Drive shaft failure

[leroysch]

KTM curse....or some other travesty?

 

Glad your adventure has everything back home and a plan forward....

[Lucky Phil]

Hey docc, just musing on the failure mechanism here which may well simply be a failed uni joint but is there any chance it could have been a loose clamp bolt causing the yoke to fail first? Maybe even backing out and catching the collar?

Just thought and hoping you would get a decent warning before the uni failed and caused that sort of carnage.

 

Ciao

[Chuck]

First, that ain't gonna buff out. Second, I agree with Lucky Phil. It appears to me to be a yoke failure for whatever reason. I would have thought that if a bolt caught on the collar, though, it would be trashed, too. At any rate, the Sausage Creature is ok. That's all that is important..

[docc]

Neither of the fasteners show any sign of impact or rubbing. This is the yoke I had to move between rear drives twice in the past: just over 2,000 miles ago, and again about 1,000 miles ago.  Also, the one I crossed a bolt into, could not obtain suitable replacements, so re-cut the threads, torqued up with LocTite Blue.

 

Nonetheless, the work of "my last technician" (me) has to be called into question. 

 

Perhaps, it would be good method to retorque drive shaft pinch bolts after a couple hundred miles?

[swooshdave]

 

That's over 100,000 miles on that driveshaft before fatigue, right? 

 

Good that you already have a replacement on the way. Off with the swingarm... and this is a good time to put a relief in the front collar for easy access with grease gun. Or did you already do that?

Yessir. On the cusp of 108,000 miles.

 

I still actually can't figure out where to make that cut (?)

 

 

I guess it's out of warranty?

[Chuck]

Neither of the fasteners show any sign of impact or rubbing. This is the yoke I had to move between rear drives twice in the past: just over 2,000 miles ago, and again about 1,000 miles ago.  Also, the one I crossed a bolt into, could not obtain suitable replacements, so re-cut the threads, torqued up with LocTite Blue.

 

Nonetheless, the work of "my last technician" (me) has to be called into question. 

 

Perhaps, it would be good method to retorque drive shaft pinch bolts after a couple hundred miles?

From my mini Southern Spine Raid report:

"After the grand tour, we walked out to the bikes, and Brad said, �would you look at that? WTF?" One of the bolts that holds the driveshaft coupler was backed off a thread.

Most people would have never seen it, but an aircraft inspector just �sees� that kind of stuff. Now the question is, �Why?� That bolt is just not likely to have backed out on it�s own.. but the Kid is a pretty competent mechanic. He said, I can only guess that I never torqued it properly. I told him that it was no doubt the final test.    �You are worthy.�

 

 

[Tomchri]

Seems to me your thinking the troubled bolt did loosen up and made the u joint to start wiggling, no extra vibration felt during the last few 100m ?

Good nothing happened, those things could be nasty. And you will soon forget thinking about rear drive and shaft. How do I know,,, had to change the rear drive on a beemer 1300s on the Autobahn

Cheers tom

[docc]

I wish I had those observational skills.   Josh does.  I'm glad others do.

 

I do ponder that the fasteners simply did not retain their torque, even with the LocTite.

 

Is it expected that the coupling clamps down tight onto the splines such that there is zero fore-aft movement of the couplings (front and rear) on the gearbox output shaft and the reardrive input shaft?

[Tomchri]

would say YES to that, splines on the shaft take care of the flex. May be a little white dot on the bolt and u joint with waterproof marker. What do I know,,,, just like motorcycles  Time for another IPA, Cheers tom

[docc]

I always have painted alignment marks on the pinch bolts and monitored them, but not every ride, every time.

 

Right now, the front half of the shaft slips fore and aft freely on the output shaft.

 

Cheers, Tom! "Nut Brown Ale!" 

[docc]

I found the front pinch bolts about 24.5 Nm. Below the spec of 25-30 Nm for an 8mm bolt.

 

Seems they must have loosened up.

 

Even at ~30Nm, the collar slips fore and aft on the splines.  [ I have one torque wrench that goes to 29.03 Nm and the other starts at 33.9 Nm. ]

 

At 33.9 Nm, the collar does not slide on the shaft.

 

I have also heard that torque wrenches are not accurate within 10% of their end ranges (?)

[Chuck]

A torque wrench is best at the middle of it's range. Shouldn't be off more than 5% from low to high, though..

[footgoose]

A torque wrench is best at the middle of it's range. Shouldn't be off more than 5% from low to high, though..

And which "style" wrench do you prefer Chuck? Inquiring minds...

[andy york]

WOW   good your OK !

 

on a lighter note --- mine lasted longer than yours!!

 

just looking at the pics- looks like the flange failed somehow....hairline crack - bolt loosed - something

Im sure you will get to the end of it 

glad you have one on the way 

I think I will start looking for one myself 

 

ps we had this conversation about the "window" on the front joint cover. Did we not determine

that yours is somehow different?

 

pss  can't make the raid   have a show that got in the way plus I'm working on the 

        bosch starter on the v7 sport

[Chuck]

 

A torque wrench is best at the middle of it's range. Shouldn't be off more than 5% from low to high, though..

And which "style" wrench do you prefer Chuck? Inquiring minds...

 

It's hard to beat a beam for accuracy. I have several types,though. I use a clicker in a production application.