speedometer needle bounce
 

Hi guys, here's the rundown on my latest problem

When I bought the car the speedometer was disconnected. I found the speedo cable chafed through. bought a brand new one, and found the speedo had a crazy wobble, over a range of about 20kph no matter what the speed.

I replaced the speedo with a second hand one, but found the same problem. I spun the back of one of the gauges with a drill, and the wobble was still there. so it's not a cable related problem. the spinning disc seems to "grab" the pointer side at one specific spot (although I cant see exactly where) so the needle pulses once for every revolution of the disc.

Is there a way to fix this? am I doomed to buy second hand speedos until I find one that works? Am I somehow killing them with the way I'm installing the cable? (it sort of hangs off the back of the speedo then bends down - should I be trying to make it straighter, and secure it like that?)

Sometimes they pick up dirt inside (it's magnetic) & careful cleaning will solve it, but if it's not spinning true on the axis then it would probably take a speedo shop to solve it.

mine bounces a little (~3-4 mph) above 70 MPH or when I pull it out of storage too early in the year and it's cold outside. It's never been enough for me to worry about but I would start with a good cleaning....possibly some electrical contact cleaner as it evaporates quickly and cleanly. That stuff has fixed multiple "annoyance" issues for me....

I'll just dig this thread up from the dead as I'm still struggling with the same problem

I've dismantled the speedo and cleared the drag cup out, but no luck.. starting to think that the shaft that the cup rests on is actually bent, so its permanently touching and getting pulled along. general consensus is "just buy another one", but I'm not too thrilled with buying a THIRD 30 year old pre-loved speedometer, especially when most sales conditions are "it was working fine when car parked up, all sales final" :/ guess I'll show up with a drill next time and spin it in person

My experience with bouncing needle was sorted by replacing the cable. With the new cable before I installed it I removed the steel inside bit and applied grease and reinserted it back into the outer.

The idea was to damp any oscillations. It worked (either the new cable or the greasing!), the speedo does bounce very occasionally very slightly bu only 1% of what it used to.

Also be careful when messing with the cup bit behind the needle. I thought I'd apply a few drops of sewing machine oil in there as my first go at fixing the bouncing. I wrecked the gauge right there, the deflection went crazy like a real 30 was indicating 100.

yeah the first thing i did was replace the cable as it was very obviously damaged.. unfortunately that didnt solve the problem. if i put something into the back of the speedo input and turn it slowly by hand, i can actually see the point at which it grabs the drag cup and drags it with it.. the interior of the cup is clean and lubed so my guess is that one or both sides of the cup are off center, and when the high points meet, the cup gets dragged physically rather than magnetically. (probably more so now that i've messed with it)

being unable to find another good FB speedo, I've had a peek at an FC one... all the numbers are in the same locations, and I know that the cable inputs are the same between them. thinking about nabbing an FC one and screwing the FB faceplate to it...