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ANSWERED Drive shaft failure

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Thanks, guys! :thumbsup:

 

Riding today, I recall another clue something had gone awry and I did not act on.  The week before the failure, the Sport started exhibiting an odd noise rolling up to a stop. It was a sporadic and not repeatable, "rowl-rowl-rowl" . . .  sometimes just one "rowl" or two. Reminded of the noise we sometimes get from the rear rolling the V11 backwards.

 

Evidently, that is pidgin Italian for, "Check your driveshaft." :whistle:

Yes docc add it to the faint clunking/rattle feel through the footpeg on floating throttle when your rear wheel bearing is totally shot with about 500klms left in it.

 

Ciao

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Wow, that's a scary failure.  I'd sure like to not experience that one!  Glad it seems to have gone pretty uneventfully for what it was.  I have needed to re torque my u joint couplings a couple of times in the past (and I only have a third of the miles that Docc does).  I'm not sure how I noticed it the first time, but now I use a small prybar to try to slide the couplings fore and aft whenever I'm doing any work around the rear wheel.

 

I'm busy getting my newly resurrected V11 ready for the SSR, so last night I pulled the rear coupling off of the final drive to look for cracks.  It looks like Doccs cracks may have started at the root of the splines.  I'm surprised to see how dark one entire half of his coupling was.  It seems like it was running for a while with one side fractured all the way through.

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docc, you had asked me about a needle tip for greasing the front u-joint recently. I recall posting a photo... but I've lost it ... and the tip, so I got another today. Not the same but it works! Thought I should post results, a good a place as any. The sharp point is tapered and is just the correct size to depress the tiny ball in the zerk. It doesn't have a straight approach, but good enough to get the job done. Keeping max downward pressure, only a tiny bit gets out around the tip. The rest gets through to fill the little bastard.

O'Reilley's Auto Parts $15

IMG_1042.JPG

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On 8/13/2018 at 7:08 PM, docc said:

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

Docc.....could you use these locking bolts instead of regular ones? 

Vibe-Lock Fasteners

I don't know the thread pitch

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Those are kewl! Never seen anything like that.

Pretty sure my failure was a combination of my failing to torque pinch bolts correctly (go back and forth between them and not just once per side), not torquing to the higher side of the range (instead of the middle), and reusing fasteners that had been crossed and the threads chased. Is it possible that excessive pinion play may have contributed to rattling them loose?

Testing in process, as I have moved the back of the shaft to another reardrive almost 400 miles ago. I must have clicked the torque wrench back and forth between those bolts twenty times!

(Trying to earn my :luigi: back . . . )

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Guys.
I've read this post with interest and decided to check the UJ's on my newly purchased 1996 1100 sport.
No play in joints but both clamp bolts are torqued up correctly ( backed them off and 're torqued) and the UJ still slides on the splines.
Is this normal or have I got a more sinister problem On my hands?

Regards
Andy

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Isn’t there a groove there that means there’ll always be a bit of fore-aft wiggle?

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When I first retourqued to the front yoke to the slightly higher value, it clamped tight to the output shaft.  After a couple thousand miles, the sliding play returned. I was tempted to retorque it again, but the fasteners have not loosened.  So, good question. Is the sliding movement normal and acceptable?

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I'd say this is not acceptable, even when it's quite common. Make sure you use 12.9 bolts and torque them to 40Nm. You may also cut the slots some millimeters deeper to ease the clamping. Of course, that's up to what nerves you have in real life, internet off. But done properly it's a proofen modification.

Some words about the alignment: Because of the wide rear tyre the U-Joints don't move in one plane only. Look from above and you'll see the shaft pointing outwards. That's the reason they weld them with some degrees more/less then 180°, it's to reduce the resulting transmission failure.

And be easy with grease on the moving part of the shaft. The spines should be able to glide 'freely', too much grease and they're stuck. Common fault because this zerk is the only one everyone can reach

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I found the bolts on my '97 to be f***ing TIGHT. But both ends still slid on the shafts. After <insert u-joint horror story> I cleaned everything and tightened the bolts until I felt the yoke clamp  the shafts, then torqued. In the end it was to about book spec for that fastener/thread, which escapes me at the moment. My conclusion is that the fit and finish at the factory, coupled with inadequate initial torque allows a bit of wear- or 'smoothing' and goes slack in the splines. Has anyone read the factory maintenance documents, to find if they recommend periodic retorquing?

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