Hi All,

Took out the driveshaft yesterday and I have what appears to be great splines both sides. It was well lubed.

However.....

I have slight notchiness directly in the middle of the swing in both axis'.

Is any notchiness a deal breaker and a call for replacement?

Does this picture indicate anything?

Thanks.

If it was one of my Moto Guzzis, I'd be throwing it away, so I'm also waiting for a reply to this one. My guess is that the bike did a lot of straight line work.

best to replace the ujoint ...can be hard to find if its the smaller version , but they do exist 

the notchyness is a sign that the rollers inside have flat sided ...ie worn on one location because the grease has dried out and the rollers just arent rotationg anymore...and then left without use for a long period .

likely outcome if left as is in service , is that the ujoint will bust out  damaging the retaining housing ...making it useless .

a stich in time could save hundreds and availability is becoming less every year

charlie99 wrote:best to replace the ujoint ...can be hard to find if its the smaller version , but they do exist 

the notchyness is a sign that the rollers inside have flat sided ...ie worn on one location because the grease has dried out and the rollers just arent rotationg anymore...and then left without use for a long period .

likely outcome if left as is in service , is that the ujoint will bust out  damaging the retaining housing ...making it useless .

a stich in time could save hundreds and availability is becoming less every year

Thanks for the reply Charlie. I was afraid of that. This particular bike was definitely left without use for a long period of time. Looking at the various discussions about replacing this "non-replaceable" u joint sounds not fun. Unfortunate to have such great looking splines and a bad u joint. I'll need to do a think on this one as this is beyond DIY for myself.

On that note... does anyone know of anyone that can replace these u joints in Calgary or Alberta or Canada? I'll start researching and if I find anyone I'll report back. I bet that buying used will be cheaper so I may also look at that option. It's only money right???

I recall looking into replacing the u-joint for one of my past bikes.  While I didn't actually do the replacement, it didn't seem too difficult. 

The u-joint itself is fairly easy to source.  As I recall, the drive shaft uses the smallest common joint size, and the cost wasn't really all that bad, something like $20-25.  The tricky part is that this small joint isn't normally carried by the automotive places that service drive shafts so it can be a little hard to find.  I think the best place to find them is online and from sources that supply agricultural equipment(think tractor PTO drives) or some industrial supply shops.

The last caution is the HP rating of the joint.  There are several different ratings and obviously the BMW shaft needs the highest rating.

As far as getting the joint installed, again, there are places that do agricultural equipment repairs.  It may be possible to have a drive shaft or industrial shop do the job as well.  The old joint is staked in place and requires grinding out the stakes, remove the joint and stake the new one back in place.  I doubt it takes more than one hour of shop time to do the job.

The first place I would try in Calgary is Pats Driveline on Blackfoot Trail.

https://patsdriveline.com/

As a final (?) addendum to this thread: I did have a Guzzi UJ explode on me shortly before entering a fast right hander. That was... 'interesting'. The swingarm is still in use, albeit with a huge flat on one side of the housing where the UJ tried - and thankfully failed - to exit. Mind you, the Guzzi swingarm is made from 3mm steel, so that gives you a rough idea of the violence involved. Taking that damage as a baseline and with the K swingarm being a cast housing, it is highly likely that a UJ breaking up on a K would do a good job of destroying the swingarm too. The following consequences don't really want thinking about.

Did you have any luck finding a replacement u-joint?

Here's a list of standard size part numbers and instructions on how to measure.  Prices aren't all that bad.

https://www.moog-suspension-parts.com/universal-joints-ujoints.asp

Point-Seven-five wrote:Here's a list of standard size part numbers and instructions on how to measure.  Prices aren't all that bad.

https://www.moog-suspension-parts.com/universal-joints-ujoints.asp

Good info, there. Thank you. I wonder who the OEM was for BMW at the time? It looks like Super Strength might be the way to go due to rotational speed of the shaft?

There have been photos of these joints disintegrating. All the photos I saw there was a resultant perforation of the swing arm. Being a cast single side swing arm means its may well come apart. So if in doubt.....replace it.

If I was to replace the u-joint, I would find a shop that could machine the grooves for the retaining clips if the price was not exorbitant.   That would allow me to remove and service/replace the joint myself in the future.

Instead of well meaning links to catalogues with 100s of items, please link to the exact dimensions of the k100/75 joint. There also seems to be great confusion and mix up of Monolever/Paralever and R/K models.. The Australian Hardy Spicer number leads nowhere, no price or dimensions listed. Most search results just lead to fruitless discussion threads like this one here.

Tranberg, I understand your frustration at not having the all answers laid out here for you, but if you go back to my post of October 16, you will see that the link I posted included instructions for measuring your joint so you could determine the correct Moog part number for your bike.  

I suppose I could take my final drive off the bike and take measurements, but unfortunately I have a Paralever and it appears the original poster has a Monolever.  Also, I am pretty busy right now so it might take a few weeks for me to get around to it.

Another thing, most u-joint manufacturers have their own part numbering systems and I personally just don't have the time to research every manufacturer's catalog to post a comprehensive list of the part numbers our bikes use. 

At the end of the day, since you will probably have a specialist replace your joint, the easiest thing would be to just take the shaft to them and let them figure out the part number from their inventory.

I see no point in taking out my driveshaft to take measurements, when somebody has done it previously - The K's were not hand-made.

With the dimensions at hand, I could search for the joint, get a price and availablity and then decide what would make more sense to do.

I have a couple of machinist friends, who have the tools needed. They might even be able to repair the splines.

Searching some more the dimensions er given here: https://www.k100-forum.com/t14437-drive-shaft-universal-joint-replacement-part-number

19x44 or 19x48mm bot rarities

Searching some more the dimensions er given here: https://www.k100-forum.com/t14437-drive-shaft-universal-joint-replacement-part-number

19x44 or 19x48mm both rarities

40-80 Euros from Germany

Tranberg wrote:Most search results just lead to fruitless discussion threads like this one here.

That could be disappointing if you are a fruitarian.

RS Rider wrote:Did you have any luck finding a replacement u-joint?

No, not yet. Life got busy and besides ordering a few small parts on black friday, I haven't touched the old girl. She's pushed to the side of the garage so I can get my car in there for winter now.

I've been meaning to call Anderwerks and see if I can bring it in for a second opinion. Its been sitting on my workbench since September and occasionally I'll swing it through it's rotation and it doesn't feel completely bad so I'm on the fence about it.

If I make any progress I'll post again.

I spoke to a parts person at Pats Driveline back in October armed with the info in Tranbergs post, but haven't had the time to drop by. They repair/rebuild driveshafts with staked-in u-joints all the time. I have a spare 16Z shaft with great splines to play with if I want to. However, if I have it disassembled and they can't find a replacement, what then?

I was quoted $60 (if I remember correctly) to have the old one removed so that they could measure it properly and then see what is available as a suitable replacement. They said reinstallation would be a matter of tack-welding washers up against the caps to hold the u-joint in place again. I didn't ask for a cost on that.

I should think that tack-welding will introduce weight to the rotating mass of the driveshaft, so I don't know to what degree that will affect its balance, and if it's even enough to be concerned with.  BMW had/have engineering numbers that state how fast the output shaft of the transmission turns and, therefore, the driveshaft. I have no idea what it is, nor would I be capable of calculating it. Clearly, though, centering the new u-joint in the yoke is a must.

Perhaps someone on this forum could comment further regarding the welds adding additional mass and possible balance issues.