Begging for a ticket

[JG1966]

My 150 mph rallye speedometer in 72 RR is reading way too low. Says I'm doing 20 MPH when I'm doing about 50 (hello officer). Based on tire size (295 50 15) and 3.91 gears, I need a 38 tooth gear. I pulled gear and it's an orange 40 tooth gear (part number 52068062). So I'm close to the right gear. What else would cause such a wildly inaccurate speedo? If it matters, the rallye dash is not original to the car and the speedometer "hand" sits well below 0 (straight down at '6 oclock') when car is off. Thanks for any help.

 

[texas69bee]

Have you used a gps to determine your actual speed before tearing in to it?

 

[JG1966]

Have you used a gps to determine your actual speed before tearing in to it?

Just a seat of pants test. Could tell it was way off. I think speedo pointer is the issue. It should come to rest on O mph not negative 20 ;).

 

[Jcharger]

If it is steady and not bouncing, it could be the magnet or the hair spring.