Mopar Muscle Association UK

I know the tach is not the most accurate in the world, but I'd like to get mine working anyway, so if yours is working could you stick your head under the dash and check something for me?

I have two connections on the back of the tach, a spade terminal and a stud. I've connected the coil connection to the spade terminal and put an accessory feed to the stud and promtly filled the whole place with smoke and fried the feed wire...

...so even me, Captain Dopey of the guild of the electroniocally dyslexic knows that is wrong...

I've probably fried the tach, but before I cause any more damage, can anyone help tell me what should be connected to what?

The clock still works!

Got it sorted!

First of all, there is a 12 volt feed, but it appears I had it on the wrong terminal

Secondly, as accuracy isn't gonna be worth a light now, because I've got an orange box ignition, there's a company called RT specialties that's doing a PCB for the tick tock tack that not only gets the tach working, it's accurate too.

If you are interested, check them out on www.rt-eng.com

Hey Ivor,

The tach works on mine but the tic toc doesnt. Got any ideas how the clock obtains its feed?

I havent had mine out of the dash, and wouldnt mind knowing if you discovered anything of the inner workings during your toil

Cheers
c

Clive. The clocks are electro-mechanical. By that I mean they are a mechanical device that need winding up.

They get wound up every couple of mins by a solenoid.

As the clock winds down two contacts come together. When they touch the solenoid is energised and it winds the spring up a bit. It does this every few mins but what happens is the contacts soon burn and the clock stops working.

Cleaning the contacts usually gets it working again for about a week.....

Dave's right on the money Clivey, there should be a grey wire with an insulated connector going to the clock and that's the feed.

I've done the contacts on mine and it's working perfectly...at the moment...but electrical experts on the board should be able to tyell us if we can put some sort of condenser or whatever in there to stop the points burning, because while the tach is not particularly accurate, the tick tock appears to keep good time.

Thanks Dave / Ivor.

Sounds like a nice little project one evening. If the contact tips are burning out (I saaume through arcing or possibly high continuous current flow) is it worth getting the contact tips coated in a more conductive material like gold or something (this may sound silly but may not be as silly as it sounds).

Dave, you mentioned cleaning the contacts and how that allows the clock to wind itself. Does this mean that the problem is purely as a result of oxidisationfrom the arcing then? I would love to have my clock working properly and dont mind going over and above to keep it working.


Lastly, why does the tach needle bounce around so much? Is this a needle damping issue and can that be fixed or should i just put up with it?

Year one do new ones for about $500-ish. Are these improvements to the original, or just copies?


Merci beaucoup

I have to shock my clock to get it working, either by tapping the glass or taking off the battery wire and putting it back on then it only works for a few days

The contacts burn. That is the problem. You get a spark every time they touch.

The usual remedy is to replace the movement with a modern quartz electrical version. There are places that do the conversion for you.

I did my own DIY version. However I was unable to hook up the hand adjustment knob so the only way to set the time correctly is to disconnect the battery and then re-connect it when the time happens to correspond to where the hands are...

Of course this was just a temp fix to get me by. But it has been ten years now....

The clocks are fairly simple and I really like them becuase when you gut them they look like clocks with a movement !

There are usually two things that stop them working.

1: as has been mentioned they are electo mechanical, they work using a small solonoid, when it sees power it fires and shoots the winder round, there is a spring which then assists the movement back to where it started, at the end of this is half a set of points, as it reaches the end of it's travel the points meet the other half, as this happens the solnoid activates and shoots the mech back round for another go ! simple and great to watch work!! The points rarely burn out, as Dave says they oxidize and eventually the contact is lost. To solve this part of the problem simply get a tiny piece of 1000 grit wet and dry, fold in half and rub up the points until they are shining and smooth, be very careful not to bend anything as it is a fragile piece, once you have renewed the ponts surface they should be good for a few years, this leads us to.....

2: The mechanical part, you need to think of this part as a standard clock, to check it is working manually open the points to around half the distance the solonoid would fire them, hold the clock as it would be in the car and observe, the clock should move slowly and steadily back to the points closed position without slowing as the second hand climbs towards 12 O'clock chances are it won't ! the whole movement runs on tiny brass bearings with steel pins running into them, over time ( ) the brass wears ever so slightly and the bearings start to bind and slow the ,ovement and eventually the resistance stops the second hand climbing past 6 O'clock, this is a simple fix as well! VERY carefully damp the whole movement with WD40 keep it away from the face at all costs and try and keep it of the pin that goes to the fingers, leave it a few minutes then blow the excess off and go through the manual test again, it should now be very happy and climb enthusiastically towards 12 O'clock, if not repeat.

Now apply power to the clock and check the solonoid fires and the clock runs smoothly for a few cycles the re fit to the car, job done.

Note: B body tic toc tachs can be removed from the dash by squirming under the dash and removing the wires and the three screws that hold it in place (remember to remove the adjuster knob first!)

Just had a go at the clock in the fury,it works mechanicaly but the solenoid coil is burnt out. Any fix or have I got to strip the lot and wind a new coil? Or has anyone got a clock part #2927078-18479-34455