Calibrating Speedo

[ShonE]

Hei guys

Realized my stagea's speedo is reading wrong but some margin. Its showing more than im actually traveling, know that traffic is usually slower than the speed limit and even when i was driving 10 over there would still be cars passing by so I took this GPS unit to check it as they are supposed to be accurate and speedo is actually showing more than gps unit. Its like 10 over at 60 and almost 20 over at 100. When speedo is showing 120 GPS says im traveling at some 100-103 kmh...

So was wondering has anyone had similar problem or is this not that common, what causes it and yeah most important how to fix it.

[Duncan]

I don't have stock wheels and tyres, but they are about the standard diameter and my speedo was also reading about 10% over.

I put on of these in the car (tapped in near the dash): http://www.jaycar.com.au/productView.asp?ID=KC5435

BTW ADRs specify a speedo must be between 0 and 10% over actual speed....how crap is that?!?

[ステージア]

I run 245/45r17 tyres and its still 5% out

[scotty nm35]

M35's are notorious for the speedo reading high, I run 235/45/18's and they still read 10k's over at 100. I hoped the Nismo cluster would be more accurate, but it wasn't.

The ecu is reading the correct speed according to my informeter, but the speedo is still out, so I just use the informeter for accurate speed measuring.

[Daleo]

245/45/18's take the error (on an NM35) to 3-5 km/h below at 100km/h.

The added bonus with this size, its a VE crummydore OEM size, so plenty of well priced tyre choices.

[iamhe77]

245/40/19's have the speedo displaying 104 when travelling at 100kph (tested via Torque's GPS speedo).

[Footo]

damn so I've been speeding everywhere on my 245/45/19

[wolverine]

I am pretty sure there some speedo adjustment on the back of the cluster. I am digging through the garage later so I will have a look see on a spare cluster.

[scotty nm35]

Not on the M35 I am fairly sure. The speed data goes down the CAN line, so there is no chance of modifying the data until inside the cluster.

[wolverine]

I am pretty sure I must have been smoking something. Certainly nothing on the R33 cluster when I looked earlier today.

[Blek]

I don't have stock wheels and tyres, but they are about the standard diameter and my speedo was also reading about 10% over.

I put on of these in the car (tapped in near the dash): http://www.jaycar.com.au/productView.asp?ID=KC5435

BTW ADRs specify a speedo must be between 0 and 10% over actual speed....how crap is that?!?

Hey Duncan, was it difficult to splice in & get accurate?

My speedo is approximately 10% out as well, which is a PITA for me, with 110kph limited factory cruise control

[ChrisB]

My ARX runs 225/55/18 as per the placard and when the spedo is at 110 the car is actually doing 103 (per my GPS)

The V36 is out by about the same. I reckon they are built like this to slow people down.

Now I figure if i run 245 45 18 as suggested above, this will reduce my rolling diameter from 2214mm down to 2129mm and throw the spedo out by another 4 kms/hour.

I figure that if I were to run 235 55 18 then at 110 on the spedo the car would be going around 105 kms an hour.

Found some Dunlop SP Sport 235/55/18 100V LM703 for a reasonable price. Anybody running these?

245 55 18 would produce about 107 kmh at 110, an error of only 3kmh but this tyre size is likely an off road tyre and if it didn't touch my plastic guards would sound like a truck anyway!

[Daleo]

My ARX runs 225/55/18 as per the placard and when the spedo is at 110 the car is actually doing 103 (per my GPS)

The V36 is out by about the same. I reckon they are built like this to slow people down.

Now I figure if i run 245 45 18 as suggested above, this will reduce my rolling diameter from 2214mm down to 2129mm and throw the spedo out by another 4 kms/hour.

I figure that if I were to run 235 55 18 then at 110 on the spedo the car would be going around 105 kms an hour.

Found some Dunlop SP Sport 235/55/18 100V LM703 for a reasonable price. Anybody running these?

245 55 18 would produce about 107 kmh at 110, an error of only 3kmh but this tyre size is likely an off road tyre and if it didn't touch my plastic guards would sound like a truck anyway!

You're right Chris, the tyre set up I have suggested won't solve the issue on an AR-X, as they run a larger rolling dia than the RS/RX/AXIS. Do they use a different Speedo cluster?

Using a tyre size guide, should allow you to plug in easily available tyre dimensions, and reduce the error.

[Duncan]

Blek it was pretty straightforward to install, the wiring is actually marked on the rear of the cluster so I just intercepted the signal on the way into the dash. AFAIK in most of these cars the signal goes from gearbox to dash and then everywhere else (eg ECU and cruise control) so the dash is a good place to intercept.

The only thing to be aware of is that the link I posted is a kit, so you will need a soldering iron and some patience to put it together.

I'd normally prefer to just change tyre size (am doing that in the leaf ATM to fix the same issue) but that's expensive if you aren't already due for new tyres anyway.

[ChrisB]

You're right Chris, the tyre set up I have suggested won't solve the issue on an AR-X, as they run a larger rolling dia than the RS/RX/AXIS. Do they use a different Speedo cluster?

Using a tyre size guide, should allow you to plug in easily available tyre dimensions, and reduce the error.

I have a feeling that the cluster may be different.

when I've seen Nismo clusters on Yahoo, if I remember correctly, they state NOT ARX.