XB Rear Engine Mount Warning

[konarider94]

Don't get me wrong, I agree it's good to be informed and this post is definitely worth a read. But I'm also a Mechanical Engineer that started as a Machinist. One thing you Cannot predict with exact accuracy, is how metal (especially alloys) will act in the Real World. It's like trying to predict weather or the wave height of a tsunami - there's simply too much information that isn't considered or isn't even yet to be understood.

maybe not exact but its pretty damn close. we have a very good understanding of alloys. its not like the composition of alloys change now, we have a pretty good control over materials. even composites are becoming very well engineered. this is why cars and airplanes are getting lighter every year. its fea programs that help us optimize designs. i too am a ME that started as a machinist. I realize im a young engineer but i also understand the newest technology very well.

 

[Stevenc150]

I understand that, do failure analysis on a fairly regular basis concerning support structures (automotive door pillar beams and suspension). Thing is we do the stress test, get the nice colored renderings showing likely failure points - then I have it machined/formed and do a "real-world" test and it's different. You cannot account for everything because we don't understand everything.

Edit: Again, yet to see/hear of any rear engine mounts suffering catastrophic failures in the "real world". No matter how much analysis is put forth, until something is physically proven - it remains a theoretical outcome.

 

[BRatigan]

Will hardening the exterior surfaces through type 2 anodization help with distribution of stress loads? Might make the difference.

BR

 

[ElliottM]

Again, yet to see/hear of any rear engine mounts suffering catastrophic failures in the "real world". No matter how much analysis is put forth, until something is physically proven - it remains a theoretical outcome.

Unsure if you read above posts, but there have been cases where specifically the rear engine mount has failed catastrophically, which I understand as the part breaking completely off of the engine itself, thus causing riders to crash their bike. So far this failure has only be linked to previous accidents, although the possibility of wheelies eventually causing a similar outcome is there.

 

[kyle_dewald]

Mine broke in a wreck but didn't break causing a wreck.

 

[boosted]

Will hardening the exterior surfaces through type 2 anodization help with distribution of stress loads? Might make the difference.

BR

Probably not. The stress concentrations will exist regardless of the surface finish. In addition the Anodiziation will, if anything decrease the tensile strength and fatigue resistance due to micro cracks in the coating.

 

[BRatigan]

I did not know that. This is another good thread.

BR

 

[hobby10k]

I hit a pot hole on a trip recently, and the bike started to slightly vibrate more than normal. It seemed different but I wondered if it was just in my mind. I quickly checked over the tires and belt etc when I stopped, nothing out of the ordinary.

well I continued on the trip and one my way back it started to vibrate more. so I stopped to really inspect the bike. Thats when I noticed the rear motor mount was broke off. It seemed like it would be ok to at least get back home if I took it easy, so I took it easy and continued on. After I got home thats when I noticed the front motor mount was broke too!! that could have been very very bad!!

so yeah it is prone to failure and that was just from normal riding, I don't wheelie or race, and have never wrecked the bike.

I will post pictures if anyone is interested.

now I need to find a couple motor mount replacements.

 

[DualSportDad]

I think we would all be interested in pictures. Also year and model of the bike.

 

[hobby10k]

I dont know how to get a darn picture to show up...I'll try and get the rear up


front:
http://i30.photobucket.com/albums/c332/hobby10k1/PicsArt_1435238593057_zps25ni99s7.jpg

 

[DougH]

You can upload to photo bucket then get the direct link. Paste thate in the popup when you click image on here.

 

[dmopar1]

I just want to confirm this rear mount failure, I have an 04 XB12r with 2900 miles on it, never been dropped or in an accident, did probably a dozen wheelies on it, then was on my way to work and hit a pot hole, rear mount snapped the 2 top bolts off on the crankcase and snapped the ears off the mount on the bottom. I'll try to upload some pictures.

 

[thrstrmech]

never had an issue with mine over the 9-1/2 yrs and 70k plus miles...'03 9s

 

[TPEHAK]

I just want to confirm this rear mount failure, I have an 04 XB12r with 2900 miles on it, never been dropped or in an accident, did probably a dozen wheelies on it, then was on my way to work and hit a pot hole, rear mount snapped the 2 top bolts off on the crankcase and snapped the ears off the mount on the bottom. I'll try to upload some pictures.

Please upload pictures. I recently hit a pothole so hard even the license plate had been bended by the rear wheel. But the muffler has no marks which is strange. Do you have scratches or dents on the muffler?

 

[Chicknstripn]

I believe your failure/broken rear isolator is an anomaly.

9+ years on my Buell, and I've put it through some hell, and I've had zero issues. 4 years as a member on the forum and since joining in 2012 this is the first rear isolator failure I've read about.
I've hear of the front isolator having issues but that has also been pretty random.

The study that's referenced in the beginning of this zombie thread doesn't account for all the other systems on the bike that share in the load/stress/strain that the chassis is subjected to in a "typical" riding environment.
The suspension, rear isolator, tie bars(top,rear and front), the V bracket and the front isolator all share the load/stress/strain of everyday riding.

So, to answer your post dmopar, you're that lucky one in one thousand.
It's a crappy feeling. I know. I felt the same way when my crank bearing failed.
It's just the luck of the draw.

Are you the original owner of the bike?
Are you sure the bolts were properly torqued prior to hitting the pot hole? If the isolator bolts were over or under(loose) torqued that would dramatically reduce the service life of the isolator.