Speedo Error on Accord Euro

[MalGib]

First time poster and proud owner of a Euro Sport 2006 6MT, 3000km on the clock, 4 weeks old. Luv the forum, very helpful and informative.

I've noticed there is a definate error in the indciated speedo readings. The problem I'm having is trying to find out the exact extent of the error. I dont want to end up with a speeding ticket one day just because I thought I had somewhere from 5 to 10 km/hr margin of error to use for speeds above 100km/hr and find out I was wrong!

I've done some work on this, as well as read other posts in this forum and elsewhere. I've summarized my findings below in a table (just for 5th and 6th gears only to keep it compact) :

SPEED : INDICATED / CALCULATED / FORUMS

5th @ 1000rpm : na / 33.0 / 32 km/hr
5th @ 2500rpm : 84 / 82.5 / 80 km/hr

6th @ 1000rpm : na / 41.3 / 40 km/hr
6th @ 2500rpm : 105 / 103.3 / 100 km/hr


To explain the headings:

INDICATED : Speed as read off the speedo

CALCULATED : Speed calculated from published rolling radius for 225 x 45 R17 tyre (502 rev per km)

FORUMS : What others have quoted elsewhere as the accurate speed.

Just as a rough check, I've used the 5 km test posts along the Hume Hwy between Sydney and Goulburn with a stopwatch. Indicated speed was 116km/hr (on cruise control), time calculated speed was 111km/hr.

OK, from this it seems that the error is either +5% over actual, or a fixed +5km/hr error across the indicated speed range. Which is it?

Also, the calculated speeds from the rolling radius of the 17" tyres is actually closer to the indicated speeds than it is to the generally accepted figures quoted by other owners in the forums. In this case the indicated speeds are only about +1.7% above the calculated speeds.

Now that the NSW RTA has increased the demerit points to 3 for 0 to 15km/hr above the speed limit (which means on a double dermit points long weekend there goes half your licence!), it is now more important than ever to know what is the 'true' speedo error for Accord Euros.

Does anyone know for sure, or can quote some reliable source of information on this subject? How does this error affect the accuracy of the odometer?

Thanks ...

[EuroAccord13]

Not going to be able to answer your main question but I what I can say is...

Analog speedos are never accurate .. If you read car magazines, some road tests that they perform on their cars will show speedo error against their GPS ones..

I won't be too concerned over it if the error is not that much of a difference but however, the higher the speed is, the higher the difference..

Your problem covers cars in general not just the Euro so I'm moving it to the correct section for better response...

[EuroDude]

Virtually all cars show a higher speed than what the car is actually driving.
Wheels magazine tested the Euro to go 96km/h when 100km is indicated.


Plus there is a 3% (possibly 10% soon) overlimit threshold where the cops dont fine you, so if you were driving 103km/h, they wont book you anyway.

So basically its safe to drive at an indicated 107km/h and not worry :thumbsup:

(107km speedo = 103 fine threshold + 4km speedo difference)

[aaronng]

Just drive at the indicated 100km/h to be safe. Especially for those in Victoria where 103km/h in a 100 zone is considered speeding and the cameras will take your pic.

[panda[cRx]]

what's the problem, if you keep the car at or below the designated speed limit (according to speedo) there won't be a problem if the tacho is reading over

you will find that most hondas have the same thing (well most cars in general)

[MalGib]

Thanks aaronng ... my point exactly. Although I've heard there's an unpublished +10% over-the-speed-limit is ignored by the police in NSW, there are still plenty of stories of people beng booked for 84km/hr in an 80km/hr zone and similar. A digital speed read-out would be helpful for setting the cruise-control, but unfortunately our in-car computers dont have this option ... or a speed-limit alarm settings option! Thats a real oversight by Honda in my opinon.

[EuroDude]

You can buy speed limit alarms, they arent expensive.

Its a manual one off course, but no doubt they will eventually have GPS based ones that can read the speed limit at your location.

[yfin]

A digital speed read-out would be helpful for setting the cruise-control, but unfortunately our in-car computers dont have this option ... or a speed-limit alarm settings option! Thats a real oversight by Honda in my opinon.

That is why I use the APEXI RSM. And i have it calibrated to the correct speed rather than the speedo indicator.

I love having digital speed read out. The RSM isn't very expensive especially if you don't get the G-sensor. I don't really need the g-sensor.

[kam]

if you want to see if your speedo is correct, drive around till you find a street with those mobile speed reader's on a trailor, and drive past it, tells you wat speed your doing.

[EuroDude]

Thats an idea, but really how accurate are those things? Most of them are probably not calibrated properly.

[aaronng]

Back to the speedo error. I think they make it display a slightly higher speed so that if you have a short lapse in your accelerator foot position, you are stll safe below the speed limit. I think it was for the DC2R that Wheels reviewed in the original Celica vs MX-5 vs Tiburon article that they found that 100 km/h on the speedo really meant 100km/h on the road. So maybe they make it accurate for "serious" cars and have a little buffer space for passenger vehicles.

[MalGib]

I'd like to get some feedback on this subject before the thread dies. (See my original post at the top of the thread).

I've noticed that no matter where I'm driving or at whatever the speed limit is for a road or highway, I'm constantly being overtaken by other drivers as if I'm travelling below the speed limit. I've not had this happen like this with all of the other cars I have owned in the past, only with this Accord Euro (now 5 weeks old). This is what prompted me to submit the post and ask the questions about the accuracy of the speedo in the Honda Accord Euro's.

Does anyone with the same car have information on this subject, or been able to confirm what the margin of error is reliably by one method or another?

Thanks for the comments made so far, much appreciated.

[aaronng]

Does anyone with the same car have information on this subject, or been able to confirm what the margin of error is reliably by one method or another?
Wheels magazine reviewed a manual 2005 Accord Euro Lux with the 17" rims, and found that when the speedo indicated 100km/h, the car was only travelling 96 km/h.

[MalGib]

OK I have run several tests using a stopwatch, different set speeds on cruise control, and the 5 km speedo check posts on the Hume Hwy between Sydney and Goulburn. Thankfully I have needed to travel that road quite a lot this week for work reasons. I wont go through all the calcs here, but the average result is that the speedo is out by +3.75% (well at least for my Euro Accord it is).

So, for example, at an indicated speed of 106km/hr, 6th gear @ 2500rpm, the corrected speed is 102km/hr. This ties in well with the Wheels Magazine review of a manual 2005 Accord Euro Lux (17" rims), which found at a speedo reading of 100km/hr, the actual speed was 96 km/h.

So I'm using a cruise control setting of 115km/hr when travelling along the Hume from here on ... at least I know now that I'm doing a shade over 110km/hr, and maybe I wont be passed by so many other drivers because I'm travelling below the speed limit.

Was it so important? ... probably not ... its just the engineer in me!

Anyone got an update as to what their speedo errors are? Thanks.

[invertiga]

I always felt I was going slow due to how many people passed me on the highway too; my speedo was way off. I went through 3 different radar guns that reported back speed on a neon sign, i went through all three on cruise control @ 82km/h on speedo, the signs all told me i was doing 75km/h or 76km/h. So basiclly i now drive 105 in 100 and 115 in 110... I've been through lots of cops with radars at these speeds and none have hunted me down, nor have I recieved any speeding tickets from stationary speed camera's.

I'm deffinetly not saying everyones car is like this, but I always questioned the accuracy of the speedo, and now i'm quite confident its wrong. Wheels always does a 100km/h test, almost every car is wrong, and i'm guessing as your tyres wear down and you loose overall tyre diameter may also cause incorrect speed.

[aaronng]

It is a widely known fact that car speedos are not accurate as you reach speeds of around 100km/h. The DC5R's was tested to show 100km/h at 100km/h though. I've heard of stories that Peogeot 206's speedo rear lower than the car was actually going at. But I can't say if that was true or false.

[MalGib]

Thanks for the input invertiga & aaronng.

My previous car was a Camry V6 Touring series 5M, and with the standard 60 profile tyres the speedo error was about +1.5% ... not a great deal. The last set of tyres I put on the car were 55 profile, and the speedo error became zero! True, the rolling radius of the 60 profile tyres vs the 55 profile tyres is going to be different I know, but I was amazed that the difference compensated perfectly for the speedo error.