I like to use Lubriplate white lithium grease on a speedometer cable. If there happens to be a tight bend anywhere in the cable housing, it's possible for the inner cable to wind up and snap forward repeatedly, causing a chatter of the speedo needle.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!