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Pulsing speedometer

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fogdot

Jedi Hopeful
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My speedometer (TR3A w/OD) pulses. It waves in a 5 to 10 mph range roughly centered around the correct speed.
I have had it apart, cleaned the old hard grease and reassembled it (there goes my "calibration").
I swapped it with the tachometer, and it shows engine rpm nice and steady. The tachometer attached to the speedometer cable is nice and steady.
I have a new speedo cable from VB, and I think it may be the problem. The pulsing coincides exactly with the small movements of the odometers when the ratchet moves them.
I think the new long speedo cable is flexible enough to wind up a bit with the ratcheting, and then release. I don't remember this happening with the old cable. I don't the old one anymore to compare.
Does that sound logical? Anyone else seen this happen? Are there "bad" speedo cables out there?
 
Hi There fogdot;

Now there`s an Un-Usual User Name! What does it mean?

I had the same problem with mine in my TR4A:

I loosend the Cable at the Guage / Shot some WD40 directly inside the Threaded area & She just straightened right out! Steady as a Cucumber:

But Yes; There are typ. cable problems & most of them are a simple replacement:

Try the WD40 trick; It works:

Regards, Russ /bcforum/images/%%GRAEMLIN_URL%%/banana.gif
 
If spraying WD40 into the cable housing helps then that may prove to only be temporary relief. If so, removing the inner cable and lubing it (some say grease, some say graphite) may bring lasting improvement.

If spraying WD40 into the fitting on the speedo head... that is probably going to cause a headache later.

One place speedo can bind a bit is in the shaft of the fibre gear that operates the odo. That shaft can develop a bit of corrosion and not turn smoothly. It turns slowly but with lots of torque. As I recall the shaft has a small depression mid-way to accept a bit of grease and keep it trapped in there. A corroded shaft can be dressed with a bit of crocus cloth, lubed & reassembled.

Unfortunately the first warning mine gave was when it seized and snapped the cable.
 
Hi There fogdot;

Now there`s an Un-Usual User Name! What does it mean?

FogDot is a Peruvian expression of dismay. In high school in Connecticut, we had a very lazy Peruvian living with our family.
When we told him he had to get up an hour early and shovel snow before going to school, that was his reply.
 
/bcforum/images/%%GRAEMLIN_URL%%/laugh.gif /bcforum/images/%%GRAEMLIN_URL%%/laugh.gif /bcforum/images/%%GRAEMLIN_URL%%/laugh.gif /bcforum/images/%%GRAEMLIN_URL%%/laugh.gif
 
fogdot said:
FogDot is a Peruvian expression of dismay. In high school in Connecticut, we had a very lazy Peruvian living with our family.
When we told him he had to get up an hour early and shovel snow before going to school, that was his reply.
Click to expand...

Great story, and a distintive ID. I will have to save that for my cursing vocabulary after a very dismaying stroke on the golf course...

Thanks for the explanation.
 
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