Speedo spinning wildly

[d9103365]

I know there have been a few posts on this issue before, but they didn't quite answer my question...I'm trying to nail down whether the problem lies in the speedometer gears, the cable, or the speedo itself. Here are the symptoms:

1. speedometer spins wildly while driving, once it a while it will stablelize for short periods, but event then it registers about 10mph faster than true speed.
2. the odometer doesn't work at all.
3. The speedo makes a dinging sound like a little bell as the needle moves from side to side.
4. My cruise control works perfectly..don't ask me how!
5. I had a bad transmission leak recently, and the shop told me it was the seal around where the speedo plugged into the transmission. They replaced the seal for a small fee and that stopped the leak. They didn't say anything about my speedo problem.

So based on all of this info, what should be replaced? I'm thinking that I may need to replace the speedometer itself because of the pinging sound and the frozen odometer, but I wanted to make sure before i drop $100+ on a NOS speedo. My understanding is that the speedometer cabling goes thru the cruise control to the transmission....if my cruise is working ok, then the problem seems like it would be between the cruise and speedo...not down at the trans...however i did have a leak there recently...so I just don't know. I appreciate any advice. My car is a 1977 Chrysler Cordoba.

 

[smyythe68]

Sounds like you might have a bad needle bushing that's causing the shaft inside the speedo to not remain centered. The speedo needle is magnetically connected to the cable insde a small metal cup. If the bushing is bad, it can catch and slip causing the needle to jump and drop. This would also explain the dinging sound. The cruise control, I belive, is a sensor in the actual cable coming from the transmission so as lond as the cable is spinning the computer can match that speed. The seal problem should not be a problem because the cruise works so the cable is spinning. I would definately look towards the speedo itself. Or the cable coming from the cruise sensor, but because of the sound you are hearing I suspect the speedo. If you remove the speedo, try spinning the inner cable that goes back into the dash. Not to much, you should get some deflection but you should not be able to spin it around freely. Hope this helps.

 

[SUPERSTOCKRACER]

what year car?
put some graphite inside the cable.