My factory SW 503-C speedometer has sat still for over 3 years and now that the ambulance is driving again, it reads about 15-20 MPH lower than the speed I'm traveling. The cable is new NOS that I pulled the center out and cleaned with solvent to remove all the gummy lube and then I re-lubed with speedometer cable lube before I installed it. The speed seems to be more off the faster I go.
I'm basing this assessment on both GPS and generally knowing the speed of the traffic around me on roads I'm familiar with.
I can't find anything on here about being able to service or open up that speedometer. Anyone have any recommendations in this area or had this same problem?
I also just posted a "wanted ad" for a good used speedometer in the classified section of the zone. Please let me know if you can help me out either way.
Cheers,
Bryce