Mechanical Tach Repair

[TimberHole]

My JD 950 has the original tach. It is in excellent cosmetic condition and has a perfect face. It is indicating about 600 rpm's low.

Does anyone have any experience repairing mechanical tachs? We used to have a great speedo shop here in the Midwest but they are gone to the best of my knowledge. According to my research the guts of the tach is a spinning magnet with a calibrated spring. We'll call it electromechanical magic The only good news here is that since there isn't any electricity involved I probably won't let any smoke out

I'm thinking I will split the unit and see what's going on inside. If anyone has experience with this let me know. Otherwise I'll pull it and see if I can figure anything out.

Thanks.

 

[mark in portugal]

I have some experience repairing speedos and tachs.

Well, I have experience in trying; I never succeeded once.
But if I have another broken one, I'll try again!!

 

[CincyFlyer]

In my area, there's this guy: Gene's Speedometer: Welcome to Gene's Speedometer

 

[TimberHole]

Thanks Cincy. I just called him and he doesn't work on the old stuff anymore.Good try though.

 

[CincyFlyer]

Thanks Cincy. I just called him and he doesn't work on the old stuff anymore.Good try though.

The old man probably died and the kids don't know how.

 

[JRobyn]

These guys in North Atlanta are great. Tiny shop. The "old man" is still there. At least last time I had them do some work on my old Triumph speedometer a few years ago.

Hamp's Speedometer Repair - The Nation's Best Quality Instrument Cluster Repair Company

 

[boomer1025]

Remove the drive cable and check the ends. Then remove the cable from the casing and grease it with thin/light grease.
Most of the times problems with a mechanical tach is a dry drive cable.

 

[mark in portugal]

Boomer has a point there; you can also replace the inner part, get a kit from any auto parts store.