How to inspect and service an R1100 Alternator

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ibjman
Posts: 65
Joined: Sat Nov 09, 2013 6:35 pm
Location: Phoenix, Arizona

How to inspect and service an R1100 Alternator

Post by ibjman » Fri Jan 30, 2015 2:46 am

Here (hopefully is the link to the pictures that go with this post:

"http://tinypic.com/a/3bz2c/2".

Our RT is our long distance tour bike, hence I try to maintain it in such a way as to avoid on road failures if possible.
We acquired this bike from an ebay auction at 72,000 miles with no service history. The seller stated that he had bought it at auction.
The bike had a knock in the engine when I rode it home so a lower mileage (14,000 mi, 1995) engine was obtained & installed. The 72,000 mile alternator was reinstalled at the swap. We now have 81,000 miles on the machine. I am preparing it for our second annual journey to the MOA Rally at Billings Mt.
I've always thought perhaps I could hear a light "hissing" noise from the area at the top of the engine so I decided an inspection of the alternator was due.
I have attached my photos to a "tinypic" account link, but I do not know how long they will keep them on the server.
The procedure was pretty straight forward for those of us who have experience with alternators, but I thought there might be some readers who could benefit.

After removal of the assy. Disassembly was begun. I'll try to list a description of the steps, but the pictures uploaded in no particular order so the user will have to hunt & peck to sort it all out.

I began with removing the rear 1/2. remove the 3 screws that hold the plastic cover on the rear. Next, careful unseat the 3 locking plastic locking tabs around the cover (these are very fragile and break off extremely easy due to their exposure to the engine temps. I broke 1 of the 3 immediately but elected to go forward as I felt the retaining screws would do an adequate job of retaining the cover with only 2 of the 3 tabs remaining.
After removing the back cover, I took a moment to make a match mark on the sides of the aluminum from & back housings with a magic marker.
I next removed the 2 screws that secure the voltage regulator/brush holder to the rear end frame/rectifier board.
Inspect the amount of free travel remaining with the brushes as they fit against the armature slip rings with internal spring tension. Mine appeared to have about 1/4" of useable brush wear remaining and the charging voltage was within spec before disassembly so I elected to re-use this part.
Next, unfasten the 4 screws that hold the rear end frame to the front half. One screw remains trapped behind the protrusion for the power terminals on the side. Remove the other 3.
After unfastening of the screws the entire rear 1/2 assy. can be dislodged from the front half with only a little gentle prying & tapping. The stator or field coil stays attached to the rear 1/2. NOTE: the white plastic bearing sleeve that surrounds the rear bearing. it may or may not come out with the housing. Note carefully its positional orientation in the rear housing. It only fits correctly one way with the water drain slot pointing straight down. It should slip either out of the rear housing or off the rear bearing quite easily.
With the rear 1/2 removed, remove the drive belt pulley from the front of the armature (Rotor). The front of the rotor has a center fitting to insert an 8mm hex key which can be used to hold the rotor while unscrewing the pulley retaining nut. (I used an impact wrench instead).
After removal of the nut and washer, the pulley slips off by hand, fully exposing the four small screws that secure the front bearing retaining plate to the inside of the front housing. Remove those & set aside.
The entire rotor assy. complete with both bearings can now be removed from the front housing. A bit more tapping and wiggling is required, but mine came out quite easily. You may want to apply some gentle heat on the aluminum casting to expand it from the bearing.
Now we are left with the rotor assy. in hand. The resistance across the slip rings can be inspected with a multi-meter at any stage of the work. Reading is approx. 3 Ohms.
At this point, one can turn the bearings by hand to inspect for any roughness or tight spots that might indicate a failure, mine were silky smooth.
At this point I elected to move away from standard recommended practices and add some fresh grease to the bearings. Most people would not recommend this procedure as it has the tendency to damage the bearing seals. Over the years I have inspected and repacked many sealed bearings with good success including motorcycle wheel bearings. (Again, probably not recommended).
To gain partial access to the bearing innards, one of the 2 grease seals needs to be removed. This is a very delicate procedure so be prepared to go shopping for some new bearings if you have difficulty. (Not for the faint of heart).
The rear bearing seal is exposed and accessible. The outer front bearing seal, however) is partially shielded behind the pulley spacer washer that will be found pressed on to the shaft behind the pulley. Fortunately, I found the spacer to be only lightly press fit on the shaft and since it incorporates a slight raised collar on the back side it's easy to get under the edges with some prying tools. I gently clamped the sides of the rotor in a vice on the larger steel parts.
Again extreme caution must be exercised here to keep from squashing the rotor housing. Also a great deal of care is offered to avoid bending the fins of the fans on the rotor. If you've gotten this far we'll assume you know how to be careful of things. A few of moments with a couple of large screwdrivers under the edge of the washer had it removed about 1 inch up the shaft from it's base. For convenience, I used my power steering and alternator pulley removal kit to lift it the remaining 1/2" or so off the shaft. You can be creative here and use whatever you have that works. Not when removing the washer that the raised shoulder side goes down against the rotor upon reassembly.
Now that the spacer is off, clean the bearings and related areas in a suitable way. I just wiped them with clean paper towels, others may want to use some gentle solvent washing to accomplish this. Common sense prevails.
Next, we need to remove 1 front and 1 rear bearing seal to gain access to the heart of the bearing.
I do this with a needle sharp pick tool. Carefully place the pick against the inside circumference of the seal and slide around the bearing center shoulder slightly and carefully rolling the edge of the seal up over the point of the pick. It is all to easy at this point to poke a hole or tear the edge of the seal. I've had years of experience ruining these so I have better luck these days......LOL. t any rate after the point of the pick is under the lip of the seal, it can be levered around and DOWNWARD until it can be slid part way under the entire seal and pointing back out towards the outer edge. A little pressure at this point will deform the seal body upward (it's VERY thin brass under the rubber) and the seal will pop out of the bearing.
Repeat the same process on the rear bearing. See the pictures if possible.
Hopefully, at this point, we have two slightly bent but otherwise undamaged seals on the bench.
I found that by selecting a suitable size socket from the tool tray and standing it on end it makes a perfect miniature anvil. Place the seal on top and give it an extremely light "tap" with your tiny 2 oz. ball peen hammer......it should look perfectly flat again. Ready for re-installation. The actual picture on the web link where I show the pick, were taken after the seal had been tapped back into shape and reinstalled.
Once the seals are correct.......move on to adding some extra nice wheel bearing grease to the existing stuff that's preloaded in the bearing from factory.
Be sure you don't have a can of that old 1950 Thick sticky "fibrous" grease form the be bob age laying around. Modern wheel bearing grease is light and slippery and does a great job in a sealed bearing without overheating.
Follow the lead of the photos.......wipe out what old debris you can with clean paper towels.....then get one of those syringes at the drug store that are used to force feed your cat or administer liquid potions to a stubborn child. Pack the syringe with grease and gently insert it as well as possible between the rollers of the bearing and their plastic bearing cages. Follow up by "packing" the grease down in the bearings with a gentle finger compression move. A little more grease , then some more finger pressure......the bearing should now be fill of grease.
Clean out the top surface of the bearing edge with more paper towels so that there's sufficient room for the deal to be reinstalled.
Reinstall both seals by just sitting them in place and gently sliding around their edges with your thumbs.....they should go in quite easily. A little extra care at this point should be used especially on the inner circumference of the seal to see that it's fragile lip edge rolled down perfectly in against the bearing inner race.

Some folks will elect to replace these bearings instead of trying to re-grease them. It should be a relatively simple procedure to extract these bearings with a small standard style 3 jaw puller. It appears that there is sufficient room under the edges to get the puller jaws in there.
I did not see in the parts fiche where BMW sells these. It's likely that one could take the old ones to any big bearing supplier & match them up if desired.
Now, it's a pretty straight forward procedure to reassemble the unit in the reverse order that it came apart. I included some pictures of supporting the rotor on various deep impact sockets while reinstalling the pulley spacer on the rotor and some pics. of how to reach under and lift the inner front bearing retainer with a pick tool so that you can get the retaining plate screws started in their treads.
I am sure I've made some errors in posting this up.....so I'll look forward to any suggestions on how to edit it to make it more understandable.
I tried hard to include a few suitable cautions to inform that these are "shade tree" procedures and certainly would not be recommended by a lot of viewers.
I've grown up through my 67 years learning to take things apart and fix things where I felt I could instead of just installing new stuff all the time.
As I said......others are free to disagree.
Likely in this oilhead section very few people will read it anyhow!
"There is a big difference between the parts changers and the mechanics"
Regards & happy wrenching: Ibjman

Major Softie
Posts: 8900
Joined: Tue Aug 03, 2010 1:46 pm

Re: How to inspect and service an R1100 Alternator

Post by Major Softie » Fri Jan 30, 2015 1:19 pm

Your link did not work, but pasting it into my browser takes me to you pics.

Haven't read your tome yet, but will respond when I'm done. ;)
MS - out

Major Softie
Posts: 8900
Joined: Tue Aug 03, 2010 1:46 pm

Re: How to inspect and service an R1100 Alternator

Post by Major Softie » Fri Jan 30, 2015 1:31 pm

Yeah, I don't think I personally would go to all that trouble and not replace the bearings, especially if I was hearing a noise that I suspected was from the alternator, but then I don't have all your experience with successful repacking, so I'd be expecting to mangle them anyway. :lol:

I've never heard that noise from an Oilhead, but I've heard a couple K75's that sounded like jet engines their alternators were making such a loud "hissing." Your post (including the pictures) is certainly very helpful for anyone interested in getting inside one, even if they plan on replacing those bearings.
MS - out

User avatar
ibjman
Posts: 65
Joined: Sat Nov 09, 2013 6:35 pm
Location: Phoenix, Arizona

Re: How to inspect and service an R1100 Alternator

Post by ibjman » Fri Jan 30, 2015 10:32 pm

I have decided that whatever noise I thought I was hearing probably was not from the inside of the alt. Perhaps just the sound of the serpentine belt spinning on the pulleys......probably nothing to worry about. As it turned out this alt probably would have lasted the rest of my days, as it was. The satisfaction is no being sure that everything in there is "jake". The belt looks pristine but I'll replace it anyway & then just forget it for the rest of my life (67 years now....lol.
As soon as that's back together, I need to replace a small plastic "dress bezel" that's cracked in two at the top of the right fork tube under the handlebar. After that, I'm moving to the rear wheel to get access to the final drive where I intend to replace the crown wheel bearing & seal.
Finally, I have to repaint the right side plastics and both mirror shells for they've suffered some damage.
Then it's all back together and off to Billings in July.
Going out tomorrow morning in forecast light rain to thunderstorms to attend (My) first meeting after joining the AMCA
Antique Motorcycle Club of America. Will be riding my old standby 85 K100rs. I hope it qualifies to the membership as "Vintage". It's almost exactly 30 years old.
The original plan was to drive the newly acquired (almost finished) 1977 Yamaha RD400.....but alas ongoing motor difficulties make it still not ready for prime time. I Also have a 1970 Moto-Guzzi in the shed that someday will shine again if I ever get back to fixing on it.
I'm still intending to do some edits on the alternator fix story as soon as I gat time.
Thanks & best regards, Ibjman

Major Softie
Posts: 8900
Joined: Tue Aug 03, 2010 1:46 pm

Re: How to inspect and service an R1100 Alternator

Post by Major Softie » Sat Jan 31, 2015 7:08 pm

Actually the belt is a regular maintenance item. Supposed to be replaced every 30k? Mine's due.
MS - out

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