shaky tach and speedo

[Milanoverde]

Both the tach and speedo on my 80 DHC are shaky at various speeds. The speedo gets shakier as the speed increases, the tach swings back and forth like crazy when increasing the rev's. Any ideas on a cure? Should I just try to replace?

Anthony Brucia
Long Island, NY

[John_C]

It's possible the speedometer cable isn't sitting into the gauge properly. Try pushing it fully home as sometimes they can hang out a little. The tacho will likely be a different issue so is the car running properly? Over here I'd suggest the points needed adjusting but you'll have electronic ignition on yours.

[Milanoverde]

Correct . Here in the USA its electronic. Where does it get its signal?

[FI Spyder]

Shaky speedo is bad/dry cable, dry service counter (if you have one) or some people have had success with spraying WD-40/silicone in the speedo mechanism (never personally tried this. Shaky tach (electronic) is likely dodgy wiring/connections. Not sure were it gets signal off hand without having an electrical diagram in front of me.

[littlepippin]

You can disconnect the speedo cable at the dashboard end, pull out the inner drive (its like a very long spring with squared off ends) and clean off all the old dirt and grease. Before reinseting it, liberally spray some lubricant down the outer tube, and then reinsert the spring/cable.
You will need to grip the cable with something (I used an electric crimp) and have a few goes to get it to locate all the way back in at the gearbox end by turning 90 degrees at a time while pushiing firmly as it probably wont go fully back first time.

[Milanoverde]

Little pippin: Do you recommend I try to do this from under the dash or take the speedo out from the front? Thanks for your help.

[littlepippin]

You can just do it from under then dash. you have to kind of lie on your side to peer up above the pedals etc to see where the cable clips to the back of the speedometer. The clip can be hard to pull off, and I seem to remember you just push one side of the clip in, rather than squeeze both tangs together - but your cable may be different.
Careful not to allow the greasy cable to mark your seat cloth, and hold the outer up as vertical as possible when spraying your lube with its straw adapter fitted to your nozzle.
as I said, it may take a bit of fiddling to get the cable fully back home again so that it has its square tip flush with the end of the metal boss and not still sticking out.
All but eliminated my needle wobble, except for a small amount at 10 mph, but when you get it out, you will see that the cable/rod is not solid - it is like a spring so any resistance against the outer sheath will cause it to bind/release/bind/release causing the flicker effect,

Good luck - its not too bad a job by the way. 15-20 mins..!