Resolved 1993 Cobra SRS Crash Sensors Front Right and Front Left

jeremyzcook82 said:

So if the odometer and tripometer is right, but the speedometer needle is off, that means I would have to change out / check the speedometer gear, right?

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If the odometer/tripometer is spot on, it means the speedo drive and driven gear is correct. This is all driven purely by a mechanical connection.

If that's right, but the needle points to the wrong number, then the issue is likelty in the magnetic head. You'd need to find an old school speedo calibration shop and have them recalibrate it, or swap the speedo head out to another unit. Correcting the mileage is very easy on these cars (which is both a good and bad thing)

Let me grab a pic of a speedometer that may help you understand.

SO hopefully this helps. SPeedo cable connects up top at that little gold fitting there. It spins a shaft connected to gears that drives the two green gears on the right hand side. one for the odometer and one for the tripometer. This connects by gearing to the actual number displays



As for the speedo head itself, it's a mag head. the shaft the cable spins on has a pair of magnets that "drag" a speed cup. There is a tension spring. These speedometers are set up when built by connecting to an electromagnet and "adjusting" the magnetic force. That's how they are calibrated using various alignment ticks on the gauge face. Over time, this can drift. They only way to get it back is by recalibrating on one of the electromagnetic speedometer adjustment tools. Those faded by the late 90's so that's why i said oyu gotta find an old school shop.




But that's why i recommend seeing if the odometer is spot on. If it is, you know your tire size,speedo drive and driven gearing is all correct. If that's off, then it is a clue that some parameter there is wrong