Electra speedo

hello my electra has the same size speedo as the other lightweights, but calibrated up to 100 mph,haven't checked the gearbox ratio, so it might be a good idea to do that if you are going to change

Mine has a 100mph and we have a lot of wind in Norfolk.

Too much gluten? Well, lots of wheat is grown in Norfolk!

Sorry, lowering the tone again.

Yes you have the wrong speedometer only the jubilee has the 0-80 speedo. The Navigator and Electra both have 0-100mph speedo's. You will not have to change the gear box unless you change wheel size or tyre section as it is the circumference of the tyre that matters. I think you want the SSM20000/00 1600 series grey faced Smiths speedo. I am just rebuilding my second jubilee. A big task from boxes of bits.

After the size of the Speedo, the next important thing is the gearing - how many turns of the cable for 1 mile. The clue is given in the reply above by Peter F - the magic number you need is 1600.

This ratio should be printed on the face of the speedo.

Jubilees had 0-80mph speedos, While Navigators & Electras had 0-100mph instruments.

Initially, black faced units with white lettering were used, but from about 1964, a newer type with a grey face was used - initially on Electras, later on the other models as stocks were used up.

Attached is a picture of a black-faced 0-100mph speedo - but if you look closely it is not the right one - as its showing a ratio of 1632

Similary, the 2nd photo shows a 0-80 grey faced (later) speedo, with the ratio 1500 printed at the top. So you can see there are many variants about.