Thread: speedo inop

No. Nothing electrical in the Series 3 speedo. First check, disconnect the speedo cable at the speedo, and have it out where you can see it. Go for a drive, or better and safer, put the back axle on stands so you can "drive it " without going anywhere (or disconnect the front of the prop shaft). Check that the inner cable rotates. If it does, the problem is in the speedo head, which you can easily disassemble to check what is wrong.

If it does not rotate, the problem is almost certainly that the worm gear on the output shaft is not turning with the output shaft. This gear is not keyed onto the shaft, but is simply clamped between the output flange (that carries the handbrake drum) and the output bearing. Disconnect the universal joint (the bolts are captive so don't worry about them, even though they seem a bit loose as you loosen them, they can't go anywhere). You will then see a large nut with a split pin locking it. Remove the split pin and tighten it, repin. Reassemble, and check that the cable now turns. If this has not fixed it, the gear that engages the worm may be seized and stripped (never seen this, but you never know!) and you will probably have to remove the output housing (after removing the handbrake) to replace it. It can be removed without this, but if this is the problem it is probably seized.

But my guess is that the problem is the nut on the output shaft.

Hope this helps,

John