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  • Electrical: Tachometer

    Hi All,
    63 Hawk, 289, with electronic ignition. Dave T unit with Mallory E-spark 6100m sender. Anyway, module decided to fry itself, so as a long term fix I purchased the replacement module, ballast resistor, and a Mallory 29351 in-line Active power filter. So... rewired ,.installed, turn key, started up straight away. Vroom Vroom, very happy.

    However, I now have no tacho, and it was working fine before. Curses!! Have not touched anything under the dash, and am assuming there is a wire somewhere that I have lost that needs to go to the coil from the sender unit.

    So, some questions. Is there a wiring diagram anywhere for the tacho (having looked throughmy manual and unable to locate) ?? Where is the sender unit, and what does it look like? When I find it, what color wire needs to go to the coil? Which side of the coil?
    Many thanks. Quentin.

  • #2
    Quentin, there is no tacho wiring diagram in the shop manual. But the correct wiring connections have been recorded and noted.

    Australian assembled 1963 GT Hawks had the tacho sender mounted in two possible locations; either on the engine side of the firewall between the wiper motor and RH bonnet hinge, or under the dash on one of the diagonal support braces.

    If it's an original sender it will look like a rectangular block about 4" long, has a natural metal skin, held on with 2 screws, and will have a ceramic surface underneath.

    Chris.

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    • #3
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      Bill L.
      1962 GT Hawk

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      • #4
        The Hawk tachometer wiring diagram is in Service Bulletin No. 366, page 8.

        Comment


        • #5
          Hi Quentin,

          My original tachometer set up stopped working also with the Mallory Unilite distributor upgrade. I had my tachometer upgraded to modern electronic internals, which bypasses the need for the tachometer sender etc. and also comes with a guaranteed level of accuracy. My tachometer would supposedly now work on any V8 with or without electronic distributor, and certainly now works perfectly in my Hawk. My one concern for you would be that you may have the Australian style tachometer, and I am unsure if the modern electronic conversions would work suitably with the unusual needle sweep of an Australian tachometer. Otherwise I would strongly recommend converting your tachometer to modern internals.

          Wayne.
          sigpic

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          • #6
            The Australian style Tacho was a VDO unit only used on 1962 models. Quentins car should have a Stewart-Warner unit like all US built GT'S.

            Chris.

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            • #7
              Originally posted by waynedavey62 View Post
              I would strongly recommend converting your tachometer to modern internals.
              Check your PM's

              thx
              64 GT Hawk (K7)
              1970 Avanti (R3)

              Comment


              • #8
                Originally posted by waynedavey62 View Post
                Hi Quentin,

                My original tachometer set up stopped working also with the Mallory Unilite distributor upgrade.

                Wayne.
                Initially I had no issues, had electronic ignition AND a tacho. However, one day I attempted to start the vehicle after about 2 weeks of non-use, and nothing. Now I have updated the electronic ignition on advice from the vendor with a ballast resistor. I have also included a Mallory 29351 power surge protector as well. Vehicle starts easily, but not quite as easily as first time around, and now have no tacho. I am wondering if the initial issue that fried the Mallory module also fried the tacho sender unit? Is this possible? There are many contributions on tachos on Bobs website, with one stating that I should remove the pink resistor wire now that I have a ballast resistor? However, given the 2.85amp difference between 1.8 ohms resistance (ballast alone) and 3.8 ohm (ballast + pinky), does the tacho sender unit require a certain amperage to function? http://www.rapidtables.com/calc/elec...calculator.htm
                Pink resistor wire - 12 volts /2 ohms = 6amperes. Wire + ballast - 12v/3.8ohm = 3.15 amperes. I could bypass the ballast resistor and see if I miraculously have a tacho again, but am afraid of a "refried Module" (a dish known to the English as "bubble and squeak") if I do. Ditto I could bypass the 29351 power surge module. Is there anyone with auto electrickery experience who could explain "tacho operation for dummies", and preferably how to test the tacho sender (before I lash out 70 bucks for a new one). ??
                PS - tacho is normal Stewart Warner type.

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                • #9
                  Originally posted by 64V-K7 View Post
                  Check your PM's

                  thx
                  Nuffink on my PM's, Bob.

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                  • #10
                    The required information to solve this problem exists. But..........

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                    • #11
                      an article on Bob's site is informative for those with electronic ignition and 63 -64 pink wire (reader target group size of at least one!), under Tachometers and entitled " Studebaker and Avanti Pertonix/Tachometer Installation with pertonix high voltage coil" (author unknown). http://www.studebaker-info.org/tech/tach/tachpert.html
                      According to the article, Pink wire removal and substitution with normal wire may solve the issue, given that the tacho sender is a " current pulse" type instead of a voltage trigger like most normal tachs. So having in effect 2 ballast resistors in series may limit the current pulse to the extent it no longer has enough grunt to drive the gauge needle. I will try this.
                      Another solution according to the original Vendor of my electronic distributor, is to substitute the tach sender with the Avanti version at $70, which works just fine with electronic ignition. He also said that it is highly unlikely to have fried my sender when the module blew its innards

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                      • #12
                        I installed a used factory tachometer in my 1962 GT Hawk. It came without the "pink resistance wire" but I was told that any wire would do. I tried a piece of wire of unknown gage but the tach wouldn't go beyond 1200 rpm or so. I substituted a smaller gage wire with more resistance and the rpm reading onn the tach went up -- but still not high enough. I'm strictly guessing that the tach needs more resistance from the junction block to the coil but I could be wrong.

                        I tried Bob Johnstone's article on this site, "Bob's Studebaker Resource Website 2016," but it didn't help my situation. I'm not installing a Pertonix systm. I have a stock coil without an external ballast resistor.

                        Does anyone on the Forum happen to know what the actual resistance is for a factory pink thermistor wire before I take the tach apart to see if there's anythig wrong with it? I'd like to install a wire and resistor with the actual factory pink wire ohmage before I go any further.

                        Thanks.

                        Bill L.
                        Bill L.
                        1962 GT Hawk

                        Comment


                        • #13
                          Originally posted by 56GH View Post
                          Does anyone on the Forum happen to know what the actual resistance is for a factory pink thermistor wire before I take the tach apart to see if there's anythig wrong with it? I'd like to install a wire and resistor with the actual factory pink wire ohmage before I go any further.
                          Thanks.
                          Bill L.
                          Hi Bill, I believe the pink wire is 2 ohms, and has to run a certain length? Others may assist with this.
                          To test your tacho, run 2 wires with alligator clips up behind the dash to the two tacho terminals, and connect a 1.5 volt battery. Tacho needle should swing around in a leisurely fashion. For 62, either you have a pink wire or you need a ballast resistor on your coil - Sounds like things changed halfway through the model year - ."Prior to 1962, the factory used an External resistor near the coil for the ignition to function properly. During 1962 and later, factory wiring changed to a 16 gauge Pink thermistor wire from the ignition switch to the coil,"

                          Anyway, as per my original posting, in terms of my issues with electronic ignition and no tacho, this was apparently caused by pink wire plus ballast resistor in series. Following the article on Bobs site, having now removed the pink wire and substituted standard cable, I have a tacho again. Hooray ! However, accurate at idle, but now not very accurate at revs, but working in a fashion. Have the standard non R series sender - I note a small "plug" on the opposite side to the 6 cylinder/8 cylinder terminals - does this hide an adjuster ? are these senders adjustable to again make my tacho accurate as before? Any assistance greatly appreciated. Quentin

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                          • #14
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ID:	1707089Quentin:

                            Your information has been the most helpful so far. Thank you. Armed with it, I examined my wiring a little closer.

                            1. I took a 1.2V AA battery and put two wire leads on the tach terminals. Sure enough, the tach went up over 3,000 rpm! So nothing is wrong with the tach.

                            2. I was not aware that the pink thermistor wire was fitted by Studebaker later in the 1962 production run. My car is a late-April 1962 assembled car (62V37103) and has a one-wire alternator installed and no ballast resistor. I assumed that somewhere in its history a previous owner installed the alternator because the threee-wire cable assembly for a generator is still in the car and all the under-hood pictures I've seen of 1962 GTs showed generators. But having no history on the car, I can only guess.

                            3. Examining the coil, I found that there are two wires on the positive terminal: one green and the other pink. I didn't think that this might be the pink wire shown in the tachometer wiring diagrams since mine goes to the ignition switch and the car will not start with it disconnected. I assumed that since tachometers were an S-P option, there was a separate pink wire from the positive side of the coil to the tachometer junction block. Otherwise, why would all C-K wiring harnesses be fitted with an extra pink wire to a tachometer if one was not installed? I assumed that if you ordered a tachometer to be installed after the purchase of the car, a pink wire would be included in the tach installation kit.

                            4. If my pink thermistor wire goes from the positive side of the coil to the ignition switch as in the quotation you gave, and the car won't start without it, then how does it connect to the junction block by itself to the green tach wire as shown in the wiring diagrams? Do you install a jumper wire from the pink wire in the ignition switch to the tach junction block? I'm confused!!

                            At least I know that nothing is amiss with the tachometer itself, but I don't understood the wiring.

                            Bill L.
                            Bill L.
                            1962 GT Hawk

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                            • #15
                              As I am sure many people have tampered with the wiring on my car in its lifetime, I cannot vouch for my wiring being factory. Also, it is an Australian Hawk, and some of our stuff is a little odd in comparison to US vehicles.

                              My pink wire runs from the ignition post labelled "IGN" and connects with the GREEN wire that runs from the starter relay. These two wires then join up with one of the wires from the Tacho sender unit.(Sensibly, Oz Hawks have the sender unit mounted on the firewall in the engine bay, right hand side. Very convenient.) Unfortunately I cannot tell you what colour wire it is from the tacho unit, as the fabric covering has long since faded away. Anyway ANOTHER wire from the sender unit then goes to the coil.
                              So, in summary, 5 wires from the sender unit. Black One is to earth. Two skinny wires go to the gauge itself. Then One joins with the green and the Pink. The last one goes to the coil. I stress that this is on my car, and while it functions fine, may not strictly be correct. While it works I am not going to worry.Hope this helps.

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