Testing: Tire / Speedo / Differential Calculator - try it out! - Page 6

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  1. #51
    CelicaSupra.com Member
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    No problem about it needing updating for what's actually available. This is not anyones job and these things are all wonderful contributions done on someone's free time and freely shared. This doesn't explain why it suggests different ratios / gear combinations than what Toyota has always used for the exact same configurations. I do understand that the accuracy can change over time but both of mine have always been off by about the same amount towards the high side and certainly not within the mentioned tolerance of 3.75% being more like 5% over. Either may have changed over time but only very slightly if at all. This is not something I just noticed.
    Where did this recommended tolerance come from anyway? Maybe it really is a reasonable tolerance to expect in the real world but I would expect that the calculated results would be exact and that the recommended ratios would be as close as possible to them based on the closest gear sets available. But it sure seems to me that if this was true, the actual results achieved would be within a certain tolerance of expectations and not off even more and in the same direction as stock. The one thing I can think of that does indeed vary some in reality is the exact diameter and rolling circumference of different types and manufacturers tires in the same size. This might just be why the real world tolerance is as generous as it is but I would think OEM's would generally be much closer and probably well under half of this.
    Of course this doesn't apply in the motorcycle world. I've seen and known of bikes that their indicated speed was sometimes well in excess of 110% of reality and this isn't much of a secret.
    And, even this wouldn't necessarily be of much concern if it's calculated solutions were within approximately the same tolerance either way. But all the examples I tried suggest ratios that were off towards the high side by an even larger amount than the stock combinations are. This is why I asked what causes this. Certainly the formulas listed are indeed correct. Either some part of something isn't being implemented correctly or some part of its database is incorrect by some small amount somehow or something else is causing a small but consistent error.
    If its suggested solutions were a bit off towards the other direction from OEM and actual results showed even better accuracy, I would think that this had either used more accurate data or a more accurate implementation of the formulas or something else that further improved real world results. My tests showed the opposite. This is why I mentioned my results as they weren't what I expected.
    Hopefully there's some possible explanation for this. If anyone finds anything I'd like to know what it might be.

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  3. #52
    CelicaSupra.com Member SupraFiend's Avatar
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    My experience with the formulas within this calculator produce perfect results. I'm quite positive the math is correct. I think you're just running into the realities of running an analog speedo driven by a cable on a 30ish year old car with many miles on it. My high mileage daily driver mk2 still reads high after putting in the correct speedo gears (it had the wrong one in due to a tranny swap for a bit, all stock and oem size tires). Its just old and worn. While my project car is showing the indicated variance the calculator reports with the gears and tires I'm running, and the other car I swapped the correct gears into is dead on.
    Black 86 mk2 Project Car
    New SDR 86 mk2 Daily User, Highway Cruiser AND Parking Lot Abuser in the works!

  4. #53
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    Hi guys..is there a latest link available ? Cant download from the old one.

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  6. #54
    CelicaSupra.com Member SupraFiend's Avatar
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    I'll bug Deanfun to rehost or fix the link, not sure what's wrong but he's still around and the original author so the first post should continue to maintain a link to the current version. However, goto this post for a mirror. Not sure if any changes were made since that duplicate was made.

    http://www.celicasupra.com/forums/sh...l=1#post391059
    Black 86 mk2 Project Car
    New SDR 86 mk2 Daily User, Highway Cruiser AND Parking Lot Abuser in the works!

  7. #55
    CelicaSupra.com Member Deanfun's Avatar
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    Updated link in first post.

    Over winter I'll come back and improve usability.
    Dean L.
    1985 Toyota Supra - Hidden Content
    1987 Toyota Land Cruiser BJ73
    2007 Lexus LX470

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