John Larkin
Member
The speedometer on my 1974 P6B (E suffix) UK-market automatic is over-reading by 17.5%. The differential ratio is correct (3.08:1), the speedo drive was new about two years ago, the gearbox is the original unit as far as I know, the tyres are 185/80 14", and the speedo itself is original. Has anybody got any idea what the problem might be? I'm baffled.