Noisy speedometer, 88 5kq

[S. Jaworski]

    Speedo makes intermittant noise when cold. Sounds like a spinning
bushing. Noise comes and goes in colder weather. Going over small bumps on
highway will set the noise off, and I can feel vibration in the instrument
cluster. Tapping the instrument cluster will make the noise and vibration go
away . . . only to return with the next bump.
    I had the cluster out last winter to fix the odometer. At that time I
used a drill to spin the speedo . . .could hear the noise come and go. So,
I'm pretty sure its the speedo and not the cable. I did lube the cable using
a vacuum pump and heated heavy oil . . . worked like a charm.
    Before I tear it all apart, does anyone have BTDT on this? What's the
theory of operation for this type speedometer?

    Anyone have an instrument cluster to sell?

SJ
88 5kq
90 100q