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Cato
25-06-2010, 03:57 PM
Usually, is the odometer run off the same sensor as the speedometer?

Thanks.

wratterus
25-06-2010, 04:14 PM
Afaik, yes. Generally off the gearbox. Not sure on the brand new cars though, they are probably getting fancier.

coldfront
25-06-2010, 04:26 PM
As stated above

Cable operated speedometers/odometers run via cable from the Dashboard to a gearing set called the head which in turn runs off the gearbox.

Inveriably the error is so slight you would not notice it unless travelling measured distances at a higher speed limit.

Sweep
25-06-2010, 04:35 PM
What I would like to know is what do people do with the time they think they save by travelling at 120 Kph as opposed to 100 Kph?

Cato
25-06-2010, 04:39 PM
Now here's the bugger of a question related to that other thread.

Say Japs do read a higher speed than actual, the odometers would also read higher than actual. So for all the poor buggers with diesels (myself included), we're paying more than we should!
Interesting though ain't it?

Cato
25-06-2010, 04:42 PM
What I would like to know is what do people do with the time they think they save by travelling at 120 Kph as opposed to 100 Kph?

I don't think people speed to get anywhere faster.

Hell if you are so worried about speeding that you look at the speedo ever 1 and a half seconds I bet you are more likely to crash than cruising at 120.

tweak'e
25-06-2010, 04:50 PM
As stated above

Cable operated speedometers/odometers run via cable from the Dashboard to a gearing set called the head which in turn runs off the gearbox.

Inveriably the error is so slight you would not notice it unless travelling measured distances at a higher speed limit.

and modern ones run off an electronic sender on the gearbox. some are adjustable, some are not.

Sweep
25-06-2010, 04:50 PM
I don't think people speed to get anywhere faster.

Hell if you are so worried about speeding that you look at the speedo ever 1 and a half seconds I bet you are more likely to crash than cruising at 120.

So why do they speed then?

And I might add I use the rear view mirrors more than I check the speedometer.

Microwaves, radar and speed cameras are not the only means of checking speed.

Cato
25-06-2010, 04:54 PM
So why do they speed then?

Usually it's because they are not aware they are speeding.
Surely you have been guilty of "accidental" speeding right?


And I might add I use the rear view mirrors more than I check the speedometer.

Microwaves, radar and speed cameras are not the only means of checking speed.
So you can accurately gauge speed to within 1km/h based on...?
Not everyone has speed calibrated super vision. We are human (for the most part).

coldfront
25-06-2010, 05:04 PM
So why do they speed then?

And I might add I use the rear view mirrors more than I check the speedometer.

Microwaves, radar and speed cameras are not the only means of checking speed.

Because people trust that dial in front of them to be showing the true speed they are traveling.

Valuable lesson I learned was driving a van to Wellington I was doing the 100kph yet people were passing me the assumption they were speeding! Wrong when I later checked it with a GPS I was doing 90kph and consistant out by 10kph in the speed range from 50 kph up.

Another occasion driving in convoy with another car of identical specs driven by my other half I put down here slower speed to being over cautious. We swaped cars and she ended up pulling away from me at 100kph.:eek:
No differance between them with GPS and Dyno road check discovered a 9kph differance in speed at100kph registered! One up 3 kph the other up 6kph the ironic thing though is both at 50kph were spot on doing 50kph.

coldfront
25-06-2010, 05:07 PM
Now here's the bugger of a question related to that other thread.

Say Japs do read a higher speed than actual, the odometers would also read higher than actual. So for all the poor buggers with diesels (myself included), we're paying more than we should!
Interesting though ain't it?

Two edged sword that because it means your also more efficant on fuel burn :waughh:

Cato
25-06-2010, 05:09 PM
Two edged sword that because it means your also more efficant on fuel burn :waughh:

Good point!

coldfront
25-06-2010, 05:10 PM
Usually it's because they are not aware they are speeding.
Surely you have been guilty of "accidental" speeding right?


So you can accurately gauge speed to within 1km/h based on...?
Not everyone has speed calibrated super vision. We are human (for the most part).

Ironic with over 20 years of driving the same modern technology thats rapping our wallets is also the same technology that has made me question everthing I was taught about driving of being within 5kph of the speedlimt and maintaining the flow of traffic. Now I find out I was wrong!

PaulD
25-06-2010, 05:10 PM
Say Japs do read a higher speed than actual, the odometers would also read higher than actual. So for all the poor buggers with diesels (myself included), we're paying more than we should!
Interesting though ain't it?

The odometer is basically just counting. That is easier to do than convert revolutions of the cable or pulses to an analog display.

Do many cars have a digital readout of speed?

coldfront
25-06-2010, 05:11 PM
Good point!

Two cars same model and I got a 2km per litre fuel differance because of an odometer error. BUt if I was to drive at half the speed of what I normally drive that error would not exist :waughh:

coldfront
25-06-2010, 05:13 PM
The odometer is basically just counting. That is easier to do than convert revolutions of the cable or pulses to an analog display.

Do many cars have a digital readout of speed?

Most of them are in the upper reaches of the market though and european.

Cato
25-06-2010, 05:21 PM
The odometer is basically just counting. That is easier to do than convert revolutions of the cable or pulses to an analog display.
But if the speedo is inaccurace you could assume that the odo too would be innacurate, right?
In which case all of us paying RUCs are being ripped off.


Do many cars have a digital readout of speed?

Some do, some Mazdas (def RX8, possibly M3 or M6), post 2002 Altezzas and Windoms?, I know Hondas S2000s, so do newer civics (not sure if it's all models). Late model BMWs, Audis too.

Almost all sport bikes do though.

pctek
25-06-2010, 05:32 PM
But if the speedo is inaccurace you could assume that the odo too would be innacurate, right?
In which case all of us paying RUCs are being ripped off.




Husbands ute is out, we measured it on one of those mileage things on the road. His speedo is out too. And yes he mentions how he is ripped off everytime we buy RUCs. LOL.

Sweep
25-06-2010, 05:42 PM
Usually it's because they are not aware they are speeding.
Surely you have been guilty of "accidental" speeding right?


So you can accurately gauge speed to within 1km/h based on...?
Not everyone has speed calibrated super vision. We are human (for the most part).

Yes. I have been ticketed for speeding and that teaches me not to do it anymore.

I can't really afford it and it gets me nowhere anyway.

Cato
25-06-2010, 06:00 PM
Husbands ute is out, we measured it on one of those mileage things on the road. His speedo is out too. And yes he mentions how he is ripped off everytime we buy RUCs. LOL.

Off by a lot?

Sweep
25-06-2010, 06:20 PM
Well as the odometer is showing more than actual it would be unlikely he would get a speeding ticket unless being driven at a speed over what is indicated by the speedo.

coldfront
25-06-2010, 06:44 PM
Well as the odometer is showing more than actual it would be unlikely he would get a speeding ticket unless being driven at a speed over what is indicated by the speedo.

True but he would be a mobile road block that would incite (sp?) motorists travelling at an accurate speed to par take in more dangerous driving style to pass the obstruction.

Cato
25-06-2010, 06:45 PM
Well as the odometer is showing more than actual it would be unlikely he would get a speeding ticket unless being driven at a speed over what is indicated by the speedo.

Speeding, sure, but not everything in life revolves around it.

I'm more concerned about RUC charges. 49$ per 1000km. That ain't cheap. If the odo is off by say 10% that's quite a big difference. I have driven nearly 20k km this year. If my odo is off then I'm paying too much or too little. This is not cool.

Can we please leave speeding to the other thread and let's stick to RUCs on this one, OK?

coldfront
25-06-2010, 06:46 PM
Husbands ute is out, we measured it on one of those mileage things on the road. His speedo is out too. And yes he mentions how he is ripped off everytime we buy RUCs. LOL.

Has he checked that the Tyres are the correct size for the vehicle? First thing worth checking.

ryanjames.powell
25-06-2010, 07:02 PM
Most of them are in the upper reaches of the market though and european.

Most cars made in the last 15 years or so have a digital speed reading feeding into the ECU, which you can attach a monitor to through the OBD port. This would probably read exactly the same as the analog reading though. Things like tyre pressure and wear can affect the speed readout because the alter the diameter of the wheel, so it's damn near impossible to be perfectly accurate.

Sweep
25-06-2010, 07:58 PM
True but he would be a mobile road block that would incite (sp?) motorists travelling at an accurate speed to par take in more dangerous driving style to pass the obstruction.

OK. But if I was driving a truck and trailer and the max legal speed is 90Kmh how do you get past me?

coldfront
25-06-2010, 08:14 PM
OK. But if I was driving a truck and trailer and the max legal speed is 90Kmh how do you get past me?

Easy because you are more likely to be a considerate motorist who will pull to the side of the road when they can ;)

How you know if your doing 90kmh then? Trucks more accurate you reckon? Cancels itself out really. Think about it!;)

Sweep
25-06-2010, 08:33 PM
Sigh. And what about the truck going downhill with exhaust brakes on?

And let's say approximately 90 Kmh.

And let's say people sit behind until it is safe to pass which they should do. You seem to be nitpicking over 1 kmh.

PaulD
25-06-2010, 11:15 PM
Another occasion driving in convoy with another car of identical specs driven by my other half I put down here slower speed to being over cautious. We swaped cars and she ended up pulling away from me at 100kph.:eek:
No differance between them with GPS and Dyno road check discovered a 9kph differance in speed at100kph registered! One up 3 kph the other up 6kph the ironic thing though is both at 50kph were spot on doing 50kph.

What do you mean "no difference between them with GPS"?

In your other post one was down 3 kph. Why not mention model?

coldfront
25-06-2010, 11:45 PM
What do you mean "no difference between them with GPS"?

In your other post one was down 3 kph. Why not mention model?

Does it matter the model? Not really just matter that there was a reading differance of 9kph between them.

The GPS and Dyno just confirmed which was where on the speedo compared to actual.

coldfront
25-06-2010, 11:59 PM
Sigh. And what about the truck going downhill with exhaust brakes on?

And let's say approximately 90 Kmh.

And let's say people sit behind until it is safe to pass which they should do. You seem to be nitpicking over 1 kmh.

Talk about nit picking

You make no sense? As I said it would be your duty as a considerate motorist to allow traffic to pass if you are not able to maintain the flow of open road traffic.

Passing a truck going down a hill would be a much simpler task providing it was a safe passing. But hang on you are scared to go above 100 on that speed dial of yours therefore you can not overtake unless it is safe to do so.

why cause yourself problems?

coldfront
26-06-2010, 03:13 PM
What do you mean "no difference between them with GPS"?

In your other post one was down 3 kph. Why not mention model?

3 kph or more accurate 3% is within acceptable universal standards of other OECD countrys except New Zealand. An increase of Tyre size would actually reduce that percentage to zero however I run to manufacturers specs, for some reason this model in this country is run with deeper profile tyres probably because as I found out those tyres are cheaper.

The other vehicle has a differance that reducing to the correct tyre size has helped however it exhibits a curious error that for typical urban driving a 50kph would not be apparent. At open road speeds which is the majority of driving I do then it is noticed!

I am more than familier with this particular make of vehicle having driven several extensively in Europe.

What ever the problem is it is unique to what was imported to this country and the specs required. From what I can tell the speedometer has some time in its history been calibrated as the speedo head from the other car and one I know would work do not or I should say show speeds out quite excessively approaching 100kph.

The problem most likely is the result of a gearbox or gearing repair, replacing the gearbox head with a componant I know has accuracy (ie the other car) may well cure the problem but at the same time cause the speedomter head to be out of calibration.

Easy fix? Cheap fix? No.