| Author | Message | ||
     Dfbutler |
Apparently one of the studs for my rear cylinder exhaust header on my 99 S3 fell out. How do I replace it and why do you think it happened? | ||
| Brokeneck |
Are you sure it fell out --- I thought mine fell out but it had actually sheared off behind the clamp. They had to pull the head to fix it -- luckily it was warranty. | ||
| Dfbutler |
I was planning on looking at it today. I hope it isn't sheared. | ||
| Reepicheep |
All is not lost if it is... lots of threads about it in the knowledge vault. The short answer is use the Jims tool (either you, or your mechanic). | ||
| Jlnance |
If it fell out, just screw another one in. I'm betting it sheared off. There are lots of ways to fix it. Don't use mine, which was to drill it out free hand and get it sideways. If you do manage to screw it up like I did, Pammy can fix it for you, but that requires taking the head off. The Jims tool is supposed to be excellent. It's about $80, which is why people like me try and figure out how to get it out w/o the tool. In retrospect it would have saved me a lot of money to buy the tool. | ||
| Dfbutler |
What's Jim tool? | ||
| Jlnance |
This is the tool: http://www.americansportbike.com/shoponline/ccp0-p rodshow/16029.html  | ||
| Silenc3r |
Yeah, it's probably sheared... Mine did that 3 times last year... starting with the first long ride in the spring. That's the tool you want. I didn't have it my first time, and I just tried using a craftsman bolt extractor and a drill, and well, Craftsman replaced the busted tool. but getting it machined out of my cylinder head was on my on nickel. While yer at it... Check your rear muffler hanger, make sure that all the bolts are there, and that the rear of the can can swing a bit to compensate for engine vibration. Also, check your front engine isolator. If the rubber in the mount is going, you'll get a LOT more vibration... And since the exhaust is solid mounted, while the engine is not, almost all the stress is transfered to the header studs... especially with some of the after market pipes out there. Also, if your engine mount is going, you MIGHT notice that the bike behaves much better leaned over toward one side than another... I HATED leaning to the right on my bike for the longest time... Didn't have a problem leaning to the left. I had it in to get the brakes looked at, the bearings, the suspension, EVERYTHING... but they never found anything wrong. But as soon as I swapped out that mount, it was like having a brand new bike again. I run a one-piece Force Pipe on my M2, and whipped up a rear can mount that allows the can to move a little. | ||
| Dfbutler |
Silenc3r You hit it. The tailpipe was rigidly mounted to the frame. Not only was the stud sheared, there were several cracks in the header that needed to be welded. I fabricated a rubber mount for the tail pipe, so hopefully it won't happen again. | ||
| Jos51700 |
You guys do realize, that on ANY tube-frame Buell, the exhaust isn't mounted to the frame in any way, right? The exhaust is not completely solid mounted (on the stock setup), but does mount only to rubbermounted components. It all moves with the motor, just like XB's. | ||
| Jos51700 |
By rubber mounting the muffler, you're allowing all that mass to move even more. My crystal ball sees many broken studs and much shattered stainless in your future. | ||
| Djkaplan |
"The exhaust is not completely solid mounted (on the stock setup)..." Except for where the headpipes are clamped to the heads, this is true. The rest of it is rubbermounted to the engine, which in turn, is rubbermounted itself. | ||
| Jos51700 |
"Except for where the headpipes are clamped to the heads, this is true. The rest of it is rubbermounted to the engine, which in turn, is rubbermounted itself." Out of four mounting points for the exhaust, only one is in rubber. My point is, the exhaust does not break because part of it mounted to the frame, and part is mounted to the motor, with the resulting difference in motion causing breakage. Part of it would have to be mounted to the frame, for that to even be possible. It's the looseness causing these to break, not the (implied) rigidness of a frame mounting. Mounting the rear of the muffler in rubber as DfButler described is inviting disaster. The studs break because the front muffler mount is rubber, and as the rubber fails, the weight of the exhaust, and the motion allowed by the failed mount, overstress the studs and/or header. The Buell remedy of spreading the load over dual rubber bushings (updated mount) is good because it makes it harder to fail a bushing (although I will never understand why they chose rubber....), but..... I know for a fact that rigid-mounting the front of the muffler has prevented stud/exhaust failures on multiple bikes that I have done. I'm not sure if it's a manufacturing convenience, or an engineering necessity, but that rubber mount the root cause of many problems. Proof in the pudding? XB's! | ||
| Djkaplan |
"Out of four mounting points for the exhaust, only one is in rubber." Out of the five mounting points to the engine and swingarm block my M2 exhaust came with from the factory (which it still uses), three of them have replaceable rubber bushings. The only part that isn't separated from the engine by a rubber bushing is where the headpipes clamp to the exhaust ports. Look up in the swingarm block... there are two rubber bushings supporting the rear hanger for the exhaust can. | ||
| Dfbutler |
OK, here's my logic. About a year ago, the hanger on the tail pipe fell off and I went to a local muffler shop to get something to replace it. They fabricated a couple of metal hangers that were bolted to frame and attached to the tailpipe with clamps. They also attached a spring to the front hanger to support the front. Around that time I started to have things vibrate loose. The screws holding the tail light lens kept coming out and on a ride it fell off. The bolts on the back header fell off a couple of times. At the time I thought it was caused by a new harmonic from the 1250 kit that was installed befor the hanger fell off. When I noticed the missing stud on the rear cylinder - prompting the original post - I figured it was just another vibration related problem. When the headers were removed to fix the stud, several cracks were found in the rear pipe, which needed welding. The question was what caused the problem in the first place. The logical culprit was the rear hanger. The failures were the result of stress, what caused it? The headers are attached to the engine, which is isolated from the frame and moves independently on the mounts. Logically, by attaching the exhaust rigidly to the frame it becomes the primary attachment of the engine since it doesn't move and the others do. What happens is the exhaust must absorb the movement the engine mounts allow by flexing. By supporting the rear of the muffler with a hanger that lets the exhaust move with the engine, removing stress on the exhaust. | ||
| Jos51700 |
Where does the exhaust mount to the frame, exactly? Everything the exhaust mounts to is isolated (Rubber-mounted). And my apologies to djkaplan, he is correct. Later bikes DID use rubber (and sometimes plastic) mounts. My S1 and apparantly the older bikes, do not have rubber at the rear, so I'd guess that says we're both correct. | ||
| Djkaplan |
No apology is needed, but the acknowledgement is much appreciated. I was unaware that S1's had solidly mounted rear muffler hangers. It was an assumption on my part (why does it always make an ass out of just me when I assume things?) that all Buells had the same arrangement. Part of the reason for that was this blurb that was posted about this very issue some time ago... http://www.badweatherbikers.com/buell/messages/384 2/17534.html -------------------------------------------------- ------------------------------ Quote: According to Erik Buell, this muffler mounting system was a big step forward in reliabilty for the XB motorcycles compared to their predecesors. Previously, Buell mufflers were rubber-mounted, which presented engineers with a "three mass" problem: The Buell chassis suspended the engine mass from rubber mounts, which, in turn, suspended the muffler. Predicting the vibrational behavior of two masses connected by a spring and a damper (collectively, the rubber mount) is a simple matter for engineers. Knowing those characteristics, they can then design the whole system to stay "out of resonance" over the range of vibration frequencies the engine produces between idle and redline. But make it a three masses, and the problem becomes vastly more complex, which is why Buell engineers have chased muffler-mounting problems continually throughout the history of the tube-frame bikes. And even when these problems were solved for the stock components, the aftermarket would always come up with something that looked good but once again woke the resonant vibration demons. -------------------------------------------------- ------------------------------ I think this article actually does a pretty good job supporting your assertion about the XB's muffler mounting. I like win/win situations... and hey, it's Friday! | ||
| Jos51700 |
I saw a race-kit mount on here a while back that someone made, and I liked it. If I actually ever rode my bike, I'd make a heave-duty aluminum mount similar to XB's. I think they used rubber initially on tubers to allow for expansion/contraction issues. I know the header moves around alot when you heat it up, if there's no muffler on it. (Stainless welders complain about stainless expansion with heat, too). Even with no problems on stock mounting, I still run a race-kit style safety loop. | ||
| Jos51700 |
"I was unaware that S1's had solidly mounted rear muffler hangers" I don't want to say all S1's, or all prior to 19XX, or anything like that, because I distinctly remember seeing a few with rubber, a few with hard plastic, and a few with aluminum. I'm sure someone somewhere will find one I altered with aluminum, and think it's OEM. I might do some research on this, now...... And I always give credit where it's due. Everyone tells me I'm stuck in my ways, and I don't think about other points of view, but I dunno why...... |
