Advise wanted: Alternator photos here

[gsmetal]

OK I took the alternater out of my 93 K1100LT with 50,000 miles.

I was getting some vibration and the battery light on my dash was dim so I figure the "rubber goobers" are shot.

I took some picture of the alternator with the rubber goobers in them and the goobers are clearly shot. But I also notice the metal shavings - what's up with that??

You'll also see on the next post down the photo of the "drive dog" (cool name..who thought of that one!) that's mounted on the motor.

Any advise on how to proceed? Should I have the alternator rebuilt right away? Is there a test to see if it's sick?

As always, thanks in advance - (isn't the Internet great?)

[gsmetal]

Here's a photo of the drive dog:

[breyfogle]

I just got done doing the same thing to my K75s at about 110,000 miles, no vibration but the charging light was coming on dimmly more than "normal". Sometimes at idle but also sometimes at high RPM. FWIW, I had NO metal shavings at all in the drive coupling. That can not be a good sign since the metal has to come from either the alternator drive coupling or from somewhere inside the engine block.

In my case, I expected to replace the brushes but when I removed the voltage regulator to inspect the brushes, I found that one of the two commutator slip rigs was very deeply grooved by its brush. The old brushes were not making good contact with the slip ring and new brushes would have been even worse. I had the whole alternator rebuilt at an auto electric shop. New slip rings, brushes, regulator and a thorough cleaning of the housing. It should be good as new and ready for another 100K miles.

I don't think the guy that did the work had ever seen a motorcycle alternator, he asked me if it was from a light plane or somthin', but apparently Bosch alternators are easy for professionals to work on.

[bmwmick]

I pulled my alternator out ('93 K1100LT) at 125K miles and it looked like new. The rubbers were a little worn but there were no shavings. Do you have ANY lateral play in the driving dog shaft or the alternator shaft. Something has clearly been running metal-to-metal and that is NOT a good thing.

[kbasa]

Is there any axial play in either component? I notice that the monkey nutz don't even come close to filling the cavity they're supposed to.

[gsmetal]

I'll have to check and see if there is any play...I really haven't checked that yet.

What bothers me about the metal shaving is, if you look at both photos, you don't see ANY sign of wear or shinyness that indicates wear.

I pulled this out late last night :hungover and didn't really get into a post mordum...I'll do that tonight and see what I see.

[gsmetal]

The bearing in the alternator is shot....that's where the metal files are coming from.

[gsmetal]

Well after some closer inspection the bearing isn't shot after all.

Turns out the nut holding the coupler on the alternator worked it's way loose and the metal shavings are from the coupler bouncing around the nut. No damage to the shaft just needed a new coupler. A trip to the alterntor fix it store reveals a very healthy alternator with a healthy charge rate.

So with a new coupler ($12.00) and new rubber dampers ($12.00) and the diagnosis and coupler nut from the alternator fix it store (no charge) I'm back in business.

I'll post a photo of the coupler damage when I get a chance.

Looks like I caught it in a nick of time before any major damage was done :dance

[riderR1150GSAdv]

Lucky for you that the 'damage' wasn't more serious and required a simple fix :clap

[bmwmick]

You're VERY lucky it wasn't the 'driving dog' side. :)

[gsmetal]

Here's the damage to the coupler.

The damage to it is actually worse than it looks - the whole inner portion where the shaft goes is missing...

[kbasa]

Yucky. That's probably what toasted the rubber hoobers too.

[Burnszilla]

Yucky. That's probably what toasted the rubber hoobers too.
I thought they were called Monkey Nuts.

[gsmetal]

In the first photo, you can see the rubber dampers have a bridge which connects two dampers. You can see that the bridge goes over a fin in the coupler.

THIS IS WRONG.

It's wrong and it's what I believed led to the failure.

The bridge should actually be on the floor of the coupler and against the wall of the coupler (according to the manual).

How's that for a CSI moment?

[Burnszilla]

Speaking of alternator problems...
After working in the yard all day, I decided to move my bikes back to their parking spot in the driveway. A rattling noise came from the alternator area as it idled. I cussed like the father in the basement in 'A Christmas Story'. I took off the black plastic side cover on the alternator and stuck my finger in to touch the cup. It moved! Found the problem. It was loosey goosey.

It was 7pm and the sun was going down. I hooked up a work light and dimantled the battery area and pulled out the 50watt alternator. The four screws behind the cup that hold the bearings in were all loose, just hanging there. I took the cup off with my impact driver on the kitchen counter and put thread locker Red on all the screws and tightened them all up. There were also a bunch of metal shavings laying under the alternator dog. I'm guessing it was from the fins rubbing against the inside of the alterator case.

Put the bike back together in the dark with the work light. The neighbors must think I'm nuts. Got the job done in 2 hours flat. Told the wife I saved over $300 labor at the BMW dealer... That should help justify my Garmin 2720 purchase on Friday.. ;)

[tjtraver]

I've read about quite a few failures of these rubber bits .

Rather than having problems alongside the road this summer , considering these are so inexpensive and easy to replace , should I consider replacing them at my leisure in my garage as periodic maintenance item ? I have a 1995 K75 with 21,000 miles with no indications of any problems and want to keep it that way ;-)

Hmmm ...I had the dealer do a clutch spline lube recently, if he have to pull the alternator to do that , I'd think he would have placed them if any indication of problems ?

Any thoughts or suggestions welcome.

Todd

[gsmetal]

Knowing now what the job involves, I would classify this as a very easy repair that should be done before it's a problem on the side of the road. :hungover

Burnszilla really pushed the time envelope getting it done in about 2 hours. I probably spent a little more time than that but not too much more. The actual repair is about 5 minutes with the rest of the time moving things out of the way and putting it back together.

I'm glad it's done!

[breyfogle]

I've read about quite a few failures of these rubber bits .
Any thoughts or suggestions welcome.
Todd

At 11 years/21,000 miles your Monkey Nuts should last you 'till about the year 2050 or so. It might be a bit premature to be worrying about such things. gsmetal's problem had a lot to do with the rubber gubbers being installed upside down and the coupler nut not being tightened to spec. When I had my alternater rebuilt at 110 Kmiles, the rubber bits looked like new. I suspect that if the alternator has never been off the bike or only taken off by a good mechanic, the Monkey Nuts will outlive the alternator.

Go for a ride, don't worry about it.