Inaccurate Speedo

[r.mojo]

Chaps,

A recent test flight in the suprisingly sunny weather this week gave me a chance to confirm my suspicions about my inaccurate speedo.

Using GPS as a nearly accurate yardstick, I'm finding that the speedo is reading anything from 5 to 11mph difference. It is over-estimating the speed (which can only help me keep my license), but is frustrating and making me wonder about the 'genuine' mileage of my car.

I have searched the forums, but haven't found anything conclusive with regard to a fix (or a definitive statement to tell me 'that's just the way they are').

Any suggestions / comments would be gratefully received.

Thanks
Rich.

[brummiewedge]

Checked mine against my road angel today, same as yours.

[everitj]

some have a calibration screw on the speedo which can be used to adjust. Use the GPS and get someone to adjust while going along (with dash top removed).

[chris_chim]

What makes you think the odo over reads as well? My speedo over reads by 10% but odo is accurate. Unless you are running non standard wheels/tyres it shouldn't be out by much.

[r.mojo]

Thanks for the replies chaps.

How easy is it to get to the screw on the speedo, and where exactly are we talking?

As far as the odometer readings go, I was hazarding a guess that the odometer and the speedo were receiving their signal from the same speed sensor - if this was the inaccurate part, I would expect incorrect readings on both. However, if I'm wrong and the problem is the calibration of the speedo which does not affect the odometer, then I'm a happy chappy.

Cheers
Rich

[everitj]

r.mojo said:

Thanks for the replies chaps. How easy is it to get to the screw on the speedo, and where exactly are we talking? As far as the odometer readings go, I was hazarding a guess that the odometer and the speedo were receiving their signal from the same speed sensor - if this was the inaccurate part, I would expect incorrect readings on both. However, if I'm wrong and the problem is the calibration of the speedo which does not affect the odometer, then I'm a happy chappy. Cheers Rich

You can get to it quite easily (if it has one) Just take the dash top off and have a look at the speedo, should be obvious if it has one, it's on the side if i recall.