Alfa Romeo Forums banner

1 - 2 of 2 Posts

Premium Member
912 Posts
Discussion Starter #1
Anybody use a GPS sender in their OEM speedometer?


Is anybody using a GPS sender along with the OEM speedometer? The transaxle based sender in my Milano is failing. I'd like to replace it with a GPS based sender.

For this to work, the GPS sender is going to have to send a signal to the OEM speedometer that is a mimic of the signal currently being generated by the OEM sender/ amplifier.

I've downloaded the instructions for lots of GPS senders and they all seem very vague about what kind of signal output the GPS sender produces. Typically there's a glib assertion like "...compatible with most electronic speedometers."

I've separated a (non-working) Milano speedometer from the instrument cluster and examined it for some clues as to its operation. I didn't really find any.

It has the phrase "1 Giro = 0.447meters" giro being Italian for one revolution, 0.447meters equals 17.59 inches, which doesn't correlate to any of the tire's dimensions.

A 195/55R15 (the stock size) has the following dimensions

Diameter 23.4 inches

Circumference 73.6 inches

Sidewall height 4.22 inches

Any thoughts out there?

738 Posts
Since I "play" with tires, wheel sizes, have a different transaxle, and general circumference changes, I can't always rely on speedo for the street and kinda gave up. I use the QStarz Color below at the track for lap times. It also has a speedometer application that is pretty darn accurate from all of my tests. Then when I bolt up a given set of tires, I make a mental note of like 3 positions on speedo for like 30, 50, 65 and it's not hard to keep at legal speeds. Completely removes all of the headache calculations you mentioned.

1 - 2 of 2 Posts