Spedo needle sits until 30 MPH

[speedster911]

My mechanical speedometer needle sits at zero until I get to about 30 MPH. After I reach that speed, needle moves as it should and reflects accurate MPH in all ranges above 30 MPH. If I stop and start up again, same issue- needle sits at zero until I reach 30 MPH -Whats the cause and the fix?

[arbita1]

I had the same thing. Send it to Palo Alto Speedometers to be repaired.

[PCA7GGR]

Try this before sending it to repair - pull out the speedo from dash, disconnect the cable then spray WD40 (or similar lubricant) into cable end.

Nothing ventured, nothing gained.

[arbita1]

Originally Posted by PCA7GGR

Try this before sending it to repair - pull out the speedo from dash, disconnect the cable then spray WD40 (or similar lubricant) into cable end.

Nothing ventured, nothing gained.

Good point although may not be cable driven.

@speedster911-What year is the car?

[speedster911]

74 - mechanical spedo

[dar636]

Clean the grounding point associated with the instruments, I don't have a drawing at hand, sorry - I think mine was under the frunk near the brake master cylinder.

[Walt Fricke]

Mechanical speedometers don't depend on electrical grounds (other than for instrument lighting), do they? The cable rotates a magnetic piece in the speedometer, which uses magnetic drag to turn a cup which surrounds the magnetic piece and is attached to the needle. A spiral spring is also attached to this cup/needle part, and it is designed and adjusted so that needle movement relates to speed of rotation.

Hence the importance of lubricant in the rather long cable assembly. And, if that isn't the problem, the best option is sending off to a speedometer repair shop - dealing with this yourself is sort of like trying to fix a wind up watch or clock.