Gauges are lagging after replacement

[afatrat]

I've recently been fixing my 2000 500e after an off and have had to replace the speedo and speedo cable. I also disconnected the tach cable because I had to replace the gauge plate and surround. Now when I reconnect the tach and speedo, both gauges lag and are very slow to respond. The odometer and trip meter seem to be working fine but it takes a while for the speed needle to register as well as the tach needle. Both cables spin up when disconnected so it is obviously the connection between the cables and gauges. Anybody have any suggestions?

[Watcher]

I would have guessed bad cables if it wasn't for the fact you said they're replacements...

Obviously something is causing resistance.  Maybe drip some engine oil down through each cable and see if it gets better.  If the cable is sticky inside the jacket it'll be twisting while it is spinning and cause the lag.

[prmas]

I would have guessed bad cables if it wasn't for the fact you said they're replacements...

Obviously something is causing resistance.  Maybe drip some engine oil down through each cable and see if it gets better.  If the cable is sticky inside the jacket it'll be twisting while it is spinning and cause the lag.

New cables should be "pre-lubed" by the manufacturer. Do not add any extra oil or grease or you can create problems such as the excess oil/grease working its way up into the instrument. I have seen it happen many times.
It is very strange for the instruments to be lagging behind. Usually they do the opposite.
You state that you replaced the Speedo head but did you also replace the Tacho head?
If so, were they new or secondhand and from the same supplier?
If secondhand and from the same supplier perhaps they were stored in a poor environment and have either rusted internally or "dried out" in the needle bearings. Mechanical instruments like these can easily be damaged.

Macka

[afatrat]

The speedo is a used replacement that has about 11000 miles on it. When I first received it, I stuck the broken cable in it and spun the other end with a drill and it seemed to spin up and back down to 20 mi/hr just fine. The tach and the tach cable is the same one that has been on it as it took no damage and was working flawlessly until now. The fact that both gauges are showing the same lagging behavior yet have nothing to do with each other is what has me thinking it is the connection. Regardless of how tight or lose I connect the cables, however, there is no change. I might try lubing the cables a little just to see but they don't bind and feel smooth when I rotate them by hand. This just doesn't make any sense.

[Watcher]

The bind might be in the cluster, then.
Is it possible the "glass" is sitting tight against the needles and causing resistance?  I never had my cluster apart that far, I don't know what's possible in there.

Here's another thought.  If the mount for the cluster is bent might it be kinking the cable a bit?  If there's a tight bend in the cable it could be binding it.

[prmas]

It is very strange. It would seem to be something that is common to both head units.
Perhaps there is something in the thought that the mounting plate may be out of alignment.
The cables really cannot be binding enough to turn slowly, they would break first and it does not make sense.
They are steel cables and both ends MUST turn at the same speed.
When you span the speedo up with the drill, and then stopped, did the needle drop back to 0 quickly or slowly?
It should return quite quickly. If slowly, the problem is inside the head unit. 

Macka

[afatrat]

I just wanted to follow up on this thread in case anyone else replaces their gauges or cables and has the same problem. Apparently new cables need time to wear in so the grease gets worked to where it needs to be and the inner cable gets lubed and seated in the gauge (at least that's what I was told by two shop techs). After a pretty lengthy ride, both gauges work perfectly and I have not had any problem since.

[Watcher]

Awesome.  Thanks for the update.