Thread: D4 speedo vs Hema HN7

My D4 at 96km/h indicated on the speedo is 90km/h according to my HN7 and at 116km/h indicated on the speedo is 110km/h according to my HN7......that could be why the police cars going the other way never bat an eyelid as I sit on 116km/h with my cruise control set. There are many other comments on the error / inaccuracy of the D4 speedo (factory set I believe) on this site in numerous threads.

Legally the speedo cant read less than your actual speed. Usually speedos are set so the actual speed is 3-4 kmh less than the speedo. So your GPS would be correct. In some states speed cameras are set with a 3 kmh error margin.

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Grab a coffee, pillow and a blanket and settle in to read this thread...

http://www.aulro.com/afvb/l319-disco...do-vs-gps.html

Originally Posted by Garfield

I was travelling up the Hume Hwy again and noticed D4 speedo at 100 km/h but Hema HN7 states speed is only 96 km/n. Which one is correct ????????
I am running 265/60r18 - compared to original 255/55r19

Yours sounds about the same difference as I get on mine. I am running 265/60R18 Mickey Thompson tyres - if I set the cruise control on 114 km/hr and sit on this speed, the Hema HN7 indicates 110 km/hr.

When I had the slightly smaller diameter original tyres on the vehicle, I would set the cruise control on 116 km/hr to achieve an indicated 110 km/hr on the Hema HN6 that I had in the vehicle back then.

Australian Design Rules require that the speedo in all new vehicles read "safe" - that is, the speed must read greater than or equal to the true speed of the vehicle, by an amount not more than 10 percent plus 4 km/hr.



So in answer to your question - the speed indicated on your Hema HN7 is far more likely to be correct, subject to the accuracy / limitations of any GPS device.

Sounds like a dicky speedo on my new D4. Came back down the Hume Hwy this arvo and went through the overhead speed detector. D4 112km/h, HN7 GPS 108 km/h and overhead speed detection 108 km/h. This probably some up why a number of people are passing me.
I knew speedo's these days had to be conservative by regulation but by 4 km/h at highway speed ???

Originally Posted by Garfield

Sounds like a dicky speedo on my new D4. Came back down the Hume Hwy this arvo and went through the overhead speed detector. D4 112km/h, HN7 GPS 108 km/h and overhead speed detection 108 km/h. This probably some up why a number of people are passing me.
I knew speedo's these days had to be conservative by regulation but by 4 km/h at highway speed ???

4km/h difference ..... not faulty, that's exactly as per Brian's post.
Did you read the regulation he posted?

Cheers,
Scott

Originally Posted by BMKal

Interesting point that "There is now no requirement to have an odometer"

Yes, the speedo regs that Brian posted are spot on with regards to my D4 speedo - conservative by 4km/h. Will just have to mentally just my conscious to 114km/h down the Hume Hwy from now on