speedo...

[Mr Tonka]

Has anyone noticed that the 10 mph increments get smaller (in distance from each other) from 80mph and up?

We all know that speedometers lose their accuracy and show exaggerated speeds once you get around triple digits, but logic would tell me that if that were an attempt to correct that problem they would actually be spaced further apart rather than closer.

[sg///M3]

I would imagine that it's because most speed limits are posted well below 80 MPH, and having more larger incremental spacing would make it easier to determine your speed.

[SlammedR8]

Originally Posted by sg///M3

I would imagine that it's because most speed limits are posted well below 80 MPH, and having more larger incremental spacing would make it easier to determine your speed.

+1 , thats for sure!

OP, nice pig in your sig! looks awesome!

[GregW / Oregon]

Originally Posted by MP0WER

Has anyone noticed that the 10 mph increments get smaller (in distance from each other) from 80mph and up?

We all know that speedometers lose their accuracy and show exaggerated speeds once you get around triple digits, but logic would tell me that if that were an attempt to correct that problem they would actually be spaced further apart rather than closer.

The speedometer is equally inaccurate at all speeds. Part of it is the way German regulations are written, but it will read a little fast at all speeds, it's just a larger amount at high speeds. The speedometer mechanism varies the needle movement to match the increment spacing, however.

[Mr Tonka]

Originally Posted by GregW / Oregon

The speedometer is equally inaccurate at all speeds. Part of it is the way German regulations are written, but it will read a little fast at all speeds, it's just a larger amount at high speeds. The speedometer mechanism varies the needle movement to match the increment spacing, however.

Seems like a lot of extra work just to change the increment spacing.... Could have saved us at least a few hundred bucks if they didn't do that!

[Mr Tonka]

Originally Posted by slammedm3

+1 , thats for sure!

OP, nice pig in your sig! looks awesome!

thanks, i was quite impressed with it myself. i believe it's probably in the top 10 pics i've taken.

Larger size can be viewed HERE

[MrAdams]

which ones the speedometer?

[Mr Tonka]

it's the one attached to the muffler bearing.

[GregW / Oregon]

Originally Posted by MP0WER

it's the one attached to the muffler bearing.

So if you get an aftermarket exhaust, your speedo may be off?

[MrAdams]

Originally Posted by MP0WER

it's the one attached to the muffler bearing.

Oh I removed the muffler bearing when I installed my wheelie bar.

[gr8000]

Originally Posted by GregW / Oregon

The speedometer is equally inaccurate at all speeds.

I don't think the speedo is "equaly inaccurate at all speeds" because if it was then it could easily be offset by a constant "correction factor" in order to achieve a perfectly accurate speed reading. In all likelihood the odo error varies (slightly) with speed and (thus) tyre distortion.

[GregW / Oregon]

Originally Posted by gr8000

I don't think the speedo is "equaly inaccurate at all speeds" because if it was then it could easily be offset by a constant "correction factor" in order to achieve a perfectly accurate speed reading. In all likelihood the odo error varies (slightly) with speed and (thus) tyre distortion.

As has been explained before, German TUV regulations prohibit speedos from reading under by any amount. My understanding is that German manufacturers purposely error a little on the safe side so they don't run afoul of this regulation.

[Gelsenpower]

Originally Posted by GregW / Oregon

As has been explained before, German TUV regulations prohibit speedos from reading under by any amount. My understanding is that German manufacturers purposely error a little on the safe side so they don't run afoul of this regulation.

Hey,

it's not a TUV regulation, it's by german law.
This law says a speedo never must show less than real speed.
And it limited the running ahead to max. +10% +4 km/h.

examples:
real speed 100 km/h - speedo may display max. 100 + 10 + 4 = 114 km/h
real speed 200 km/h - speedo may display max. 200 + 20 + 4 = 224 km/h
real speed 290 km/h - speedo may display max. 290 + 29 + 4 = 323 km/h

The main reason for this allowed great variances is because of different tyres
(different rolling circumference), examples:
265/40/18 tyre has a 203,4cm rolling circumference
265/35/19 tyre has a 203,1cm rolling circumference
295/25/20 tyre has a 199,3cm rolling circumference
so this all affects to speedo. And 3mm less tread will affect about 1% to speedo.

In reality (by own experience) the german speedos displays about 5% + 4 km/h more than real speed, so

real speed 100 km/h - speedo display 100 + 5 + 4 = 109 km/h
real speed 200 km/h - speedo display 200 + 10 + 4 = 214 km/h
real speed 290 km/h - speedo display 290 + 15 + 4 = 309 km/h

regards
Gerd

p.s. hopefully you can understand my terrible english

[GregW / Oregon]

Originally Posted by Gelsenpower

Hey,

it's not a TUV regulation, it's by german law.
This law says a speedo never must show less than real speed.
And it limited the running ahead to max. +10% +4 km/h.

examples:
real speed 100 km/h - speedo may display max. 100 + 10 + 4 = 114 km/h
real speed 200 km/h - speedo may display max. 200 + 20 + 4 = 224 km/h
real speed 290 km/h - speedo may display max. 290 + 29 + 4 = 323 km/h

The main reason for this allowed great variances is because of different tyres
(different rolling circumference), examples:
265/40/18 tyre has a 203,4cm rolling circumference
265/35/19 tyre has a 203,1cm rolling circumference
295/25/20 tyre has a 199,3cm rolling circumference
so this all affects to speedo. And 3mm less tread will affect about 1% to speedo.

In reality (by own experience) the german speedos displays about 5% + 4 km/h more than real speed, so

real speed 100 km/h - speedo display 100 + 5 + 4 = 109 km/h
real speed 200 km/h - speedo display 200 + 10 + 4 = 214 km/h
real speed 290 km/h - speedo display 290 + 15 + 4 = 309 km/h

regards
Gerd

p.s. hopefully you can understand my terrible english

Thanks for the clarification.

[///Monster]

Originally Posted by sg///M3

I would imagine that it's because most speed limits are posted well below 80 MPH, and having more larger incremental spacing would make it easier to determine your speed.

[Jimmer]

I fully believe all this now. I was driving beside a newer Honda on the highway tonight. It was one of the ones that has the huge digital speedo up on the dash so I could see it.
My cruise was set at 110 km/h and the Honda was passing me and it said 107 km/h. When we got off the highway I got beside it and it was reading 61 and mine was reading 68 (I went to the V= in my display).

Our speedos do read a higher speed then we are going by a fair bit. Guess I can set my cruise at more then 10 km/h over now!!

[SlammedR8]

Interesting info!
thanks!