What is the best way to lubricate the cable.
The speedometer dial is bouncing.
1967 MkII/340
First thing to check would be if there are any kinks in the cable run. If thats ok then I would use graphite powder but be careful I think you would not want to use oil as that will migrate into the workings of the speedo.
From my experience, for what it’s worth, the bounding needle issue is the result of a worn cable, not so much lack of lubrication. For decades my MOD 3.8S ran without an angle drive at the gearbox end resulting in a large sweeping curve in the cable under the car. This caused the cable to wear every 15-20K miles causing the speedo needle to bounce. Finally learned the angle drive was removed by the previous owner, replaced it, and have not had this syndrome since.
In addition to the comments already posted, I too had a bouncing needle on my Mark 2 1967 LHD.
I found that the odometer nylon gear had a damaged tooth that gave a periodic thump to the mechanism. The symptom was that at very low or higher speeds the needle would kick the same amount. In other words it was not mainly speed dependent.
I fitted new ones from odometergears.com and great improvement was seen but there was still some wobbling which I deduced was caused by an overly long drive cable.
I then fitted a right angle drive at the gearbox and had a custom made cable that was as short as possible. It was made by British Vintage Cables in Alberta and the order was for Part DF1110/00 75"long
The result is a very smooth operating speedo.
As a postscript, if you find a video of a Mark 2 being driven down to Bath UK, back in the day, you can see the speedo needle wandering on what is probably a new car so don’t feel too bad (they all do it).
The video is https://www.youtube.com/watch?v=YIgskqk5PB4&t=46s and at about 3 minutes you can see the needle wavering.
Thank you, the video was right on, my speedo needle is doing exactly the same thing. I will get to the job in the next few days and see what find. A little graphite for lubrication . Thank you all for the suggestions. By the way I remember my drive into Bath in a rental car, it would have been much nicer in a Jag. Keep your distance and be well.
Richard