Gentlemen,

RE: previous post (Ripped Clutch Disk). I have the new disk ready to go in, found a second trans also, just in case. Will be putting in new seals next. Finding everything I need for parts is the slow part! My question is. How can I safely check the drive train, to help ensure that everything will work, before it's all together?

I personally don't think it's possible.
I still cannot figure why the clutch disk ripped. The only thing that I can see is a defect in the product.
Before reinstalling everything, I would check the brass bushing at the end of the output shaft. I saw some in really bad shape and totally oval.
I am talking about the bushing where the front of the clutch push rod is riding.

Thanks I will check the bushing. The disk material was rough and feathered a bit I believe it was stuck. After cleaning everything, there are no signs of wear or cracks, anything abnormal. The disk looked barely worn except for the feathering. I really want to eliminate all the possible causes before I screw it up again! Cause it would be my fault next time!!

feathering i beliveis and alignment issue weather the spikot bush or where the box meats the block. sticking is usally caused by contaminents like oil or grease, if the pads where riped or partly riped off the disk i think u might be right in thinking it was stuck, if it was stuck the nexttime the clutch was engeged it would of riped the pad off due to the motor and box turning at differnt speeds. i just went thew my old tafe books and found nothing on riped disks thats my thoughts,

Thanks for the response. The bike is still apart while it gets a good cleaning and hopefuilly a new paint job. The rear seal did not leak. (new seals anyway!) The throwout rod bushing is fine. The clutch material is fine (almost no wear), and intact except for the rough areas. The pressure plate surfaces are slightly spotted with a brownish rust looking residue, but otherwise very good, smooth no pits or grooves. It was partially reasembled and seamed to work fine (engine not running). The clutch ripped through the steel plate, not the disk material coming apart. I believe it will be fine, just a wierd failure probably from a defect as suggested. But any thoughts are greatly appreciated!
The bike has just over 20k on it so if I do it right it should last a while! This site is great when researching! My thanks for an excellent tool!

Regards, Steve

Sorry as dont want to look like I am hijacking the thread here but seeing as you are on the subject of replacing clutch components can anyone advise how best to re-assemble one when the balance marks that were on them have been removed from repair shop while getting friction surfaces reground after glazing up from getting oil on them while running. They sandblasted the components clean and they no longer have the markings painted on them aghhhhh

so does anyone have any suggestions etc (short of getting a machine ground dead true spigot made so that they can sit on it and see where it then rolls to -Heaviest point on each item, not a good option due to expense) or is it a case of suck and see by assembly and hope that the one of 9 combinations is the best one

I am working on a small web page about replacing the shaft seal. (replacing output seal), and I am warning people about worn factory marks. I always do my own one.
Once I had a clutch where the marks were worn and I re-installed it without balancing. Maybe I was lucky but I have not found any vibrations and the bike has an extra 50K without any problems.

Stupid idea: Would it be possible to re-assemble the clutch and test it on an electronic wheel balancer? you could rotate the parts in stead of sticking a weight.
To be investigated.....

Bert

it would be possable i think but maybe better on an old school wheel balancer ie the old upright oil filled 1's

One thing I do recall noticing though was that there were several small drillings on the side of the cast sections that were on the same radius but were all different depths obviously in effort to reduce weight and probably to balance the items.

the mule wrote:One thing I do recall noticing though was that there were several small drillings on the side of the cast sections that were on the same radius but were all different depths obviously in effort to reduce weight and probably to balance the items.

Yes, this is for balancing.

Hi Bert

yes I realised that as I am a qualified fitter machinist/toolmaker by trade but wondered why the additional need if this is done to set each component 270 degrees out to one another ie 1/3 offsets to one another or is it simply that there maybe a sweetspot on each component.

A learned friend here in Ulysses club who has tinkered with beemers for most of her life and can tell you how to do something straight off suggested that if it has all been reground and new friction plate I probably will need to readjust to riding a whole new bike and most likely wont notice any undue vibration at all other than it will want to launch and grab a lot more readily

Believe it or not, long time ago, I was also a machinist/toolmaker (for a European car manufacturer). I won't expose my career as I did so many things that it would take pages. I ended up becoming a computer network engineer! You will ask what is the relation between both trades: In 1980 I was programming APT language for CNC machining. This was the old time of mainframes and perforated ribbons. At this time, I even got an offer for teaching it in an industrial college. This was also the time when network were popping up in every businesses and I decided to specialize on them.
Enough about me, but it's always good to know the background of people.

To correct you, the components can be set at 120 degrees from each other and both ways (CW and CCW). This leaves you with 9 different possibilities for 3 pieces (better than our 6/49 lottery giving you a chance of 1/14 millions) .
If all the weight is set on one side, it will create a lot of lateral pressure on the bearing and it will wear prematurely.

Now, I also realized that if each piece was individually balanced, you could put them at any position and it would not make a difference.
Maybe, BMW balance approximatively each individual pieces and then assemble the whole clutch, test it and finish the balancing on one specific piece. Who knows!
I didn't make up the story of the 3 marks and if they are on the clutch, it should be a good reason.
Today I was talking to a good friend owning a K100 and being the manager of a tire place. I asked him about using the tire balancing unit for the clutch, and his answer was no. The shaft on the machine is bigger than the diameter of the splines.
How can we solve this problem? Maybe a smart reader will give us the solution.

I took the chance once and re-assembled a clutch without lining up the marks and didn't get any adverse effect. Maybe pure luck!

Cheers

Bert

Two questions. Firstly Bert did you then go and purchase a lottery ticket and secondly dumb question if you sat the clutch assembly on a spindle of some sort and rotated it slowly when it came to a stop would the heaviest part be at the bottom?

Regards,

Phil

Gee Bert

That brings back memories on a forgotten trade the old punched hole ribbon programming as I was involved in the early development from those to one of the first CNC multi spindle drilling machines at the dockyards making condensor plates for power stations. What a transistion that was back then from reading rows of 8 holes per line in a grid on the paper tape so on. As for there 1 of 9 combination I agree. I guess I will just have to wait and see if there is any vibration when I get it up and running next week.

I am looking at seeing if a local electric motor repair shop can do it. Normally after rewiring a rotor they need to balance it.
The positioning makes perfect sense if they don't balance to the umpteened degree. Just mark the heavier part of the component and if each of the three parts have their relative unbalance 120' different they would equal out as much as possible.

phil_mars wrote:Dumb question if you sat the clutch assembly on a spindle of some sort and rotated it slowly when it came to a stop would the heaviest part be at the bottom?

Regards,

Phil

Yes it would work, but where can you find a spindle big enough and spinning so freely that a couple of grams will rotate it?
The other way is how you balance things like big grinding wheels.
The shaft/wheel assembly rests on 2 parallel and level sharp edges and you roll it to find the heaviest point. The use of sharp edges is to reduce the friction to the minimum. This method may work for the clutch too but you would have to manufacture a shaft of the exact diameter of the splines of the output shaft.
Now we are talking about machine shop and $$$$$ but The Mule being a machinist, it may be easy for him to make it at work.
Another method is using a strobe light. I remember seeing this years ago when I was working in a zipper manufactury. The machinery runs so fast that every things has to be perfectly balanced. I remember seeing one of the mechanics using it.
This could be tested directly on the bike. I would be the top of the line method as you could compensate for any balancing imperfection of the output shaft too. In order to keep this perfect setting, the clutch will have to be paired with the output shaft after each removal.
Check for the principle of balancing with a strobe light here

Bert

Bert I am qualified but have not been in that career for about 20yrs now went on to other career path. Although I have kept my hand in with small projects etc. Designed and built a trailer for the bike to tow. Oh how I wish I had a machine shop though.

What I did suggest previously was having something like a spindle that basically has bearings mounted both ends of the spindle and flange mandrel that the clutch components slides onto a stepped spigot. The flange spigot a firm slide fit to the inside of the clutch ring components the imbalance of the clutch ring would then rotate on the bearings until it settles. Obviously the bottom would then be considered the heaviest point on that clutch ring. Not rocket science but simple physics and gravity. Virtually a static balancer the same as is done to fitting motorbike tyres without a machine balancer.

Each piece appears to have been balanced. At least each part has holes drilled in mine, housing, pressure plate and cover plate. So it would apear that while a sweet spot may exhist it should also mean that you should be able to get by even if you have no aligment marks. Who knows if to much material was removed when balancing, making the heavy side opposite. I re-assembled using the old marks.. Want me to take it apart and try the other way? LOL! NOT!

Finally my machine is all back together and running again. while on the centre stand did a test to make sure nothing went crunch bang whatever and went up and down the gears smoothly. Today I took the bike out and with a gentle run up and down the driveway (1klm) changing up and down gears up to speed of 50kph was smooth and firm as. No noticeable vibration so far from new clutch parts. Mind you it was interesting to see how much more the clutch grabs now too. So all going well will take the bike for a for a longer run tomorrow while waiting for family members to arrive for our sons 21st birthday and see if any vibration can be felt at higher speeds. Oh it is soooooooo good to have the bike up and running again though.