TRExp

TR2 & TR3 Forum

Condensers.

Moss Motors
AutoShrine Sponsor
AutoShrine Sponsor
AutoShrine Sponsor
AutoShrine Sponsor

KingstonO Avatar
KingstonO Simon Oliver
Vancouver, BC, Canada   CAN
Had the latest in a long list of condenser problems, on a road-trip to the Rockies last week. Fortunately I was carrying a spare, so only a little time wasted, but I'd certainly like to avoid this 'issue' in the future. I've gone to Pertronix ignition on my classic Mini, but am reluctant to do the same with the Triumph. Does anyone have any thoughts - about a source for reliable condensers, perhaps - or do I simply carry spares and accept that roadside maintenance is part of the fun?! Any suggestions gratefully accepted!

. Hide banner ads & support this website by becoming a > Gold Supporting Member <

Attachments:
IMG_2768.jpg    62.9 KB
IMG_2768.jpg

CJD john durant
Southlake, Texas, USA   USA
Are you replacing the points and condenser at the same time? The only way to know if the condenser fails is that it takes the points out with it...and then it becomes the chicken or the egg question. How do you know if it was the points or the condenser that failed first? Likewise, if you are replacing the condenser and not the points, then it may not be the condenser failing. So, what are the symptoms?



John
Southlake, TX

'55 TR2



Edited 1 time(s). Last edit at 2017-07-24 09:19 PM by CJD.

M. Pied Lourd Pied Lourd
Ontario, Canada   CAN
Hi Simon,

Just curious why you don't want to run a Pertronix in the 3?

Cheers
Tush

. Hide banner ads & support this website by becoming a > Gold Supporting Member <
TR3driver Randall Y
Confusion, Los Angeles, USA   USA
In reply to # 1473221 by CJD The only way to know if the condenser fails is that it takes the points out with it...
That's true only if the condenser is just a bit off, which lets the points transfer metal. A total open circuit will keep the engine from running; while an intermittent connection can cause all sorts of weird stuttering and backfiring. I've had one of each, and both times the points were still fine. Replacing the condenser fixed it.

I have occasionally thought about trying a higher quality capacitor, but haven't actually done it. But I've certainly had better luck than Simon; that first failure was back in 1975 or so and I only got to the second one last year. I covered a whole lot of miles in between. Anyway, here's an example that might work
http://www.mouser.com/ProductDetail/Cornell-Dubilier-CDE/940C6P22K-F/?qs=zsnhSutGCZWd1UevJM1khQ%3D%3D

Obviously it's too big to fit inside the distributor, so I would mount it to the coil instead. There's no reason it has to be close to the points.

The failed one from last year is still on my bench; I bought a capacitor tester just to try to see what was wrong with it. According to the tester, it's fine (actually tests better than a new one that works). But the articles I've seen describe the construction as basically a roll of aluminum foil that is just stuffed inside the can. There is no positive connection between the actual capacitor and the case (which seems to be very common with Lucas electrics). So I believe the problem with it is that, under heat, vibration, and electrical stress, that connection isn't good enough and lets the voltage go high enough to jump the points (and not develop the high voltage to fire the plugs). The tester I bought doesn't check ESR directly; my plan is to try one that does. Someday.



Randall
56 TR3 TS13571L daily driver
71 Stag LE1473L awaiting engine rebuild
7? Stag awaiting gearbox rebuild

CJD john durant
Southlake, Texas, USA   USA
So one failure mode is for the condenser to short out internally? Interesting. It would seem in that case the engine would die and coil would be extremely hot from absorbing the constant current.

The only failure I've experienced is the opposite, where the condenser goes infinitely open, the points fry and no longer pass enough current to charge the coil, so the engine dies a slow sputtering death. In that scenario the coil is not any hotter than the rest of the parts in the engine bay.



John
Southlake, TX

'55 TR2



Edited 1 time(s). Last edit at 2017-07-24 09:26 PM by CJD.

chucktr33aa Chuck Murphy
Carrollton, Texas, USA   USA
Randall, what is ESR?

Chuck

mgedit Mike Graham
Kemptville, Ontario, Canada   CAN
I just looked it up:

ESR is the sum of in-phase AC resistance. It includes resistance of the dielectric, plate material, electrolytic solution, and terminal leads at a particular frequency. ESR acts like a resistor in series with a capacitor (thus the name Equivalent Series Resistance).

Just don't ask me what it means!

Cheers, Mike

. Hide banner ads & support this website by becoming a > Gold Supporting Member <
TR3driver Randall Y
Confusion, Los Angeles, USA   USA
That's right. Basically, it's a measure of capacitor performance that is important in this circuit, but not the same thing as capacitance.

When the points first start to crack open and interrupt the current flow; the inductance of the coil resists the change in current by generating a large, fast voltage spike. The spike happens in both primary and secondary windings. But the points move slowly in comparison to the voltage spike, so without the effect of the condenser, the spike in the primary causes a spark to jump the still tiny (at that moment) point gap. That draws energy out of the coil and limits the voltage generated until there isn't enough in the secondary to jump the gaps and cause a spark at the plug.

So the main function of the condenser is to absorb that first rush of current, thereby slowing down the voltage spike just long enough that the points can open far enough to avoid having a spark on just a few hundred volts. It doesn't take long, but during that short time, there is a lot of current flowing through the condenser. ESR resists that current flow, making the condenser less effective no matter how high it's capacitance is. If the ESR is high enough, the circuit won't work and the plugs won't fire reliably.

So, what I have on the bench is a condenser that appears to be in good working order as far as capacitance, leakage and dielectric strength (voltage breakdown). It's not shorted, or open; it just doesn't work in my TR3. My theory is that it has developed a high resistance connection between the actual capacitor foil conductor inside, and the can. Measuring ESR is one way to confirm that, before I cut it open.

Does that answer the question?



Randall
56 TR3 TS13571L daily driver
71 Stag LE1473L awaiting engine rebuild
7? Stag awaiting gearbox rebuild

chucktr33aa Chuck Murphy
Carrollton, Texas, USA   USA
Thanks, a very good explanation! Thanks for your help.
Chuck

. Hide banner ads & support this website by becoming a > Gold Supporting Member <
KingstonO Avatar
KingstonO Simon Oliver
Vancouver, BC, Canada   CAN
When the condenser is failing, there are intermittent 'misses', becoming more regular as the failure progresses. Sometimes this happens quickly, but last week I covered about 600 miles between the first 'blip' and the point at which action had to be taken. The points gap was fine and there was no apparent damage .. confirmed by the fact that the car ran smoothly and managed the 700+ miles home without incident. I'm a bit of a fatalist - if something can go wrong, it will - so it seems easier (and cheaper) to carry a spare points/condenser/rotor set than a spare Pertronix unit .. hence the reluctance to change.

As for the capacitor idea, Randall, I'll be really interested to hear where you go with it. If replacement of the condenser seems a viable (and relatively simple!) operation, it may be just what I need to do. Anyway, food for thought.

Thanks, all, for the responses .. much appreciated. Finding a new, 'up-market' condenser to replace my spare is now on the to-do list, but more pressing is removal of the bug carnage from the nose of the car. It may take a day or two cool smiley

Cheers,
Simon.

brucejon Avatar
brucejon Bruce Jones
Santa Cruz, CA, USA   USA
1962 Triumph TR3B
1963 Triumph TR3B "Tupperware TR3"
1969 Triumph Spitfire MkIII
1972 Triumph TR6
Fred Winterburn Avatar
Ripley, Ontario, Canada   CAN
Found this a few months ago, but haven't bought one. http://www.retroclassiccarparts.com/lucas-25d-motorsport-spec-condenser
In the heat of the distributor, I would want a capacitor with at least 125 degrees C rating and the polypropylene film types seem to be 110 at most. I don't know what type of capacitor this company is using, but presumably they've tested it thoroughly so the high price might very well be worth it for peace of mind. I hope it's better than 110 degree rated. To perform its best, the condenser should be placed as close to the points as possible, but the coil is so close to the distributor with these engines that mounting a non-standard condenser at the coil negative to ground would be 99% as good. Fred

In reply to # 1473238 by TR3driver
In reply to # 1473221 by CJD The only way to know if the condenser fails is that it takes the points out with it...
That's true only if the condenser is just a bit off, which lets the points transfer metal. A total open circuit will keep the engine from running; while an intermittent connection can cause all sorts of weird stuttering and backfiring. I've had one of each, and both times the points were still fine. Replacing the condenser fixed it.

I have occasionally thought about trying a higher quality capacitor, but haven't actually done it. But I've certainly had better luck than Simon; that first failure was back in 1975 or so and I only got to the second one last year. I covered a whole lot of miles in between. Anyway, here's an example that might work
http://www.mouser.com/ProductDetail/Cornell-Dubilier-CDE/940C6P22K-F/?qs=zsnhSutGCZWd1UevJM1khQ%3D%3D

Obviously it's too big to fit inside the distributor, so I would mount it to the coil instead. There's no reason it has to be close to the points.

The failed one from last year is still on my bench; I bought a capacitor tester just to try to see what was wrong with it. According to the tester, it's fine (actually tests better than a new one that works). But the articles I've seen describe the construction as basically a roll of aluminum foil that is just stuffed inside the can. There is no positive connection between the actual capacitor and the case (which seems to be very common with Lucas electrics). So I believe the problem with it is that, under heat, vibration, and electrical stress, that connection isn't good enough and lets the voltage go high enough to jump the points (and not develop the high voltage to fire the plugs). The tester I bought doesn't check ESR directly; my plan is to try one that does. Someday.

Born Loser Avatar
Born Loser Silver Member Matthew Taylor
Land O Lake, Florida, USA   USA
Had the problem with a couple bad ones, drove me to drop in a Pertronix. I added the one that fits in the original dizzy - you can't see it. The only change is the color of wire (ones red). And it drops in so easily, I carried a plate with points and a condenser for years. Never needed it. In fact, I have only changed the cap, wires. and plugs in the last 15 years, the ignition is maintenance free otherwise.



Matthew
1960 Triumph TR3a
1970 Triumph Spitfire MK 3
2012 Mini Cooper SS Convertible

CJD john durant
Southlake, Texas, USA   USA
We must be getting more bad parts, which does not surprise me with the rash of them I've had this last month alone! I have over 2 million miles logged on points cars...single points, dual points, magneto points, etc., but I have only had a single condenser failure in all those miles. Statistically you guys have to be getting bad condensers to loose that many that fast!

Also, I've seen many more petronix problem posts than point posts...



John
Southlake, TX

'55 TR2

TR3driver Randall Y
Confusion, Los Angeles, USA   USA
I agree, definitely bad parts. And it does seem like we are getting more of them lately; although the problem has been ongoing for many years.

Not just Triumphs either. I had the engine in my 95 Buick professionally rebuilt; and the water pump drive gear was defective. Skinned the teeth off in only 5000 miles or so.

But a condenser can be changed in just a few minutes on the side of the road. Quite a bit more effort to change a Pertronix (and I have seen them fail), especially since it affects the timing. You also get a spare condenser every time you do a tune-up, since the old one is almost always fine. Spare Pertronix is kind of expensive.

The thing that drove me to throw the Pertronix back in the parts bin is that it won't work if the battery voltage is too low. My gear drive starter will still turn the engine (slowly, but fast enough to start) on about 6 volts; but the Pertronix quits at 8 volts. I'm not sure how far down the points will still work; but it's much lower than enough to turn the engine. Most of you will never have that problem I guess; but I can't count how many times I've gotten the car started on just the last little glimmer of battery, often pushing it myself. The thought of an 'improvement' that can make it not start when it would start without the improvement just seems absurd, to me.

But every aftermarket electronic ignition I've owned has let me down at least once.



Randall
56 TR3 TS13571L daily driver
71 Stag LE1473L awaiting engine rebuild
7? Stag awaiting gearbox rebuild

. Hide banner ads & support this website by becoming a > Gold Supporting Member <

To add your reply, or post your own questions

Members Sign In   or   Create an Account

Registration is FREE and takes less than a minute!


Having trouble posting or changing forum settings?
Read the Forum Help (FAQ) or contact the webmaster





Join The Club

Sign in to ask questions, share photos, and access all website features

Your Cars

1978 Triumph Spitfire 1500

Text Size

Larger Smaller
Reset Save

Sponsor Links