Restoration of a Bosch ZEV magneto

[BoschZEV]

If you are a gambling man I would get your name in there and take a chance.

I appreciate the advice, but even with a provisional entry I would need all the parts for an appropriate bike in a bunch of boxes sitting on my garage floor many months before the start.

all one as to do is remove the old points assembly install the new assembly with the isolation in place and connect battery and off you go... The credit for this idea (if I've done it correctly) goes to Joe Gimpel,

I'll be very interested in seeing how Joe dealt with the issue of the rotating points. A carbon brush?

[10E]

Bosch ZEV
I wouldn't give up hope as regards entering the Cannonball, there will be a reserve list I'm sure, and though it may be full we out here think there will be a good few who will not either get a bike or will not get it together in time. If you are a gambling man I would get your name in there and take a chance.
Besides, I have just completed bench testing the total loss system as discussed earlier in this thread.
It appears to work ok. The ultimate test will be to test it on the bike.
As it stands the mag used on the bench test did not produce a spark, the armature turned freely. An electric motor was used to drive the magneto at approx. 2000rpm engine speed. Two wet cell batteries and one lithium battery were tested. It appears that a 10 amp/hour battery will give 8 to 10 hours of spark, allowing one to loose spark at the days start and still run a 300 mile day with the conversion.
If the system is set up on the bike prior to the run Battery,Coil, Condenser, HT leads, then all one as to do is remove the old points assembly install the new assembly with the isolation in place and connect battery and off you go. About 5 mins switch out.
I have video and photos of the test, if I can get somebody to post it for me.
The credit for this idea (if I've done it correctly) goes to Joe Gimpel, a Cannonballer from Florida.
regards
Victor Boocock 10E

Four months have passed and it's time to call 'time' on my idea/offer. I would have just let it drop but today a very persistent person who managed to find my name, and from that my phone number at work, called about rebuilding his magneto. This guy has an entry in the Cannonball and learned of me from a friend who read this thread on the forum. He's actually the third person who has contacted me, the first two offering "merely" money, not old motorcycle parts. This guy has parts. Unfortunately, there's not enough of them to build a complete bike so more scrounging would be required but, even more importantly, entries already have closed for the next Cannonball.

Oh well, it was an idea whose time I hoped had come (but now has gone...).[/QUOTE]

[BoschZEV]

On September 22 I wrote:

...the cutoff for the next Cannonball will be bikes at least 100-years old (pre-1916) so having a reliable magneto will be essential for the success or failure of most of those machines. This has seeded an idea, although one that clearly has flaws. ...While I don't have any interest whatever in rebuilding magnetos as a business, how about doing so in trade for enough parts and components for me to piece together my own pre-'16 Frankenbike to ride in the next Cannonball?

...if no one stumbles across this thread and takes me up on this idea in the next few months (or proposes something better), time will have run out.

Four months have passed and it's time to call 'time' on my idea/offer. I would have just let it drop but today a very persistent person who managed to find my name, and from that my phone number at work, called about rebuilding his magneto. This guy has an entry in the Cannonball and learned of me from a friend who read this thread on the forum. He's actually the third person who has contacted me, the first two offering "merely" money, not old motorcycle parts. This guy has parts. Unfortunately, there's not enough of them to build a complete bike so more scrounging would be required but, even more importantly, entries already have closed for the next Cannonball.

Oh well, it was an idea whose time I hoped had come (but now has gone...).

[BoschZEV]

I'm going to stay away from the grease issue, but I must say I forgot to mention. I believe Joe said " they use dielectric grease in aircraft mags" A far more critical use than motorcycle mags.

I agree, it's best to tiptoe around the grease issue since discussion of lubricants tends to bring out strong opinions. But, while aircraft magnetos indeed are more critical, it's worth pointing out significant grease-related differences. Modern aircraft magnetos use a different type of bearing than our old rotating armature ones do, their internals are specially designed with small gaps everywhere to eliminate the corona breakdown that the reduced pressure at altitude otherwise would bring on, and for the same reason the grease they use also needs to have low electrical conductivity. But, that doesn't mean it is the silicone compound commonly sold as "dielectric grease."

As an aside, the corona breakdown problem at altitude is an extremely serious for aircraft magnetos. Precisely because of this in WWII Bendix invented what they called a "low tension" system that separated a magneto into its major components in order to place the high tension coils as close as possible to the spark plugs. If you're familiar with the Lucas "ET" (energy transfer) system of the 1960s used on BSA and Triumph competition machines, it's the same "low tension" magneto layout as used on Pratt & Whitney Double Wasp engines (Corsair, Hellcat, Thunderbolt, …).

Thoughts on the butler and chef scenario...

But, more distressing than the issue of grease, you now tell me I have to leave my butler and liquor cabinet behind. This is very troubling; I'll have to rethink this whole Cannonball thing…

Will post when something is working.

I'm looking forward to seeing what you work out.

[10E]

Bosch ZEV
Thanks for the advise on the the grease. I'm going to stay away from the grease issue, but I must say I forgot to mention. I believe Joe said " they use dielectric grease in aircraft mags" A far more critical use than motorcycle mags.

I've entered two of the past Cannonball Runs and found that just about all of the riders strive to get a perfect score and I can see you seem to be heading in the same direction should you manage to get a bike together. (I hope you do) The Cannonball Run is a great event for those who want to test themselves and their machine and enjoy every type of geography and weather.
Whilst not without personalty issues, it's been my experience that friendships and the feeling of comradeship are formed during the event that leave one hungry for more of the same. Of course, there is a lot mayhem at times, but that just part of the run.

Thoughts on the butler and chef scenario.
Because this is a timed event and there are rules to take into account and keeping in mind the above comments, I would lose the butler, any help by your crew on the route has a points penalty, worse still, if your chef served alcohol with your meal and you happened to be in Utah or any other state for that matter, you could receive a traffic citation, and points penalty, from Loni, no alcohol allowed during the timed parts of the days event, another points penalty, there goes the perfect score. If one is interested in that. Enough of the John Cleese stuff.

Getting close to putting something together in regard back-up system.
Will post when something is working.
Joe's cobbling sometimes is the only option at the time, (it as been working for 2 years) , similar to the Lunar modular that had great trouble but after some cobbling managed to make it back to our planet with it's occupants.
Thank you again for you input in helping us keep our motorcycles running.
Victor Boocock 10E

[BoschZEV]

What type and grade etc. grease do you use on the armature ball bearing races.?
PS if you have mentioned it in the past posts I must have missed it.

I did mention it in an earlier post but I'm happy to repeat the information. I use Sta-Lube high temperature disc brake bearing grease because it is formulated to withstand a much more hostile environment than the grease ever will see in a magneto.

[10E]

BoschZEV
Thanks for the continuing advice and opinions.
Quick question.
What type and grade etc. grease do you use on the armature ball bearing races.?
Thanks in advance
Victor Boocock
PS if you have mentioned it in the past posts I must have missed it.
More to come on the back up system.

[BoschZEV]

What damage is possible when trying to set up this type of system. ...
The scenario is.... In 10 mins the back up is working and it gets you back home...

Yes, I realize that's the scenario you're hoping for. My own hoped-for scenario also would have a gourmet cook drive by during those 10 minutes and serve a delicious snack while my butler dealt with the ignition system. But, the reality is more likely to be that the system your friends cobbled together would look good but would fail in short order taking an otherwise perfectly functional magneto with it because of some defect in the design/implementation that hadn't been apparent.

I was talking to 2014 Cannonballer Joe Gimpel about mags and other things too... He said he thought many of the 2010 riders had mag problems due to the fact that they used the wrong bearing grease. He saw disassembled mags with High temp moly grease in the bearings ("this grease will conduct electricity" Joe said) Only dielectric grease should be used in a magneto otherwise arcing of the bearing and besides pitting of the balls, will lead to other problems.

I'm sorry to say this about your friend but this is a case where a little knowledge is a dangerous thing.

If you look at the schematic I posted a few days ago you will see a connection to ground (earth) of the primary coil on the armature. This is needed because the current from the spark plug needs some way to get back to the primary after jumping the gap in order to complete the circuit. If you look at the following link in my restoration thread you will see this ground connection is provided by the sliding contact of a carbon brush on the back of the rotating points plate:

http://www.britbike.com/forums/ubbth...359#Post450359

If that brush weren't there and if the outer race of the bearings weren't insulated from the body of the armature, the path the current would take would be through the outer race, through the balls, and through the inner race to the shaft of the armature. Even though that current is small, it happens ~2000 times/minute so it would slowly cause pitting of the balls and race. This much your friend got right. However, that brush is there. But, this isn't the only thing he got wrong.

Although molybdenum disulfide grease has some electrical conductivity, it is very small. Still, grease slathered between the body of the magneto and making contact with the balls would carry some electrical current in parallel with that being carried by the carbon brush. However, when a current is faced with the choice of two parallel paths it divides in proportion to the resistances of those paths. Because the conductivity of the moly grease is so small, the resistance of the "ball bearing" path would be very large so the current through that path would be very much smaller than that through the brush. Because of this, the time required for this tiny current to cause pitting would be huge.

This is to be contrasted to the concern I'm sure your friend had read about but had misunderstood. If the bearing had been installed without an insulating cup between it and the housing the current would have the choice of a path through the carbon brush and an entirely-metallic path through the bearing. If that were the case, most of the current would take the lower resistance path through the bearing.

However, he got it even more wrong than the above since the dielectric grease he told you to use isn't designed for lubrication of bearings, but rather for one-time uses like lubricating a spark plug boot so it slides on easier, or smearing over an aluminum electrical connection to keep it from oxidizing. While I don't recommend moly grease for a magneto, using dielectric grease to lubricate the bearings would trade the essentially hypothetical failure mode of pitting that with moly only would happen after many tens of thousands of miles, with the very real failure mode of rapid wear of the bearings due to use of a completely inappropriate grease.

To a non informed Joe's thoughts made a great deal of sense, ... He mentioned he had made one for his Bosch mag in the past, and used it. ( batt. and coil set-up)
His system, using isolation parts etc uses the existing points assembly.

I would have to see photographs of the system Joe said he built before I could comment on it because as tfburke3 wrote:

With no wires to the spinning points I see no way to make this work to switch over to battery coil ign.without extensive modification.

Also,

I would like to see all Cannonballers and others have the least amount of trouble with mags

My sentiments exactly.

[tfburke3]

BoschZEV
What damage is possible when trying to set up this type of system. It would be good to know before firing it up.
The scenario is-- Riding by myself, the mag quits on Utah on Hwy 50, the armature shaft still rotates, your 98 miles from anywhere, the cell phone doesn't work, you only see another person every 45 mins. and they don't always stop to help. In 10 mins the back up is working and it gets you back home 1000 miles away. or it gets you to the night stop where a back-up mag can be delivered, if needed.
This is not a dream, I've done it three times, without trouble. Maybe the 4th time, next spring, I won't be quite so trouble free.




Whoops-- All change, maybe.
Whilst my mag as proved to have been rebuilt in the correct manner and still continues to spark reliably I still maintain that trying to finish a Cannonball day or get to home base after a 400 mile day it would be a great help having a quick change back-up system.

Having a "proper belt".
Keeping in mind if the 2016 Cannonball is a pre-17 event there will be a lot of magneto bikes entered. For the best enjoyment of the riders it would be great if the problems of the 2010 magneto problems are not repeated.
You have covered a rebuild that would help prevent this from happening. Riders would do well to at least read up on your articles whilst there is is good time to take it all in and get their mags in good order.
I was talking to 2014 Cannonballer Joe Gimpel about mags and other things too.
He mentioned something that really shook me. He said he thought many of the 2010 riders had mag problems due to the fact that they used the wrong bearing grease. He saw disassembled mags with High temp moly grease in the bearings ("this grease will conduct electricity" Joe said) Only dielectric grease should be used in a magneto otherwise arcing of the bearing and besides pitting of the balls, will lead to other problems.
To a non informed Joe's thoughts made a great deal of sense, and I believe I read some where that Mr Bosch went to a great deal of trouble by installing a device to help eliminate this problem.
I know that condensers appeared to be part of the problem too, but non the less if Joe is correct, The un-informed people may have never stood a chance of a reliable mag.

Just to throw a spanner in the works. We talked about a back-up system. He mentioned he had made one for his Bosch mag in the past, and used it. ( batt. and coil set-up)
His system, using isolation parts etc uses the existing points assembly. He said it worked fine, in fact, he lent it to a friend 2 years ago whilst his mag was being re-built, in Germany. and the back up system as been working ever since.
Would appreciate your feeling about both the grease issues and Joe's back-up system.
The reason for this conversation is I would like to see all Cannonballers and others have the least amount of trouble with mags
Regards
Looking forward to your reply
Victor Boocock 10E

As Bosch ZEV stated the spinning points and condenser in the bosch mag,at least in my FFVRS,complicate things.With no wires to the spinning points I see no way to make this work to switch over to battery coil ign.without extensive modification.
However a mag with fixed points and spinning cam are easily converted to wasted spark or a distributor,but in my opinion not a road side switching situation.
Tom
Tom

[10E]

I wrote an article on my extensive toolkit in 'The Antique Motorcycle' a few issues ago so it's not that I don't expect things to break. However, although someone might have a spare carburetor or piston in a chase van on a cross-country ride, few people head out with such parts in their saddlebags expecting to need them for roadside replacement.

I realize electricity is a perplexing subject for many motorcyclists, but there is no reason the electrics can't be at least as reliable as any other part of a motorcycle. You said your current magneto has 11,000 miles on it without problem. I would suggest to people considering having a backup electric system that rather than hoping a "belt and braces" approach might keep the electrics working, where neither the belt nor the braces has passed inspection, it would be better to concentrate on having a proper belt in the first place. As you have experienced yourself a proper belt, er, I mean, magneto, will be reliable for many thousands of miles.

At best, whatever your friends do when messing with your magneto to equip it to also run a backup battery ignition system won't inadvertently make your magneto less reliable. But, my worry is that it will. Still, if you do proceed with this, please don't forget to post photos of what the modification looks like.

BoschZEV
What damage is possible when trying to set up this type of system. It would be good to know before firing it up.
The scenario is-- Riding by myself, the mag quits on Utah on Hwy 50, the armature shaft still rotates, your 98 miles from anywhere, the cell phone doesn't work, you only see another person every 45 mins. and they don't always stop to help. In 10 mins the back up is working and it gets you back home 1000 miles away. or it gets you to the night stop where a back-up mag can be delivered, if needed.
This is not a dream, I've done it three times, without trouble. Maybe the 4th time, next spring, I won't be quite so trouble free.




Whoops-- All change, maybe.
Whilst my mag as proved to have been rebuilt in the correct manner and still continues to spark reliably I still maintain that trying to finish a Cannonball day or get to home base after a 400 mile day it would be a great help having a quick change back-up system.

Having a "proper belt".
Keeping in mind if the 2016 Cannonball is a pre-17 event there will be a lot of magneto bikes entered. For the best enjoyment of the riders it would be great if the problems of the 2010 magneto problems are not repeated.
You have covered a rebuild that would help prevent this from happening. Riders would do well to at least read up on your articles whilst there is is good time to take it all in and get their mags in good order.
I was talking to 2014 Cannonballer Joe Gimpel about mags and other things too.
He mentioned something that really shook me. He said he thought many of the 2010 riders had mag problems due to the fact that they used the wrong bearing grease. He saw disassembled mags with High temp moly grease in the bearings ("this grease will conduct electricity" Joe said) Only dielectric grease should be used in a magneto otherwise arcing of the bearing and besides pitting of the balls, will lead to other problems.
To a non informed Joe's thoughts made a great deal of sense, and I believe I read some where that Mr Bosch went to a great deal of trouble by installing a device to help eliminate this problem.
I know that condensers appeared to be part of the problem too, but non the less if Joe is correct, The un-informed people may have never stood a chance of a reliable mag.

Just to throw a spanner in the works. We talked about a back-up system. He mentioned he had made one for his Bosch mag in the past, and used it. ( batt. and coil set-up)
His system, using isolation parts etc uses the existing points assembly. He said it worked fine, in fact, he lent it to a friend 2 years ago whilst his mag was being re-built, in Germany. and the back up system as been working ever since.
Would appreciate your feeling about both the grease issues and Joe's back-up system.
The reason for this conversation is I would like to see all Cannonballers and others have the least amount of trouble with mags
Regards
Looking forward to your reply
Victor Boocock 10E

[BoschZEV]

I will work towards making a back-up ignition system using your principles.

I wrote an article on my extensive toolkit in 'The Antique Motorcycle' a few issues ago so it's not that I don't expect things to break. However, although someone might have a spare carburetor or piston in a chase van on a cross-country ride, few people head out with such parts in their saddlebags expecting to need them for roadside replacement.

I realize electricity is a perplexing subject for many motorcyclists, but there is no reason the electrics can't be at least as reliable as any other part of a motorcycle. You said your current magneto has 11,000 miles on it without problem. I would suggest to people considering having a backup electric system that rather than hoping a "belt and braces" approach might keep the electrics working, where neither the belt nor the braces has passed inspection, it would be better to concentrate on having a proper belt in the first place. As you have experienced yourself a proper belt, er, I mean, magneto, will be reliable for many thousands of miles.

At best, whatever your friends do when messing with your magneto to equip it to also run a backup battery ignition system won't inadvertently make your magneto less reliable. But, my worry is that it will. Still, if you do proceed with this, please don't forget to post photos of what the modification looks like.

[10E]

BoschZEV
Thank you for the schematic and explanation.
I will work towards making a back-up ignition system using your principles.
Thanks again
Victor Boocock

[BoschZEV]

Magneto_Battery.jpgI edited/combined two schematics to show both systems side-by-side. The "only" things you have to do are remove the portion of the circuit in red on the left and then connect the points (in green) to the corresponding part of the circuit on the right. Of course, complicating matters is the portion of the circuit in red is the bolt that holds the points to the armature, and the points on the left are rotating at a few thousand rpm while the ones on the right are stationary.

[BoschZEV]

My friends are puzzled by your statement "while a standard points/coil system fires when they close".
Are they confused about this system, or is this a typo.

Yes, it's a typo. I had originally written something longer but at the last minute edited it down resulting in that error.

If you simply connected a "standard" battery and coil system to the points of a magneto the ~0.5 Ohms of the magneto primary would be in parallel with the points and the current would divide itself between those two routes according to the relative resistances. If the resistance of the points was very much less than 0.5 Ohms the parallel path wouldn't matter, at least as far as current flow when the points were closed, because most of the current would flow through the low resistance points. However, when the points opened, instead of the current being interrupted, the magnetic field collapsing, and a spark being generated, the current would just reroute itself through the magneto's primary. Now the 12V of the battery would be directly across the 0.5 Ohms and 24 Amps would flow through the magneto generating I^2R = 290 Watts of heat in its coil. If the points are open ~20% of the time as they are with the cam that's in my friend's Bosch ZEV the average heat would be ~60 W. You know how hot a 60 W light bulb is, so imagine the temperature it would reach if covered with insulating varnish and in an enclosed space. That's why the magneto's coil would have to be switched out of the circuit at the same time an external battery system was switched in.

Any chance of a schematic.

I have a very nice schematic for this purpose, and normally it would be easy to upload, but it's a little complicated at the moment. I'll see if I can post something later today or tomorrow. But, the engineering problem you face in trying to accomplish this is that the points in a magneto rotate with the armature while the cam is fixed. It would be much easier if they were fixed and the cam rotated, like in a car's distributor.

[10E]

BoschZEV
I think all could benefit from a seminar on Magnetos. I will mention it at our next club meeting.
My friends are puzzled by your statement "while a standard points/coil system fires when they close".
Are they confused about this system, or is this a typo.
They are going crazy trying to know the truth. Appreciate your response in advance.
I have a rebuilt spare mag. so I am ready to go to work on setting up a bench test, but need more information on how to isolate the points etc from the mag coil and any other needed information when switching from mag to battery . Any chance of a schematic.
I talked to my friend about a rent a bike for the Cannonball. He's open to a discussion. If interested.
Looking forward to your response
Victor Boocock