Speeding, and well....speed....??

[mrvette]

I had been going by my tach and speedo, and then the web sites on the gearset and o/drive and exact tire size all typed in.....the tach and speedo agreed I was doing say 130 mph.....RONG.....

I varified my tach with a digital audio oscillator/generator...and my Tektronics scope that I know the tach is accurate at 1500-2000 rpm, but at 3 grand it's 300 high, at 4500 & 6000 it's still high by 300 rpm....strange, must be mechanical I figger....

SO, I get a offer I can't refuse on a Garmin NUVI 200w 120 bux at the local West Marine.....take it for a ride....speedo is 10%+ over indicating....uh oh....

so I change gearsets in the tranny, add 10% more teeth to the driven/cable gear....

now the thing is dead nutz right on, at 15-70 mph......80 is only really 78 mph....100 is really only 94 mph someone says it's deliberately calibrated that way....don't see why or how, but well....anyway...

Wife's Miata, same thing 10% over on all speeds....really only doing 55 and it sez 62 type shit....like when the tach/speedo USED to agree with the so called tables on the net....several sites....
some by tire diameter, some by tire size, same results....

ok, so I have a issue now with cops and tickets....they measure my speed, but somehow they know what my speedo says, so they measure me at say 75, but they know the speedo says 83, so they issue a ticket for 83.....

now I wonder about all the tickets I have EVER gotten going back some 50 years....legit or not??? I suspect NOT, never ticketed for reckless or anything really silly, just like 15mph over, like most guys....

which if it was really, fine, but what the cops says is not the case....
as it's what the speedo said, so I never bothered to argue the case.....

interesting.....to say the least....

:clobbered::banned:

 

[DeeVeeEight]

It's OK Gene. They really ARE out to get you. Not anyone else, just you.

As far as my speedo's go

'04 Ford E250 about 10%+
'99 Ford 150 about 5%+
'79 Corvette about 5%+

I figure that they are reading higher than my actual speed so I do not worry too much about speeding tickets.
Every time I pass one of those flashing "YOUR SPEED" signs it indicates less than my speedo does.

And if my speedo (in my 'Vette) says 100 MPH I do not care if it is off a bit, the thrill is THE SAME!

 

[turtlevette]

I varified my tach with a digital audio oscillator/generator...and my Tektronics scope that I know the tach is accurate at 1500-2000 rpm, but at 3 grand it's 300 high, at 4500 & 6000 it's still high by 300 rpm....strange, must be mechanical I figger....

:

Now the truth comes out. Maybe you will finally cut the BS about doing 150 with the top down.

 

[mrvette]

I varified my tach with a digital audio oscillator/generator...and my Tektronics scope that I know the tach is accurate at 1500-2000 rpm, but at 3 grand it's 300 high, at 4500 & 6000 it's still high by 300 rpm....strange, must be mechanical I figger....

:

Now the truth comes out. Maybe you will finally cut the BS about doing 150 with the top down.

In various threads it HAS come out, thing is I bought this Garmin maybe Feb or so this year.....not all that much opportunity to play with it and after finding out the truth of the shituation, I find it was about 130 at most 125 mor likely...

my question revolves around WHY??? how in hell can the tach be correct but the tables widely published be saying everything is right, and still be off by 10%+?? and given that shituation,

I have checked Garmin in other cars....10% over indicated....SO, if that is a average....that speedos over indicate, it get down to the fact that cops write tickets on NOT a ACTUAL SPEED, but what he full well knows your speedo SAYS....

or Garmin is rong.....

but if Garmin is rong, how is the vette NOW tracking fine at speeds up to say 80, where it's 2 mph over indicated...but at 100 it's 6 mph too fast??

something not kosher.....

wonder if it's tire slippage?? due to speeds and loading/drag??

I can't see Garmin blowing it s mind at say 90 mph and loosing it's accuracy...i'ts electronic, it don't give a shit doing 10 or 1000 mph....I even had the sales dweeb call Garmin and ask their tech rep...he said it's good to 1000 mph....no choice to accept it, how in hell would I know??

:clobbered:

 

[JPhil]

You're just now learning that OEM speedometers read high, to keep people artificially running slower, and the cops know this and so write tickets based on that knowledge and the citizens don't argue because they don't know better? And then you wonder why when you have calibrated your speedometer so you know it's accurate and then a cop writes you a ticket for what you know to be a patently fraudulent speed reading you feel all put upon?
Jeez, Gene, here I thought you were a competent conspiracy-theory brother, but you didn't know this basic, simple one that's been true for ever??? I am deeply disappointed, you've really let me down, Gene.....

 

[mrvette]

You're just now learning that OEM speedometers read high, to keep people artificially running slower, and the cops know this and so write tickets based on that knowledge and the citizens don't argue because they don't know better? And then you wonder why when you have calibrated your speedometer so you know it's accurate and then a cop writes you a ticket for what you know to be a patently fraudulent speed reading you feel all put upon?
Jeez, Gene, here I thought you were a competent conspiracy-theory brother, but you didn't know this basic, simple one that's been true for ever??? I am deeply disappointed, you've really let me down, Gene.....

Believe me, I ASSumed that most speedos were correct, no reason to doubt them.....but with the electronic age some past crap is coming to light....

basically had no choice BUT to believe the indications.....but to find the tables and crap are not accurate in the upper regions, and in fact had my crap all messed up that it supposedly agreed with the tables...sorry, but something is wrong....we can't make a fucking speedometer accurate???

what got me going was this gear change crap on the overdrive tranny swaps here, and the opportunity to RUN FAST, rare though it may be.....and so the only shop in town that calibrates speedometers does it with a bench and then verifies with a Garmin type satellite link.....so hell with the bench, the quest for a sat link set out some time ago.....

Not wealthy, don't have 250+ bux to spend verifying a minor speedometer error for a power run....but at 120, ok make me an offer I can't refuse, damnit.....and THAT is what opened up this can of worms....

:clobbered:

 

[BRUTAL64]

I varified my tach with a digital audio oscillator/generator...and my Tektronics scope that I know the tach is accurate at 1500-2000 rpm, but at 3 grand it's 300 high, at 4500 & 6000 it's still high by 300 rpm....strange, must be mechanical I figger....

:

Now the truth comes out. Maybe you will finally cut the BS about doing 150 with the top down.

The most I ever did with the top off was 136 -- according to the speedo. That was interesting.

 

[mrvette]

I varified my tach with a digital audio oscillator/generator...and my Tektronics scope that I know the tach is accurate at 1500-2000 rpm, but at 3 grand it's 300 high, at 4500 & 6000 it's still high by 300 rpm....strange, must be mechanical I figger....

:

Now the truth comes out. Maybe you will finally cut the BS about doing 150 with the top down.

The most I ever did with the top off was 136 -- according to the speedo. That was interesting.

HOW in hell anyone to actually KNOW, without a GPS readout???

not choice but to believe Garmin.....and so why would Garmin lie/inaccurate, as it's electronic, IE went around the corner fell asleep and died before anything mechanical could EVER keep up....

All I had to go by was the tach and the speedo....when the two agreed...well....so the unsolved issue is why the huge disparity, seems to be tire slippage at speed is the only thing left....anyone???

:huh::clobbered:

 

[1Michel]

Hummm Gene why dont you come up with some gadget that can connect the speedo to the garmin and get the speedo to read whatever the Garmin tells him.

 

[Kid Vette]

I have a TomTom Uno. It matches my speedo within 1 mph in my '05 Canyon. Haven't tried it out yet in the Vette.

 

[mrvette]

I have a TomTom Uno. It matches my speedo within 1 mph in my '05 Canyon. Haven't tried it out yet in the Vette.

What year is the vette?? mechancial speedo or electronic?? I know the wife's Miata is a mechanical and so reads 10%+ high across the board....far as I can tell, even being 18 y/o the car is stock as a stove....

I would love to get a simple speedo to read off the 4000 ppm sending unit in the tranny for the FI computer....but dunno of one cheep enough to slip in place on this '72....not out to recreate that universe, just improve on it....

Wish I had my '87 back with that Xmas tree dash, so I could correlate between it's electronic display and the Garmin....so to tell for sure the cause of the obvious problems....

THAT would prove the tire slippage at higher speeds was more than ever thought to be....

 

[DeeVeeEight]

GPS Speedo

Hummm Gene why dont you come up with some gadget that can connect the speedo to the garmin and get the speedo to read whatever the Garmin tells him.

Like this? Hey Gene, didn't I send you a link to an automotive GPS speedometer recently? If I remember it was kinda pricey.....

http://www.bartswatersports.com/catalog/Electronics__Stereos/Boat_Instruments/Satellite_Controlled_Tournament_Ski_&_Wakeboard_Speedometer/index.asp

 

[DeeVeeEight]

» GPS Speedometer
• Summary: GPS Speedometer is an attractive speed meter on the car dash for Windows Mobile phones

• Found under: GPS, speed, tracking, meter, vehicle

• Requirements:
Windows Mobile Pocket PC 5 , 6 , 6.1
.Net CF 3.5
QVGA Version Only

• Arrived: May 21, 2009


What's this?????

 

[mrvette]

I have a TomTom Uno. It matches my speedo within 1 mph in my '05 Canyon. Haven't tried it out yet in the Vette.

See if you can find room and do a indicated 100 mph see what TTuno says....curious.....

Garmin says 94 when speedo say 100, but at 70, it's dead nutz on....go figger...

:clobbered:

 

[turtlevette]

I have a TomTom Uno. It matches my speedo within 1 mph in my '05 Canyon. Haven't tried it out yet in the Vette.

See if you can find room and do a indicated 100 mph see what TTuno says....curious.....

Garmin says 94 when speedo say 100, but at 70, it's dead nutz on....go figger...

:clobbered:

The guages have some non linear characteristics. That's totally believable and expected. Your tires are NOT slipping.

 

[mrvette]

I have a TomTom Uno. It matches my speedo within 1 mph in my '05 Canyon. Haven't tried it out yet in the Vette.

See if you can find room and do a indicated 100 mph see what TTuno says....curious.....

Garmin says 94 when speedo say 100, but at 70, it's dead nutz on....go figger...

:clobbered:

The guages have some non linear characteristics. That's totally believable and expected. Your tires are NOT slipping.

Well, that was the only escape hatch left on this conundrum, the 'tables' off the net say one thing, I find Garmin says something quite different, and so what is rong, that's why I went and proved the tach out, 4500 rpm reads 4800, it's 300 high from 2500 up....but that's only 10% that speedo was WAY in hell over, closer to 20% error factor at 'speed'....

It's not all that SUPER important, just buggs me, that's all, and to know the damn thing is correct....

at any rate 130 with the top/windows down is still a nice blast....

:rain::rofl:

 

[turtlevette]

at any rate 130 with the top/windows down is still a nice blast....

:rain::rofl:

130 Gene MPH = 90 turtlevette MPH

 

[mrvette]

at any rate 130 with the top/windows down is still a nice blast....

:rain::rofl:

130 Gene MPH = 90 turtlevette MPH

FLUKE U, the tach was 4500+ and the speedo said 150, so 20% gimme 130....bitch....:rofl::rain:

i'ts like not believing my DVM or Tek scope, when the POS instrument says something I expect it to be Hewlett Packard CORRECT, damnit....Fluke too....