Circlip revisited

[6659]

I just finished reading a fine article by Matthew Parkhouse on the circlip issue in the latest MOA magazine. It cleared up a lot of questions for me with all the great photos and such. But he mentions about the serial number 240765 being the last one with the problem. So I am looking for the serial number on the transmission and can't find one. Does anyone know where it can be found?

[20774]

Discussed a few days ago...

http://www.bmwmoa.org/forum/showthread.php?t=31624

[6659]

I found my serial number and the bad news is...

So now, as I live in fear of driving more than 10 miles from home, are there any stories out there where someone has had a failure and what was your milege when it happened?

By the way I have under 30k on mine.

[zoridog]

My bearings were worn enough at 50K to warrant rebuilding. The dealer caught it and it was confirmed by airhead transmission guru Tom Cutter.

It has been stated by others on the forum that you should be able to go to 70K before a rebuild is needed. I'd say go another 10 or 20,000 miles and check for noises.

[osbornk]

Personally, I'm not going to worry about it. My old airhead has made it 23 years without a problem and I see not reason to worry about it now. If we worry about every possibility of what could happen to anything, we'll worry ourselves to death.

Ken

[R100RS]

I had mine rebuilt at 78,000 and had the circlip added. Even though several bearings were replaced, it was a LONG way from a catastrophic failure.

If you're nervous, just change your transmission oil more frequently. If you get soft fluffy material on the magnet, you're good to go. If you get sharp metal flakes, then it's time for a rebuild. In between checks, don't worry, just ride.

[From MARS]

I found my serial number and the bad news is...

So now, as I live in fear of driving more than 10 miles from home, are there any stories out there where someone has had a failure and what was your milege when it happened?

By the way I have under 30k on mine.

My '93 GSPD, with 31K miles, has the problem. There were flakes on the plug, and the output shaft is notchy when I spin it in neutral. The input shaft spins smoothly. I've pulled it for repairs. YMMV.

Tom

[criminaldesign]

i checked and replaced the lube in the gears last week. I went by the procedure about "feeling" for inconsistency with hand on gear box and spinning wheel.

Oil was fine and only had the fluffy bits on the plug and wheel spins smoothly and felt not a think around the gears. Bike's almost on 40K.

Does the way one shifts or jams gears account for the wear? Or is this something that's going get you regardless?

I like to think I'm easy on the shifting and "bipping" on the down shifts.

Anyone have a bike that falls into the category with high mileage and never added a circlip?

[RandyB]

Does the way one shifts or jams gears account for the wear? Or is this something that's going get you regardless?

There was an article in Airmail where Oak explained the problem. His recommendation was never to lug it in 5th and keep the revs up. He goes into great detail. Use 5th only for overdrive on the highway. If for some reason you have to lug it, use 3d gear. IIRC, it was the Jan 07 issue.

Since these bikes like high revs, this makes some sense.

[CTellman]

One of my friends who rode R bikes for a long time told me that the shaft in the transmission was already machined for a circlip. Just open up and install one! Is that true?
Campbell Tellman II
"93 R100RT

[20774]

One of my friends who rode R bikes for a long time told me that the shaft in the transmission was already machined for a circlip. Just open up and install one! Is that true?

No...read the first line on this site:

http://www.largiader.com/articles/circlip/

[R100RS]

One of my friends who rode R bikes for a long time told me that the shaft in the transmission was already machined for a circlip. Just open up and install one! Is that true?
Campbell Tellman II
"93 R100RT

No, the shaft must also be machined to accept the circlip.

[114298]

1995 Model Year R100R Mystic reporting in here;

Tranny # 0244334AA1 (blue paint dot)
Year of Mfg 9/94
Mileage 5,900

Appears to be out of the danger range. Will keep a close eye on tranny oil etc per snowbum's article.

[keelerb]

Anyone know what is the FIRST serial number tranny affected? That seems a bit more in doubt (if that's possible). Thanks.

My '84 RT was built in 02/84, so I'm hoping I don't have to worry about this (just valve face deformation, thanks!)....

[20774]

Anyone know what is the FIRST serial number tranny affected? That seems a bit more in doubt (if that's possible). Thanks.

My '84 RT was built in 02/84, so I'm hoping I don't have to worry about this (just valve face deformation, thanks!)....

The only information I know about is from Snowbum who has been trying to collect information about transmissions whenever they are opened up for inspection/repair and the information is properly reported to him. He lists on his website that one '84 R80RT, transmission #Z016199 (no VIN as of yet, so no manufacturing date), had the grooved shaft but no circlip.

As one might expect, BMW used up the remaining shafts that were already machined but began eliminating the circlip near the end of the '84 production.

[criminaldesign]

No...read the first line on this site:

http://www.largiader.com/articles/circlip/


Good link for a bad situation.

Seems really goofy on BMW's side for manufacturing the shaft without that little itty bitty grove and a circlip that would cost a few cents to pass on to the customer to worry about. Especially for as long as they did.

I wonder how many of the bikes that were manufactured for those 10 years ended up having to deal with this? I wonder how many bikes there were/are?

[aaaaaa]

Good link for a bad situation.

Seems really goofy on BMW's side for manufacturing the shaft without that little itty bitty grove and a circlip that would cost a few cents to pass on to the customer to worry about. Especially for as long as they did.

I wonder how many of the bikes that were manufactured for those 10 years ended up having to deal with this? I wonder how many bikes there were/are?

All mfg's look for ways to cut costs. It'd cost a couple bucks and not a few cents to machine and install a factory circlip. Look at how much better the duplex timing chain was than the single row. BMW motorcycle history is loaded with examples of engineering changes. Some worked out better than others. Who in the 1970's would have thought that post slash 5 airheads would still be used for cross country touring and daily riding in 2009? Happy New Year. Will hexhead owners still be happy in 2030? Happy New Year!
robert

[20774]

Seems really goofy on BMW's side for manufacturing the shaft without that little itty bitty grove and a circlip that would cost a few cents to pass on to the customer to worry about. Especially for as long as they did.

Costs was a good reason, as just stated. According to the 1986 bulletin, "a new style bearing" obviated the need for the circlip and groove. Matt mentions the same thing in his Dec 2008 article..."rely solely on the tight fit" of the shaft and the bearing. The new bearing didn't cost as much as it did to machine the groove and install the circlip. Thus a win-win for BMW...

I wonder how many bikes there were/are?

Looks like it was a bunch... I added up the numbers shown in the BMW Mobile Tradition book documenting the bikes from 1969-on, basically starting with the /5s. Using the models that were essentially single-shock rear ends, from about 1985 to the end of production, the number of bikes sold was over 125,000. Now some of those may have gotten the circlip in the 1984/1985 timeframe and certainly near the end of production, they began including the circlip again. My guess is that it's probably on the order of 90,000 to 100,000 bikes that didn't get the circlip.

That would be some serious coin saved for all of those transmissions...

[From MARS]

Costs was a good reason, as just stated. According to the 1986 bulletin, "a new style bearing" obviated the need for the circlip and groove. Matt mentions the same thing in his Dec 2008 article..."rely solely on the tight fit" of the shaft and the bearing. The new bearing didn't cost as much as it did to machine the groove and install the circlip. Thus a win-win for BMW...



Looks like it was a bunch... I added up the numbers shown in the BMW Mobile Tradition book documenting the bikes from 1969-on, basically starting with the /5s. Using the models that were essentially single-shock rear ends, from about 1985 to the end of production, the number of bikes sold was over 125,000. Now some of those may have gotten the circlip in the 1984/1985 timeframe and certainly near the end of production, they began including the circlip again. My guess is that it's probably on the order of 90,000 to 100,000 bikes that didn't get the circlip.

That would be some serious coin saved for all of those transmissions...

And not installing the circlip has made for a nice cottage industry reworking the transmissions. Sounds like a win win from two points of view, anyway.

I knew about the circlip rework when I bought my airhead. I still wanted one and don't mind paying to correct this "oops" on the part of the engineers at BMW. After all, I've tried a few things that didn't workout exactly as I had planned. Besides, the rework gives me a reason to go into the tranny and replace, before failure, any worn parts.

Tom