Here are 2 sources that may be useful. If you dismantle the arm mechanism ,check the spring attached to the arm, sometimes it comes off. Clean the piston that moves in the solenoid and all fulcrums with brake fluid cleaner. I also found that the insulation on the copper wire for the bulb was shorting out. Is affected the movement.The insulation inside the arm frame had disintegrated . I unsoldered the wire, removed the copper wire for the bulb holder, cleaned it refitted with heat shrink where it goes in the frame and put it back together and re-solder it. I can send some photos via email if you need them? Good luck.
One thing I wondered when I saw the photo was whether it is definitely a 6v one. On my phone, the wire looks thinner than on the 6v ones in my car. The coil I have (found) is 12v, so of no use to you.
Hi Nick, The parts list provided in post above shows that my model SF40F is a 6 Volt model. I guess it is still possible that some one retrofitted a 12 V coil to it. Thanks for checking out your old unit.
Cheers
Graham.
There is quite a bit of info out there on trafficators...
"The critical parameter for getting the pull of the coil right is the total ‘Amp-turns’ present in the winding. For 12v coils, there are 1000 turns with a resistance of 6 ohms, giving 2 amps – so 2000 Amp-turns. With 6v, the way to go is two coils of 500 turns in parallel. This gives half the resistance, so the same current at 6v as for 12v, namely 2 amps in both coils. The total amp-turns is therefore 2 coils x 2 amps x 500 turns = 2000 amp-turns again. The trafficator works as before, but taking 4 amps at 6v instead of 2 at 12v."
I now have the trafficator working. Thanks to Colin, Nick and Peter for your advice in helping me understand the mechanism and what should be happening.
But the breakthrough happened as a result of thinking about A7JoJo's comment that he resolved the problem by fixing the insulation on the wire that runs to the bulb. I discovered that my wire had very dodgy insulation with poor attempts by some earlier owner to fix it. I soldered a new wire from the base of the coil up to the arm pivot. This gave a stronger driving force to push the arm all the way to the end of it's travel.
The arm still would not drop, though. Finally, I found that a small misalignment of the coil was causing friction on the plunger. Nudging the coil to the side has now allowed the arm to drop freely.
So all fixed without spending a dollar.
I spent about 8 hours getting to this final solution. But the exercise to the brain has been worth it. I heartily agree with comments on other posts about the mental benefits of taking on these tasks and not being defeated by them.
The next challenge is to find the where the ends of the trafficator cables were left after an earlier owner cut them to install flashers.
Thanks all.
Graham Barker.
Thanks for the update Graham, a very satisfactory conclusion. I also replaced the bulb wiring, largely because the earth return was unreliable so I put a pair of wires in. I found that the very flexible silicone covered wire works well.
