Odometer error

It may have been asked before, here goes:
My 2012 as well as 2017 GRiSO both seem to show a 5% error in odometer reading, compared to the GPS.
The +5% seems constant for most sane speeds. Any idea if or how it can be recalibrated?
Cheers
L

Hi worked in an automotive manufacturing for a lot of years, (I worked on the design of 5AM too), and I can say yiu that in Italy the speed indicators on vehicles must indicate +4% minimum by law. I think, not sure, it's quite similar for all markets.
If you don't like it, you can simply move the needle on the pin. Usually is only locked for interference, not glue.

MCR68 wrote:

Hi worked in an automotive manufacturing for a lot of years, (I worked on the design of 5AM too), and I can say yiu that in Italy the speed indicators on vehicles must indicate +4% minimum by law. I think, not sure, it's quite similar for all markets.
If you don't like it, you can simply move the needle on the pin. Usually is only locked for interference, not glue.

I feel cheated. My GRiSO has no speedometer needle, it's digital. Also, nearly all the vehicles we've owned in the past 15 years have been less than 1% difference between gauge and gps, most being spot on. The single exception being my Honda CBR-XX at 5% under actual speed.

Something I once read


GPS Accuracy: GPS devices calculate speed based on the time it takes for the signal to travel between satellites and the device. This can lead to inaccuracies, especially if the GPS signal is weak or obstructed by buildings, trees, or other obstacles.
Sampling Rate: GPS devices typically update their position at regular intervals (e.g., every second). If your car is accelerating or decelerating quickly, the GPS may not capture these changes accurately, leading to a lag in speed readings.
Road Types: GPS systems often take into account the type of road you are on. If you are driving on a road with a speed limit that is lower than your actual speed, the GPS might display a lower speed due to routing algorithms.

rick pope wrote:

MCR68 wrote:

Hi worked in an automotive manufacturing for a lot of years, (I worked on the design of 5AM too), and I can say yiu that in Italy the speed indicators on vehicles must indicate +4% minimum by law. I think, not sure, it's quite similar for all markets.
If you don't like it, you can simply move the needle on the pin. Usually is only locked for interference, not glue.

I feel cheated.  My GRiSO has no speedometer needle, it's digital.  Also, nearly all the vehicles we've owned in the past 15 years have been less than 1% difference between gauge and gps, most being spot on. The single exception being my Honda CBR-XX at 5% under actual speed.

I have some doubts that you have measured a speed errors lower than 1%. My Norge (with the needle) certainly indicates more than 1%, maybe even 5%. And the same with the cars I have owned after the advent of GPS, whether they were Italian, German or Japanese.
In any case, for the calibration of the dashboard it is not an operation that you can do at the service but is done at the final production test.
Otherwise you can reduce the diameter of the fly wheel of the ABS sensor that reads the speed (but don't do it!), if you do not have a sensor with a dedicated flywheel, or, reduce the pressure of tire.

If you open the map up in Tunerpro you can change the speedo correction factor so it is accurate. This is Mark’s field, not mine.

[pedantic mode] Firstly, odometer & speedometer are two different things.[/pedantic mode]


Down here in Big Sky Country, my GPS vs Speedo test showed a 7% error. 107 km/h on the digital speedo was 100 km/h on the GPS. Was it accurate? Fuctifino. I didn't (and still don't) give a shit.

It's even worse on the non-ABS 1200 Sport which only had a front wheel sensor. I've seen them as bad as 10% out. Bikes with ABS are much more accurate (less than 5%).

How to fix? You have to modify the speedo correction value in the map. If your speedo is reading x% more than your inaccurate non-military GPS, decrease the speedo correction value by the same percentage. Be careful.

"Was it accurate? Fuctifino. I didn't (and still don't) give a shit."

Same here..my brand new Garmin reads about 4 mph slower than the speedo my New 2025 4-85
Who cares?

Also, when getting booked at an indicated 130 in a 100 zone, you only get done at ~120.

That’s the difference between mandatory licence loss and just money.

anyway, we are all referring to the accuracy of the speedometer and not the accuracy of the odometer which was the initial question by Omnis (sorry) and whose accuracy is not affected by an intended error.
At this point, Rick pope, tell us how you perform the measurement to see a 1% error compared to the GPS?

The diameter of your rear tyre can also affect the accuracy of the Speedo reading.
A couple of percent variation would not be abnormal.

In our case, we had a gps on the dash, and compared it to the speedometer on a fairly straight, level road, with a speed limit of 65 mph or more. Mercedes, on the money. Corvette, also exact same reading. F-150 (built in gps) same reading. Kenworth T-680 with built in Co-Pilot Pro gps, same reading. Honda CBR-XX, older gps on the handlebar, about 5% difference.

On several of these vehicles, the display is in digital, so no needle variance.

Back to the original post, which does indeed ask about odometer rather than speedometer.....why the suggestion of moving the needle to make correction? I don't belive I've ever seen an odometer with a needle?

Obviously I was referring to the speedometer needle which, I repeat, deliberately reads more than the real one net of the error due to tire wear and precision of electronic control.
If instead we talk about odometer, that is miles traveled, the error is that of the dashboard which can receive the signal either directly from a sensor or from another control unit such as the ABS which gets it from a sensor.
Returning to the odometer, so you measured the road traveled on a flat road and compared it with the miles tracked by the GPS? How many miles did you consider 1, 10, 100?
To read 1% difference you will have to have traveled more than 10 miles to read 0.1miles more or less.
In short how did you perform the odometer test, not the speedometer.

Never implied that I tested the odometer. The discussion had turned to speedometer, and so that was my focus.

I have never tested am odometer.

For what it's worth, I just tested the odometer on my T3 by observing its reading over ten measured miles, using the mileposts on a straight stretch. It registered 10.7 miles over 10 measured miles, so the correction factor is 10/10.7 = 0.9346 ~ 0.93.  This means the approximate 44.5 mpg I calculated for my trip from odometer readings was really 41.6. I would prefer physical mileposts to GPS measurements I suppose. Seems like more of a curiosity than a practical concern.

EDIT: In answer to the original question, I don't know how to calibrate the odometer on a GRiSO or even on my T3.

I put a map in a guy's Stelvio, he comes back and says he went 11mph, WTF? OVER

Mark got me strait and it dialed in to on the gps, Easy to do once you find out about it.

I would say it's easier to do than a T3, hehehe

I like to know how to get the numbers strait on my V700 dash, some look kinda cockeyed.

Does anybody remember Speedometer Shops?

Seemed lime there was a couple in every sizable town.
Now, not so much.

As far as error or correction factors . . . close might just be good enough.

Just on the odometer/speedometer thing I do know that on 1200 Sports the effect on the indicated speed is also reflected in the odo reading. Discovered this when swapping maps early on with ABS and non ABS models. If you stick, (I think?) an ABS map in a non ABS machine the speedo correction factor is completely different and the moment you go much over walking pace the speedo pegs at 260kph!

While it sits there up against the stop if you look at the odo it is also ratcheting up Km at a similarly astonishing rate! That would indicate to me that the odo’s interpretation of distance travelled is tied in with speed assessment. I’d guess therefore that getting the speedo correction factor spot on would also make for an accurate odo.

Like Mark and others though to me it’s not important to be that accurate, especially as my bikes are all ancient! Red bike also has a dashboard that says 80,000km when it’s only done about 35,000 as its original dash was busted and got replaced by a second handy. Yellow bike is up to 160,000 so how far it’s travelled really doesn’t matter in any way apart from my happy memories!

Yeah, well, if you start mixing and matching your results may vary.

50K is a little out of range I'd say, needs recalibration

It is a beautiful fall day here in Wisconsin, so I did some measurement. Setting my electronic cruise control I observed that a constant 74 mph on the speedometer produced a constant 70 mph on a GPS. I also used my trip meter to find that 10 measured miles based on mile posts was equal to 10.0 miles on the odometer.
So the error of the speedometer is 5.7 percent high while the odometer is essentially accurate.

Change 1 number at a time when it's close.

?? I'm just reporting my observations today, not asking for suggestions, thanks.

Many thanks Mark, I did find the speedo correction parameter in the XDF with different methods to change it (value, %, etc).
If I decide to do it I will approach it with extreme trepidation, I can see that it could lead to a major FU if done icnorrectly.
Cheers

beetle wrote:

[pedantic mode] Firstly, odometer & speedometer are two different things.[/pedantic mode]


Down here in Big Sky Country, my GPS vs Speedo test showed a 7% error. 107 km/h on the digital speedo was 100 km/h on the GPS. Was it accurate? Fuctifino. I didn't (and still don't) give a shit.

It's even worse on the non-ABS 1200 Sport which only had a front wheel sensor. I've seen them as bad as 10% out. Bikes with ABS are much more accurate (less than 5%).

How to fix? You have to modify the speedo correction value in the map. If your speedo is reading x% more than your inaccurate non-military GPS, decrease the speedo correction value by the same percentage. Be careful.

I'm a simple man who will never correct his speedometer. For myself and others like me I suggest the following maxim based on Beetle's and my own careful observations:

Maxim: The odometer is dead-on but the speedometer is six percent high.

Chasing more precise values seems pointless, given tire model, inflation, and wear differences.

You're all welcome.
Moto