RVC tacho fault advice

[Setch993]

Hi
I have an RVC tacho fitted to my rally Imp. Worked perfectly up until this weekend.
In fact it still works, but the needle refuses to return to the zero position and 'parks' at approx 2000rpm mark. When the engine runs it seems to pick the needle up as the revs exceed 2k (but can't be sure whether the dial value is actual)
I have taken it out of the car and if the unit is rotated the needle does return to zero (just not in the fitted position) implying that it is not a physical 'stop'.
Before I wade in with my sausage like fingers, anybody got any thoughts on what has happened and what I might do to fix ?

Nick

[Whatty]

I had a similar issue with a RVC tacho that I fitted to my '68 Mini. I suspect in my case that it was a electrical interference/suppression issue from the Pertronix ignition. Sold the car before I could figure it out!

Try a search over at the The Mini Forum and look for posts by a guy called DKLawson on the subject, he knows his stuff.

http://www.theminiforum.co.uk/forums/index.php?&am...

Edited by Whatty on Friday 12th March 13:26

[Setch993]

Hi
Sussed it. Did a rally event at the weekend, bit bumpy in places ++
The needle assembly (behind the gauge face) has a lead counterweight, which was loose.
Moved it to correct the dial offset back to zero, tightened it up..job done

[Mr2Mike]

Clearly it's a mechanical issue of the gauge doesn't return to zero with the ignition off. Most likely some crud/rust has stuck to the ring magnet that the coil moves around and is jamming it. They are reasonably robust and quite easy to take apart anyway.