speedometer problems

Discussion in 'General IH Tech' started by pnwscout, Oct 17, 2016.


  1. pnwscout

    pnwscout Farmall Cub

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    Hi y'all
    I'm having problems with my speedometer and odometer on my 79 SII, the gage keeps ticking and bouncing on the speedo part and the odometer is way off I drove about 14 or 15 miles and it only went up about 1.2 miles. I had pulled off the cable when I took of my trans to replaced my clutch and greased it then and looked at the attachment point and it looked fine. Where should I look next? In the speedo or the transfer case. Any help is great.
    Andrew
     
  2. 3GunFlyer

    3GunFlyer Farmall Cub

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    Following. Having the same issue with my speedo bouncing, but my odo looks to be ok.
     
  3. pnwscout

    pnwscout Farmall Cub

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    Does it tick? If not It just might be old and the dampener in side that helps with smooth operation is wore out.
     
  4. 3GunFlyer

    3GunFlyer Farmall Cub

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    I don't mean to hijack your thread, PNW...but no ticking.
     
  5. gyrfalcon

    gyrfalcon Farmall Cub

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  6. pnwscout

    pnwscout Farmall Cub

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  7. Scott L

    Scott L High Wheeler

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    Have you tried disconnecting each end and reattaching? Possible to get either one or both cross threaded to where the actual cable is not getting fully seated in the speedometer or in the speedometer drive gear.
     
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  8. Bob BMW

    Bob BMW Binder Driver

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    Sounds to me like the problem is inside your speedometer / odometer head assembly. Before you start replacing things though. Disconnect the cable at the back of the speedometer and position it so that you can see it while driving. The inner cable should rotate smoothly as you are driving. If it does then the cable assembly and transfer case are not the problem.

    Now the speedometer assembly. The cable drives two things in the assembly. One is a magnetic disc that is magnetically coupled to another disc that is attached to the speed indicating pointer. As the cable rotates the magnetic coupling causes the pointer to move and indicate your speed. The faster the cable / disc rotates the higher speed the pointer will indicate. The second thing is a gear that drives the odometer. This gear mechanically couples the cable to the odometer gears not like the pointer which is only magnetically coupled to the pointer. As these gears turn your miles driven are increased.

    What is wrong inside your speedometer head is the odometer gears are binding / not turning easily causing the gear teeth to jump over each other and there could actually be gear teeth broken off too. This binding / jumping causes the cable to not turn smoothly which is indicated by the needle jumping and low / inaccurate miles indicated on the odometer.

    If you feel brave and competent you can take the speedometer head apart to see what is wrong and if it is fixable. Otherwise try to find a replacement or a shop that can repair yours.

    Good luck and do let us know how it turns out.

    Bob
     
  9. Adriaan

    Adriaan Farmall Cub

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    I've got the same thing going on with my speedometer. I also have a 79 SII, but I have cruise control on mine. This means I have a gizmo thingie between the transfer case and the speedometer and 2 cables (tc to gizmo and gizmo to speedometer). I have not been able to fix it.
    I have used a cordless drill to spin the cable. That's what you can try to see if your inner cable spins freely.
     
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  10. Bob BMW

    Bob BMW Binder Driver

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    Adriann, when spinning the cable with the drill motor, does your speedometer work correctly? Or does it still jump around and not indicate miles correctly?
     
  11. Adriaan

    Adriaan Farmall Cub

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    Hi Bob, With using the drill, the speedometer moves without bouncing or jumping back and forth. Ofcourse it doesn't read miles correctly because that's why there is a reducer gear between the TC and speedo cable to, basically, translate the rev's of the driveshaft to the speedometer. Like I said I haven't fix my problem yet, I only tested the speedometer with the shorter cable coming from the cruise controle module so far.
     
  12. Bob BMW

    Bob BMW Binder Driver

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    OK. Sounds like your speedometer assembly is not the problem. Next step would be to drive the complete two cables / speed reducer thingie by disconnecting the cable from your transfer case and driving it with the drill motor. Two people needed. One to lay under the vehicle to run the drill and one to observe the speedometer.

    If you observe jumping in this situation, then try lubricating the cables and speed changer thingie.

    Bob
     
  13. pnwscout

    pnwscout Farmall Cub

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    Well it turns out my speedo is the problem I disconnected both ends and the cable ran smoothly with a drill gun but when I reconnected the cable back to the speedo I was having the same problem so I"m going to do the bad thing and assume I have to replace it. found this sweet looking dash and new gages on Scoutparts, they also have NOS for anyone wanting to do a restore. hope anyone who has the same problem can fix theirs too. Thanks for all y'all advice

    https://scoutparts.com/products/?view=product&product_id=13689

    https://scoutparts.com/products/?view=product&product_id=19507
     
  14. lady355

    lady355 Farmall Cub

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    My speedometer was bouncing around until it reached about 30 mph, then it would smooth out.... until last week....I heard a pssssssfffff.... sounded like vacuum tube releasing air (sorry, I'm NOT a mechanic!lol)... Then, no movement with the speedometer and no cruise...... My Scout is also a '79 ... What do you guys think it is? And will it be an expensive monster to fix? Thanks for any help!
     
  15. jtorre4272

    jtorre4272 High Wheeler

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    yikes!!!

    Beware of Scoutparts.com.

    If you take their prices, cut in half, then take the square root, that's usually the fair price others are offering for the same stuff. Plenty of private individuals and good vendors such as this site's sponsors who can help you out. (Coonrod is my best kept secret). I also like Rob at SSS. Usually comes through with good stuff for me when I need it.
     
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