Speedometer cable bounce part 2....what I have learned. 79Z

Discussion in 'Troubleshooting & Diagnosis' started by GPN, Jun 19, 2020.

  1. GPN

    GPN Veteran Member

    Messages:
    208
    Likes Received:
    3
    Joined:
    Oct 5, 2016
    That’s ok, I appreciate you trying to help
     
    xten likes this.
  2. steve78LT

    steve78LT Veteran Member

    Messages:
    264
    Likes Received:
    8
    Joined:
    Nov 30, 2003
    Location:
    Barre, MA, USA
    I've got a two piece speedo cable in in '78. When I did the interior over a few years ago, I installed a 150mph speedo I picked up on eBay. It bounces from 0 to about 30, and then levels out. When I first installed it, I had an awful squeel too. I was leaving for the Syracuse Nationals the next day, so I decided the best way to fix it would be to peg the needle and see if it wrung the problem out. Headded out at dusk to a seldom-travelled road with about a 50mph speed limit without any houses on it. Opened it up, got to about 70-75 before I saw the blue lights in the mirror. Rolled down the window and the cop said he heard me coming way before I blew by him. Fell on the sword and told him the truth - trying to wring a squeal out of the cable before I head off to the big car show. I guess he wasn't expecting that. He told me to drive home at the legal speed and have a good time at the car show.

    The squeal went away, but the bounce never did. Someday I'll get around to replacing the cable, but for now, I'll watch this post to see if you figure your problem out.
     
  3. GPN

    GPN Veteran Member

    Messages:
    208
    Likes Received:
    3
    Joined:
    Oct 5, 2016

    Looking at red needle until you saw the blue lights—-Now that’s a good story!
     
  4. GPN

    GPN Veteran Member

    Messages:
    208
    Likes Received:
    3
    Joined:
    Oct 5, 2016
     
  5. biker

    biker Veteran Member

    Messages:
    3,454
    Likes Received:
    1,542
    Joined:
    Dec 7, 2014
    Location:
    Canada
    Congrats! Nice to have things working as they should. Tall order with a 40 year old car.
     
  6. GPN

    GPN Veteran Member

    Messages:
    208
    Likes Received:
    3
    Joined:
    Oct 5, 2016
    Fixed--not fixed. took my Z out for first time since winter (indoor) storage. speedometer not even moving. to recap--I had speedometer completely reconditioned, and replaced cable. both helped--now nothing. What else can it be?
     
  7. Gary S

    Gary S Administrator Lifetime Gold Member

    Messages:
    23,869
    Likes Received:
    1,480
    Joined:
    Apr 14, 1999
    Location:
    Bismarck, North Dakota
    Pull the cable off the tranny and connect a variable speed drill to that end. Spin it at a slow speed and have someone watching the speedometer to see if it responds. If it does, the problem is in the speedometer gears in the tranny tailshaft.
     
  8. GPN

    GPN Veteran Member

    Messages:
    208
    Likes Received:
    3
    Joined:
    Oct 5, 2016
    I suppose that makes sense---there is nothing else I haven't replaced
     
  9. TTR230

    TTR230 Veteran Member

    Messages:
    465
    Likes Received:
    216
    Joined:
    Aug 1, 2020
    Location:
    Burlington, Ontario
    I'm not sure what the cable connection looks like at the speedo end, but I wonder if the inner cable isn't seated properly in the drive gear. I've had it happen on other vehicles. It feels like it seats and looks like seats, but it's not engaged enough. Could also be the case at the tranny end. On some applications, the inner has a ferrule that prevents it from being pushed too far into the guide on install. I don't know if this cable has it.

    As has been pointed out, pull the tranny end and spin it. If it doesn't work right, try fiddling with the inner and try to seat it?
     
  10. TTR230

    TTR230 Veteran Member

    Messages:
    465
    Likes Received:
    216
    Joined:
    Aug 1, 2020
    Location:
    Burlington, Ontario
    I think those gears are all plastic, aren't they? Probably a good chance for a point of failure.
     

Share This Page