Is ballast resistor failure a myth?

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toolmanmike said:
Had the run side fail on one back in the late 70's on my 73 Challenger. I wouldn't consider it a myth or a design flaw. It is just something that happens. A part failure. GM's HEI is a 12 volt system and doesn't use a ballast but they sure had their share of module and pole piece failures.
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Yup- my GM buddy carries a spare HEI module in his toolbox, too. Different brands, different parts- same reasoning.
 
hotrod swinger said:
Carry an extra ballast resistor in the glove box? I say it's a myth, what say you?
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Definitely not a myth. I have had 2 of them fail on two different Mopars. Car will start and when you release the key it shuts off.

First time it happened I was on my way to a concert around 1978 in a snowstorm. Stopped at a store to grab some more punch and when we came out it was done. Had me scratching my head for a minute.

I didn't have a spare ballast so I jumped the wires and concert bound we were, lol.
 
In my opinion, IT IS a myth, at least so far as "more than their share." Yes they fail. But--how many times over the decades, did someone leave the key in the "run" position, either kids listening to the radio, or "you" or the "mechanic" doing some work and doing so? Mopar ECU, unlike GM HEI DRAWS COIL CURRENT when not running.

Some failures may have been due, not to the ballast per se, but things like water leaking onto the hot ballast, or "car wash"

I adapted my first Mopar breakerless system to the then swapped 340 in my 70 RR way back around 73 or so. "Some guy" in an A body thought he wanted a dual point so he yanked it out and I put it into my RR. Later, I had breakerless in my old FJ-40 Landcruiser--SB Mopar swapped.

The point is, ever since the mid seventies, I've only replaced 1, maybe 2 ballasts. One of them may have still worked, but the ceramic broke, and that may have been my doing
 
hotrod swinger said:
All the chevy and ford guys are critical of the mopar ignition system, even mopar guys themselves, but I'm really starting to wonder about the suggestion that failing ballast resistors or ECU's or VR's are the problem. I can say from my experience that electrical problems are almost always bad connections, not components, especially not original factory components (I'm not including modern Chinese made relays, VR's etc. that often times do fail right out of the box).
Conventional wisdom says carry a ballast resistor and ECU around with you, but maybe it would be better to carry some extra wire and connectors and a wire cutter/crimper tool instead?
Personally, any time I have swapped in a part that "fixed" a problem, such as ECU, coil, etc., it didn't actually fix the problem, the problem eventually resurfaced. What happened is that the replacing of the component, tightening connections and moving wires around temporarily fixed a weak connection.
A ballast resistor is simply a resistor, no moving parts. How can it be considered an inherent weakness?
Carry an extra ballast resistor in the glove box? I say it's a myth, what say you?
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Name one thing on this planet that doesn't fail eventually. The ballast resistor gets very hot, just like any electric heating element from a kitchen range to a clothes drier. When the ballast resistor broke, without firing a warning shot, in our first 67 fish, there was no other issue or subsequent failure until #5 rod went through side of block (at least 2 years later).
 
They definately fail. Usually due to the newer parts and also leaving the key in the run position and engine off overheats both. Also you should have the ballast resistor that is supposed to be in the matched system. Most replacements are not the right values. JFYI
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Same on a point system 90% of them are .5-.6 ohm not one ohm. FSM has the specs for them

I have always thought of ballasts like a safety device sort of like a fusable link for mis matched components.

kind of sort of
 
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Not a myth,70 model duster and 74 duster,both went bad for me, will start but quit when you let go of key. Quick test,run a wire jumper from one side to the other side of ballast if it starts then you will know. The jumper will get red hot ,so don't run it long,and be careful when you pull the wire,stays hot for a while
 
I have owned at least one Chrysler product car that had a ballast resistor continually for last 50 years and have only once had one fail.
That was in 1973. I was driving a 65 Dart back then. Whiled stopped at a gas station in a poring rain. The attendant opened the hood and the rain water ran off the hood, right on to the ballast resistor cracking it. I did not know it until I went to restart the engine.
I still hear Ford and GM owners at the local cruise night asking me if I carry a spare one in the glove box.
 
Again, just to be clear, I’m not saying they don’t fail, of course everything fails, rather the ballast resistor is not an inherent design flaw.
 
No it is not if you dont leave the key on for extended time. I have checked the amp draw on ECU's on and also running. When running usually 2 amps just powered on 4 amps on the average that will overheat them both not good for any electrical components.
 
I had the ballast resistor fail on my '73 Loadstar with 5 tons of gravel on it. On a two lane road. Yeah, good times.
 
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I haven't read 39 posts, but in my opinion, the GM resistance wire was more reliable than the stand alone resistor that Ch used. Both perform the same function, to reduce run voltage to the coil. It is rare to hear of GM wire failure because it is multi strand wire that does not heat & cool down like the Ch ballast res does. That cycling makes the wire brittle & eventually it breaks.
 
Forgot about those. So true I dont think I ever changed one in the years I had GM's.
 
67Dart273 said:
Some failures may have been due, not to the ballast per se, but things like water leaking onto the hot ballast, or "car wash"
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Bingo! Most every one goes in bad weather or wet weather. And as mentioned everything fails eventually.
 
There are a few types of failures. Resistor is made from nichrome wire, and it needs to be attached to terminals. That attachment is by crimping or spot welding. Heat cycles, can loosen crimps. Nichrome expands significantly with temperature, leading to fatigue.
 
spends its life turning anything from 3 volts to 5 volts at 2-3 amps into heat.
it will fail eventually

nothing wrong with mopar system although these days there may be something wrong with the the quality control and the way its manufactured.

on a 12 volt points system that resistance is in the coil...coils fail as well.

its all about limiting current through whatver your chosen " Coil switch" can handle
2-3 amps for points, similar for standard mopar box

way more for HEI and similarly specified 12-14 volt "low resistance " ignition coils with less than say 1.2 ohm primary, i.e 4-7 amps
Hei works with a 0.8 ohm primary

dave
 
There IS an inherent problem in the CH resistor, I mentioned it post #40.
 
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