Speedo gauge bounce at idle? - any idea's

[John 535is (Sydney)]

While stationary with the motor at idle, the speedo needle will bounce to 100Km/h and back. Is this a capacitor problem in the panel, and is there a write up on how to fix it somewhere?

John 535is

[shogun]

could be this
http://www.bmwe34.net/e34main/maintenance/electrical/speed_sensor.htm

[SRR2]

I vote for caps, mostly because it's happening while the car's not moving. I don't see how a flaky speed sensor would cause outputs when the gear it's reading isn't moving. That said, there's a lot of information on this forum about cap replacement. There's information in Bruno's site too, as well as a number of other places. Unfortunately, with a car the age of yours, there's some uncertainty about the number of caps you'll need and their values. For example, I never did find a reference that showed the same cluster I had in my car. So, you'll have to pull the cluster to be sure. The other thing you'll run into is that today's caps are smaller, with closer lead spacing, value for value than those made in the mid 80's. You can use higher value, higher voltage caps as replacements without problem. Be sure to get 105C, low ESR types. Nichicon and Panasonic are two excellent choices. You will find what you need at Digikey or Mouser. You will probably need to pull the steering wheel and drop the column to get your cluster out. Good luck.

[LMUNick]

I am so not used to having an e34 yet- its only been a few months- and its by far the youngest car I have ever owned. I was getting ready to suggest a good grease for the speedo cable. My how the times change-