My tacho cable is singing

[Brendan W]

PO fitted an aftermarket tacho cable in July. That was 3000 miles ago and it has started singing over 2000 rpm and the needle is jumping. I can't seem to get it fully tight at the top end. There is about 4mm of axial play in the cable end. Anyone had similar or what might be wrong ?

[koolaid_kid]

How did you lube it before you installed it?

[Brendan W]

Didn't install it , the PO did. Thought these cables were teflon - leave me alone - these days?

[Big T]

Well, pull of the top connector ad lube it

Check the routing in the manual

Are you sure it's the cable and not the tach itself?

If it's the tach, take it off, turn it over and squirt some lube down the cable hole and let it drip down

If that doesn't work, you'll have to take the tach top off and clean and lube the gears

[almarconi]

Sounds like you need to oil it.

[koolaid_kid]

Oil = engine oil, chain lube, teflon lube, cable lube. All work.

[Brendan W]

Thanks for the replies guys. Light machine oil going down the cable as we speak. Am starting to suspect the tacho itself so it's coming off for a look. Needle flicks up to 1000 rpm above real motor speed and steadies out with a bit of a kick dropping back below 1900.
Reminds me of a pre RFC 'how to fly' book I found in an old library. They advised a max rpm check every morning against the chocks. If a drop of 100 was noted the inexperienced pilot sent for the mechanic, the experienced pilot asked the ostler to change the tacho Plus ca change! ... and yes they were still cavalry I think.
Will keep you posted and thanks again for your time.

[Brendan W]

It's fixed but hard to say why it was noisy. The only thing that looked a bit off was the cable input sleeve in the tacho head had old dry grease and could be rocked about 10 thou. The rotor didn't rock with it so I presume we have two separate parts here. Anyway she's all back cleaned, oiled and quiet. Really impressed with how good the inside of a 33 year old instrument was, pristine apart from corrosion on one of the fuel gauge terminals and whatever the bezel is made of it's good stuff. Was expecting it to fall apart resealing it.