ammeter fire

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James Rosenthal
Posts: 3
Joined: Thu Jul 04, 2019 3:51 pm

ammeter fire

Post by James Rosenthal » Thu Jul 04, 2019 4:01 pm

I drove my 1941 Super Eight 160 coupe home from the shop (the work done was not related to the following problem) and after the car was shut off, noted smoke coming from under the driver's side of the dash. Ignition was off at the time. It appears that a short in the ammeter was the cause- the smoke was coming from an overloaded wire that burned up. Luckily the rest of the car did not catch fire.

I have begun removing the instrument cluster, I think you'd call it, to look for the extent of the damage. The batteries are out of the car now. A few questions for those who know more than I do, which will be pretty much everyone:

-the small window through which the ammeter dial was visible is now opaque- I assume this is because of the heat. Suggestions on making it clear again?
-does anyone know where to get a replacement ammeter for a 1941 Super Eight coupe?
-has anyone rewired the ammeter in one of these cars with a shunt included, so that all the current doesn't go through the ammeter, or was that done at the factory?
-is this a frequent problem? On other vintage cars I've worked on, we've changed the car over to a voltmeter, as it is safer, but I don't think I have that option here.
-Can I bypass the ammeter and just put a piece of heavy cable across the terminals and do without it until I find a replacement one, or is that not advisable?
-will an ammeter from another 1941 Packard such as a 110 or 120 look the same as what I used to have?

Any advice/suggestions gratefully appreciated. I was looking forward to getting the car home and driving it- doesn't look like that now :( Thanks to all for any help and advice.

Howard56
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Joined: Mon Dec 24, 2012 11:35 am

Re: ammeter fire

Post by Howard56 » Thu Jul 04, 2019 4:27 pm

The ammeter carries all the current and it's internal construction is fairly robust. I would be concerned that if you try to add a shunt there is every probability it will not read much current if any at all. Having them burn is not something that happens often but it has happened. Did you happen to notice if the needle was pegged on either side before the smoke? If something has happened to the charging circuit and the generator was putting out max current that could have caused the problem. There is no spec as to how much current the ammeter can carry but the generator is capable of outputting much more than the 30-35 amps it is typically set for. A short could have also caused the problem. The ammeter is suspended on ceramic bushings and possibly one of those cracked or broke and let the terminal touch ground. Over tightening the nuts has damaged the bushings in the past.

Kanter Auto and Max Merritt are the usual parts vendors and may have an ammeter. You might also try Flackmaster and see if he might have one as he specializes in junior parts for those years but has senior stuff too. His email is flackmaster at sbcglobal point net (substitute @ and a . for the words) As to cleaning the glass, it will depend on what it was exactly that is covering the surface. As I recall there is also some lettering on one side or the other on the glass and if that is the case it may be difficult to get it off without damage if the lettering is on the inside.

Here is a photo of an ammeter out of another year but I believe the mounting in the 41 is the same. The white cylindrical items are the ceramic bushings.
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James Rosenthal
Posts: 3
Joined: Thu Jul 04, 2019 3:51 pm

Re: ammeter fire

Post by James Rosenthal » Fri Jul 05, 2019 2:56 am

Thank you! This is very helpful. I'll ask my friend who was driving about the state of charge before it happened; I don't know. Kanter doesn't have it, but I will try the two other sources you mentioned. And I'll have the generator checked out to make sure it isn't overcharging- good point and I hadn't thought of it. Much obliged.

I've sent off for a shop manual to show me how to get the dash apart- I don't want to break any of th plastic parts since there is no way to get them new, now.

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Tinman_70
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Joined: Tue May 14, 2013 8:17 am
Location: Tampa Bay, Florida

Re: ammeter fire

Post by Tinman_70 » Fri Jul 05, 2019 9:22 am

Unfused battery running into a dashboard with 70 to 80 year old wiring seems yo be an accident waiting to happen. Surprised this doesn't happen more often. A voltmeter is a better solution but substitutes are not available for an original look.
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