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RE: [ST] new lister with license in jeopardy



It has been pretty well documented that our speedometers are 'optimistic'
and that the odometers are pretty well bang on (except when you consider
tire wear or brand change).  As a side issue, this also means that you
cannot do anything external to re-calibrate the speedo since you will screw
up the odometer accuracy in the process.

Many have also noted that the speedo error seems to be non-linear (ie. not a
fixed % error).  The ST speedo is, for the most part, mechanical in nature,
so one might wonder how this can be, since, in my mind anyway, an internal
speedo gearing 'adjustment' that only affects the speedo would produce a
constant error ratio.  The electronic speedo on the RS presents an entirely
different situation, so I won't confuse things by including it in this
discussion.

My theory is that the FACE of the ST speedo dial has been rotated slightly
counter-clockwise to produce the higher-than-normal readings.  If you think
about this for a sec, I believe you will realize that this produces a
non-linear discrepancy between the indicated and actual speed.  This is
because the speed increments that are painted on the speedo face are evenly
spaced.  For example, a 5 mph error at 30 mph will be the same 5 mph error
at 60 mph, but the % error would be different.

So in other words the speedo is off by a FIXED amount, regardless of the
speed you are actually traveling.  This also would explain why the perceived
error rate seems to decrease the faster you go.  The 'adjustment' that the
manufacturer makes would be easy to implement and it wouldn't affect the
odometer.

Anyway, that's my story and I'm sticking to it    =8o)

Cheers,
Neil


> - -----Original Message-----
>
> From: "Masiak, Richard" <Richard_Masiak@xxxxxxxxxxxxxxxx>
> Sent: Mon, 26 Jan 2004 10:14:25 -0500
> Subject: RE: [ST] new lister with license in jeopardy
>
> Yeah, 8% sounds about right.  I was doing 37-38 MPH by one of those
Sheriff
> "here's the speed you're doing" trailers and it registered 35 MPH.  I
don't
> know if that tolerance carrys thru to the higher speeds.  One would think
it
> does.
>
> Rich
>
> From: Anthony Scerri [mailto:tscerri@xxxxxxxxxxxxxxx]
> Sent: Saturday, January 24, 2004 1:50 AM
> To: ST@xxxxxxxxxxxxxx
> Subject: RE: [ST] new lister with license in jeopardy
>
>
> Greetings....
>
> I have taken this issue up with Triumph....and have been advised that
> although the speedos are between 8.5 to 10% optimistic, the odometer is
> correct - otherwise they would have legal issues with servicing etc.
>
> Subsequent testing against a GPS unit verifies this claim.
>
> Cheers
>
> Tony Scerri
> '02 Sprint ST



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