Rev counter needle bouncing a lot at idle

[daverclasper]

Hi

Couldn't find a specific section for this on forum, though as I thought it may be the dizzy drive related, I put it here.

Cant find any info on the net for mechanical clocks with this problem.

A while back my rev counter needle started to bounce intermittently a bit at idle. I took inner cable out and cleaned and lubed it with a bit of oil. Kept oil away from the top few inches near clock. cable felt like it turned freely.  No different.

Now it has started to sometimes bounce widly, to about half way around the clock.

Any suggestions please about whether I may be able to fix it myself (can't afford to send it to pro's) please.

Any help great please.

Thanks, Dave   

[Pete Lewis]

The needle twtch is generally a cable wind up and unspring flicks the magnetic disc and thenneedle takes swing same as the speedo its the same mechanism inside

Look at cable lengths , may be the inner is a bit short?

You can with some grips windnthe outer case this will grow or shrink the outer length 

Try some grease on the inner cable ??  Not lots but a good smear

Avoid sharp cable route bends 

Pete

[Colin Lindsay]

I'd suspect the cable before the unit, so replace the cable if you can or else inspect the existing one - you'll find the inner sometimes slides about and due to gravity, downwards, so may be too far out at the dizzy end with the corresponding hit and miss at the rev counter end. Take it off at the dizzy, push the inner back in a bit if possible, and reconnect.

[daverclasper]

Cheers Pete.

I guess it's hard to know what the lengths of both inners should be out of the inside of outer locking things? (what are they called?).

Would you wind the outer case clockwise to shorten?.

I can mark it to see how much it's shortening. Maybe about 3mm and see if it improves?.

Thanks, Dave 

[daverclasper]

Cheers Colin

Your message came in while replying to Pete. Will try that.

Thanks, Dave 

[Pete Lewis]

Most cables cases are a spiral wound contruction, which way to turn depends how its made 

But a carefull workmwith some  mole grips will shoe when you rotate the crimped on end fittings

You will see the inner appear to grow or shorten

 

This idea comes about as on our track the cab would follow the chassis on a hoist and if the cable end got dropped it could catch in the conveyor and get given a tug, this made the outer too long and screw it back was a solution 

Both speedo and rev counter can suffer from the needle /disc bearings failing then the disc and drive magnet can make contact , thisnwill give very erratic needle  swings .

Need to strip the insides out to see if there is wear in the  needle  spindle bearings