Erratic Speedo

[eadmr04]

My standard series 1 speedo has been pretty reliable with a half decent reading. It recently developed a fault and the needle was just bouncing all over the place especially when I went over any bumps. I took it apart and the cable spins the needle all ok in the headset when I turn the wheel and it seems like the worm is working ok. I've disconnected it several times and all appears to be ok when I spin the wheel, with a nice steady reading but as soon as I get on the road and hit a bump it jumps about and then reverts back to being all over the place. Any suggestions?

[HxPaul]

Try the speedo cable,the outer might be too long when their is a bend in it.If so cut the outer cable too length.

[eadmr04]

Any idea how much of the inner should be showing at the bottom when the cable is bent and how is the outer cable actually held in place? Is it just the friction of the rubber boot that holds it in position or should the brass ferrule sit over the outer cable and when the main knurled nut is tightened it squashes it to grip the outer. Never been too sure how this works and can't always get the brass ferrule over the end of the outer cable if that is the case?

[HxPaul]

The outer fixes with the brass olive over the outer cable and is clamped against the speedo drive housing,holding the outer cable.https://www.ebay.co.uk/itm/lambretta-sp ... rk:23:pf:0 This shows the end of the outer cable.

[Jeff t]

I had the same issue on my S2 messed about with everything even changed the drive on the disc, believe it or not squirted wd40 in the speedo and it's as steady as a rock.