Now that I realize this is the appropriate place to post questions concerning the repairs to my flooded and varmitized 76 R75/6, I will pick up where my other thread left off. My Bosch 002 coils were shot as was the housing but the rotor looked to be useable. I sourced a replacement housing and coil locally that looked exact. Today was timing cover re-install which all went well. I installed the rotor and as I was attempting to install the housing and coils, I noticed that the timing cover side of the coils wasn't seating in the timing cover. And the housing wasn't positioning the brushes correctly over the rotor. I pulled the assembly off and compared the ODs of the coils where they should slip into the three arms of the cover. Measuring I get the OD of my old coils t 105mm and the replacement coils at 106.75...damn. Do I need to replace the replacement with another 002? Does anyone locally have an 002? I am not interested in trying to machine the 005 to make it fit. Seems like my original rotor is compatable (fits) with the 005 coils. I now have some extras from the bike that I would be willing to trade. Let me know.
I am trying to get my mind wrapped around the issue here. The alternator stator (comprised of the field winding and cover housing) does not bottom in its boss cast into the timing cover?, with the rotor installed? I had a look at the online parts fiche at Max BMW, https://shop.maxbmw.com/fiche/partsfiche.aspx and the stator cover assembly, with the part number ending in 002, is indicated up to the end of the production run in the mid-90's. So, the 002 stator cover assembly is the one you want. If you have your original stator assembly, the cover can be separated from the field winding. If your cover is salvageable, a replacement field winding might be able to be fitted, if your replacement winding is identical to the original. I did not find the 005 part number attributed to anything in the alternator parts fiches that I looked at. Is it possible that the 005 part is from an oilhead or K bike?
Best of luck, Lars. Since stator field windings seldom go bad, it should not be difficult find a correct part.
former Airmarshal, IL.
@8053
Thanks for the response. I looked back at my post and realized that I was a bit vague in my description. You figured it out though...yes my housing and field wiring are not fitting into the timing cover. Could I remove the wiring from the 005 and replace into the 002? I'm sure it could be done, if it would fit. I think the best thing to do would be to find a decent replacement 002 housing and field wiring. I'd hate to dis-assemble the 005 field wiring from the housing only to realize that it wouldn't fit back into my 002 housing for some reason. I will post a WTB in the For Sale section. BTW, I am looking to torque the timing cover nuts and bolts and don't see in my Clymer's book the correct torque settings?
My Bosch 002 coils were shot as was the housing but the rotor looked to be useable.
I'm wondering about the root cause... why was the stator (the stationary alternator coil) ever replaced. Had it been physically shot with a gun, did it test bad, or did they simply look terrible ?
I ask because the fact is that for most riders with only grip heaters and a cell phone charger, the simple addition of a new electronic regulator ($10 to $35) and an LED headlamp bulb cures all the charging issues. The regulator because the mechanical type OEM regulator is usually no longer working, and the LED bulb because it lowers consumption and frees-up 2-3A of extra alternator output. This reduces the load on the rectifier board and allows the battery to charge faster during short trips.
Regards
Owning an old Airhead is easy.
Keeping an old Airhead running great is the true test.
Thanks for the response Richard. Picture a 1976 R75/6 parked outside under a tree on a farm in Boulder County, about a half mile east of the Greenbriar restaurant...near the S. St Vrain river mid September 2013. This bike at that time sported a fairing. It started raining and continued for three days. Evening of the third day (after midnight), a enormous tree's roots had become so eroded that it fell and changed the direction of the surging S. St. Vrain, several hundred yards to the west. The re-direction sent the water directly across this property, and through the house whose first floor was several feet above ground. Owners woke early due to an unfamiliar noise coming from downstairs...and as they descended from their second floor to the first, they saw the S. St. Vrain running through their living room. Fast forward a week and the waters had all but receeded. The fairing on the BMW first acted like a sail in the storm and knocked the bike over into the oncoming swamp, then eventually was removed and disappeared downstream. Laying on it's side in the swamp for that period of time gave the mud ample opportunity to find all the available/penetrable recesses on the bike. Not sure how long the bike laid in the mud, but it was not an immeadiate priority post-flood on the farm. When it finally received attention and was stood back up on its stand, it didin't look too bad as most of the damage from the unfortunate "baptism" was hidden from view. And apparently deep inside the front cover as well as the starter and airbox (which had lost it's protective screen in the flood), there was enough damp space to look inviting to the shelterless family of field mice that took up residency shortly thereafter. Over the next eight summers and winters, the insides of that bike saw generations of mice come and go...but mostly "go" as in urine and feces. The friend who owned the bike passed a couple years later and the widow offered the bike to me at what seemed a reasonable price. I'm not a bike guy, but a serious car guy...so of course I took her up on her offer. As I peeled back the layers of this German onion I was amazed at the resiliency of this old beast. Mud packed into everywhere, and where there were airholes or tunnels, I found nuts, leaves, fabric and more bathrooms per square foot than I ever imagined. I have been cleaning, scouring, wire brushing and masking all the while. And it is starting to come back together...no proverbial "light at the end of the tunnel" but I have made considerable progress with the help of a few more knowlegeable Airheads. So I'm sorry, what was the question?
What an intriguing story, and what a restoration challenge! I don’t have answers regarding your alternator, but I recommend googling Snowbum BMW for Robert Fleischer’s collection of technical articles. He has a search page which should lead you to any articles on alternators. He is quite an encyclopedia of information. May be some go info in there.
I have sourced replacement parts locally from someone who has helped me before. My original alternator was compromised several ways. Replacement is the best alternative. I will come back to the forum with more questions for sure...currently just building my BMW Airhead skillset.
@lars-waldner Another thought - a really great airhead electrical resource is Motorrad Elektrik (motoelekt.com), namely Rick Jones. Rick knows airhead charging and electric matters very well. Great guy as well.
@lars-waldner Another thought - a really great airhead electrical resource is Motorrad Elektrik (motoelekt.com), namely Rick Jones. Rick knows airhead charging and electric matters very well. Great guy as well.
...and sells a great little pamphlet explaining how the Airhead charging system works.
Owning an old Airhead is easy.
Keeping an old Airhead running great is the true test.
Advertisement
