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GT40R GT40 coils and electronic points
Jo Mama - February 24th, 2003 at 05:29 PM

Hello,
I'm thinking that the problem I've been having with my baja (see earlier post) is due to my coil. Since I installed electronic points, my car would drop revs to almost zero after about 30mins of driving. I would wait 1 min or 2 then drive off with the same thing happening 5 mins later. If I mange to keep the revs to under 2000 rpm it just manages to keep going otherwise she drops power, idles eracticly and I roll to a stop.
Now I think its because I have a GT40R coil and I need a GT40. Ive just bought the GT40, but the intructions say to isntall it without the resistor. I'm assuming its the little metalic cylinder thats already connected to my GT40R coil?

Thanks,

Nick.

[Edited on 24-2-2003 by Jo Mama]

[Edited on 24-2-2003 by Jo Mama]


555bug - February 24th, 2003 at 05:40 PM

I's suggest that you return the gt40. They are fine for other cars but the bug just gets to much vibration and heat and soon kill these coils. Get yourself a Bosch black coil (oil filled) and you'll be right for years :)


Doug Sweetman - February 24th, 2003 at 05:41 PM

Spot on. The electronic points need a low impedance coil - ie no resistor. What is probably happening is that your coil is overheating ????

Be careful, and touch your coil the next time it happens. It shouldnt be too hot to touch.


2443TT - February 24th, 2003 at 05:49 PM

Firstly, I've had problems with the GT40 coils too.

I was using the transformer type GT40, and found they fail to work properly above 4500 rpm in a 4cylendar application where your dwell angle is about 60 degrees.

The oil filled red GT40 coil is the one you want to use.

Now, these coils have an internal ballast resister so you don't need an external resistor.

The round cylendar thing you described is called a condensor, and its job is to stop arcing accross your points. Some electronic conversions allow you to remove this thing, but its a good idea to leave it on, as it also helps reduce rf interference over your radio.

You should check your compufire/pertronix instructions for more details about this.

It is critical that you use the correct type of coil with the electronic point conversion.

The pertronix ignitor II allow the use of low resistance ignition coils. If you are not using one of these conversions, a black GT40 coil could blow up you ignition module.

Good luck,

Ian.


Jo Mama - February 24th, 2003 at 05:50 PM

Is the resistor right next to the coil? The little metalic cylinder thats connected to it.? Or is that a condensor also?

[Edited on 24-2-2003 by Jo Mama]


Baja Wes - February 24th, 2003 at 06:56 PM

In case everyone has confused you...

yes you are right, the GT40R will overheat your electronic points. It will also cause your normal points to burn out quicker.

You want to either use the GT40 coil, or a more normal Bosch coil like the standard one. Some people think the GT40 is not as robust as the standard types, and I have noticed the same thing. But the GT40 will be fine until it dies like every other coil.


11CAB - February 24th, 2003 at 07:45 PM

On a different tangent, if you have an electronic ignition like the compufire, make sure you have to correct air gap between the magnetic disc and the module. I've seen the disc rub through the top of the module and cause a similar problem.
The ones that i have are designed for the 009 dissy, but the one i saw had been fitted to a standard vac advance kombi dissy.


OvalGlen - February 24th, 2003 at 08:19 PM

Jo the metal cylinder thing next to the coil is probably the Condensor. Usually they are attached to the Distributor.
Best to just run one on the distributor.
The external resistor mentioned is usually a rectangular white bit with two wires going to it.
I must agree with 555, to use the black Bosch coil. Had mine running many years.
Typically get two years from GT40.


Jo Mama - February 24th, 2003 at 08:56 PM

Anyone know why I had a condenser on my coil? Is this good or bad for the coil?


1303Steve - February 24th, 2003 at 10:05 PM

Hi

Just to clear things up. The R coils were meat to be used on cars with ballist resistors, like old Corrolars etc. They used a white ceramic resistor, it did 3 things, when you used the starter the coil got full 12 volts, when it was cold it allowed nearly 12 volts to reach the coil and as the resistor heated up the resistance increased slightly and cut down the voltage to the coil, this system increased spark when cold. The systems using R coils are almost 6 volts. The condensor is mounted on the dizzy and connects to the points and - side of the coil. The little silver tubes mounted on the + side of the coil are just noise suppresors, if your condesor fails they can sometimes be hoocked to to the + to get you out of trouble.

Its best to use the correct coil for these points, I dont think an electronic coil would be the correct choice.

1302Steve


Grey 57 - February 24th, 2003 at 10:31 PM

I had a similar problem when I first fitted a Compufire Hall Cell on my oval. Killed the coil in a month. Fitted one of these GT40 and no more problems.


555bug - February 25th, 2003 at 12:25 AM

off tangent but on your car Grey57 I notice that you have the filter mounted between the pump and carb :( Just a little story: I was dating this girl (now my wife) who got me into VW's anyway late one night she was off home, as it was late etc I decided to follow her in my civic :( anyway as she roared up Rode rd I noticed a lot of liquid pouring out of the car .. I did my look I drive a 200hp car overtake thing and the bloody brass fitting had come out of the carb :( there was fuel everwhere including all over the dizzy. I have no idea why the car did'nt go bang but I learnt a very good lesson. I'd suggest to everyone running this setup to either ensure the line is secure (hammer and a nail will work) or move the filter. Sorry off the soap box now..just hate to think about a burning oval :cry


Grey 57 - February 25th, 2003 at 01:41 AM

555 good call. There was a post on a VW catching fire a while ago and someone said not to have the filter on the pressure side of the pump. Cause these cheape filters can burst. So I have since moved it away from the hot bits and put it on the inlet side. Worst that can happen now is if it breaks I'll just run out of gas.
Already had one firey experience with this oval not long after I got it. The generator went up in flames. Scared the crapolies out of me. Went out and fitted a fire extingusher the very next day.


mnsKmobi - February 25th, 2003 at 08:18 AM

Also noticed in Grey57's picture that the leads are all connected using those push on quick connectors. I have converted all the leads on the coil to ring connectors so they don't come loose. Easy to do and can potentially save a lot of grief.


Jo Mama - February 25th, 2003 at 10:20 AM

Replaced my gt40r coil yesterday with a gt40 and I made it to work without any problems. Just wondering wether my electronic points were overheating or my coil. I'm assuming it was the coil.

Thanks.

Nick.


matara - February 25th, 2003 at 11:53 AM

I have a Bosch black coil, and an accu fire and the coil got really hot and cut out recently. It says Use a ballast resistor on the coil! Is this the wrong coil for my Accu-Fire?

Thanks

Steve


Baja Wes - February 25th, 2003 at 12:50 PM

Jo,

It was your electronic points overheating. I speak from experience :)

If you had've taken the cap off and touched them like I did you would've burnt your finger too!


mnsKmobi - February 26th, 2003 at 11:16 AM

Quote:
Originally posted by matara
I have a Bosch black coil, and an accu fire and the coil got really hot and cut out recently. It says Use a ballast resistor on the coil! Is this the wrong coil for my Accu-Fire?

Thanks

Steve


Do you mean you are running the coil that needs a ballast resistor without one? If so, the coil will overheat because it was designed to run at 6 volts and you are running it at 13 - 14 volts. These coils are designed to provide extra spark for starting. They work by having two positive feeds. The one from the starter only gets power when you're cranking the motor. This means that while starting you get 10 - 11 volts going into a 6 volt coil. For a short period of time this is OK and gives a better spark. Once the motor is running, the positive is connected via the ballast resistor which drops the voltage to 6 volts.


70AutoStik - February 27th, 2003 at 12:42 AM

Sorry if I seem a little pedantic - but I'm old enough to remember these things:

First, the ballast resistor was wired into the starting circuit on the calculation that only around 8V would be available during cranking, it was shorted during starting, then dropped into circuit for regular running (though I believe some had a smaller resistance in circuit during starting.) In the old days, some people used them as a poor-man's "hot" coil; though they would burn points quickly and not last very long due to overheating (I don't think I saw one without oil leakage.)

Second: As far as I can recall, no Beetle ever used this system, if it's fitted it will cause problems (if it's fitted with the resistor permanently in circuit it will be difficult to start.)

Third: The use of an "R"-type coil will eventually destroy any ignitor, magfire, etc type ignition - even though the DC resistance is above the minimum recommended.

Fourth: A capacitor (or condensor) fitted to the coil is there for radio interference suppression, and is never a substitute for the points condensor used with points - it may interfere with the operation of electronic ignition and cause premature failure. Try suppression-type leads and a large capacitor (& maybe a large choke in series, before the capacitor)
near the supply to the stereo (possibly a 1nF polycarbonate across the antenna if interferance is persistant.)


aussiebug - February 27th, 2003 at 11:22 AM

I'm going to add some comments here too.

Re the resistor coils. You definitely should not need one one VWs as they should be running the full 12 (or 6v on 6v cars) to the + terminal on the coil.

As others have said - some cars (old Falcons for example) started the car with the coil getting 12v but ran the coil on about 7v with the resistor in the circuit. This was to get higher voltages for starting on cars which needed it.

The normal VW distributor actually has a resistor built into the rotor arm - that is, on the high voltage side of the coil, not the 12v side. I mention this arm because we are talking about Pertronix etc here - you don't need a resistor type rotor arm with these points replacement modules(or with CDI units either). And with the added punch of a Pertronix/compufire or CDI, the resistor is likely to fail or partially fail, causing a strange ignition failure; or part failure as the engine gets hot - the resistor will sometimes continue to work when the resistor is still cold, but fail as it heats up. You might not even see a difference in a blown rotor arm resistor, since it's buried in the plastic between the centre and outer brass pieces.

John at http://www.aircooled.net  sells a replacement rotor arm without the built in resistor, or you can dig it out of a standard arm yourself and solder in a straight piece of wire (if you want to try it).

On another topic, I have never known what the problem was with "coils burning out". I have a 68 bug and a 70 bug, and both have their ORIGINAL VW coils - the silver kind. I can't swear that the 68 has never been changed (it looks original but the car has had POs) but the 70 I have had since new, and it's got the coil it came with from the factory. For many years this coil had a Dick Smith CDI driving it too (until the CDI finally bit the dust - haven't got around to building a new one yet), so it's not like it's had an easy life either (248,000 miles on that engine).

So why do so many people have trouble with coils burning out?

And re the comments about the position of fuel filters and the brass carby inlet spigot. These spigots are a push-fit into the top of the carby and 30 years of rubber fuel lines vibrating on them can gradually loosen them in the carby - and yes - you get a great spray of fuel all over the engine until the carby's float bowl empties and the engine stalls.

Hanging a fuel filter off that brass spigot will increase the likelihood of it working loose.

Toasted bugs are NOT a pretty site.

The fix for a loose carby inlet spigot is to pull it out, and place it on a piece of plastic or wood, and run the edge of a single cut file over it - rolling the spigot under the file to knurl the end of the tube which fits into the carby top. DON'T knurl right to the inner end - that's what seals it inside the carby top. The knurls (tiny raised ridges) will grip the insides of the hole and make a nice tight fit when the pipe it tapped back into the carby.

Fuel filters should always be before the pump anyway - that way the pump gets filtered fuel to work with - less chance of stuck valves in the pump; and it follows VWs original methiod - a tank screen in the fuel tank itself to filter the large pieces, and a small plastic filter built into the original tall style fuel pumps to catch the fine stuff.


Grey 57 - February 27th, 2003 at 09:59 PM

Rob , how far back did VW's use a resistor in the rotor. I have some 36hp distrubutors , would these have the resistor rotors?


aussiebug - February 28th, 2003 at 04:59 PM

I don't know for absolute certain, but I understood that all normal rotor arms had the resistor - it was probably part of the original method of supressing radio noise when wire spark plug leads were the norm.


68AutoBug - February 28th, 2003 at 10:30 PM

Quote:
Originally posted by aussiebugI'm going to add some comments here too.Re the resistor coils. You definitely should not need one one VWs as they should be running the full 12 (or 6v on 6v cars) to the + terminal on the coil.
As others have said - some cars (old Falcons for example) started the car with the coil getting 12v but ran the coil on about 7v with the resistor in the circuit. This was to get higher voltages for starting on cars which needed it.

The normal VW distributor actually has a resistor built into the rotor arm - that is, on the high voltage side of the coil, not the 12v side. I mention this arm because we are talking about Pertronix etc here - you don't need a resistor type rotor arm with these points replacement modules(or with CDI units either). And with the added punch of a Pertronix/compufire or CDI, the resistor is likely to fail or partially fail, causing a strange ignition failure; or part failure as the engine gets hot - the resistor will sometimes continue to work when the resistor is still cold, but fail as it heats up. You might not even see a difference in a blown rotor arm resistor, since it's buried in the plastic between the centre and outer brass pieces.

John at http://www.aircooled.net  sells a replacement rotor arm without the built in resistor, or you can dig it out of a standard arm yourself and solder in a straight piece of wire (if you want to try it).

On another topic, I have never known what the problem was with "coils burning out". I have a 68 bug and a 70 bug, and both have their ORIGINAL VW coils - the silver kind. I can't swear that the 68 has never been changed (it looks original but the car has had POs) but the 70 I have had since new, and it's got the coil it came with from the factory. For many years this coil had a Dick Smith CDI driving it too (until the CDI finally bit the dust - haven't got around to building a new one yet), so it's not like it's had an easy life either (248,000 miles on that engine).

So why do so many people have trouble with coils burning out?
[size=4]Some very good info there... ROB.. it seems like jo? may have been running a GT40R without a resistor at all... and most vehicles don't use a Capacitor (condenser) on the side of the coil anymore, as most spark plug leads are of the resistance type and NOT copper cored any more... [/size]


amazer - February 28th, 2003 at 10:52 PM

I think most radios these days arent affected by engine noise. Im using copper leads with no problems. Throw the condensor. One less place to have problems.


Jo Mama - March 1st, 2003 at 10:48 AM

Autobug,

You're right. I was using the GT40R coil without a resistor. I mistook the condenser on my coil as a resistor.

Nick.


70AutoStik - March 4th, 2003 at 12:45 AM

Just so no-one gets confused by this thread:

Amazer is referring to the suppression capacitor (condensor is actually an old term for the same thing, still used by many auto-elecs) fitted to the coil, not the condensor (or cap) fitted on the distributor on points-type systems.

In summary: The condensor (or cap; metal cylindracal thing) must be wired to the dizzy in a points-type system (eliminated in the "pointless" ignition) but there should be no other connection to the "-" side of the coil (unless you have a tacho or cut-off solenoids) in a modern car.

If you experience radio interference, message me: I can e-mail info on how to cure it cheaply and effectively!


bojac - March 6th, 2003 at 10:17 PM

Hi there,
I just replaced coil on my '76 1600 beetle, first by mistake I was given GT40R, the car would not run smooth, backfiring etc.
Replaced with GT40, seemed ok for a week or so, when hot the car played up again, hard starting, backfiring.
So in a desperate move, I replaced the GT40 with coil with a coil from my '68 1500 beetle. What a change...the car runs smooth, starts well, no backfiring, it has been good for couple of weeks now
At the moment I'm trying to get replacement coil same as the one from '68 beetle.


aussiebug - March 7th, 2003 at 01:03 PM

The Bosch "blue coil" is a fairly standard replacement coil these days.

Bosch part number 211 119 027 I think.

Or you can get any 12v coil from a wrecked bug and try it out - they all use the same coil.


aussiebug - March 7th, 2003 at 01:04 PM

Make that part number 221 119 027


bojac - March 10th, 2003 at 09:44 PM

Just got a new Bosch black coil, I think it is SU 12 or something similar (same type as my old one from 68 bug). Works like a charm. Thanks.