Tacho removal 2.4 Coupe

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vlad
Posts: 43
Joined: Thu Jan 02, 2014 8:46 pm
Dino: Fiat Dino 2.4 Coupe

Tacho removal 2.4 Coupe

Post by vlad » Sat Jan 18, 2020 5:24 pm

Hi, what is the procedure for removing the above, the needle in mine is bouncing all over the place, and reading much higher than the actual revs.

I have been told its the damper ?

Was going to send it off for repair over the winter.

Could the symptoms be anything other than the gauge itself ?

Thanks

Fanalone
Posts: 52
Joined: Wed Jul 01, 2015 7:15 pm
Dino: Fiat Dino 2.4 Coupe

Re: Tacho removal 2.4 Coupe

Post by Fanalone » Sat Jan 18, 2020 8:06 pm

Hi Vlad

You must remove the dashboard top, which is hold by 4 screws, mounted from the underside.
Do like this:
  1. Remove LH & RH interior light on the underside og dasboard
  • Remove the 2 dashboard screws over the removed lights
  • Open glovebox, and removed the 2 screws in front og glovebox roof top
  • Loosen the door gasket on LH & RH side og dashboard
  • Start carefully dragging the dashboard top on each side towards the rear seat. Her you must be carefull, and work from side to side
BC5222

Dario
Posts: 88
Joined: Fri Nov 29, 2013 12:18 pm
Dino: Fiat Dino 2.4 Coupe

Re: Tacho removal 2.4 Coupe

Post by Dario » Sat Jan 18, 2020 8:21 pm

Hi,

Access is a bit limited, but you can also reach behind it from below and undo the two fasteners that clamp it in place. I had removed my steering column and this helped a lot. In fact, I'm not sure it can be reached otherwise, but might be worth a try. To remove the steering column, you don't need to undo the steering wheel, just the two long bolts holding the column in place. The wires come off thanks to the plugs. You do need to remove the clam shell and remove the wires from the ignition switch (make sure you take a picture to remembers where they go!). Once the column is loose, it just slides out of the shaft going through the firewall.

Concerning the tacho, you should double check the dinoplex and make sure you have the right ignition coil. The tacho is electronic, so no damper, just transistors, resistors, and capacitors. If you have access to an oscilloscope, you can check the signal going into the tacho.

fwiw, here is a picture of the insides.

good luck,

Dario
P1070237.jpg

vlad
Posts: 43
Joined: Thu Jan 02, 2014 8:46 pm
Dino: Fiat Dino 2.4 Coupe

Re: Tacho removal 2.4 Coupe

Post by vlad » Sat Jan 18, 2020 11:39 pm

Thanks for the replies, both regarding how to get at the back of the Tacho to remove and also , regarding the damping.

Yes is interesting its only post restoration that the tacho. is exhibiting the erratic needle, I wonder if there is an issue with the wiring, I can't remember if the resto. included a replacement coil - or perhaps I lost a tachometer filter in the restoration - certainly the wiring was a mess and is now a lot tidier? (I also notice that Dinoparts have a part to smooth this exact issue - presumably a tachometer filter) - could it be a part you could source from a general auto store ?

It would be great if I didn't have to take the dash (or steering column apart ) LOL

Dario
Posts: 88
Joined: Fri Nov 29, 2013 12:18 pm
Dino: Fiat Dino 2.4 Coupe

Re: Tacho removal 2.4 Coupe

Post by Dario » Mon Jan 20, 2020 8:43 pm

Mine was giving all sorts of problems and it turns out I was running the wrong coil. What ignition set-up do you have?

The tacho is driven by 12V and a pulsed signal from the dinoplex. You can reproduce it with a function generator, or even a mechanical switch driven by your drill (eg the points distributor if you don't mind taking it off). Remember that getting to the tacho is only the start: then you need to carefully remove the metal bezel and get tot he electronics. If it was working before, chances is that it is not likely the origin of your problems (yet, but can become once you start fixing it!).
good luck,
Dario

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Tobi
Site Admin
Posts: 368
Joined: Thu Nov 14, 2013 7:56 am
Dino: Fiat Dino 2.4 Coupe
Location: Upper Palatinate - Bavaria

Re: Tacho removal 2.4 Coupe

Post by Tobi » Mon Jan 20, 2020 11:10 pm

Refer to this site for the right coil and tacho repair: http://www.dinoplex.org

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