<VV> Zeroing a Tach

Tony Underwood tonyu@roava.net
Thu, 24 Jun 2004 10:19:28 -0700


At 06:32 hours 06/23/2004 -0700, Charles Morgan wrote:
>Short of bending the dial, is there a way to zero a tachometer?  I'm 
>helping a friend fix up a 64 Spyder.  The tach works but shows over 1000 
>rpm with the engine off.



It's likely that something is hung up in the magnets in the meter.    The
tach display itself is nothing but a d'Arsonval meter movement which is
zeroed with an adjustment tab which requires that the tach be removed from
the cluster.   The pointer also rests on a peg when not operating, so
adjustment is a little tricky to get it right.    

The magnets in these meter movements are notorious for snagging bits of
rust flakes etc and hanging up the meter movement.    


I'd recommend having someone with experience do the repair.   The tach
meter movement is easy to damage if one is not sure of how to deal with
cleaning or repairing it.   


tony..