| Author | Message | ||
     Rick_a |
This morning was an interesting commute. About a 1/2 mile from work I heard a quiet "tink" sound...and ran over something. My first thought was an exhaust bracket. A few hundred yards later the bike was vibrating like a paint shaker. I rode her slowly to work...and there it was. The left front motor mount bolt broke and then the right side of the head broke off at the mount. It looks like I'll be getting mighty healthy riding my mountain bike to work until I can come up with enough money for a needed (performance) top-end rebuild. | ||
| Mikej |
Post a pic if you can, thanks. | ||
| Djkaplan |
That's it. I'm buying an aftermarket mount... TODAY!. | ||
| Rick_a |
The mount is fine. The head broke. | ||
| Djkaplan |
Just got off the phone with Al at American Sport Bike. Got one of those chunky Nallin engine mounts, a new front isolator and the bolt kit. This ain't happenin' to me! | ||
| Rick_a |
It may be better to have a weaker mount. I'd much rather have the mount break than the cylinder head. If you notice the '96 prior Buells have a very well built mount and the later bikes have a spindly mount with little reinforcement. I don't think that was an accident. If want this to not happen to you get a billet mount and the XB/XL1200R heads which are much stronger in that area. Otherwise, don't do wheelies, stoppies, or jump railroad crossings  . | ||
| Blackbelt |
I gotta see pics of the railroad crossings jumps.. There was a nice crossing that i would regularly jump w/ my car in high school.. it was a 1969 GTO, and i could get NICE air. But they re-designed the track crossing and no more jumpie jumpie... i was bummed | ||
| Djkaplan |
"It may be better to have a weaker mount." Lots of theories as to why the bolts are breaking, but it actually may have something to do with the stock mount. There is no way a grade 9 bolt could be subjected to enough shear to fail in this application. I suspect the mount is being cantilevered by stress induced from the front isolator as the engine/swingarm rocks forward and backward on the rear isolators. Or it could be a resonance caused by the mount legs not being tied together - who knows? Will a stronger mount keep the fasteners from failing? I don't know. The stock mount on my 2K M2 never gave me any problems (I ride my bike hard and wheelie it just about every time I'm on it, too) so I have nothing to compare a new mount to. Has anyone ever suffered a failure with a Nallin or S&S mount? | ||
| Rick_a |
The legs on '96 prior have thick webbing that ties 'em together...like mine. | ||
| Jlnance |
blue {It may be better to have a weaker mount.} Take a look at: http://www.badweatherbikers.com/cgibin/discus/show.cgi?tpc=4062&post=406583#POST 406583 for an example of this. | ||
| Rick_a |
I'm quite sure the right side of the head broke first and then the left bolt broke soon after. I've got a new top end on order and cams while I'm at it. I'll hopefully have it back together in about a month (due to finances). | ||
| Djkaplan |
Interesting archived stuff... http://www.badweatherbikers.com/buell/messages/3842/7324.html?1090856437 Start from the archive at the top for the full thread. | ||
| Buellzebub |
After my front isolator mount broke two months ago (standard failure, left hand bolt sheared off about 1.5 threads into the head, and the resulting lack of clamping allowed the arm between the two bolts to crack). I showed the pieces to our resident mechanical engineer to get an expert opinion. The failure looked very much like a standard fatigue failure. We came to the conclusion that thermal cycling over time may have contributed to the weakening of the thread locking compound and subsequently allowed the fastener to lose its clamping torque. Once the tensile load was removed the mechanism for the fatigue failure was in place and it was only a matter of time before the bolt would fail. As these bolts are "factory installed" there is no maintainance proceedure to ensure adequite clamping is maintained over time. This is probably a very good application for the capscrews that have a visual/tactile torque indicator (I can't remember the vendor off hand). | ||
| Djkaplan |
Interesting. I'll make sure to mark the bolt heads to see if they're backing out when I install my Nallin mount. | ||
| Denfromphilly |
Boy this is scary stuff!! I just checked my head for cracks and the blots are tight. I will preflight my bike before each ride but I don't get that warm and fuzzy feeling...Den | ||
| Buellzebub |
heres some vendors of load indicating fasteners http://www.smartbolts.com/ http://www.vfbolts.com/Home.html (maxbolt) they are not the vendors i had seen before but i cannot locate the information here, i must have it at home. DJ that is truly a simple and quick way of noting tension loss, i think i will mark my bolts too! | ||
| Iamike |
Denis, It's not something to get reall excited about. Just be aware and keep an eye open. Even if the front mount completely fails the motor can't fall out, it would just lean forward against the frame. It's real easy to get worked up when you hear of one or two people having a problem here but in most cases these are pretty dependable bikes. I am approaching 53,000mi. with my '99 S3 and have only had the side stand switch fail on me. | ||
| Rocketman |
It might be worth calling Buell Customer Services. They warrantied my repair despite it been out of warranty by a year or two. I know they did others too under similar circumstances. Seems only fair they should repeat the procedure no matter when it occurs. I stand by my findings in them their archives too! good luck. Rocket | ||
| Rocketman |
 Note the weld around the front right mount hole. Finished by hand with a file it's hardly noticeable unless you go look for it. Of course it's more noticeable from the outside view but once it's painted it looks normal unless you park it next to a head that's not been repaired. Rocket | ||
| Rocketman |
 Here's the stud and spacer. 10mm x 1.75mm pitch Shank length 46mm Thread length 30mm Spacer 6.5mm Sorry for the picture quality. I shot them last night with a Sony Ericsson T620 cell phone. Rocket | ||
| Rick_a |
Mine's been out of warranty for 8 years. I have new cams and a new top end on order. Screw it. If it's broke, fix it to the max. I'm contemplating whether to port my new heads or not. Decisions, decisions. | ||
| Road_thing |
Rocket--is that stud bent, or is it the cell phone camera? rt | ||
| Rocketman |
Jeez Thang you might be right?????? Funny you should ask anyway because I'm just about to go out the door to the hardware supplies and buy two new ones. Those in the pic's have been in and out more than once and the one in the pic on its own is sat in the car so's I can use it for reference once at the bolt suppliers! I'll let you know if it's bent but your clairvoyance skills are way ahead anyway  Rocket | ||
| Koz5150 |
FYI!!! Those bolts are designed to be used once only. I loosened mine once and then tightened it. It broke off in the head within one month. I drilled it by hand and then extracted it with an easyout. On the mount it clearly states "Do Not Remove", I guess that is why. 2000 miles and 1 trackday since the repair and all is well. | ||
| Road_thing |
Rocket, clairvoyant or not, I didn't bend it! rt | ||
| Blake |
Rocket, I understand that said bolt is a very special high grade piece of hardware, even stronger than grade-8 or so I am told. Markings on head should tell your hardware man what it needs to be. | ||
| Rocketman |
UPDATE ON FRONT MOTOR MOUNT BOLTS Yes thang it is bent ever so slightly. In the UK, and I'm told these are international standards, the lowest strength high tensile bolt is graded 8.8 and that's what I've been using. Not through choice but they are all that's available locally unless I order specially but then I can't just order 2 bolts only. The next grade higher in HT is 10.9 and then the highest 12.9. BE AWARE I MADE A MISTAKE. These are not 10mm x 1.75 bolts as I first thought. They are 7/16th UNC. Rocket | ||
| Road_thing |
Well, wottayaknow? I can see for miles and miles... rt | ||
| Al_lighton |
It is a Grade 9 bolt, 7/16-14, 2.75" long, made for Buell by F911. Don Casto did a lot of investigation on this bolt a couple years ago. He found one other manufacturer that made a similar strength bolt (Chromate something or other). The washer that it bears on is a hardened washer too, not a generic washer. These are not your local HW store items. Don't screw around, get the Buell bolts. I've had to drill mine out of the head twice, but haven't had any further issues since I put the NRHS mount on (knock on wood). Checking for the presence of both of those bolts is one of my standard preflight checks, and has been since it snapped off the first time in my head. The second time, one bolt was snapped off and missing, the second was broken, the whole engine was hanging by less than 3 threads. I caught it because of that preflight, and saved myself a LOT of grief as result. All tube frame riders should make it a point to look at those two bolt heads prior to every ride. Al (Message edited by al_lighton on June 15, 2005) | ||
| Rocketman |
The problem is Al as I've stated so many times before the Buell bolt is not long enough and that in itself puts a lot of strain on the bolt. As for drilling and easy outing. The time that the head gave way both bolts snapped. I extracted both remaining ends with a 2lb hammer sharp Snap-On pin punch and Snap-On spring punch. I used these same tools again for the same purpose when I snapped the left bolt when I over tightened it once before. Basically once you get it moving with a sharp blow from the hammer and punch - be accurate coz you don't want to foul the casting around the thread - one can use the spring punch to keep rotating the broken stud because it applies enough force you don't need a hammer. Maybe I was just lucky - or good - but I've not had to use a drill and get over involved! I'd say not to use the Buell bolt at any cost. Do your homework. Work out the depth of thread in the head and fit a same or higher strength bolt but a longer one even if it means using a spacer like I have. Good luck. Rocket |
