Jumpy Speedometer -1973 Series 1 Short Wheel Base

Hello everyone. I’m new to the group; not the XJ6. Good to have all your knowledge and experiences.
My speedometer jumps frequently at all speeds. Almost seems as if the cable is kinked or restricted. Could this be a mechanical or magnetic problem or a combination? have others had this same experience and solved the problem in the early XJ6? Is it wise to lubricate the cable and if so what is the best lube?

Welcome to the forums, I’m thinking the S1 will have a cable, yes the cable may be kinked, if not I would use graphite powder on the cable but be sparing with it.

It is a cable, remove the side/bottom panel, as well as the shelf, undo the cable at the angle drive, pull out, check for kinks by rolling on a flat table. It must be absolutely clean and very sparingly greased. Don’t grease the last few inches at the speedo.
Male sure it seats at the transmission.
If it doesn’t cure the wobble it still is important maintenance.

A few tests and checks to isolate the cause:

  1. Disconnect both ends of the cable and turn them around so that you can see both ends. Attach a small battery drill to the gearbox end and run the cable slowly to see if there is any roughness or jerkiness at the upper end. Test in both directions.

  2. Withdraw the cable completely and carefully inspect for any strands that have separated or broken as these can catch on the outer casing.

  3. Remove the speedometer unit and check for any drag by turning the cable socket by hand.

  4. Use the battery drill with a dummy drive pin and run the speedometer to see if the needle wavers.

For 1. and 2., if good then clean it and apply new lubrication.

For 3., a small flat blade screwdriver across the diagonals of the square works. If not free and almost frictionless, the lubricant has dried. Revive it with some drops of light machine oil or penetrant and turn the drive socket back and forth until it has worked through.

For 4 , if it wavers then the problem is internal and it needs to be sent for repair. Warning! Make sure you drive the speedometer in the correct direction, ie anticlockwise when looking from the back. The cause of this is likely to be a worn spindle that holds the needle. This allows the spinning magnet and disc to float in and out of contact.

An unlikely cause could be worn gears in the gearbox cable drive.

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Thanks for the advice.

Good. After digging farther into my service manuals I noted the procedure. It looks as though it will be somewhat easier to get it up on a rack so I can remove the drive mechanism at the transmission. Thanks

Your test sequence is much appreciated. It should make trouble shooting much simpler.

I had the same problem and swapped out the speedo. Went away. I have had experience with floppy speedos in the past, and I’m not talking about the bathing suits! But, by all means check the cable too. Make sure there are no kinks and the ends are nice and square.

If you’ve not gone beyond this already, pop the speedo out, disconnect cable at the speedo end, withdraw the drive cable by just pulling the whole length out then clean and lubricate as discussed.

That fixed mine and was a lot simpler than disconnecting both ends.

Thanks Bertiebloke. Have not quite gotten to this issue. close but have been tracking down an oil leak that has a greater priority.
I will do just as you suggest soon.

I notice that no one has mentioned the right angle drives. They can be troublesome and cause the problem you are experiencing. You can remove, clean, rotate by hand to test. IMHO.

Are you suggesting the drive on the transmission Robert?

I’ve had more problems with the one at the Speedo. Also had success pulling cable out from speedo end, lubing and replacing.

Only works from speedo end!