My speedometer needle bounces around until about 40-50km/h.
Is this normal or something is wrong?

Thanks

 

Mine was doing the same thing. Recently i changed the entire cluster and problem went away: all smooth now. I believe there are some gears or something that wear out causing the bouncing.

 

I don't believe bouncing is normal. It is usually a sign that the rotating flexible shaft inside the speedometer cable is rubbing/binding. You should try the following two things:

1. Removed the floor carpet on the drivers side. You will see the speed-o cable running up from the floor and into the area behind the dashboard (fascia) and toward the instrument cluster. It will be held in place by a clip about halfway up. Mark where the clip covers the cable with a marker. Remove the cable from the clip and gently push more of it toward the instrument cluster. Then carefully pull it back and push it more into the floor. Do this a couple of times and then position the cable so that the part of the cable that was under the clip (remember the mark) is either above or below the clip. Then put everything back and check the speed-o. The purpose of this is to move the whole speed-o cable around so that the pressure points (where the flex cable will wear against the sheath and start to bind) are in a different location (I found that it is easier to push more toward the instrument cluster). Mine bounced until I did this and now it is perfect.

2. Remove the instrument cluster (instructions elsewhere) and spray some silicon based lubricant spray into the end of the speed-o cable/sheath. I have done this on many other older cars and it provides enough additional lubrication that the flex spins smoothly in the sheath. Someone even used to make (and may still make) a "universal" adapter that allows you the pump in the lube under pressure.

Hope this helps.

- FD

 

Can this cause wear on parts which will cause problems later if left unfixed?

And, can I just buy and replace the whole speedo cable? Or is there something else which may be worn out?

 

Just needs a speedo cable, they wear out, get fluid, dirt etc in them. Should be able to get the cable as a unit. Won't damage anything else, its a common problem.