V8 speedo behaving strangely

[VSPantha]

Hi all.
Over the last couple of days, my speedo has been a bit weird, but this afternoon is especially strange!
Like... I'm going from say a 80 to a 100 zone. I've got the cruise on, tap the accelerate button a few times to up the speed, and although the car is accelerating, the speedo will stay at around 80, then after a couple of seconds it will jump up to 85, then go normal to around 95, then pause again, then jump up to 100! It's not at all smooth and sometimes sticks for minutes at a time.
Since I've had the car I've had the common intermittent problem where the speedo will sit at 0km/hr while accelerating and then jump up to 30, or 40 or 60 or whatever. I'm wondering if this is now causing the above issue?
I read on the forums somewhere that there's some kind of damping fluid in the speedo mechanism and over time it crystalises and causes the erratic jumping? Can this be fixed or do I need to get a new speedo mechanism or cluster?

[VrWagz1]

the speedo's rarely play up as far as sticking. Im thinking a dicky cluster or the sender. Im leaning towards the cluster itself. Pull it out a check for anything dodgy and open it up and check the solder joints. If you have a mate or somone with a VR or VS try their cluster too. If it still plays up then its possibly the sender unit.

[VSPantha]

hey Wagz. Yeah it's weird. I had the cluster out not too long ago to change bulbs and checked the flexible PCB for wear etc and it was all good. I might have to pull it apart and check the regulators etc for dry joints. I don't know anybody up here with another VS to try another cluster
What is a new sender worth to replace? And what's involved in fitting it? Easy or hard?

[hako]

Check the sender by setting your speed alert so it reads the speed and compare with the speedo when it plays up. You need to hold some of the buttons down when turning the ignition on but I'm not sure which ones.....someone else will know or do a search.

[VSPantha]

Hi Hako.
Yeah I know how to turn on the digital speedo... start engine with up & down arrows held in. It's not the constant speed issue though... it's like the needs is sticking (say at around 78km/hr)... if I accelerate a bit more, after a few seconds it'll jump up to the correct speed. I might have to open the cluster up and check to see if the needle spins freely or not.

[Vee-ard]

I have a problem with the speedo needle sticking if i've been cruising at 110 for a while, and i decelerate, it will stick on 110 till im at like 70, or I love tap the dash.

[VSPantha]

Hi V,
yeah I know if I tap the dash or go over a bump it'll jump up.. but the problem is if I don't do that (shouldn't have to constantly hit the cluster for it to read properly anyways) and forget about it, next thing I know is I'll end up getting caught by a radar or have the po po pulling me over and giving me a nice fine... so would rather try to get it fixed
I'm going to give an auto 'leccy a call and see if they can do anything about it.

[Vee-ard]

Thats not really what I was getting at, I know what you mean because I dont want to have to tap the dash to update my speed every time either. I was just sort of adding to the thread because people have said it's uncommon for the speedo needle to stick.

I'd love to fix whatever is causing mine as well, but cant be arsed pulling the entire cluster out.

[VrWagz1]

If your speed alert is reading fine,(ie not staggering its readings like the dash) then i would definatly be leaning towards the cluster itself as that shows the speed sender is working ok. It could be as simple as the needle has sagged ever so slightly and is rubbing on the cluster face or it might be some failing components in the circuit board. When you pull it appart just check its clearance. Also to get the whole needle off you have to place a folk or somthing under it and lift it off with a slight amount of pressure, then you can undo the 2 little black screws on the face and the circuit board will drop out. When you put it back on jst make sure you align it right so it sits nicley on the bump stop.