Speedo linearity....

I just can not figger out WTF.....I would think a speedo would be very linear device in it's response.....why NOT?? according to Garmin NUVI 200w that thing was WAY the hell off

dead nutz on at 10-20-30-40-up to 70, at 90 is only really 87-88, at 100 indicated it's only really 94.....

now here is the weird part....I KNOW my tach is accurate with being 300 rpm high at 3000 and 4500 rpm.....

BUT according to tables off the net, with my o/drive/rear gear set/tire size (275/50/17) and so forth, it WAS supposed to be some 12-15% faster than it really is according to Garmin....

so WTF is going ON?? so my supposed 150 mph run that the tach supposedly confirmed was only maybe 130 if that.....

why would a stock speedo go to over reading like crazy??? is this NORMAL??

both of them, enough to make me go digital, with nice big RED LED readout....If I have to make them myself.....this is bullshit....

the speedo gear I had in there had some 10% fewer teeth than the one in there now...so now it's accurate at slower speeds, but not up topside....

:huh:

Sppedometer calibration link

Here 'ya go Gene, one good link deserves another.

Look at the info in the blue shaded box.

http://auto.howstuffworks.com/speedometer4.htm

The speedo drive gears are chosen to calibrate the ODOMETER accurately. Once that is correct, the HEAD is calibrated to the correct speed. Production cars do not have super fine quality heads. Car ralleys use precision speedos.

Does anyone make a electronic speedo that runs off the 4000 PPM pulse generator running my DPFI computer???

THAT would tell the tale.... I don't care if it's digital, just gimme the truth, damnit.....same for the tach...

New GPS stuff!

Hey Gene,

I used to have a Nordskog digital gauge set up in my 'Vette, I checked out their website and they have some new stuff that is pretty trick looking. How does a GPS speedometer sound to you? Would that satisfy your need for accuracy?

http://nordskogperformance.net/home.php?cat=71

DeeVeeEight said:

Hey Gene,

I used to have a Nordskog digital gauge set up in my 'Vette, I checked out their website and they have some new stuff that is pretty trick looking. How does a GPS speedometer sound to you? Would that satisfy your need for accuracy?

http://nordskogperformance.net/home.php?cat=71

Click to expand...

You know, IF that speedo/tach/various instrumentation readout was available with a 5" dial/face....I would be super interested...even at 400 bux....

but 3.375 don't get it...soo damn small.....:hissyfit:

mrvette said:

DeeVeeEight said:

Hey Gene,

I used to have a Nordskog digital gauge set up in my 'Vette, I checked out their website and they have some new stuff that is pretty trick looking. How does a GPS speedometer sound to you? Would that satisfy your need for accuracy?

http://nordskogperformance.net/home.php?cat=71

Click to expand...

You know, IF that speedo/tach/various instrumentation readout was available with a 5" dial/face....I would be super interested...even at 400 bux....

but 3.375 don't get it...soo damn small.....:hissyfit:

Click to expand...

Try calling them Gene, I had a direct fit digital set up from them, they might have something for you.

I sold these a few weeks ago, the speedo and tach were super accurate.

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The oil and temperature gauges left a bit to be desired, they were old and a bit out of whack. Apparently my oil was frozen and my coolant not much better....