Ignition Switch

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mbowen
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First Name: Miles
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Ignition Switch

Post by mbowen » Tue Sep 14, 2021 3:24 pm

Newbie here, both to Model T’s and to these forums, and this is my first post. I’ve successfully used the search function for several other issues, but I haven’t been successful in finding much on repairing the ignition switch.

I’ve had my 1925 Express Wagon for a couple of months now, and the engine runs fine on battery, but won’t run on magneto. The magneto is producing an AC voltage; the problem seems to be that there is no continuity from the magneto wire (red) to the coil wire (blue/yellow) on the ignition switch when it’s in the MAG position. Is repairing this switch something that someone with average mechanical skills and decent electrical skills can do without destroying it (I successfully repaired my ammeter), or should I send it to an expert? I lean a little toward being an originalist, so I want to save the new repro option for last.
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Miles
1924 Touring “Bonnie”
1925 Express Wagon “Clyde”

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John.Zibell
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Re: Ignition Switch

Post by John.Zibell » Tue Sep 14, 2021 3:29 pm

A switch with tabs I would sent to Ben Martin. Call him as he doesn't do e-mail. 770-938-3376
1926 Tudor


John kuehn
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Re: Ignition Switch

Post by John kuehn » Tue Sep 14, 2021 4:29 pm

Looks like your switch hasn’t been apart in a while. They aren’t hard to repair but if you haven’t had one apart send it to Ben Martin. If you have another switch like the one you have you can carefully pry back the tabs and the switch back will come off and you can see how they work. Another style that’s used a lot is the twist in type that’s identical other than the way it attaches to the back of the switch. Those two styles are the most common to the 17-25 T’s.
As time goes on with you T you’ll learn to fix as much as you can yourself. The switch is one of them.
Hopefully your mag switch issue is in the switch. If it turns out it still won’t work on Mag it could be it’s the top contact post where the issue is.
Good luck

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jsaylor
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Re: Ignition Switch

Post by jsaylor » Tue Sep 14, 2021 6:30 pm

Before opening up the switch I would suggest using an ohm meter to check it. When you turn it to MAG, is there continuity from the Mag terminal to the coil terminal.

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mbowen
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Re: Ignition Switch

Post by mbowen » Tue Sep 14, 2021 6:33 pm

Thanks John. This being my first foray into the model T world, I don’t have any spare switches to experiment on. I just today opened up my ammeter and repaired an open circuit (no continuity from one terminal post to the “horseshoe” so I bridged both posts to the “horseshoe” with solder. Seems to work now.)

The ignition/light switch seems a lot more complex than the ammeter, and I didn’t want to do any permanent damage. I think I’ll rig a store-bought switch to see if the magneto has any other issues. If not I’ll send the switch off to Ben for rebuild. If the mag also has other issues not easily repaired, I’ll just run it on the battery.
Miles
1924 Touring “Bonnie”
1925 Express Wagon “Clyde”

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TRDxB2
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Re: Ignition Switch

Post by TRDxB2 » Tue Sep 14, 2021 8:44 pm

Model T ignition switches Both the 1919-1925 and 1926-27 operate exactly the same, the key operates the inner ring of contacts to select the voltage source and handle operates the outer ring to select the light preference. The contact in the center of the inner ring makes contact to the corresponding coil contact on the switch backing plate, It is the outer contact the positions itself to one of three places when you turn the key - there is a small indent that it rests in when OFF -turn the key to the left to MAG or right to to BAT. So if you didn't have continuity in the MAG position it is possible that the brass on the bottom of the MAG post is oxidized. A quick fix is a rubbing the entire backing plate on a some fine sand paper. Or purchase a new backing plate if yours is warped. Note groves form in the underside of the backing plate and should be on no consequence. There is no point in bending the outer contact since it makes contact with the BAT position. NOTE the backing plate is in its correct position flipped over, thr inner contact ring is turned to MAG
Hope this helps Send me an email if you need more help
IMG_2406.JPG
New and old Switch backing plates
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Re: Ignition Switch

Post by DJPeterson » Tue Sep 14, 2021 9:03 pm

Be sure to anneal the tabs (heat to red then air cool) after bending strait and prior to bending over again. Just one cycle of straitening then bending over without annealing may be enough to cause it to break off. I learned this the hard way!


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Re: Ignition Switch

Post by speedytinc » Tue Sep 14, 2021 11:18 pm

I find that a little dielectric (silicone) grease keeps the contacts smooth & maintains good contact.

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TRDxB2
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Re: Ignition Switch

Post by TRDxB2 » Tue Sep 14, 2021 11:37 pm

speedytinc wrote:
Tue Sep 14, 2021 11:18 pm
I find that a little dielectric (silicone) grease keeps the contacts smooth & maintains good contact.
Interesting, since dielectric grease (silicone) is non-conductive. Now having said that, a very small amount may act as a lubricant to help the contacts slid across the the fiber backing plate, but I would think that it in doing so, some on the surface of the contact would need to wear away to make contact wold have to wear away to make contact with the post on the backing plate. A small amount of dielectric (silicone) grease can be used under the fiber rings that rotate on the metal cup that holds them in place.
The past is a great place and I don't want to erase it or to regret it, but I don't want to be its prisoner either.
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Re: Ignition Switch

Post by Ruxstel24 » Wed Sep 15, 2021 11:44 am

TRDxB2 wrote:
Tue Sep 14, 2021 11:37 pm
speedytinc wrote:
Tue Sep 14, 2021 11:18 pm
I find that a little dielectric (silicone) grease keeps the contacts smooth & maintains good contact.
Interesting, since dielectric grease (silicone) is non-conductive. Now having said that, a very small amount may act as a lubricant to help the contacts slid across the the fiber backing plate, but I would think that it in doing so, some on the surface of the contact would need to wear away to make contact wold have to wear away to make contact with the post on the backing plate. A small amount of dielectric (silicone) grease can be used under the fiber rings that rotate on the metal cup that holds them in place.
Dielectric is the best preventive of corrosion in electrical connections....which is the enemy of brass or copper. Widely used in the modern world of cars and electronics. It keeps water away from the metal and lubricates to reduce wear on moving contacts.
Henry would have never used it as it’s not cheap. :P

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Re: Ignition Switch

Post by JBog » Wed Sep 15, 2021 5:35 pm

I hit the contacts with electrical contact cleaner and some sandpaper. They are all shiny and the switch functions well.


speedytinc
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Re: Ignition Switch

Post by speedytinc » Wed Sep 15, 2021 5:51 pm

Ruxstel24 wrote:
Wed Sep 15, 2021 11:44 am
TRDxB2 wrote:
Tue Sep 14, 2021 11:37 pm
speedytinc wrote:
Tue Sep 14, 2021 11:18 pm
I find that a little dielectric (silicone) grease keeps the contacts smooth & maintains good contact.
Interesting, since dielectric grease (silicone) is non-conductive. Now having said that, a very small amount may act as a lubricant to help the contacts slid across the the fiber backing plate, but I would think that it in doing so, some on the surface of the contact would need to wear away to make contact wold have to wear away to make contact with the post on the backing plate. A small amount of dielectric (silicone) grease can be used under the fiber rings that rotate on the metal cup that holds them in place.
Dielectric is the best preventive of corrosion in electrical connections....which is the enemy of brass or copper. Widely used in the modern world of cars and electronics. It keeps water away from the metal and lubricates to reduce wear on moving contacts.
Henry would have never used it as it’s not cheap. :P
Yes thats why I use it. It was recommended for multi pin wire connections to keep out corrosion. After using on a T & opening back up years later, the contact points were as clean & carbon free as before assembly. I didnt realize it could interfere with connectivity. I havent experienced any issue.


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Re: Ignition Switch

Post by George Hand » Wed Sep 15, 2021 6:27 pm

Miles what ever you do DO NOT allow battery DC voltage to get to the AC voltage magneto circuit, it will "Kill" the magnetos ability to generate voltage (AC). George

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Re: Ignition Switch

Post by VowellArt » Thu Sep 16, 2021 2:08 am

Your switch looks like this one with the clips...even though the one below it is a 26-27 switch, all plate switches work exactly the same and are wired the same too (with the exception of that green ground wire, that's not really on any of them).
1919-1925SwitchAssembly2.jpg
Switch26-27-2.jpg
Sometimes your magneto doesn't work because you over shoot when switching to it, this is usually because the detentes in the switch wire plate are not deep enough to hold your switch lever from going past the magneto contacts (the detentes are the holes without the contacts in them). This happens because over time they get worn almost smooth, so drilling them a might deeper may fix this problem, at least that's what I did to mine to fix that problem.

Personally I'm not big on keeping original parts, because they DO wear out (eventually) and sometimes you've got to admit there's no fixing it. You could wait for a local swap meet to happen and see if you could find an NOS switch plate there or you could buy that new repop switch, which I know you don't want to, but you may have to consider that option anyway. Those tabs on your switch housing look a might too rusted to bend without breaking off entirely. Anyhoo, you could always buy the new switch and remove the new switch lock barrel and key and replace it with your old switches parts and you can paint those shiny nickel plated rivets on the front with black fingernail polish (brand Finger Paints, color Black Vinyl...it's the blackest black I've seen in fingernail polish), scar the shiny black surface of the new plate and switch handle with a piece of 0000 steel wool and it wiill look just like your old switch. And don't cheap out and get the one with the plastic backs, they're crap...get the ones with the factory style heavy card. The detent holes are deep and hold really well.
Fun never quits!

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