Wobbly needle on tach

[priya]

I was looking at my instrument cluster today and noticed the tach needle was to the right of the zero mark and the pointy end almost touching the face.  I removed it and the needle is wobbly, its still attached to the shaft that goes through the face but the shaft itself tilts back and forth.  I can't see how it comes apart or why the shaft is wobbly, anyone know a fix for this?

[shanebo]

I hope someone has an answer because mine just did that too.

[eagleman]

I have a cluster that I was going to install but didn't because my needle on the tack does the same thing.So in fear of it not working I didn't install it and just put it away for later.Interesting huh?

[rohnk]

Well okay, but do they work with a wobby needle? If I could get my hands on one I'd try taking it apart and seeing what is going on. The problem is that they seem so rare that nobody wants to let go of one even if they think it is broken.

Has anyone tried pulling one apart? There must be a way. May have to grind off a tab or rivet but there should be a way to open one up.

[priya]

I suspect it may move the needle with engine speed but even if it does it wouldn't be accurate as the needle will also move freely between about 1000 rpm and -1000 rpm.  My husband had a quick look at mine but couldn't tell what was wrong.  I see the face has two screws holding it on, at some point I might just grab the needle and pull and see if it comes off as the tach is useless as it sits now anyway.

[Whuntmore]

I've pulled the bloody thing apart.  there's a small circuit board on the back, and I tried testing some of the electronic items (I don't have a cap tester though) and none were bad.

I honestly think it has to do with the needle.  Maybe the mechanics with the needle are inferior, and just break.

if a cap or resistor on the back of the board died, that shouldn't cause the needle to 'over-swing', or to 'come loose' it would just stop allowing electricity to stop flowing.   Then you could replace the 'resistor' (or whatever) and then it should pretty much work again.

That's not happening here.  Something faulty in the needle mechanism - or is weak

[rohnk]

Does anyone have pics of the inside of one of these things?

I'm not trying to beat a dead horse here, just trying to understand why these go bad and maybe find a solution.

[priya]

I've pulled the bloody thing apart.  there's a small circuit board on the back, and I tried testing some of the electronic items (I don't have a cap tester though) and none were bad.

I honestly think it has to do with the needle.  Maybe the mechanics with the needle are inferior, and just break.

if a cap or resistor on the back of the board died, that shouldn't cause the needle to 'over-swing', or to 'come loose' it would just stop allowing electricity to stop flowing.   Then you could replace the 'resistor' (or whatever) and then it should pretty much work again.

That's not happening here.  Something faulty in the needle mechanism - or is weak

Does the needle just pull off of the shaft?

[Whuntmore]

No, the needle is really hard to pull off.  I've tried.  You pretty much have to break it to get the face plate off.  The back is easier.

Here's a pic of the picture I had posted last year:




I don't think I took pics of it pulled apart.  But that tach was pretty much gutted.

[priya]

It never occurred to me to go at it from the back, thanks.

[Whuntmore]

Oh yeah, HUGELY easier to pull it apart from the back, then the front.  

I should get another one, and do a video on taking it apart.  Actually quite easy.

[AMCKen]

In my experience it seems the needle and it's pivot break loose from the armature inside the tach. A dab of crazyglue MIGHT fix it but it's hard to get it in the right spot.

[priya]

In my experience it seems the needle and it's pivot break loose from the armature inside the tach. A dab of crazyglue MIGHT fix it but it's hard to get it in the right spot.

Thanks a lot Ken.  I'm not sure what an armature and pivot are but maybe my husband can explain it to me and if I can get it apart from the back maybe I can fix it.

[T5258]

15+ years & I STILL haven't had one that functioned for more than a week....

[AMCKen]

In my experience it seems the needle and it's pivot break loose from the armature inside the tach. A dab of crazyglue MIGHT fix it but it's hard to get it in the right spot.

Thanks a lot Ken.  I'm not sure what an armature and pivot are but maybe my husband can explain it to me and if I can get it apart from the back maybe I can fix it.

I was thinking pictures would explain better - I'll see if I can get one/some.