16's and is out by 6k/h(doing 106 at an indicated 100)
    Of course some variation in tyre design/manufacture will change that from car to car, and I guess add some inherent speedo differences too.

    as an example:
    I used to have 255/70s and changed to 245/75 just recently myself.
    Theoretically, the 245/75 are about 1% larger, so will slow speedo down by that 1% or so(maybe 1.3 or whatever the calculator said.
    So, I expected this on my test run.
    But, my speedo went the other way .. went an indicated -1%(roughly), instead of +1% actual speed.
    So instead of seeing a 0% difference or maybe 1% difference, .. ie. either 100 or 101 at an indicated 100, I now get 97-ish, where I used to get about 98 at in indicated 100.

    Unless there was a monumental issue with the GPS system on that day a few days ago, both GPSes showed the same speed.

    But you're right .. 245/70 .. shouldn't alter speedo by that much.

    .. maybe Trout's D2 had a speedo corrector installed by some previous owner
    Arthur.

    '99 D1 300Tdi Auto
    '03 D2 Td5 Auto

  5. #35
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    Quote Originally Posted by AK83 View Post
    Interesting point!

    Brother is running 245/75 16's and is out by 6k/h(doing 106 at an indicated 100)
    Of course some variation in tyre design/manufacture will change that from car to car, and I guess add some inherent speedo differences too.

    as an example:
    I used to have 255/70s and changed to 245/75 just recently myself.
    Theoretically, the 245/75 are about 1% larger, so will slow speedo down by that 1% or so(maybe 1.3 or whatever the calculator said.
    So, I expected this on my test run.
    But, my speedo went the other way .. went an indicated -1%(roughly), instead of +1% actual speed.
    So instead of seeing a 0% difference or maybe 1% difference, .. ie. either 100 or 101 at an indicated 100, I now get 97-ish, where I used to get about 98 at in indicated 100.

    Unless there was a monumental issue with the GPS system on that day a few days ago, both GPSes showed the same speed.

    But you're right .. 245/70 .. shouldn't alter speedo by that much.

    .. maybe Trout's D2 had a speedo corrector installed by some previous owner
    Your brother's car is about right, the variation from standard (29") to 245/75/16 (30.5") is 5.2% so 6 Km/h above indicated works. As you say variations in tyres.

    I have no idea what's going on with yours though. That's just weird, even with the 255/70/16 you should have been getting about 104 at an indicated 100. And then a further increase of a little over 1% with the 245/75/16, so should be doing about 105-6 Km/h at an indicated 100.

    My brain hurts.
    There is no eraser on the pencil of life.

    Now - 2008 D3 SE 4.0l V6
    Was - 2000 D2 TD5 with much fruit.

    Ray

  6. #36
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    Quote Originally Posted by ChookD2 View Post
    .... That's just weird, even with the 255/70/16 you should have been getting about 104 at an indicated 100. And then a further increase of a little over 1% with the 245/75/16, so should be doing about 105-6 Km/h at an indicated 100.

    My brain hurts.
    LOL! I can add to the strangeness, but I'll leave it at that for now .. don't want to cause you any more pain!

    I'm guessing: std from factory, they probably had a +5k/h error built into the speedo, which is what I usually see from most vehicles I drive/have driven.

    So lets say LR had tried to achieve a +5k/h error from new.
    Add the variation of the 255/70's correction amount, that would bring the speedo closer to actual. So that'd take my 255/70's to about 99-ish .. which is what I generally saw.
    Arthur.

    '99 D1 300Tdi Auto
    '03 D2 Td5 Auto

  7. #37
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    The original tyres when i bought the D2a were crappy little road tyres and the speedo was pretty much correct.
    I have had a set of Yokohama Geolanders on since then and i got 60k out of them without any dramas an i now have a set of MT ATZ P3's on and they both give me the same speedo reading so the car May have a speedo "gizmo" fitted.
    You only get one shot at life, Aim well

    2004 D2 "S" V8 auto, with a few Mods gone
    2007 79 Series Landcruiser V8 Ute, With a few Mods.
    4.6m Quintrex boat
    20' Jayco Expanda caravan gone

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