my needle is very jerky at low speeds, like a metronome!

when I reach supersonic speeds of over 40mph it begins to smooth out and become steady.

car has covered 40K miles, but unsure of clock mileage as its from a USA car, that went to Germany, and I swapped the owner my KPH gauge for his MPH one.
Original Post
Likely the Speedo cable is going bad. Look to make sure there are no sharp bends in the speedo cable. Larger sweeping curves is desired.

You can try to lube the cable. Lot of effort to removing the old cable, pulling the center cable, greasing and re-installing. Might be just as easy to replace with a new cable and know it will last many more years. $125 from Wilkinson Pantera.
quote:
Originally posted by Peter Fenlon:
my needle is very jerky at low speeds, like a metronome!

when I reach supersonic speeds of over 40mph it begins to smooth out and become steady.

car has covered 40K miles, but unsure of clock mileage as its from a USA car, that went to Germany, and I swapped the owner my KPH gauge for his MPH one.


Hi Peter,
I have the same problem after fitting a new speedo cable (inside and outside complete). The original one wasn't working at all. Mine is slowly getting better, after trying to get the routing as straight as possible, lubing with one of the teflon containing spray lubes, also playing around with how tight it is screwed into the speedo and the ZF, and the thickness of the o-rings, or lack of them, which can cause the speedo to stop working altogether if it is screwed in too tight. I also probably need to drive the car more!
Cheers, Tim.
Peter,

One often overlooked item is the bushing at the rear of the speedometer. Disconnect the cable from the speedometer and spray some lube on the rear of the speedometer.

As Tim points out, routing of the cable assembly can make a difference.


@ Tim,

If tightening the speedo cable at the back of the speedometer causes the speedometer to stop working, most likely the problem is that the inner cable is too long.

John
my new speedo cable lasted about 3 months, I stripped the old one down and greased it , its now even better than the new one.... I wonder if there is an issue with the new speedo cables being made, mine sheared off from the Gearbox end , and was very erratic from the day I fitted it.
Think of your speedo drive cable as a very long flexible screw thread. Over the years rubbing on the the middle layer of plastic, things wear. The inner cable is spring steel so it tends wears the liner & outer steel jacket at the center of bends where the pressure is highest. Nice, attractive, tight bends wear fastest. Once the plastic low-friction liner is worn thru, the drive cable can catch worn edges of the liner or steel jacket and cause the needle to jerk. Eventually, it breaks. This is why replacing only the broken inner cable usually results in quickly breaking the new one.

New cable assemblies are built with better materials than 45+ yrs ago and come in two lengths depending on what's in your car now. Remember, unless you are an original owner, you have no idea what's been kludged together by POs. Lubing a worn cable is a very temporary fix at best- if it does anything besides make a mess.

The way your right-angle drive ass'y is attached to the ZF influences smoothness as well. The left/right-threaded nut on the assembly should be adjusted ALL THE WAY UP, so when applied to the threaded adapter sleeve, the drive tongue inside is all the way DOWN into the visible forked end of the ZF drive gear. On some cars, you will have to play around with the position of the right-angle assembly to get the drive fork down far enough. This alone smooths out speedo action and extends the life of the whole drive unit. The tightness of the big left/right nut has no effect on leaks- those come from a broken o-ring inside the drive assembly. Pliers-tight is good enough.

When I fix broken right angle units (up to about 50 now), I add a zerk fitting so the poor thing can be lubed occasionally. It was not designed for service but with difficulty, it can be modified. Mangusta right angle drives are built differently and wear the gears & thrust surfaces (which are irreplaceable so far), rather than breaking the fork-&-tongue drives. A Pantera assembly of the proper cable thread size can be substituted. New OEMs are no longer available as far as I know.
I recently bought one of the Wilkinson odometer cables and decided to compare it to the original Veglia before installation. I discovered the aftermarket cable has a longer shoulder on the pressed on nut at the speedo end. I had to drill the outer sheeth fitting about a half millimeter wider to get that shoulder to clear so the inner cable could slide further into the sheeth. If I hadn't that nut would have gotten clamped between the back of the speedo and the sheeth causing drag and a broken cable at some point.
Cratecruncher, I bought a speedo cable from Wilkinson as well but it has been making my speedo needle flutter badly. It's routed just like my original and the ZF angle drive is in good shape. I wonder if I'm having the same problem. I don't fully follow what you did. Do you have any pics of where you drilled by chance? I didn't keep my old original cable.

I've tried all kinds of lube in it and can't return it so looking for a fix or just buying one from another source. I've bought other good parts from Wilkinson but I don't want another one of their cables.

Anyone buy a cable from someone that worked well? Please PM me if you have a good source.
Interesting issues. my cable was rusted solid and broke. so I looked into a new one. heard of issues so I went to wrecking yard a pulled one out of a chevy van. swaped the ends out to fit my trans n speedo. cut to length and wala! works perfect.
I have also speedo needle flutter at low speed and have tried all kind of fixes (some mentioned her) without success. Recently I attached a drilling machine at the cable end (ZF side) and found that the needle was not at all fluttering including very low speed. Seems that in my case the fluctuation is generated by the ZF angle drive. I removed the angle drive and found it in very good condition, however, when turning it I noticed at one specific position a very light resistance which could cause the needle flutter. I could not find out where this resistance is coming from, but it is not due to lack of lubrication.
Brgds
Hartwig

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