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Discussion Starter #1
I would never have believed it, but the shop that also calibrates the Pinellas County Florida Sheriff's speedometers (you know, so they can follow a speeder and be assured of the correct speed they are clocking them at) did my 87 spider. I had it done cuz I figured if was way off...

Shockingly, it came out almost perfect. :
at this speed indicated: actual speed
20 22
30 32
40 42
50 51
60 60
70 70
Only an insignificant 2 miles off up to 50 or so. After that, right on
So, it was so very close, it surprised the heck out of me. Too good to be true? Gotta trust them for now....... Anyone ever had this done? By a cop shop?
 

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But Mad North-Northwest
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That's pretty good. This a mechanical speedo or the monopod?

I've checked/calibrated mine with a GPS. The Milano was dead on, with a little tweaky-tweaky I got the Spider within 5% or so up to 60, which ain't bad.
 

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Discussion Starter #4
Update

Not again.....5 minutes ago, son called from Tallahassee....got a speeding ticket in the alfa. Told the cop he just had it calibrated, of course. Cop said bring the document to the judge, and he should drop it. Sheeeeeesh!!!!

PS It was tested without the AC running (stupid me). He was running the ac at the time, and he believes it really messes up the spreedo. Maaaaaaaan. Gotta fix this mess.
 

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But Mad North-Northwest
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Monopod is the '86-and-up electric one. The dual pod is a cable speedo I believe.

You should put your car in your sig.
 

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Speedo Calibrated at Sheriff's Shop, Guess What?

I would never have believed it, but the shop that also calibrates the Pinellas County Florida Sheriff's speedometers (you know, so they can follow a speeder and be assured of the correct speed they are clocking them at) did my 87 spider. I had it done cuz I figured if was way off...

Shockingly, it came out almost perfect. :
at this speed indicated: actual speed
20 22
30 32
40 42
50 51
60 60
70 70
Only an insignificant 2 miles off up to 50 or so. After that, right on
So, it was so very close, it surprised the heck out of me. Too good to be true? Gotta trust them for now....... Anyone ever had this done? By a cop shop?
I'd say the speedo had been tampered with previously or changed. Everyone knows about the 5-7 mph setback; you know that liability thing, recall notices, fault etc.
 

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I had mine tested last week

Got a speeding ticket last week.
I thought I was doing about 36 ~38 in a 35Mile/Hour zone.
I saw the cop but did not slow down as I trusted my speedometer.
Man, was I wrong I got ticketed for 47 Miles/Hour

Took the vehicle to a test facilty.
The results: (average out of 3 tests)
Tester Vehicle
10 10
18 20
32 30
47 40
60 50
74 60
88 70

Note: from the tester
Speedometer readings are inconsistant and erratic depending on battery load.

So I assume I have some bad grounds and maybe should also clean the Potentiometer on the back of the Speedometer.
 

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yes, but how's the calibration when it says you're doin' 135 ? :p

sorry . . . couldn't resist :rolleyes:
 

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Speedo Calibrated at Sheriff's Shop, Guess What?

yes, but how's the calibration when it says you're doin' 135 ? :p

sorry . . . couldn't resist :rolleyes:
If he hasn't stumbled across "that" thread, he's probably left going, "Ah, What," "Hummm?", "What are you talking about?" etc.
 

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Discussion Starter #14
I'd say the speedo had been tampered with previously or changed. Everyone knows about the 5-7 mph setback; you know that liability thing, recall notices, fault etc.
Pat,
Thing is, I trust the shop, but what I didnt realize was I the car is driven usually with ac on, and when ac is on, electronics, now I found out, behave v wierd. I was a fool, had my son drive it to FSU yesterday, with ac on, and he later told me the speedo was behaving badly, hence the ticket. Should had the shop test with all loads on the car... Man, never ends........

Now I have to hunt for a shop in Tallahassee that can do such a test.....and maybe the hearing judge will forgive him, the cop assured him.....
 

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According to a friend of mine his GPS says my speedo is about 5% high. Easy to check in Florida every county seems to have portable electronic road side speed readouts.
 

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...Now I have to hunt for a shop in Tallahassee that can do such a test.....and maybe the hearing judge will forgive him, the cop assured him.....
I would go to court an not mention anything about the A/C, and simply show proof of the calibration. If you are going to have another shop re-do the test, then do it with the A/C off, so that it agrees with the original reading. Judges also know that speed guns and officers are not infallible. In fact, when officers take their tests with their guns they are far from 100% accurate, and that's in a controlled environement... Judges know this, and besides showing the proof of the tests from the shop, a legitimate question to ask in court is how accurate has the officer been in his tests, and then ask why he would be 100% prefect in the street, when he can't achieve this in a controlled environment.

Best regards,
 

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his GPS says my speedo is about 5% high
5% high at what speed ?

it would be very unusual for a speedo to stay exactly the same percentage off all the way across the board. in fact, from what i have seen over the years, they tend to get less accurate with higher speeds.

surprisingly, Joe Papa Sr.'s speedo actually became more accurate as speeds climbed . . . up to dead on at 70.

Incompatible's got worse : 6% off at 30mph, and 20% off at 70, in the pessimistic (wrong?) direction :eek:
this is exactly opposite my Honda Hawk :), which is nice, since i am not speeding nearly as bad as i think i am :cool:
 

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Discussion Starter #18
I would go to court an not mention anything about the A/C, and simply show proof of the calibration. If you are going to have another shop re-do the test, then do it with the A/C off, so that it agrees with the original reading. Judges also know that speed guns and officers are not infallible. In fact, when officers take their tests with their guns they are far from 100% accurate, and that's in a controlled environement... Judges know this, and besides showing the proof of the tests from the shop, a legitimate question to ask in court is how accurate has the officer been in his tests, and then ask why he would be 100% prefect in the street, when he can't achieve this in a controlled environment.

Best regards,
Wow, thanks, Enrique....now youve got me thinking in another direction. First, I thought, if my son shows up in court with the certificate showing the speedo is quite accurate, it would be suicide, since the judge would figure the cpo cant be off, and the speedo cant be off, so the DRIVER MUST have been speeding.

But If my son asserts that he was observing the speed limit AND the speedometer, and the cops radar could be in error, he MIGHT have a case??

Where can I go to get more data on cop's radar calibration and documentation, hmmmm. But, sometimes, I would think a judge could get preterbed if one drowns him with "proof", that he is already aware of, no?
 

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Discussion Starter #19
I would go to court an not mention anything about the A/C, and simply show proof of the calibration. If you are going to have another shop re-do the test, then do it with the A/C off, so that it agrees with the original reading. Judges also know that speed guns and officers are not infallible. In fact, when officers take their tests with their guns they are far from 100% accurate, and that's in a controlled environement... Judges know this, and besides showing the proof of the tests from the shop, a legitimate question to ask in court is how accurate has the officer been in his tests, and then ask why he would be 100% prefect in the street, when he can't achieve this in a controlled environment.

Best regards,
Wow, thanks, Enrique....now youve got me thinking in another direction. First, I thought, if my son shows up in court with the certificate showing the speedo is quite accurate, it would be suicide, since the judge would figure the cop cant be off, and the speedo cant be off, so the DRIVER MUST have been speeding.

But If my son asserts that he was observing the speed limit AND the speedometer, and the cops radar could be in error, he MIGHT have a case??

Where can I go to get more data on cop's radar calibration and documentation, hmmmm. But, sometimes, I would think a judge could get preterbed if one drowns him with "proof", that he is already aware of, no?

Sorry about repost....
 

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Discussion Starter #20
Now, the big question for the fix.....I gotta figure out if it is the electrical speedo's fault, or the electrical system which adds a huge error with the ac on, or what. Just buying a new/remanufactured speedo may not fix the problem. So I have some troubleshooting to do here. Where's John M with his speedo cal method.....guess Ill do search, as he posted it many times....
 
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