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Bouncing 355 speedometer??

Discussion in '348/355' started by hjp, Feb 28, 2016.

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  1. hjp

    hjp Formula Junior

    Feb 23, 2013
    591
    Kansas City, Mo.
    Full Name:
    Jerry Peterson
    #1 hjp, Feb 28, 2016
    I had a bouncing speedometer at speeds below about 40. At higher speeds it acted normal and read correctly. I assumed it was the sending unit so I bought a new one and put it in. Much to my surprise I now had nothing. The speedometer didn't register at all. The other day while coming back from a drive, the speedometer briefly started to bounce again just like before. This only lasted for a few seconds and then it resumed back to nothing. Its possible this could have happened before too but I didn't notice it. Anyway, this means there is some signal, if only intermittent. This leads me to believe its not likely the sending unit which is reinforced by the fact that I'm told new ones have been extremely reliable.

    That leaves the connection plug itself, a broken wire or possibly the speedometer itself.

    Does anyone have any insight here? I'm not sure how to check this.
     
  2. mshobe

    mshobe Karting

    Mar 28, 2015
    112
    Seattle-ish
    #2 mshobe, Feb 29, 2016
    Love to see any additional insight here. My '95 features speedo oscillation primarily around 60-75mph –*a different range than you're experiencing. Can't find anything in the service history that points to replacement of any component in the chain, so I'm assuming my gear is factory original.
     
  3. Beetle

    Beetle Formula Junior

    Apr 10, 2013
    776
    #3 Beetle, Feb 29, 2016
    My 96 GTS does this from time to time after sitting at a constant 100Klm Hr for a period of time and the odd low speed occasion
     
  4. John_K_348

    John_K_348 F1 Rookie

    Sep 20, 2013
    2,757
    Boston, MA
    Full Name:
    John E. Kenney
    #4 John_K_348, Feb 29, 2016
    Hmm. I just had my 348 sender replaced. Working fine and I do a lot of city driving. I made a small blanket patch out of header tape and fireproof aluminum tape and hung it, wrapped it over the header side of the unit. The cable junction is at an awkward 180' s bend since the plastic cable armor and sender lead are too long to join directly. I hope this doesn't stress the wires any more over time either. I have seen a thread here on a failed speedo in the cluster. Not an easy fix. Good luck.
     

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