International Lancia Forums

I recently drove my B12 1800 km up to the combined Queensland and NSW Lancia Clubs' rally in Orange. A thoroughly enjoyable weekend and a great trip too..
However, suspecting that my speedo was reading fast, I fitted a push bike electronic speedo/odometer.
I found that my car speedo was indicating 115 km/h at a true 100 km/h. Not only that, the km total was high by the same percentage. I checked the bike speedo against the roadside distance markers and it was correct.
The differential is stamped 11/49 as is the housing for the speedo drive on the side of the transaxle. Any ideas as to what may be causing this inaccuracy?

Happy Lancia motoring to all.

Brian.

...nobody got any ideas as to what may be wrong????

No experience with Aurelia speedometers, but I have some with Fulvia speedometers.
In one case oil was pumped up through the cable. In the other case current went through the speedometer cable because of a missing ground wire between engine and body. The current heated up the spring in the meter and altered its characteristics.

Brian,
I have verified like you did the deviation on my b12 speedo during an enjoyable one day and 500 km trip. I also find 15% deviation, across the whole range, from 60 km/h to 150 km/h on the speedo, using a garmin portable navigation system. I send you the detailed results per pm.
Maybe Lancia ordered specially calibrated speedos, to satisfy the customers of the time, who had no way to check the real speed? (not quite true, they had good swiss watches and kilometer markers)

On a B20 I have seen another phenomenon: the speedo stopped showing speeds over 120 / 130 km/h, and you had to estimate real speed using the rev counter in 4th and a speed diagram. I found this very satisfactory when on the motorway with my wife, who never understood why other cars were so slow (with the B20 at 4000 RPM in 4th) !