No dash lights, then engine died

[n3303j]

Brush spring base can also be fitted 1/2 turn wrong in rotation and not supply sufficient pressure for consistent charging. Found that one out after reading brush pressure specs somewhere or other.

[Groover]

Thanks again guys, ended up scoring and ordering a new Rotor (NOS Bosch Original) The spare I have doesn't look too good, so opted for a new replacement. The one that just failed only had about 11,000 miles on it, it was from one of the replacement kits I bought when I restored the bike.

I may replace the brushes and brushes holder with springs maybe, I don't think that was ever replaced. I did replace the brushes as part of the kit at that time.

Thanks again, I should have checked the rotor continuity to begin with and also as advised here. What got me was the battery dying and the bike ALSO dying out, which still doesn't make any sense.

For others and myself in the future - I have been chasing the battery charging issue for over a year now, been living with putting on the the charger when home. All has checked out, has been a truly frustrating and intermittent issue, and I think it may have been the rotor all along, which may have had a split in the wire winding that maybe was open at times maybe not open others, who knows.

What finally did it I think, which made the it go out for good was a nice stretch of highway at high speed, as this last all this happened off the exit ramp once I got into town.

Before this, all was looking good (would even get a charge voltage of 13V + and the light would come on at idle, seems it charged, but then there were those random days on occasion that the battery would be dead by the time I got home (daylight running headlight would run it down).

[n3303j]

[SNIP]
Thanks again, I should have checked the rotor continuity to begin with and also as advised here. What got me was the battery dying and the bike ALSO dying out, which still doesn't make any sense.
[SNIP]

If the battery dies and the alternator can not supply current there will be no source for sparks. The engine will stop.

[PeteS]

Most often when a rotor or DC armature goes a wire breaks where it goes into the slip ring or commutator.  When you get your new rotor check the resistance between the slip rings and compare with the one you are replacing.

Pete

[Chuck in Indiana]

Rotors seldom go past 50K miles if the electrical system hasn't been cleaned up, etc. It's the most common problem on the Bosch system.

[Groover]

Just received this delicious NOS OEM Bosch Rotor - Reads 3.4 Ohms, the old one I was going to install reads 3.2 Ohms. The one currently installed is open circuit so it's a failed one for sure.

Has some sort of protective coating, it's not wax, it's almost like a really thinned out paint - should I leave it or remove it? If so, with what? Almost thinking I should keep this as an antique and put my 3.2 Ohm one it ;-)





Thanks again 

[guzzisteve]

Do not remove the shellac that coats rotor windings. It protects the wires. 

I used to get my rotors from-----------http://www.motoelekt.com/
Made to meet aircraft standards. Never had one of his go bad.

[John A]

Wot Steve says. It helps keep the wire from moving around under centrifugal force

[Mike Tashjian]

I have a spray can of red shellac for armatures that I bought years ago.  Make sure if the shellac is damaged you are not open and either spray or brush on more shellac and recheck after it dries.  It insulates the winding which must be wound tight but not make electrical contact with each other.   A Wikipedia quote that says it well.  "The shellac locked the wire turns in place, provided extra insulation, prevented movement and vibration and reduced buzz and hum. In motors and generators it also helps transfer force generated by magnetic attraction and repulsion from the windings to the rotor or armature".  Preventing vibration which may be a cause of failure would be a good reason to make sure the shellac is in good shape. 

[testa_di_formaggio]

On one of these Bosch systems, always check the continuity/resistance of the armature FIRST. 95% of the time that's the problem. If you really do have an OEM NEW OLD STOCK armature, (it doesn't look NOS to me, those didn't have all that shellac), pay attention where the two ends of the wire come and run to the comm rings. Like Pete says, that's the weak point. If I remember right, the old OEM ones didn't have holes, and the wire came up and over the frame thru a paper or fabric tube to insulate it before reaching the rings. Even more failure prone. In either instance, if that wire isn't shellacked down good, do it. Don't forget, if the wire is uninsulated, make sure it's not touching the frame when gluing it up. Once upon a road trip long ago, I had one fail. The wire broke, where I could get at it at least. Thanks to a solder gun at the gas station up North, from the friendly old timer running the place, and a magnum or so of JB Weld to glue it down, I made it the rest of the way. And I got another couple three thousand miles out of it.

TdF

[Groover]

Thanks again, still haven't has a chance to install it. Looked at the listing where I got it, and it says New, Unused, and said Bosch, so assuming NOS, but who knows. Good link guzzisteve (http://www.motoelekt.com), will use that in the future. Thank you all for clarifying in the shellac, makes sense. Its the green part of the metal that I was wondering if I should remove, seems it can stay?


Posting a few more photos just to share.








Thanks again.

[n3303j]

Maybe just the pictures, but those commutator rings look really rough. Almost like they are not finish machined.

[Groover]

Finally replaced the rotor, worked like it should for 1 day, now the charge light is permanently on. Might be stator, yellow output is low

[testa_di_formaggio]

New rotor. Polarize it.

TdF

[guzzisteve]

Check it across slip rings for ohm's or open(broke wire). Good Luck

[John A]

The slip rings look like they have shellac on them. They should be clean.

[n3303j]

Charge light is lit by the continuity of the exciter current passing through the brushes, slip rings and rotor coil. If the charge light is lit your brushes, slip rings and rotor coil are continuous.

This is assuming all your wiring is stock and there are no shorts.

[Groover]

I cleaned the slip rings, they were just dull, the rotor has continuity, wiring is stock (Greg bender), it all worked perfectly for a full day. Parked later in the day, then when I started riding the light would stay on. I had parked and started tre bike throughout the day a few other times, and all was working. I checked the regulator with another I had, sane difference. I have a spare diode board I might try later. All looks good otherwise. Thanks again for the assistance.

[blackcat]

I had a similar problem on the CX, brush holder had a hairline crack and it was enough to cause a charging problem. At the time there was no way to buy a brush holder but they can now be purchased through MG Cycle. Worth a close look.

[n3303j]

You do have the brush springs wound about 3/4 turn when they are pressing on the brush. This puts about a 1 pound load on the brushes.

The brush springs installed 180° incorrectly will still push on the brushes but at a pressure insufficient to guarantee contact while the rotor is spinning and vibrating.

[Groover]

Would someone be able to clarify what testa_di_formaggio mentions please? The polarizing, which I think is the same as what is mentioned here: https://wildguzzi.com/forum/index.php?topic=91322.0

I do have a spare 12v battery I could use for it if that makes it easier.

A bit at a loss with this, I ordered a good/used stator and rotor, will try that next. Again, all seems to be OK when I look around test what I have in there now, though I don't get the expected 40v between pairs of the 3-yellow wires when at/around 4K RPM (mentioned on the linked post), I got maybe 20volts between pairs), and 1 pair was less, so thinking the stator is faulty?

Last try at this, then I may just order a whole new kit. I had replaced them one already around 11,000 miles ago.

[moto]

Would someone be able to clarify what testa_di_formaggio mentions please? The polarizing, which I think is the same as what is mentioned here: https://wildguzzi.com/forum/index.php?topic=91322.0
...

Testa di Formaggio himself, if have this nom de net correctly associated, polarized my own new rotor in front of my eyes. Worked as advertised. Try it. The battery in your bike will do.

[Groover]

Ok, thank you Moto. I read the first part of that thread again, and makes sense I think. Basically + and - to each slip ring for ?? amount of time, thinking 30 seconds maybe (?) and that's it?


Edit: Isolated of course. (no brushed touching)

[moto]

Ok, thank you Moto. I read the first part of that thread again, and makes sense I think. Basically + and - to each slip ring for ?? amount of time, thinking 30 seconds maybe (?) and that's it?


Edit: Isolated of course. (no brushed touching)

Isolated. This was over 30 years ago. I think there are only two slip rings, right? Briefly press the positive wire to one and the negative to the other. Not more than about a second, I recall. Could do it longer if not successful at first. No need to repeat the other way around, or to worry about which ring gets the positive charge, I believe, since it is an alternator.

[n3303j]

Alternators don't have to be polarized. If wired correctly the alternator is fed a current through the charge light filament each time  you turn the key on. That current is enough to generate a magnetic field in the rotor and start a current flow in the field.

It was generators that had to be polarized. From the factory they had no magnetism in the field. So a spinning armature did not generate electricity. Running the battery (once at install) through the field left residual magnetism in the field poles. This was enough to start the process of generation when the armature was spun up on subsequent starts.

[moto]

Alternators don't have to be polarized. If wired correctly the alternator is fed a current through the charge light filament each time  you turn the key on. That current is enough to generate a magnetic field in the rotor and start a current flow in the field.

It was generators that had to be polarized. From the factory they had no magnetism in the field. So a spinning armature did not generate electricity. Running the battery (once at install) through the field left residual magnetism in the field poles. This was enough to start the process of generation when the armature was spun up on subsequent starts.

I agree with this reasoning. Nonetheless, the very knowledgeable TdF performed this simple operation on my T3 with immediate effect.

[n3303j]

I'm still curious if the OP has confirmed proper pressure on the brushes. It's easy to mismount the springs by 1/2 turn and not get proper contact on the slip rings.

[Groover]

I checked the springs and brushes last week, and they looked good. I did not remove the springs nor the brushes when I pulled it off the front of the engine to replace the rotor, so all stayed in place in the housing in that regard. Everything worked correctly for 10,000-ish miles until this last rotor failure (which did have a broken wire), that is when the dash light went out prompting this thread. Last week or so, I finally got around to replacing the rotor (which is when I checked the springs), checked everything else while at it again. Once the rotor was replaced, the dash/battery light would only come on at low rpm. then off once it hit 2k-ish maybe (normal operation), also was charging (voltage would hit around 14v+ when giving it a little throttle), thought the problem was solved, until this last failure, which stopped the charging and also made the battery/dash light stay on consistently. When I check things now, seems the only issues that I can tell is the low output from the yellow wires. At this point, going to wait until this eBay stator replacement shows up, then I'll follow-up with an update.


Sorry for the slowness on this. I don't have a garage, then it's too hot, then it rains, when the weather is nice I opt to go for a ride; the trickle-charged-up battery gets me through the evening rides after work, so I've been able to 'get by' that way, and I also carry a small jump starter with me if it completely died out, which hasn't to this point, though I don't go too far


Thanks again for the help - I will hopefully and soon be able to get the final answer on this.

[testa_di_formaggio]

Ron is correct. In theory, alternators don't need to be polarized. However, I've had to do it numerous times over the years, and recommended it to others having problems. Perhaps "exciting" is a better term. Usually, on installation of a new or re wound armature, or on bikes that have sat for a long time. I've figured it's related to residual magnetism, at least that's what I took away from the old instructor at Delco in Indiana when I was there for DC unit diagnosis and repair 30+ years ago. The busses I worked on had "generators", providing 12 and 24V DC. And then I realized that they were pretty much the same setup with the Bosch charging system on my T3. It's an alternator, producing AC, then rectifying it to DC ? Whatever, have forgotten the theories. None the less, our instructor told us we had to polarize the unit on install. His statement was kind of "you need to kick the ass of the electrons in the circuit so they know which way to flow". And low and behold, Dave R mentions it in Guzziology as well. And NOTE. You are not jumping the C rings. You "flash", meaning quickly touch and remove a jumper wire from your battery + to D+ (I think) on the stator. You'll see a spark, pull the wire off. You don't need (or want to I would think), to sit there holding the wire there for time eternal. Since I can't remember which terminal on the stator it is, if D+ doesn't do the trick, try it on the DF terminal, same deal, quick touch of the wire. I've never hurt anything doing both. That or look it up in Guzziology, trust me, it's there.     

TdF

[n3303j]

The older Bosch generator as used on the BMW /2 series was a generator that produced direct current. The rotor consisted of a series of coils that were connected to a segmented commutator. The brushes picked up the current at the same point in the rotation cycle. Hence they got DC directly from the device.



These had to be polarized at install (or after years out of service). It was something about dropping a hot line in an external stator terminal on the fully assembled unit for a half second or less. Been about 20 years since I had to polarize the /2.