Wobbly temperature gauge

[richarde]

Hi guys,

I am having a bit of a problem with a new aftermarket temperature gauge I installed on the RGV. The needle on the gauge is very wobbly. I pulled the gauge off today to check that it is isolated properly to avoid vibration and that all looked fine. When I started the bike for a test ride it was fine, and revving the engine didn't upset it at all.

After it had warmed up I stopped for fuel and turned the bike off. Shortly after turning it back on and riding off I noticed that the needle was wobbling a lot. I tried pulling the clutch in and it seemed to stop, so I don't think it is vibration that is being transmitted from the road, I think it is interference or something from the engine. The wobble of the needle seems quite violent - the needle goes back and forth by a good centimetre or so. When I parked up at home I revved the bike a few times, and got it to wobble one time too.

Could I be getting voltage spikes from somewhere, or interference, or is there an electrical explanation for this?

The gauge is a VDO, and I replaced the sender with a VDO too. It appears to read accurately when it is sitting still.

Richard

[Nero Diablo]

The question wouuld be is it vibration from the motor or an electrical problem, the symptoms almost suggest vibration from the motor. Next stupid question does it oscillate around the correct reading ie the reading you expect is in the middle of the needle movement or is the reading you expect at the top of the needle movement. If its at the top of the needle movement this suggests the gauge is dropping in and out so i'd be checking the connections of where you have powered it from and where you earthed it too as well as the connections to the sender.
If the correct reading is at the bottom of the correct reading then it suggests and extra signal is been injected into the signal line from somewhere although oscillating around the middle could also been a sign of this but is more likely to be mechanical vibration. At this point you really need a nerdy friend with their own oscilloscope and a understanding how to use it.

[richarde]

The question wouuld be is it vibration from the motor or an electrical problem, the symptoms almost suggest vibration from the motor. Next stupid question does it oscillate around the correct reading ie the reading you expect is in the middle of the needle movement or is the reading you expect at the top of the needle movement. If its at the top of the needle movement this suggests the gauge is dropping in and out so i'd be checking the connections of where you have powered it from and where you earthed it too as well as the connections to the sender.
If the correct reading is at the bottom of the correct reading then it suggests and extra signal is been injected into the signal line from somewhere although oscillating around the middle could also been a sign of this but is more likely to be mechanical vibration. At this point you really need a nerdy friend with their own oscilloscope and a understanding how to use it.

The correct temperature is in the middle of the wobble, not top or bottom, and when I stop the bike and let it idle the needle doesn't wobble any more.

I might try to move it and mount it in a different way to see if it affects the wobble.

[druu]

Dud gauge perhaps? Trace the wiring to the sender as it may be shorting, but otherwise I would try another gauge. Wouldn't be an air pocket would it?

[Nero Diablo]

The correct temperature is in the middle of the wobble, not top or bottom, and when I stop the bike and let it idle the needle doesn't wobble any more.

I might try to move it and mount it in a different way to see if it affects the wobble.

If you can hold the gauge in your hand with it still connected and give the bike a bit of a rev that should tell you if its a vibration related problem.