Need Help with Speedometer Calibration

[beastmode86]

Hey guys i'm having problems with my speedometer not reading correctly. It seems to be reading double the speed. First off I have a 86' C10 TH350/350 with 3.73 gears, I am running 20' s also. I have a new speedo cable, I've done the math and gotten the correct tooth count driven gear, I also have a new speedometer. I've seen some comment about re-magnetize the magnet in the back? Can anyone help me out?

[TerryY]

Find a speedometer shop. Have the cluster ready to take out so there is no removal/installation charges and it should be fairly inexpensive.

The adjustment of the magnets and cup is a pretty touchy thing and without a reference speed source it would be impossible to get it accurate.

Simpler is that if you have a phone with GPS just add a speedometer app and use that mounted on a bracket. I like DigiHud and use it in about everything because out of the 7 cars I use none of them are right.