possible cardan problems R100gs...
 

Hi! I'm in Uzbekistan on a R100gs, and my back wheel has some hard spots when I turn it with the hand. It makes some "klonk klonk" on the side of the gearbox when i turn the wheel by hand. When I ride I don't feel anything special.. The oil level in the gearbox and on the back (don't know the name in english) are ok, I just changed the oel.. There is no radial play with the back wheel.

What should i do? Continue riding like this? Here in Uzbekistan, I think it's difficult to find a good mechanic... and I don't know which parts I need...

Thanks for suggestions... I should ride 3000km to be back in russia, then I have no problems with visa (have a 1year multi entry) and could wait for parts...

Hi Zimi
I presume the bike is on its centre stand when you hear these sounds? The angle of the drive shaft to the gear box output bearing is very steep and it may be that the drive shaft is knocking on the inside of the swing arm.

I'd suggest the following:
1. Push the bike down the road with no motor running and listen, or get somebody to push the bike while you crawl with your ear next to the back of the gearbox. If there is no sound, you should be ok (I had the same symptoms as you and when I crawled next to the bike there was no noise).

Just to really check I took the driveshaft off and put it on a lathe to see if it was out of allignment: mine was ok. I did this because I had just replace the U-joint 500km before and I was concerned. In this case I was just being paranoid.

If you are still not sure:

2a. Try to inspect the front U-joint by pulling back the rubber boot and spinning the wheel.

2b. remove the drive shaft and inspect both u-joints. A car/truck mechanic replaced mine in Ecuador. Any good mechanic can do this: car/trucks have many u-joints, just usually a lot bigger than on a BMW bike.

If you need a new u-joint, the part you need is easily available in Germany. I don't recall it was very expensive either. I'm sure you can search on google.de or search/post a question on a German speaking BMW forum.

The German for universal joint is Kardangelenk.

If your gearbox is losing no oil and there is no oil in the swingarm, then your gearbox output bearing and seal are probably ok.

Good luck
Chris

Hi chris, thanks for your answer!!!

no I'm not loosing any oil and had the gearbox completed rebuilt before my trip (new bearings and sealings). I will try, but I think it make some noise when I push it, maybe a little less, but still. But I don't feel anything particular when I ride it...

Will keep in touch

Hi Zimi
If it is still making a noise when pushing it, I would look very very carefully at the front u-joint and where it connects to the gearbox and the kardan.

Before I replaced my u-joint I had noises too (don't remember exactly what kind, but something made me stop and return to the town I had just left (Locha in southern Ecuador). A man in a car took me to his mate's garage. He spoke English and he did everything for me.

Luckily I spotted it in time and replaced it before everything (u-joint and 2 holes/mounts on kardan) broke completely. This prevented the hole (on the kardan) that part of the u-joint fits into from breaking off completely. On mine it was only cracked a little and was welded successfully. Then the new U-joint was fitted.

Also if the u-j breaks completely while riding you'll have a kardan smashing about the inside of your swingarm for the time it takes you to stop the bike.

If it is the u-j that is the problem, then getting one small u-j posted and fitted will be much cheaper and easier than a whole new kardan with 2 u-js.

Let me know how you get on.
cheers
Chris

Do not like "klonk klonk"...

Have you used a long screwdriver, tire iron, or what ever of solid material as a stetoscope?

Locate the sound!

It is not likely that anything inside the gearbox broke - but it is prudent to rule-it-out.

Just grasp across the rubberboot and feel how the U-joint moves. If anything feels a bit "not right" - unfasten the boot and inspect.

What I fear have happened is far worse... a damaged bevel... sounds like it comes from the gearbox, but it really steems from the bevel (final drive).

See, I suffered just about what you describe a couple of years back.
- put the bike in neutral on soft smooth level ground. Pull and push the bike backwards and forwards gently; any kind of non-smoothness from the bike will indicate drive-train damages -:(

Perhaps this link is fully open - so that you can see what happened to my final drive:
Svenska BMW MC Klubben • Visa tråd - Tandläkare sökes till slutväxel


Summation:
- rule-out gearbox by using a "stetoscope"
- check the u-joints
- beware of final drive internal damages, like broke teeth and bearing failure.

My experience is that we noted a small vibration at certain speeds between Springbok and Capetown. By the time we arrived at Johannesburg (about 3000 miles) it was more consistent but not bad. We flew the bike to Luxembourg and after 800 miles in France it eventually packed up in Rouen. I can't say if it's the same problem as your's but I would say that if you don't notice the problem whilst driving continue gently and arrange for a new shaft to be awaiting you at the next major city or BMW garage. Keep hold of the faulty part and get it serviced/repaired by a specialist

Thanks for your help guys!!!

So I tries to push the bike on the neutral, it makes just a little bit of noise, but much less than when it's on the central stand. If I sit on the bike and try to push it, almost no noise...

So maybe I can still ride those 3000km to Volgograd, carefully. The thing is there are some pretty bad roads on the way...

I didn't want to open the rubber boot because it's so hard to put back on, but I think I will do it to have a idea.

I will try to locate the sound more precisely as well, and write back.

My idea is try continue like this a let me ship a spare shaft (have one at home) at some place.

Will keep in touch, thanks to everybody!
Zimi

From what you describe it is possible that the driveshaft is on its way out, DO NOT RIDE IT LIKE THAT, if it breaks it can lock up the back wheel as happened to one member of this forum nearly bringing him and his partner off on the motorway at 110 kph. Take the trouble to remove the rubber gaiter, take it off at the gearbox end it is easier to get back on there and check it.
A tip for getting longer shaft life on a 100GS is to use the rear shock absorber from the R100R, it keeps the shaft more inline increasing its life, my last shaft did 165,000 km before failing, longer than most last.

Hi, so I check the upper side. There was a little oil leak on the rubber. Then nothing looked broken... If I hold the part going in the gearbox and turn the wheel, I can turn about 5mm (made a mark on the outer diameter of the enddrive, before that it starts to move there. So I don't know how much play there should be normally...


then... I opened at the back, and had a couple of centiliter oil coming out, very black, and more concerning... 3 joints and broken parts of needle bearing...

Looking at the pictures, were does these come from? I think the joints are from shaft and the bearing from one of both bearing on the swingarm....

Are those bearing standard or do I have to get them from BMW...

I probably rode 1000-1500km with this problem...

How critical it is do you think? I should better put the bike on a truck?

If I let me send my spare cardan, should I get as well 4 news screws to bolt it on the gearbox?

The bits of bearings might be from the u-joint (it has bearings) or possibly from the bearing(s) where the rear bevel box connects to the swingarm or from the rear bevel box itself. I can't tell from the image (not sure of the scale). The other bits look not too clever either.

I would very stongly suggest you remove the rear bevel box, the shock, swing arm and kardan (it is quite easy to do: my only problem was finding an allen key big enough for 1 of the bolts connecting the bevel to the swingarm) and inspect everything in detail to find out the causes of the problem.

Then try to source the parts locally if possible. If not get them from home from a trusted source who won't mess you about (I personally, but I'm biased, would never go to a main BMW dealer: use somebody who is small and reliable and specialises in old Airheads).

I would not ride the bike any further until I have diagnosed the cause of the debris in your photo.

Yes you should get 4 new bolts.

NB. Please note the bevel box to kardan bearing bolts only have very small torque settings, or at least 1 does. When you order new ones I suggest you remember to be gentle with them when you put them in.

cheers
Chris

Thanks Chris,

from a friend that know well the old airheads, theses needles are NOT from the both bearing that connect the bewelbox to the swingarm, first they are too small (around 1mm diameter, lenght around 8mm, but most are broken...

The both swingarm bearing are bigger and conical, these are cylindrical.

the joints have a diameter of approx 16mm when closed...

That's probably what I will do, take out the cardan to look at it, jsut to be sure, I am just waiting a little longer, because If I have to move the bike from the guesthouse for a truck, it's easier with a shaft inside... Because If I open, probably I would not bother put the shaft back inside!

Those seals are from the driveshaft bearings but some of the rollers might be from the swinging arm pivot bearings. If you are going to dismantle the swinging arm you will need a 10 mm allen key and a long piece of tube to use as an extension, the inside pivot bolt is very tight and has thread lock compound on it. It is easier to undo this with just the rear wheel removed and the rest of the swinging arm in place on the bike, get somebody to steady the bike on the stand and use an extension of at least 500 mm on the key.
As Chris has said if you are having a new shaft sent out get a set of new bolts to bolt it to the gearbox and pivot bearings sent out as well. With luck you will not have damaged anything in the bevel box.
Putting this back together is a job for somebody with experience of doing it, there are a few things to look out for so I would suggest to truck it to a mechanic, perhaps somebody looking at this knows of one near to you or there is one mentioned elsewhere on the hubb.

I would like, if I can, not dismantel the bewel box from the swingwarm, because it's gonna be difficult here to have proper tool and especially a torkwrech to adjust it properly.

I have seen on a picture in my pdf service book, that there is as well a needle bearing in the end of the bewel box, how big is it?

Looking at the size of the needle, I would suppose that they are not from them, but... I will have to open to be sure...

and for the procedure, there is the best BMW webpage on the web from a german friend that lives in switzerland, he has good explanation and pictures in english

Joergs R80GS Page

for now I have another issue, impossible to find a 27 key arround!!!! :(