On Sat, 26 Nov 2005 01:10:03 +0100 (CET), Nomen Nescio
>Low reading speedometers are costly in terms of police citations and create
>safety problems as well.
>Speedometers are inaccurate inherently and made worse as new tires are
>installed and worn down due to the rolling radius variation.
>A speedometer can be designed using the same principle as the optical
>mouse. It reads the road and calculates V = D/T. Such a speedometer need
>not be digital. A calibrated analog readout is feasible for 0.5% accuracy
>at all speeds. It does not have to calibrate continuously if light or road
>conditions are not within its capability. It simply uses memory and
>reverts to the most recent self-calibration.
>Some speedos are 5 or 6 mph off at road speeds. This should not be
>tolerated in this day and age of high tech.
>Such a speedo is quite elementary and involves absolutely no technology; I
>have actually constructed a working model, breadboarded testbed. Although
>it is the size of a shoebox and far from practical, it is entirely possible
>to miniaturize it via a single dedicated I.C. I suggest this type
>speedometer be standard equipment in the 2007 models and be made mandatory
Speedometers might be off slightly on a stock vehicle. If you change
things like wheel size, then you have cause to be concerned.
Generally, police, depending on jurisdiction, concentrate more on how
I think it's a waste of time and money to seek the kind of exactness
you want. There is too much to throw it off. Like tire pressure. And
wouldn't it require ever tire manufacturer to produce exactly the same
size tire so that the owner could not change the aspect ratio by
changing tires from what was OEM?
Many places I have been, you can be well above the limit, but as long
as you are flowing with the pack, it is ignored. The one who weaves in
and out trying to get ahead of the pack is the one asking for trouble.
Naturally, there are exceptions. And the 5mph rule can go either way;
either be a fudge factor, or be a citation.
1965 Ford Mustang Fastback 2+2, Vintage Burgundy
w/Black Std Interior, A Code 289 C4 Trac-Lok;
Vintage 40 16" rims w/225/50ZR16 KDWS BF Goodrich
gForce Radial T/As, Cobra drop; surround sound
See my ride at....
Feb 2004- http://220.127.116.11/albums/86810/003_May_21_3004.jpg
Feb 2004- http://18.104.22.168/albums/86810/005_May_21_2004.jpg
Jul 2005- http://22.214.171.124/albums/86810/d..._11_05_002.jpg
Jul 2005- http://126.96.36.199/albums/86810/E...ebuild_006.jpg