Speedo needle bouncing

[thomp1983]

Does anyone else find when sat at idle there speedo needle bounces? Is it a failure in the speedo's pcb or the gearbox sender becoming worn?

Thanks
Chris

[Torero]

I had exactly the same on a previous motor and it was the sender becoming worn, however this was a mechanical drive and you're running an electronic one as far as I know, Chris.

May be worth getting a spare one to try.

[alanmr2turbo]

Mine bounced around for a good while then would stop and start working then totally stopped working.

I'veound my fault which turns out to be the nylon ring inside the gear box just rotates when its not meant to lol. Hope its not same problem as yours as it means its either a gearbox strip down or replace the gearbox

[Peter Gidden]

Does anyone else find when sat at idle there speedo needle bounces? Is it a failure in the speedo's pcb or the gearbox sender becoming worn?

Thanks
Chris

The gearbox sender gears won't be rotating when the car is stationary.

[thomp1983]

Could you expand on that Peter? Is it the gears not turning when stationery and should be so needs replacing or the gear doesn't turn when stationery so the gear can't be at fault?

Im leaning towards the later as presumably the drive of the wheels turns the sender?

[Martin F]

I had a speedo display where the needle bounced, i bought a 2nd hand speedo display and it worked perfect, that was just my experience, i can't guarantee the above would work in every case though.

[Peter Gidden]

Could you expand on that Peter? Is it the gears not turning when stationery and should be so needs replacing or the gear doesn't turn when stationery so the gear can't be at fault?

Im leaning towards the later as presumably the drive of the wheels turns the sender?

The driving gear is attached to the diff casing. If the car is stationary, so is the diff casing, and so is the ring gear. If the ring gear isn't rotating, nor will the cog gear, so there will be no driven output signal from the sender.

[mr2magic]

How often is it bouncing? In time with the revs in any way? sounds like it may be interference

[thomp1983]

It's random sometimes it does it others it doesn't. Ill swap my spare speedo in at some point

[SteveH]

If you're running an electronic sender, could this be the alternator? Are you getting any flashing lights on the dash at all?

I had the same problem before my alternator died, but it was the tacho

[thomp1983]

No there's nothing else different going on with the car just the speedo occasionally bouncing. It's also possible my speedo converter is defective but that will be getting replaced in a few weeks anyway