In physics, if I remmber correclty, the way a speedometer works is when the wheels go fast, it generates amagnetic force, which pulls the spring, moving the needle. but in physics, the farther u stretch a spring, the harder it is to continue stretching it. That's why the fact each interval is linearly spaced, it is inaccurate. u can tell by the fact 0-10mph (diffrence of ten) shares the same spacing as 15-20 or 25-30 (differences of 5). At what speed is the tach accurate at? Zero obviously, but there is one more. Is it 65, since that's the speed limit, and would be important to set that as a reference value?

 

I wouldn't get too worried about it...if it wasn't accurate enough to be sold, it wouldn't be.

 

What you need to do is run on the highway with a GPS unit. That will tell you how close the speedo is. I'll let you know after I get mine.

My S2000 is within 1mph at least up to 80mph. My Civic, however, is a couple mph above the real speed. There seems to be lots of variability.

JonasM

 

And how do you figure your GPS is 100% accurate? Where do you think it's getting its speed signal from?

 

i opened up a few Civic guage clusters and the needle is connected directly to the magnetic coil there was no string. Maybe some other sompanies use the tring method but i dont think honda does. the speedometer in my caar seems to work fine and very acurate

 

It doesn't get any speed signal from anywhere (certainly not from your car). It computes your speed based on how quickly you get from one point to the next. GPS is pretty accurate these days. Certainly more accurate than your average speedo.

JonasM

 

Which civic? not the 2006 one is it? cuz that also has a digital display.

I asusme s2000 is accurate, b/c it's digital so it would be bad to lie to u. Altho it must also use a spring coil, it calculates so it gives u the accurate reading. On a nal og, i assume dealers worry about asthetics, so thats why they'd set each spacing even, even if it costs accuracy.

how much is a gps unit? i kinda want one, cuz i hate getting lost going to unfamiliar places.

 

From what my TomTom Go 700 says, it's nearly dead on, sometimes it's off by 1 or 2 mph, nothing to worry about.

 

I have a Garmin 2720 GPS, and the speed indicated by my FITspeedo is exactly the same as the speed indicated on the GPS. The Garmin represents that their GPS is accurate to: 0.05 meter/sec steady state.

I think that's highly accurate, and therefore the FIT's speedo therefore must also be accurate. If you leave the stock tires on the car, you can probably avoid speeding tickets if the speedo indicates a number below whatever the posted speed limit.

The GPS unit is very nice because a sexy women gives me voice commands on how far to go and where to turn. I just have to point the car where the GPS tells me to go and I arrive at my desired desitination.

I've been using this GPS on my motorcycle and I have been to all 49 states in NA.

 

of course not a new civic how would i get my hands on one of those things??.. the older EG/ EK civics is what im talking about. this thread is pretty much useless becuase ofcourse new cars are gonna be acurate...

 

it's not about new or old. it's easy to make an accurate speedo. the reason they dont, is cuz it'll be ugly. for example, on the speedo, the distance from 0-10 would be the largest. 10-20 is slightly smaller. 20-30 is slightly smaller..[etc] 70-80 is tiny, 80-90 is small u can't see it, etc.

is that right? then how come the space between 0-10 is so small. i always got annoyed, b/c before i noticed 0-10 is different than the resti used to revmatch incorrectly to 1st gear.

 

my GPS indicates my speedo is pretty much dead on, Garmin also

 

just for a second...think...

we've had speedos in cars for HOW long now?

Dont you think if they were wildly inacurrate someone would have come up with something better by now

 

All speedos will be off by a little. Even in the S, at higher speeds the error becomes noticeable. By the time you hit top speed (somewhere around 160 I'm told) you're probably off by 5-10mph. It's accurate at freeway speeds, though.

I have a '93 Civic that I'l hoping wil limp along until my Fit shows up. It's speedo is about 4mph off at freeway speeds (shows high). So I'm always going slower than I think.

JonasM

 

digital gauges arn't anymore "correct" than ****og ones. They both get the same information. I just hooked up my scangauge last night. MPH is about the same as the speedo on the car. Just like the fuel gauge, I'm sure honda spent some time fixing it so it'll be a little more "correct". (I remember in my '93 accord, half way on the gauge was about 1/3 of a tank left.)

 

are you kidding me... a n a l o g is bleeped out?

 

Yup, the censoring software is very A N A L about that word

 

As long as you are travelling at a steady speed on a reasonably flat and straight road then GPS is generally reckoned to be accurate to within +/-0.1mph. They take a while to "catch up" with your real speed because they are averaging at short intervals.

The reason why speedos can never be as accurate is that all they do is measure the number of revolutions that the wheel makes in a set period. However the distance you travel for each revolution will depend upon the outer diameter of the tyre. That in turn will depend upon all sorts of factors such as wheel diameter, tyre make, pressure, and wear. For that reason in the UK by law speedos can show up to 10% faster than actual speed, but are not allowed to show too slow.

I have checked my wife's UK Jazz speedo with her Tom Tom Go 700 GPS and it is as close to exactly correct as it is possible to gauge when looking at a needle against a dial. I expect it to start showing a bit faster than actual speed as the tyres wear and the distance travelled per revolution gets shorter.

 

not to get off topic too much, but after installing the 16" wheels on my fit, what differences in speed and mileage am i looking at?

 

yeah i was wondering that too, thats ****in **** and *** and stuff..WOOT!