MTFCA Forum

My 14 has the coil box inside obviously and it has a clatter that can be heard when driving.
I had issues with the first set so swapped out 4 from one of my other T's while waiting on some rebuilt units, ran lovely but clatter still there.
I have just installed 4 rebuilt coils and clatter is still there but I noticed when I start the car on Batt (6v) no clatter but when I switch the Mag the clatter starts.
So that the same with 3 different sets of coils.
I have recharged my Mag and it is putting out about 10v at idle and about 30v when driving. Do you think the increase in output is the reason for the clatter?

Nothing is wrong. What you hear is normal.

Thanks Adam.
I dont hear clatter driving my 23 Hack however the 14 has a lovely quiet balanced motor, maybe that's why its noticeable.

Does the clatter change when you are pulling or hill climbing , or while going along at a steady speed, or while gradually slowing down? If so, you might have a connecting rod knock Another thing is does the position of the spark lever affect the clatter? It sounds to me like it is related to timing. The spark will advance more while on magneto than when on battery because the timing of the spark on battery occurs at the instance the rotor makes contact with the segment in the timer, however it is depending on the sine wave of the AC produced by the magneto. So try retarding the spark lever to the next more retarded position and see what happens.
Norm

That noise is each coil firing. Idle way down & you can hear each coil alternating firing.
That tune is a good reason to not run a dizzy.
"It aint a steak without the sizzle."

Clatter is a term I have never heard to describe coils doing their things inside the box! They are sometimes called Buzz coils, hence the buzzing you hear, which is very normal. A well tuned set of coils functioning is Model T music to me and one of the unique things about owning a T. When that noise stops is when you need to worry.

No its not the rods, it coming from the coil box and its not the normal buzz its a metallic chatter.
The sound doesn't change when I adjust the timing or when hill climbing etc its a constant noise. On that subject these new coils are so much better on a steep hill, the previous rebuilt coils I just removed (from my 23 Depot Hack) had the car running smooth and even but the rebuilt set that arrived on Thursday has a marked increase in power when under strain on a steep hill.
Ive never had this clatter in any of my other T's, some of which have the coil box on the engine but you would still hear it when the bonnet is open while engine is running.
Remember this clatter starts as soon as I switch from Batt to Mag when idling in the garage. However I dont think the clatter goes away when driving if I switch back to Batt but I'll try that today and post result.
Thanks for your feedback guys

Your noise sounds normal. 45 years ago I was concerned about this noise and thought it was from loose magnets. An old timer said it's not the magnets, it's the coils. Typically they make noise when running on magneto.

Your engine probably runs better on mag than on battery.
I would be more concerned if there was no clatter.

Art Mirtes

Is your coil box securely mounted to the firewall? Looseness could cause noise.

Coil box is mounted firm. I pressed my ear to the coil box when idling and that where the noise is coming from.
I just completed a road test and at 30 mph the chatter disappears when switched to Batt then starts again when back on Mag.
Art I think you are correct. Yes the revs go up on Mag, I believe its just a result of my Mag recharge being so successful.
Here is a link -

https://www.youtube.com/watch?v=k2g7YG9j6As

Kevin... Believe what you think, I agree with the others that the coil sound is normal. Each coil will have its own distinctive sound when firing, does not indicate same firing timing.

And Heinze coils are a lot quieter!

Considering the sound was produced from 12 different coils its just what this car does.
None of my other T's have ever done it but this car does.
Interesting.
It drives lovely so I will just ignore it.
Thanks for all your feedback guys

Rather than buzzing like they do on battery, the coils' vibrating spring will each make a distinct metallic *click* when running on magneto because of the pulsing nature of the alternating current. The top of the coil box is exposed on a '14 (not under a cowl), making coil noises easier to hear through the tin lid. Wood boxes in earlier cars muffle the sound better.

Thanks Dan, that makes sense

Just a thought.....
Could 2 coils be grounding out at the same time so that instead of making a tick-tick-tick-tick sound its making a tick-tock-tick-tock-tick-tock-tick-tock sound. Not all coils make the same sound when buzzing, especially if they have not been set by an expert.

I've had worse electrical shorts than this! Commutator wires with insulation wires worn off and rubbing on the block or other grounded part would could a double tick-tock-tick-tock-tick-tock-tick-tock

By definition, if it's clatter, it is not the coils buzzing. If it is the coils buzzing, it is not clatter.
Allan from down under.

I have a 1914 Touring and sometimes my coils clatter. If you take the top off the coil box you can hear it very clearly and can tell which coils are clattering. The sound changed as I changed the timing and/or the RPM of the engine and it only happens once in a while and it did not seem to impact the performance of the engine.
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The important thing to be aware of is that sometimes when you are going down a long shallow hill with the timing advanced and light throttle you may hear a clatter sound. That is not your coils, that is a rod bearing. It is telling you that you need to drop the pan and tighten things up to stop the knocking. Dropping the pan and tightening the bearings seemed a little scary at first, but it was not that bad.
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Good luck.
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That's the sound I love most about my T's. I miss it on my '27 where the coil box is under the hood!