Tachometer and speedometer bounces....

[Bozo]

So the Toyota oil was perfect for the Fuel gauge, but insufficient for the Speedo gauge?

What was the last fluid you tried for damping the speedo?


For the speedo, is it possible that the fluid is too light, and so it doesn't provide enough resistance when the cable provides a certain amount of force? Sounds weird. Odd that it goes too *high*. Cable binding, I think, would provide a number that would be too slow to keep up with speed increases, not the opposite...

...then again, I cannot fathom how the speedo works. How in god's name is some kind of damping fluid involved? In my mind this should just be a straight mechanical device, I've never heard of a problem like this. Do other vehicles use this design? It just seems crazy to me. Some kind of explanation on what is going on and the actual physical role that the damping fluid plays in the system would be great, if anyone knows... Or has a resource they can point me to.

I used the standard Dimethicone (ebay) for the speedo but I would consider using the Toyota oil in the future.

Fluid too tight, as you stated I don't understand why the needle would go up in speed?, as you said - weird, I'll investigate more when I have the time.

The fluid actually causes a resistance on the needle shaft i.e like holding it between two fingers, this can also be similar to suspension shock which prevents the suspension from continually bouncing

[fintip]

I assume there is some kind of spring in the speedo, and that the cable drive pushes against this sprung force, no? So, perhaps your spring is weak, and only slowly adapts to the pressure applied by the speedo cable?

So Speedo and Fuel gauge, both show no bounce now? Rock steady?

Where did you originally read/hear about using dimethicone?

Thanks for the responses!

Super helpful.

[Bozo]

I assume there is some kind of spring in the speedo, and that the cable drive pushes against this sprung force, no? So, perhaps your spring is weak, and only slowly adapts to the pressure applied by the speedo cable?

So Speedo and Fuel gauge, both show no bounce now? Rock steady?

Where did you originally read/hear about using dimethicone?

Thanks for the responses!

Super helpful.

The speedo works on a floating magnet, as it spins faster the drum that is part of the needle shaft goes up (shows higher speed) the oil that is in the small container on the needle shaft prevents the needle bounce. The spring acts as a restriction to prevent the speed needle going straight to maximum, the spring is what they move forward or back to calibrate the speed at certain revs usually listed somewhere on the speedo frame, I have to admit I couldn't find this on my speedo but my Kawasaki does.

As I mentioned I'm not 100% happy with the speedo but it is a lot better than before, the fuel gauge is perfect

Somewhere on this forum someone mentioned Dimethicone

[fintip]

Since it still fits the title of the thread...

...Noticed something new about my dysfunctional tach the other day. If I am still in third when I hop on the freeway, the tach will hang out registering a little north of 4k (obviously low) for as long as I stay there (I think--at least, as long as I have ever wanted to stay in third on the highway, maybe 30 seconds or so as I burst around a few cars and then stare at the tach wondering why it's doing what it's doing).

Up to fourth, registers something lower for a while. Up to fifth, registers around 1.5-2 for a while, sllllloooooooowwwwly, gently easing down to rest at 0.

Does that make sense to anyone?

[fj johnnie]

 I read this thread because I also have a speedo that bounces around. My cable came loose on a trip to the east coast and the contents of said cable are somewhere in Maine. After returning home I quickly installed the cable core from my 86 that I am restoring. Oddly enough the bouncing has stopped. I think a new cable is around 15 bucks so  I can say the advice to replace the cable first is the easiest way to start. If the cable is somewhat suspect then all the other work is for nought.

[fintip]

My cable fell out about 3 weeks ago. I replaced it; still bouncing as before.