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Discussion Starter #1
So what happens when a drive shafts fails?

I checked mine (54K miles) and one of the u-joint has slight sticking spot. I suspect that it will go for many more K miles before it fails, but the manual says to replace it.

A new shaft is ~$700... so I am considering if it is a good idea to stay with the one I already have and use it until it _really_ fails. I just want to know what to expect and what possible consequences of if failing.

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My buddy's R1100RS broke the rear u-joint and the result was a cracked rear drive housing in addition to the driveshaft. The rear drive damage was the result of the spinning shaft and the time it took to realize what was going on and get the bike off the road. Not very long at all.
Mucho $$$$$$$$$!!
 

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Take it to a driveline shop. They can take the old bearings out and install new ones. No big deal and some can even balance them. I had my old RT rebuilt and I think the guy said they were same size as some European sports car.


Mack
 

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MIK said:
Hm... I'll try. But I wonder, if those are replaceable, why BMW manual tells you it is not serviceable and to replace it as a unit?
BMW wants to sell you the whole shebang. They do it with almost everything that they don't want the shops to mess with like starter brushes, alternator rebuild, fuel pumps, etc.

One of the yoke bearings on mine was really loose in one twist and not so much in the other. Bearing seemed almost dry at 70K miles when I was doing a spline lube that turned into a tranny seal replacement. I think my old drive line bearings were crimped in, but it didn't seem to matter to them. It's what they do for a living and they do a lot of stuff including weird steering and compound axle and drive line assemblies. Buddy had them rebuild his CVC joints too. The only thing they probably can't do is replace the rubber in that section of the BMW drive line should it split out - but maybe they can do that to now? Dunno, but the drive line BMW sells is nearly $1,000 on the K1300R now. A couple of yoke bearings and labor was maybe $90 if I recall. Long as the splines are good and the rubber is intact, they shouldn't have a problem.

I'd ask them to mark the phasing too when they get done. That sort of messed me up when I put it back together. I even went around to two other drive line shops to make certain the rebuilder was right as it didn't seem right to me for some reason. They all concurred it was right.


Mack
 

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It's good to read there are still places around that re-condition.

Many years ago I had a similar problem with a Ford. First there were joints made by 'Hardy Spicer' that were serviceable - you could upen them up by removing circlips to replace needle roller bearings. Then the car manufacturers thought failures of driveline joints were rare and went over to a factory assemble technique. They pressed and staked in the caps covering the needle rollers and went for smaller more compact bearings. Shops in UK sprung up sourcing the bearings and with the right press tools, but I haven't heard of any for years. The important thing about a shop repair is the equipment to re-balance and you must get ALL the U joint bearings replaced. If I had to look for service shops in UK I'd start looking at those firms that manufacture for the car aftermarket. But these days, they are probably all in Korea!

If you leave drive shaft joints to wear and go out of balance, the rear drive pinion oil seal may start wearing and possible the pinion bearing to. Check out the price of repairing those!



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A thought. Maybe your dealer would recommend a drive line rebuilder? I know my old local took a lot of stuff like starters and alternators to rebuild shops if the customer balked at the BMW prices.

Some of the really old K bikes seemed to smoke out their alternators and he had a good rapport with one German rebuilder who did a lot of foreign car electrical stuff. His name was Otto and he used to tell us "He was a smart man as he could spell his name forward and backwards." We took him a starter out of an old Jaguar XKE and he took it apart in about 3 minutes while complaining about "How hard they were to work on" (He was laughing the whole time.). He found a bad winding and they had a whole room full of huge 3 foot diameter spools of magnet wire and he wound a new commutator while we watched. It was pretty amazing to see as it spun in some jig, but if you got the tools it's easier too. He said he could make a whole starter from scratch if he needed too as he had a complete machine shop. True German craftsman that actually like his work.


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We don't have people with those skills in UK anymore and have lost the skills to survive in adversity and breakdown of world order! If cell phones and the Internet were lost tomorrow, many would probably lose the will to live.

Everything is throw away and people in shops just need to learn how to use a stock search computer and order from re-sellers who themselves order from other re-sellers who get stuff from China!

Even the service shops have procedures and labor charges set. As long as your vehicle problem fits with what the computer knows about, or a defined service operation, you are O.K. If the computer doesn't help, they change everything and charge you the bill, whilst throwing away some perfectly good components.



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Discussion Starter #9
GMack said:
I'd ask them to mark the phasing too when they get done. That sort of messed me up when I put it back together.
Now, I looked at that thing again and I am confused about phasing. This shaft is 2 part. You can assemble it anyway the splines align. The manuals (clymer and bmw) don't mention anything about it. Just slip one part into another and that's it. Is it not important in this setup or I am not understanding the phasing correctly? :confused:
 

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MIK said:
Now, I looked at that thing again and I am confused about phasing. This shaft is 2 part. You can assemble it anyway the splines align. The manuals (clymer and bmw) don't mention anything about it. Just slip one part into another and that's it. Is it not important in this setup or I am not understanding the phasing correctly? :confused:
It's a drive shaft, it's not a timing chain or belt with critical timing. There should be no reason it has to be aligned to a certain spline. If it slides onto the spline it's good.
 

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Discussion Starter #11 (Edited)
Yoda said:
It's a drive shaft, it's not a timing chain or belt with critical timing. There should be no reason it has to be aligned to a certain spline. If it slides onto the spline it's good.
All I am curious about is why phasing is important on a car driveshaft and not on this one. Sounds like it should be important for longevity of the u-joints and bearings they connect to.

http://en.wikipedia.org/wiki/Universal_joint
http://www.bmw-k.com/forum/viewtopic.php?f=3&t=14033&start=0&st=0&sk=t&sd=a
http://www.custompistols.com/cars/articles/ts_ujoints.htm
 

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The models of the 90's and early 2000 used a different Paralever final design that used a two-piece driveshaft like this one that I had rebuilt:



The two pieces need to be indexed when slipped together (i.e. yokes "in phase" as the two units splines could allow it to be assembled in any of number of ways with the yokes pointing in any number of directions. Hence my bugging the other shops for the correct way to assemble the thing to be in phase. The idea behind the two joints is to cancel out any rotational differences that exists with a single Cardan joint; out of phase can compound the rotational differences and lead to vibes.

This was an issue with a lot of models since BMW used more acute angles in those older Paralever final drives (i.e. the big ones without the hole in the axle and the torque arm on the bottom instead of on the top like the newer smaller ones with the axle hole). Owner's were doing a lot of spline lubes (another "lifetime lubrication" issue then) and stuff was getting out of phase on reassembly as the front half of the driveshaft needed to be pulled hard to unsnap from the tranny and most gave up on pulling the front part out to lube. Owners would just shove the second one in and go with a few vibes added. Probably a reason for a lot of the final failures back then too.

Design changed later with a long male spline at the front instead of the female spline on the above. Phasing shouldn't be an issue unless they cut off the forks and weld on a new end. I'd still mark the thing on disassembly if at all possible. Never know what BMW does sometimes nor if some bad spline will go after a good one.


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Here's a general diagram I have showing correct phasing, NB There are NO alignment marks on our drive shafts.

The article notes that phasing becomes more important when the driveline is long and the angles move away from horizontal. We have short drivelines and I don't think the angles are that far out, unless you mess with custom torsion links to change the ride height.



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I just had to replace the driveshaft on my K1200RS at 32,000 Kms...... :( Why did it fail at such low milleage? Because the previous "Specialist" that worked on that bike did not phase it correctly, but that was only one of his screw-ups....! :teeth That also caused the tranny output seal and the rear drive input seal to both fail from the vibrations.

There has been quite a lot of discussions on the net about them driveshafts, them GS guys seem to bust them regularly, but all agree that they have to be phased correctly to insure long life of the U-Joints. There is a good article on that in the BMWON magazine by Paul Glaves, I think one of the early summer 2009 issues.

Here is a pic, two driveshafts, one is in phase, the other not.

I agree all the shop manuals are ignoring this important step, even the BMW manual states replace as found or something like that.......easy enough to say but what if the previous mechanic did not do it like in my case. :confused: Some of us have already looked into that, and there does not seem to be a way to phase with the front driveshaft in place, the swingarm has to come off unless you can find a way to pull the front part out without removing it. Then you can mark both pieces, try not to loose the marks in the lube and then carefully mate the rear end to the front "In Phase". Not too easy to do because you are holding the rear drive at the same time as you line up the splines, but a few minutes of contortions and it should line up. :teeth

Here are the paint marks I used to phase.




My driveshaft was only showing roughness at one of the U-Joints, but after applying Grandpa's trick to loosen up tight new U-Joints to it, it then really showed play at both U-Joints. What you have to do is lightly tap the end caps, not hard but often, do that to all the caps, then check for play......like me you may get some unpleasant surprises....!
Pic here on how to do that, that one was for demonstration purposes, so you may need a bigger vise and smaller hammer.....! :D



This by the way was my third BMW Driveshaft, I had one fail at low milleage on a R100GS, destroying the swingarm in the process.....and then again on the same bike at 90,000 Kms, the front U-Joint failed again and I had to have that one rebuilt for big $$$$ I tought. But a BMW mechanic I know well agrees that a good aftermarket suspension goes a long way in insuring the longevity of the driveshaft, less up and down uncontrolled travel of the joints with better adjustments.

Considering all the money and grief them driveshafts caused me....I made sure I mounted that one "In Phase" and try to pass that phasing thing along every chance I get. And that is something I should have learned quite a while ago, considering all the U-Joints I also replaced on full size Chevy Vans with two-piece driveshafts, most probably because I was not phasing them correctly.

Yes there is now rebuilders for them driveshafts, Bruno's in Canada, and also HPNGuy on ADVRider, the last also replaces the rubber dampener with some better Polyurethane, I think he also does the RS/GT. But I did find a brand new driveshaft for my bike on E-Bay, at less than 50% of the BMW cost, and last time I looked there was another one listed. Let me see here..... :confused: Looks like you could be lucky with a new one...... :clap: And.....it is a "make an offer" :clap: he took mine......! :thumb:
http://cgi.ebay.com/ebaymotors/BMW-K1200GT-K1200RS-Dive-Shaft-Comp-26117663759-/350174589570?pt=Motorcycles_Parts_Accessories&hash=item5188083282

And at last.......BMW now makes their driveshafts (at least on the GSs) with one of the splines bigger, that way it can only go in one way.....IN PHASE !!! :thumb:
 

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My father was an auto mechanic who owned a speed shop for most of his life. Certainly all of my childhood. I worked for him starting at age 13 and quit at 18 when I left for college. I myself have modified classic rear wheel drive American iron too many times to count since those days. Never in my life have I heard of phasing a drive shaft on an automobile. Of course automobile drive shafts are one piece so phasing is out of the question from the mechanic's perspective as there is nothing to adjust. Balancing on the other hand is very important but once the piece is balanced it's balanced and that's that. Put it in.

When working with transmissions mechanics will sometimes note the spline orientation of the gear sets if they know they are going to re-use the gears. They do this to keep existing wear patterns matched. It has nothing to do with phasing. There is no phase in a gear. In a 2 piece drive shaft the only phasing possible would be in the orientation of the U-Joints as has been show in photos above. In that case you would still want to keep the splines matched if possible to keep the wear patterns matched but if the pieces were properly balanced from the factory and the repleacement Ujoints were properly balanced from the factory and if everything was installed squarely and securely there will be no out of balance situation if the yokes are not perfectly phased. Once each piece is balanced then they are balanced and that's that. End of story. Put them in. If you have marked the splines for wear pattern matching then please realign them if possible. Otherwise, put them in and go riding. The laws of physics do not support this other Voodoo practical magic. The folks at BMW are not children that we need to oversee their work and correct their mistakes. Niether are the folks at Clymer. They've been doing service manuals for decades and they often pride themselves at being more succinct and descriptive than factory manuals.
 

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...............Never in my life have I heard of phasing a drive shaft on an automobile

Most automobile shafts I've worked were one piece shafts without splined sections. Drive line phasing was never an issue.

BMW say the clutch assembly is 'balanced' but as previously mentioned, if others get things mixed up you can't always assume what came out goes back the same. Say you replace just 1 or 2 components with new, so where is the balance then?

The drive shaft joints are most likely to fail if you didn't spot that the rubber boot at the tranny end came 'unplugged' for some time, allowing the swingarm to fill up with water! Splosh-splosh munch-munch, as the shaft rotates. That also has something to do with spline seizures, although these splines are coated with some kind of plastic.


Google search, About 3,960 results (0.32 seconds)

http://www.google.co.uk/search?hl=en&lr=&as_qdr=all&q=driveline+phasing+yolks&btnG=Search&aq=o&aqi=&aql=&oq=&gs_rfai=



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Yoda, 5 years does not make a mechanic, I learn something new everyday.

For those of you that would like to know why drive-shaft U joints need to be in “phase” please see this site at http://www.custompistols.com/cars/articles/ts_ujoints.htm

The short of it is:
The U joint speed is increased if they are out of phase. The speed variations would be felt as vibration. The U-joints, bearings, clutch, gears, etc. would be getting constant, reversing impact loads. As the angle of the driveshaft increases, so do the speed variation and the impact load.

“To work properly the U-joints must be in proper “phase” with one another. Unfortunately, Murphy’s Law rears its ugly head. Occasionally some enterprising person will disconnect the driveshaft at the splined joint to save unbolting the four driveshaft flange bolts during a clutch job.(this would be on cars or trucks) When it gets reassembled no attention is paid to the “phasing”. If they are not in phase the speed change effect will be cumulative, making the situation much worse. It can get twice as bad as a one U-joint system!

Hope that helps.
 
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