[futurR]

Well, you all should remember the saga of the broken swingarm at 70mph. He was able to keep it upright and get it off the road. I got it in and the rear diff and swingarm were destroyed. For those that are not aware and those that do not remember, the link to the previous post is below.

http://www.m109riders.com/forums/showthread.php?t=120370

Well, I was able to find the time and space to get it in to find the damage. At first, I thought there was a slight chance of the clutch hub nut had backed off and caused all this---not so. Got the engine pulled with alittle help from Josh and then pulled the pan. Found broken teeth immediately, so the pics say the rest.

A few teeth missing here.

A few teeth missing there.

And the teeth were found there.

Yes, that was 5th gear idler, 5th gear itself, and the evidence in the pan. What this shows and proves, is that the problem did not start in the tranny. The tranny was shocked from the deadly rear wheel lockup and ate the teeth right off the gears. To be honest, I expected much more damage. There are now only 2 options for the cause, which were mentioned in the other post. The swingarm broke or the secondary bevel gear bolt that backed out. Now the cause of the bolt backing out has been solved. This engine has been apart before---appearantly for tranny issues. That person or tech did not do their job and torque/locktite that bolt down. Well, the true cause of all the damage lies between those two points. We may never know which one, but now know more about his bike than was previously know. All in all, it could have been much worse and we were able to get a crazy deal on a spare engine where most of the parts will be coming from---plus a couple of new parts. Josh is trying to get free for the meet. Hope to see him there!
http://www.flickr.com/photos/[email protected]/4569837580/

 

[Zoom]

Wow, I remember that post and actually mentioned the swingarm failures to a Suzuki mechanic we ran into on a ride today. He said he's had two 109's in with 2nd gear failure, and this is a local shop. He said he'd never had one in for a swingarm failure or really any other mechanical failure.

Is it possible one of those teeth broke initially, got lodged between the gear sets, and that set off the rest of the reaction? Or have you seen broken teeth on tranny gears in this bike before?

 

[futurR]

Wow, I remember that post and actually mentioned the swingarm failures to a Suzuki mechanic we ran into on a ride today. He said he's had two 109's in with 2nd gear failure, and this is a local shop. He said he'd never had one in for a swingarm failure or really any other mechanical failure.

Is it possible one of those teeth broke initially, got lodged between the gear sets, and that set off the rest of the reaction? Or have you seen broken teeth on tranny gears in this bike before?

I would say no. All the teeth a pretty much intact as if sheared off at their perspective bases--D demdum. So, evidence shows a failure due to mph and rpm at immediate lockup. Amazing I did not find any clutch issues. Plus, normally if such a tooth were to get lodged in there, you would expect damage in the cases or teeth that were smashed--none found. So, what I see is that it started in the final drive train.

 

[ooinkk]

Thanks for the follow up Matt, do you think the bevel gear screw backing out could have caused all this ?
I can understand how the Swingarm failure could have created all that damage , i just cant picture how that screw backin out could have done all that

 

[futurR]

Thanks for the follow up Matt, do you think the bevel gear screw backing out could have caused all this ?
I can understand how the Swingarm failure could have created all that damage , i just cant picture how that screw backin out could have done all that

Well, if that bolt backs out far enough, it put pressure on the secondary torque shaft. The head was ground down quite a bit. Now it is more likely the swingarm break caused it---logically speaking. However, no way to truely say what the real cause was.

 

[Guest]

I believe I mentioned this in the original post, but if the engine locked up at speed it would cause the swing arm to break just as it did. The rear wheel would still be trying to turn and would rotate the dif downward at the front hard enough for the swing arm to break as it did. I would tend to believe it was the bolt backing out as things would have to still be rotating for it to be ground off a little as you said. and nothing would have been rotating after that lockup.

 

[jdmitchell]

Holy crap, that is a catastrophic failure. Hopefully nobody else has that happen, there could be some serious injuries involved in a breakage like that. Looks like the guy that owns that 9 has a good excuse to rebuild everything better than new with backcut gears and all the goodies.

 

[futurR]

Holy crap, that is a catastrophic failure. Hopefully nobody else has that happen, there could be some serious injuries involved in a breakage like that. Looks like the guy that owns that 9 has a good excuse to rebuild everything better than new with backcut gears and all the goodies.

Well he would, but again, it was apart previously for tranny isses. Meaning, with exception of the broken items, the tranny is in really good shape--looks to have been completely gone through. Now he is not the original owner and owned it for a very short time when this all happened. We are replacing the shift forks as a just incase---but they appear to be in good shape. So, for $175 in parts, and the other parts from the spare engine, he will be good to go.

 

[MSgt]

failure

WOW that is just plain insane. This guy was so lucky

 

[V42A9]

I believe I mentioned this in the original post, but if the engine locked up at speed it would cause the swing arm to break just as it did. The rear wheel would still be trying to turn and would rotate the dif downward at the front hard enough for the swing arm to break as it did. I would tend to believe it was the bolt backing out as things would have to still be rotating for it to be ground off a little as you said. and nothing would have been rotating after that lockup.

:agree: Only time could grind down the bolt, how much time is anyone's guess. The description tells the tale of the other parts failing at an instantaneous moment.