2015 drive shaft phasing

[jimbem]

I'm not sure if I even know what drive shaft phasing is. I ask about it because last summer I had a rewired stator installed by my dealer in my high mileage 2015 RT. Less than 2 weeks before the stator went bad I had the bike well into triple digits with no more vibration than before. In fact that bike always seemed smoothest vibration wise between 90 and 100. After getting the bike back later that summer the bike felt fine. Shortly before we headed south for the winter on the new RT late last year I had an occasion where the traffic and road conditions made me feel comfortable going fast on that bike . At 90 the bike had noticeably more vibration than before the stator replacement. I let it get up to 100 to see if the vibration might change but it got worse. In years past there were times in the far west where we could set the cruise control at 100. Now the bike vibrates so bad at that speed that i am afraid it will self destruct. Someone at a dealership here in Florida told me that maybe the shaft was installed out of phase.
What is driveshaft phasing and do modern bikes require certain shaft phasing? Or does someone know of another reason why this bike vibrates so bad now. I would not have spent all that money having a stator rebuilt and then installed on this bike if it vibrated like this. I did do because I felt with the new stator the bike would be fine for another 100k

 

[Visian]

With the caveat that this info may not apply to your specific bike, Anton presents good info here:

http://largiader.com/articles/driveshaft/

He will probably comment here before long, but this is worth reading.

 

[Omega Man]

I guess the first question is "how old or how many miles" are on the driveshaft? Sometimes when a driveshaft is removed and not reinstalled really close to its original position, it will vibrate as it is now working against a new set of (for lack of a better term) wear areas.
If you do a search via the "Tag Cloud" you will find a number of threads on the subject of driveshaft phasing.

OM

https://forums.bmwmoa.org/showthread.php?75890-Do-you-ever-use-the-quot-Tag-Cloud-quot

 

[SteveAikens]

What do you consider "high mileage"?

My 07 RT "shafted" me at @ 90K or so. There was no warning whatsoever. All was well, then pulling onto the interstate, U-joint went south in a hurry.

My 15 RT is more vibration free than any of my previous BMW's. Any unexpected vibration would mean a run to a dealer to have it checked out for me. I can't work on my bikes any longer, unfortunately.

That said, since I rarely run as hard/fast as it appears you ride, I may not be having the same experience as you are, or pushing the bike as hard.

My 07 now has @ 150K on it and is in my son's garage. He and his wife ride with me from time to time.

 

[robsryder]

Anton's info on driveshaft phasing and problems with out-of-phase operation are found here -

http://largiader.com/gs/shaft.html

Following are some YouTube videos that illustrate phase angle on drive (or propeller) shafts -

<iframe width="560" height="315" src="https://www.youtube.com/embed/dt69zYAcXME" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" allowfullscreen></iframe>


<iframe width="560" height="315" src="https://www.youtube.com/embed/Idk3BVDVHq4" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" allowfullscreen></iframe>


<iframe width="560" height="315" src="https://www.youtube.com/embed/Ek8c4nLlBF0" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" allowfullscreen></iframe>

 

[millsaps2]

U Joints

It sounds like the u joints are going bad and not related to phasing, the u joints are welded in place on the shaft with the proper phasing from the factory. The u joint at the transmission output shaft has a circlip to hold it in place, most movement on the shaft splines would be at the rear gear side. I could see the phasing changing from one bike model to another(to reduce pulsing) due to the overall angle from the output shaft to the rear gear box, there would be no phasing if the shaft and u joints were in a straight line or parallel as shown in the clip above.

 

[jimbem]

The bike in question is 2015 that had 224,000 on it when the stator went bad . I has less than 1000 more miles since the stator replacement job.
The original drive shaft went bad at 168,000. It was replaced with a used shaft from a totaled 2015 RT-P with 22,000 miles on it.The bike ran as smooth with the replacement shaft as it did with the original until after the stator replacement.
I watched the videos and from what I got from them improper shaft phasing should not be my problem the u-joints are welded onto the shaft and can't be installed out of phase.
I have not ridden that bike since late fall as it stays in Illinois for the winter.But the way I remember it the bike only vibrated bad under load at speed. Not while coasting or at more normal cruising speeds. When we get back north in mid May I will take it back to the dealer did the stator work. But in the mean time I am open to suggestions as to what may be the cause of new vibration. It would be nice to be able point them in the right direction to fixing it . Thanks

 

[millsaps2]

RT Drive Shaft

https://shop.maxbmw.com/fiche/DiagramsMain.aspx?vid=56210&rnd=09082020

Looks like a one piece welded shaft, note some phasing of the universal joints.

 

[robsryder]

Here is the image from the MaxBMW fiche -



The original driveshaft on my airhead GS was a bit "out-of-phase" as shown in the image above. I obtained a rebuildable EI driveshaft from Ted Porter for the airhead. That EI driveshaft had both u-joints in phase.

 

[topophilia]

Driveshaft phasing

While I understand that this is not a direct comparison, a recent experience of mine illustrates the importance of phasing.
I had removed the rear driveshaft on my ATV to do some work on the rear end and when I reassembled the driveshaft I did not put it into correct phase. This was due to ignorance.
The first time I took it out of the shop, it felt like something was binding and releasing in time with the speed of the ATV.

After some research, I learned about phasing and watched some of the videos shown in the post above. I removed and put it into proper phase and the difference was incredible.
I will never again make that mistake. I even checked the PTO shaft on my tractor to insure correct phasing and found it to be wrong. Much less vibration with it corrected.

Bob

 

[52184]

Posts #9 and #10 illustrate why it would be nice for an engineer to chime in and explain why all GS driveshafts, even the new lower-cost ones BMW is selling, are slightly “out of phase” like the illustration in post #9. Aftermarket driveshafts seem to come with conventional phasing, no offset. Is there an actual engineering reason for the OEM off-phasing? Or…?

Best,
DeVern

 

[robsryder]

I can think of no good reason for drive shaft u-joints to be out-of-phase. Following are some other videos that illustrate the effect of out-of-phase u-joints on the output shaft rotation. Also some more in the math behind the operation of the u-joint, constant velocity joints, and cardan joints -

<iframe width="560" height="315" src="https://www.youtube.com/embed/DDmz0tibVGM" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" allowfullscreen></iframe>


<iframe width="560" height="315" src="https://www.youtube.com/embed/LCMZz6YhbOQ" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" allowfullscreen></iframe>


<iframe width="560" height="315" src="https://www.youtube.com/embed/FTiJAdJjsqA" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" allowfullscreen></iframe>

 

[LFarling]

I had thought I read that Ted Porter had stopped his after market DS to redesign them?

As to the diagram showing slightly out of phase DS from BMW.

Is it maybe because when it is installed, and all the angles are made when both ends of the shaft are seated, and then rider weight is added, it is then in phase?

I think of running the bike on the center stand and that is just not a good thing to do because of the angle it puts the shaft and joints in.

The last time I read a phased DS discussion was when I had my 07 LT.

 

[52184]

The last time I read a phased DS discussion was when I had my 07 LT.

Kind of an important discussion on those bikes, as IIRC they had a two-piece driveshaft like the K1200RS/GT bikes, with both ends retained by a circlip and the splined section in the middle requiring periodic cleaning and greasing. Once cleaned and greased, it was important to properly align the two halves for proper phasing on reassembly. And phasing alignment on those shafts, while never perfect, was always much closer than what we now see on the GS shafts.

Best,
DeVern

 

[pglaves]

Kind of an important discussion on those bikes, as IIRC they had a two-piece driveshaft like the K1200RS/GT bikes, with both ends retained by a circlip and the splined section in the middle requiring periodic cleaning and greasing. Once cleaned and greased, it was important to properly align the two halves for proper phasing on reassembly. And phasing alignment on those shafts, while never perfect, was always much closer than what we now see on the GS shafts.

Best,
DeVern

I will add to this comment that nowhere in the Oilhead service manuals did BMW ever instruct anything about proper phasing of the two-piece driveshafts, even when they sold the two pieces separately. The instructions were pretty much take it out, grease it, put it back in. I spent words on this in a few of my Benchwrenching column articles over the years.

 

[BC1100S]

I spent words on this in a few of my Benchwrenching column articles over the years.

Speaking of which, those columns are sorely missed. No disrespect to the individual who tried to fill your shoes.

 

[pglaves]

Speaking of which, those columns are sorely missed. No disrespect to the individual who tried to fill your shoes.

Thank you!

 

[pauls1150]

"Benchwrencing" is a huge part of the WHY I read these magazines!

LFarling - Changing the angle of the driveline doesn't change the phasing; phasing is totally dependent on the orientation of the U-joints with respect to each other.
(Side note - How "close" you can get depends on how many teeth are available to slot the pieces into; more teeth = closer alignment).

I've said it before but it needs saying again: I have personally witnessed brand-new shafts still in the BMW packaging that were out of phase. It is up to the mechanic working on the bike to look at what he's doing and do it right.

 

[52184]

I've said it before but it needs saying again: I have personally witnessed brand-new shafts still in the BMW packaging that were out of phase. It is up to the mechanic working on the bike to look at what he's doing and do it right.

ALL of the new GS driveshafts I’ve seen or have seen pictured are out of phase, and while you are absolutely correct that it’s up to the technician to verify and correct, that’s not possible to do on the shafts where the two pieces are joined by an elastomeric filling. As inexpensive as the new shafts are, I believe I’ll wait for EI/Beemershop to release an aftermarket shaft for the LC boxers, one that’s properly phased. Unless, of course, an engineer steps in and explains why GS driveshafts should intentionally be out of phase.

Best,
DeVern

 

[robsryder]

I had thought I read that Ted Porter had stopped his after market DS to redesign them? ....

I purchased the EI drive shaft from Ted Porter several years ago. I just looked at his website and the airhead version is still shown (for $700).

https://www.beemershop.com/product/...00r-r80gs-paralever-models-generation-ii.html