08 R1200RT drive shaft

[hgordee]

I first want to say that I am not a wrencher. So if my terminology is incorrect I ask your tolerance. I purchased my bike new in 08. At 57k miles I had the bike painted. There was considerable disassembly to complete the paint. A non BMW motorcycle shop dis & re assembled the bike. I picked it up and rode it about 1500 miles home. I then met 3 friends and spent 2 weeks riding the Texas Hill Country. About 1500 miles into that ride so 3000 + - I had a catastrophic drive line failure. The front u-joint broke. I had it towed to a BMW shop. The estimate was 5k to fix. I trailered it home to WI. I had a BMW certified Master Mechanic repair the bike with used parts. I picked up the bike around April 1st. I made a trip to the East Coast in early June riding about 2,700 miles. I left mid July for the Rally in SLC. 1400 miles. I left the Rally and rode to Tucson another 900 miles. Leaving their I headed towards home. About 400 miles out of Tucson on I-40 outside of Albuquerque I had another catastrophic failure with the front u-joint breaking. I was towed 50 miles to Sandia BMW. They diagnosed the same issue. I arranged to have the bike shipped home (not delivered yet) and flew home. Sorry for the long story. I'm trying to figure out what may have caused this to happen TWICE. I need to decide whether it's worth fixing. I have way much into it now and have it farkled out very well or is it time to upgrade?

 

[johns3]

Having recently experienced a U joint failure myself ('92 K100rs4v w/~100,000 miles) and repairing is myself, I have a few thoughts on your double failure.

-you didn't mention whether or not the swingarm and driveshaft were removed by the shop that painted it- I'll assume that they did. I would be curious to see if they knew anything about driveshaft phasing. Look here especially at about the 2:00 mark

Using your driveshaft out-of-phase when it already had 5x,xxx miles on it is a plausible reason for failure.

-when the second repair was done by someone (BMW certified mechanic) who probably would know about phasing, you mentioned about using used parts. Was the history (mileage) of the parts known? Could have been the cause there.

These are just my thoughts. Others with much more experience will hopefully join in.


A couple more things I have learned (I do all my own work and am constantly learning)

-if one U joint is replaced on a driveshaft, replace BOTH! Even if the second joint feels great in your hand- replace BOTH.

-used parts should always be viewed with suspicion. A seller may state that it came off a bike with, say 15000 miles. But was it on another bike before that?

 

[patiodadio]

After watching the video, does it mean that when I remove the final drive to drain the fluid and lube the splines, I might be getting the drive line out of phase when I rotate the components to reinstall them ?

 

[johns3]

After watching the video, does it mean that when I remove the final drive to drain the fluid and lube the splines, I might be getting the drive line out of phase when I rotate the components to reinstall them ?

If the front of the driveshaft is kept from rotating by having the transmission in gear but you did rotate the final drive which rotates the rear section of the driveshaft, then yes your driveshaft will probably be out of phase.

 

[patiodadio]

Yikes ! How do I get it back in phase ?

 

[johns3]

OK- you should know that my driveshaft knowledge is based on my K100, but that shouldn't make a big difference with an RT.

Pull the final drive back and pull the driveshaft splines apart. Look up into the swingarm with a flashlight. Placing the trans into neutral, you should be able to rotate the shaft and hopefully see when the driveshaft yolk (as opposed to the transmission output yolk) is straight up and down. Now look at the yolk that is directly attached to the rear driveshaft part. That needs to be straight up and down also.

Now you need to figure out how to keep the final drive output (what you bolt the wheel to) from rotating. I have used several wraps of electrical tape vertically around the entire final drive. Now slide the splines together- you might have to rotate the splines slightly to get them to mate.

Overall this is how the assembly should be:

Output yoke of the transmission should be on the same plane as the input yoke of final drive

Input yoke of the driveshaft should be on the same plane as the output yoke of the driveshaft

Clear?

If anyone has a better method, other than removing the swingarm, please post it

 

[52184]

Yikes ! How do I get it back in phase ?

IMHO and limited experience:

You didn't mention a bike model. Some BMW driveshafts are two-piece and have a splined section in the middle where the two ends of the shaft can be pulled apart, leaving you with two halves of the driveshaft. For those shafts, the center splines must be periodically lubed AND properly phased when reassembled. Perfect phasing on these shafts is rarely possible, the splines don't seem to be cut to allow that so one gets as close as possible. On the two-piece shafts, periodic disassembly, cleaning, and lube of those center splines is important as that's where the shaft length has to compensate as the suspension moves up and down. If that center section seizes up, no length compensation takes place and extra (excessive) loading is placed on the knuckles at each end of the shaft. DAMHITK

Some BMW driveshafts are one-piece. Accordingly, phasing is set at the factory and cannot be changed in the field. Length take-up on such a shaft is accomplished on the splines at one end or the other, and one end of the shaft is circlipped in place while the other end slides freely on it's splines. Again, periodic cleaning/lubing is a necessary task to keep the splines moving freely and allow compensation for the change in distance between swingarm pivot and final drive as the suspension moves up and down. As with many other areas, "lubed for life" is a pipe dream.

The two-piece shafts seem to fail at a lower rate than the one-piece, and at the rear knuckle. One-piecers seem to fail at the front knuckle, which is circlipped to the transmission output shaft. And, if you take driveshafts from an airhead, oilhead, brick-k, and wedge-k side-by-side, there is surprisingly little difference in the size of the knuckles being used--yet that's a difference of 100hp or so being transmitted through those shafts. Finally, there seem to be many more reports of shaft failure on RTs than on wedge-K bikes, but that may just be due to the difference in sales volumes for those models. Clearly, more data collection and failure analysis is need--but most of the failures appear to be happening outside of warranty, so the costs are not being borne by BMW and failed parts are not being shipped back to BMW where they could be analyzed.

Again, all IMHO and limited experience.

Best,
DG

 

[deilenberger]

A few clarification points on hex/camhead driveshafts.

1. It's a two piece driveshaft, with a bonded rubber "cush" between the two sections with a universal yoke welded to each end. There is no way to assemble it out of phase since the rubber section doesn't disassemble. It would only get out of phase if someone spun the end that goes into the rubber cush - and if they did that - it would mean the driveshaft would no longer function to transfer power. Crib-notes: don't worry about phasing on a hex/camhead - if it's wrong you need a new driveshaft.

2. Due to the design of the paralever suspension on the hex/cam's - there is almost no length displacement as the suspension moves up and down. This was accomplished by putting the rotation points on the swingarm at the rotation axis of each universal joint. Simple solution that did away with spline wear on the rear-drive/universal-joint splines. Crib-notes: "spline lube" on a hex/cam is not a critical service operation. It's one you do when you're in the area so to speak. I have yet to hear of these splines failing (I'm sure someone has had it happen - but it's nothing like early K bikes that ate them for lunch, along with clutch splines.)

That's it. What applied to earlier designs doesn't necessary apply to this design. Carry on...

 

[johns3]

I stand corrected. Thanks Don

 

[williambrown]

Is Long Travel The Problem?

I toss this one up to see if it gets smacked

Watching that video showing the change of angle as the rear suspension compressed raised an issue.

I have never heard of airheads doing final drives and drive shafts in normal use. Airheads had relatively much less rear suspension travel.

Oilheads and hexheads have the driveline issues, and they suffer from BMWs later fixation with long suspension travel ( and high seat height )on road bikes.

Is that large variation in shaft angle, particularly on over-loaded oilhead and hexhead bikes, the base problem ?

INCOMING !!!!!!

 

[AntonLargiader]

You may just have really bad luck with driveshafts. Don explained it well; there's really no operator error possible here. If you really like that bike, you may want to just go with a new driveshaft or one that has been rebuilt with new U-joints by a reputable shop. New from BMW carries a two year warranty.

I wish I could charge $5000 for a driveshaft replacement... man, I would do that all day long.