Re: Speedometer cable
Posted by 39SixSedanMan On 2019/11/28 10:35:08
All,
Chris gave me permission to show some of the repair of his 39 Six Stewart Warner speedometer.
This unit was a good example of needing cleaning and lubrication. Very good original unit.
Cleaning: Removing the old, crusty gear grease and bearing oil is always a given. What most people are not aware of is the tendency of the spinning magnet (cylindrical in the case of Chris' Stewart Warner) to attract metal debris (see photo). If large or thick enough, the debris then begins to contact the speed cup, whose shaft is directly connected to the speed pointer (or in older cars the rotating speed indicator, ala pre-30's Packards and other makes). The contact of the rotating debris then clutches with and drags the pointer to either full scale or bouncing.
As I stated prior in this post thread, hardened grease and oil can also cause needle bounce. Notice the before photo of the dirty mainshaft oil wick. Also, all the tan areas on the frame are the dried residue of oil and grease.
Lubricating: I use silicone based grease and oil so that the final unit should last longer than any of us. Not only does this make the needle pointer more steady, but makes the unit quieter and puts a much lower load on the drive cable and transmission driven gear, for long lasting service.
I hope this helps to explain the process.
Pat
Attach file:
(184.90 KB)
(167.95 KB)
(203.21 KB)
(159.37 KB)
(29.97 KB)
(197.74 KB)
(237.84 KB)
Chris gave me permission to show some of the repair of his 39 Six Stewart Warner speedometer.
This unit was a good example of needing cleaning and lubrication. Very good original unit.
Cleaning: Removing the old, crusty gear grease and bearing oil is always a given. What most people are not aware of is the tendency of the spinning magnet (cylindrical in the case of Chris' Stewart Warner) to attract metal debris (see photo). If large or thick enough, the debris then begins to contact the speed cup, whose shaft is directly connected to the speed pointer (or in older cars the rotating speed indicator, ala pre-30's Packards and other makes). The contact of the rotating debris then clutches with and drags the pointer to either full scale or bouncing.
As I stated prior in this post thread, hardened grease and oil can also cause needle bounce. Notice the before photo of the dirty mainshaft oil wick. Also, all the tan areas on the frame are the dried residue of oil and grease.
Lubricating: I use silicone based grease and oil so that the final unit should last longer than any of us. Not only does this make the needle pointer more steady, but makes the unit quieter and puts a much lower load on the drive cable and transmission driven gear, for long lasting service.
I hope this helps to explain the process.
Pat
Attach file:
(184.90 KB)
(167.95 KB)
(203.21 KB)
(159.37 KB)
(29.97 KB)
(197.74 KB)
(237.84 KB)
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