I had a rattle in the speedo cluster on a 140 that was driving me crazy.

Took the cluster apart and figured that there was too much slop in the axis of the speedo drum. Tightened up on the left side spindle to take out the slop. Could still move it easily by hand so I reinstalled it. Took it for a ride and the noise was still there, but now the speedo was reading slower than the actual speed.

Took the cluster out again and loosened up the left side spindle. Reinstalled and the noise was still there but now it was reading way too fast. Nuts!

Took it apart again and re-adjusted the spindle to tighten it a little and figuring to hell with the rattle. Reinstalled and the speedo was back to reading correctly. I have always found the speedo and odometer to be quite accurate so long as I had the proper height tires.

Conclusion: That spindle adjustment is very sensitive. I don't have a clue as to the proper procedure to set it up, but for me it just took a few tries to get it right (or back to where it was originally).

Oh yea, the rattle was in the ductwork to the defroster on the drivers side!
--
'60 544, '68 220S, '70 145S, '72 144E, '86 745T