121K is not a lot for a mechanical speedo, I've had one that hit 300K miles and was still working fine. The first thing to fail is generally the mileage recorder.I'd say that at 121K the speedo has done well & now had it's day.
I shall be renewing the second-hand unit in my Classic this year, despite the cost
I took the cable out and pulled it out of its sleeve. I can’t see any sign of damage whatsoever, so I am afraid that Norsemen was right and the speedo has had its day…Well, I rather first check the speedocable before emptying my pockets on a new unit
Twist the cable with you fingers and see if it turns freely, the failure may be the outer.
Well, I just had a brainwave and decided to use my batterydrill to power the angle drive (as Jeremy Clarkson would say: “sometimes I am frightened by my own genius”). Not only have I established that the speedo works as it should, but also that my batterydrill runs about 50mph. However, I kept on hearing the clicking noise and the odometer seems to be still stuck. I tried pulling the unit further apart but stranded because I couldn’t take te needle off.
The clicking noise is the ratchet mechanism that advances the mileage counter and it is always the bit that wears out first in the speedo. It may well be the cause of the jumping. Sounds like your cable is OK to me.Well, I just had a brainwave and decided to use my batterydrill to power the angle drive (as Jeremy Clarkson would say: “sometimes I am frightened by my own genius”). Not only have I established that the speedo works as it should, but also that my batterydrill runs about 50mph. However, I kept on hearing the clicking noise and the odometer seems to be still stuck. I tried pulling the unit further apart but stranded because I couldn’t take te needle off.
Anyways, I will replace te cable. I will keep you posted
Ps: I tried twisting the cable in the outer. It twists fine, although it is a bit wobbly
Aha, is there anyway to take the needle off so I can take apart the mechanism at back of the speedo?
I do not know on your car, but if you get it off you will have problem recalibrating the speedo. On the ones I have looked at in the past, I was able to get to the mechanism without removing the needle of the face. A wash out of the gears and a little lubrication (NOT WD40) may help.
The speedo was off anyways so I tried again and managed te remove the needle with a fork. Was quite easy actually. I have taken apart the mechanism as far as I could without doing damage and found the culprit. The screw shaped gear that drives the odometer won’t turn and moves upwards instead causing the ticking sound. I used a whole lot of teflonspray but it didn’t do anything. Couldn’t even get to move it with a screwdriver. However, the speedo seems to be working just fine now. So I will reassemble everything next week and see if the speedo still works when fitted to the car.
