Anyone fix reproduction tach?

Discussion in 'Sparky's corner' started by tubecatgs, Jan 9, 2020.

  1. tubecatgs

    tubecatgs Finally a 4 speed......

    I bought a Parts Place dash tachometer about 5 years ago for my 72 Skylark. Ever since i got it, when starting the car it would always max when cranking the engine but would perform well once engine started. Over this last season it got temperamental.... it would sometimes work or not or get stuck at at certain rpms.... now it just doesn't do anything.

    I haven't traced the wires yet but if it's the tach, does anyone fix these or am i stuck buying another one?

    I think i saw years ago there was a green wire i was suppose to snip for the tach and believe i did that but if someone can refresh me on that as well it would be appreciated.

    Thanks
     
  2. flh73

    flh73 Gold Level Contributor

    Not sure but i think mine is an older after market unit. wasn't working, took it apart and fixed loose solder joints. Pulled old solder and applied new, all is working. If your patient and have some soldering skills it's not that hard. Good luck.

    Gary
     
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  3. Golden Oldie 65

    Golden Oldie 65 Well-Known Member

    Red line Gauge and Clock Repair
    John Dvorski
    469 Windy City Rd.
    Humboldt, TN 38343
    Ph: 731-571-0766

    John has repaired a number of original and aftermarket tachs and clocks for us over the years. Nice guy and usually a pretty quick turnaround.
     
    Last edited: Jan 10, 2020
    tubecatgs likes this.
  4. tubecatgs

    tubecatgs Finally a 4 speed......

    Thanks guys...... just hate taking the dash apart so have been delaying getting to it.......
     
  5. flh73

    flh73 Gold Level Contributor

    Pulling dash is pretty easy. The hard part is pulling cluster forward enough to get tach removed. It really wasn't that bad though. Couple hours and its back together and working again, hopefully. Good luck.
     
  6. tubecatgs

    tubecatgs Finally a 4 speed......

    Yeah, i've done it a 30 times before on these cars.... i usually drop the column a bit which helps. Tbanks
     
  7. sriley531

    sriley531 Excommunicado

    I'll be interested to hear how the repair turns out. I have not one but 2 repro buick dash tachs that don't read accurately. Would love to get them repaired and sell them to recoup some funds. But the repair may make that cost prohibitive. As of now they're shelf fodder....
     
  8. BYoung

    BYoung Stage me

    I drop the column completely. Much easier access to the back of the cluster that way. I also place a towel over the column so that when I manipulate the cluster I don’t scratch the column.
     
    Brett Slater likes this.
  9. CJay

    CJay Supercar owner Staff Member

    You can try sneaking it out thru the radio opening
     
  10. BYoung

    BYoung Stage me

    And if you drop the column, don’t forget to first unscrew the small hook for the shift indicator on floor shift cars.
     
  11. tubecatgs

    tubecatgs Finally a 4 speed......

    Made that mistake once haha.... this car is a 4 speed though. Thanks!
     
  12. 87GN_70GS

    87GN_70GS Well-Known Member

    I repair them, have done a few repro techs for customers
     
  13. basherbob

    basherbob Active Member

    Hi Scott. Looking for some assistance with the 71 OEM Dash Tach. This has been going on for a few years and just need to resolve it. At 800 RPM the tach reads close enough, at 2000 it reads 1200 and at 3000 it reads about 1800, I believe at 5000 its reading around 3000. For S&Gs I checked the voltage off the coil wire and it read 7.5 -11.5 volts in the same ranges. I am using a Pertronix module and a Flame thrower coil.
    Does this sound like something you can help me with? And if so where are you located and how long to get fixed?
    Bob....
     
  14. 87GN_70GS

    87GN_70GS Well-Known Member

    Bob, yes I can, if it's a tach issue. Unfortunately, I have had some tachs on the work bench and there was nothing wrong with them other than the aftermarket ignition they were attached to. Pertronix has been a habitual offender unfortunately. I can look at it no charge, other than shipping costs. If you could test it locally on a known good points ignition, that would save you time and money.
     
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  15. basherbob

    basherbob Active Member

    Thanks you Scott, I can easily do that. BUT since I was using an RPM tester off the same wire to do the comparison wouldn't that rule out the Pertronix impact?
     
  16. tubecatgs

    tubecatgs Finally a 4 speed......

    Hmmm... i have a pentatonic system... my tach worked for years and now doesn't but every once in a bmue moon it will... when it does work,.when I am cranking the engine on a cold start the tack goes up all the way and fluctuates ba k and forth a bit but when car starts it was fine (but again only when it does work).....

    What is the pentronix tach problem you reference? Thanks
     
  17. basherbob

    basherbob Active Member

    At 800 RPM the tach reads close enough, at 2000 it reads 1200 and at 3000 it reads about 1800, I believe at 5000 its reading around 3000.
    Also your tag line of finally a 4 speed, did you buy it that way or convert it?
    You're welcome.
     
  18. 87GN_70GS

    87GN_70GS Well-Known Member

    Not necessarily. The issue with pertronix is that some ignitions or modules are multi spark. Our original tachs will not read right in that case. Your rpm tester, depending on how sophisticated and modern it is may read correctly because it may have smarts built into it that can accommodate multi spark
     
  19. Gary Bohannon

    Gary Bohannon Well-Known Member

    My 67 GS has a Pertronix 3 distributor with multifire and rev limiter. My tachometer is from a 1963 wildcat.
    I mounted it on my dash and love it. Works good, same it did with the stock points distributor.
    However, sometimes it will hang at about 2000 rpm and I have to slap it to get it moving.
    So.
    Who do you recoment to upgrade and calibrate the needle movemement?
     
    Last edited: Dec 26, 2020
  20. 87GN_70GS

    87GN_70GS Well-Known Member

    You have debris inside the meter movement (actually, inside the magnet gap near the coil). Very common issue, i end up cleaning 99% of the tachs i rebuild anyway.
     

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