[barefoot]

My S4 Spider mph speedo reads nearly 30 mph too fast at 70 it's def been converted to mph any ideas how to correct it?

 

[anglospider]

There is a potentiometer on the back that allows adjustment. Have a look at this thread on the AlfaBB which describes it in a lot of detail. How to fix your slow reading speedometer or tachometer on 91-94 Spiders - Alfa Romeo Bulletin Board & Forums

Its titled slow runnning but the principles are the same. When I last calibrated mine I rigged up a separate connection so that I could run it outside of the binnacle. My son then held it and adjusted it against the speed on a TomTom satnav as I drove.

 

[spiderserie4]

My S4 Spider mph speedo reads nearly 30 mph too fast at 70 it's def been converted to mph any ideas how to correct it?

only the speedo is incorrect or the mileometer too?
drive a distance you know is correct, and see what the mileometer reads.

 

[barefoot]

Thanks Anglo Spider I did the quick way taking the surround off and from the front, I ended up with the speedo connected got to 70 mph on a speedo app on my phone and put the needle back on the pin/spline at 70 and it seems to be fine now....fiddly job and a tight squeeze with the steering wheel left on but doable!

 

[anglospider]

Well done!

Sounds like whoever changed the face on the speedo to convert to mph didn't get the needle lined up properly afterwards.