Speedo

I have a Speedo issue as it bounces around from zero to seventy. I have checked the cable both ends and the drive cog all seem ok. Odometer still works ok.
My question is can I change just the Speedo into my existing cluster? Will a Mk 2 Speedo fit ( seem cheaper) ? Are there any internal parts that I could change to save my Speedo ?

Many thanks

I would try a new speedometer cable first.

if you have a VDO then look for a VDO.
As you didn't mention that or the year, for oem stay with the oem clock set.  mix and matching a clock set may involve moving the wires around a bit on the harness.
It isn't that hard just have to be careful.

I personally have had issues with bouncing dials, since my clocks have never been apart, I tried the speedo cable first.  They can wear out and the inner sheath can deteriorate and can make the cable catch.

could it be an earth/grounding issue?
Im sure i had a problem with the needle bouncing when my battery connections weren't tight.

What speed are you going when it bounces between zero and 70, or is this at all speeds, including stationary? Is it continuous or intermittent?

Hi, only does this when moving needle bounces all over the place no matter the speed I'm doing. Thanks

Sorry, forgot to mention that I can hear a ticking sound behind the Speedo when in motion.

The speedo is driven purely by the cable - it is not connected to the vehicle electrics. The clicking sound suggests the cable is rotating, but for some reason not reliably operating the speedo mechanism. My guess is either the cable is slipping in the speedo pick-up due to wear or incorrect fitting or the speedo itself is faulty

It is way easier to replace the entire Cluster than to take it apart.  If the Clusters aren't from the same type and model, then the connections to the clusters may no match or the wires are in a different location in the connector.

Perhaps a job to be done in the comfort of your own home…. If it's clicking it's likely a cog not doing what it should , probably made of plastic.

Only take to bits if you are not using the car for a while, or get a spare binnacle