A cable on its way to failure can also cause bounce as the wire strands
alternately lay and unlay.
Best--Michael Oritt
-------------------------------------------
On Sun, May 1, 2011 at 11:43 AM, Rich Chrysler
<richchrysler at quickclic.net>wrote:
> Ron,
>
> I think there is probably some information in the archives on this but the
> summary of the causes of a bouncing speedometer can be two things:
> 1. the speedometer cable is kinked in some way causing it to repeatedly
> stick, wind up and let go, then stick again, etc. The best way to check for
> this is to completely withdraw the inner core and lay it on a clean flat
> surface. Bring the ends almost together in a large loop. Carefully turn one
> end while the cable is remaining completely flat on the table surface.
> Watch
> to see if the other end is lifting and flopping at all at the end or
> anywhere along its length. Ideally it should lie completely flat and turn
> smoothly.
> 2. there is excessive lubricant that has travelled up the cable and
> entered
> into the speedometer head. This is most commonly caused by oil escaping
> past
> a worn seal in the brass sleeve that the 90 degree gear drive screws into
> on
> the side of the overdrive unit. Most people don't realize that there is a
> seal within the brass drive sleeve. When worn, gearbox oil can escape and
> travel right up the cable like an auger, and enter the speedo, causing the
> problem.
> I deal only with Nissonger Instruments (long story). When they encounter
> this oil contamination problem they clean and test the unit and return it
> with a preprinted warranty label stating the problem and that it must be
> fixed on the car or their cleaning repair warranty will not be honoured.
>
> Rich
>
> -----Original Message-----
> From: healeys-bounces at autox.team.net [mailto:
> healeys-bounces at autox.team.net]
> On Behalf Of Ron Ray
> Sent: 2011-05-01 9:52
> To: 'healeylist'
> Subject: [Healeys] Bouncing Speedometer
>
> Folks,
>
> Recently I replaced the angle drive on my 1959 3000 in hopes of eliminating
> the factory optional bouncing speedometer.
> While this did result in somewhat less bouncing, it is far from the results
> I had hoped for.
>
> The speedometer was rebuilt twice by MO MA a few years ago, after the
> initial rebuild failed to correct problems with the odometer. The second
> attempt by MO MA simply changed one odometer problem to another odometer
> problem, so I gave up n MO MA.
>
> The speedometer cable is relative new and the distance the cable extends
> into the speedometer is correct per Norm Nock's book.
>
> Any suggestions?
>
> Thanks
> Ron
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