Occasional sharp clunking sound under chasis on R1200GS?

Discussion in 'GS Boxers' started by AMAL, Sep 17, 2004.

  1. AMAL

    AMAL Virtual Poseur

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    I have had a sharp clunking/snapping sound on occasion that almost sounds like something has broken or snapped under stress. It originates beneath the chasis, directly below my seat as far as I can determine. The sound is quite disconcerting when it occurs :eek1 . It appears to happen when I have hit a bump, or an expansion joint in the roadway. It almost sounds like the centerstand may be have slapped the bottom, but I doubt it.

    It happened again last night on a rather smooth portion of road while I was accelerating. I thought it was something in the rear suspension that time. It is difficult to locate the origin of the sound not knowing what I am looking for. This is especially vexing since it doesn't appear to happen consistently under the same conditions :huh.

    I keep thinking about the postings I have read here regarding rear drive and gearbox failure issues, and wonder if I have something like that going on. I noticed the first one at about 500 miles. I now have 790 miles on it. Has anyone here experienced anything like this, or have a notion what it may be?

    Thanks in advance.

    AMAL
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  2. Wimke

    Wimke Adventurer

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    Sounds :eek1 to me. you could check your real wheel drive simply yourself. That would eliminate one possible source. Take the rear wheel with both hands in a 10.20 h position if you is moving (margin) you could have the beginning of a problem. Some margin is allowed though (1 or 2 mm)
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  3. AMAL

    AMAL Virtual Poseur

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    It has happened four times total. It has never occurred while decelerating. Is that the "drive chain slack" (backlash?) you are referring to?

    I will try moving the wheel as you suggested.

    AMAL
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  4. HarveyMushman

    HarveyMushman Long timer

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    Is this your first BMW? It could be normal driveline slack, which will cause a clunck now and again (on the 1150 anyway; I don't know about the 1200). Not to be alarmist, but it could be rear suspension components being loose--check to make sure the rear shock is mounted securely.
    #4
  5. rideLD

    rideLD The further the better!

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    Are you running a top case? My bike was making a "clunk" when I hit big bumps. It sounded like it was comming from under the seat. So I pulled the seats and I checked all the fasteners. I found that both the fasteners that hold the grap handles / top case mount on had loosened up enough to make a noise when they moved. I tightened them up and no more noise.

    Of course it could just be the normal drive line lash you are hearing but you saying that it happens when you hit a bump makes me thing it could be something loose.
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  6. AMAL

    AMAL Virtual Poseur

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    I just checked the rear wheel on the centerstand. I held the wheel at 10 and 2 O'Clock, 12 and 6 O'Clock, and looked/listened for loosness. It did not move at all, although I did hear some clicking/snapping that appears to be coming from the brake calipers. It would click/snap lightly while rocking the wheel in both directions. I loaded it one way and grasped the caliper. Grasping the caliper created the same click/snap as rocking the wheel. So, that sound I am sure is from the brakes. This is not the same sound, or one that is capable of the amplitute I have experienced.

    I also checked the centerstand for slapping. The centerstand has rubber bumpers, so it would not create the metal-metal sound I am referring to.

    Harvey- I have owned two other BMWs. They were both used; a 1976 R75/6, and a 1991 R100GS. I didn't own either one a very long time. I had "issues" with them, and unloaded them. I got tired of buying other peoples problems and went with a new one this time. I have had Jap bikes previously, and have primarily been a dirt bike guy. I recently sold my 2000 KTM 300 E/XC, and am looking to buy something similar again...probably a KTM 4-Stroke...400 E/XC maybe.

    AMAL
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  7. AMAL

    AMAL Virtual Poseur

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    Yes I am. I had the noise problem before the top case though. I just had the cases put on while it was in for the 600 mile service. The "sound" is much much lower though. It sounds like it is coming from the underside of the bike, and directly beneath my seat.

    AMAL
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  8. AMAL

    AMAL Virtual Poseur

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    I will be going over this thing looking for something loose. It needs a bath anyway...maybe tomorrow. It will be a good time to inspect some things then.

    It is a work day today. I need to cut some grass before I go in this afternoon. The joys of home ownership. :puke1

    AMAL
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  9. kirby

    kirby Adventurer

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    Hey AMAL, I've had the same thing on my 11 GS. Like you, it's intermitten and I can not reproduce it.

    What freaks me out is that it is quite loud and for this metal clang to be so loud, it must have done some pretty serious damage. But, it seems everything is fine??? I've had no problem with the bike. It's certainly not the sound of back-firing.

    Of course, because of the wind noise I can't be sure where it is coming from. But most definitely, its coming from the engine area and not from behind.

    I might be wrong, but it might be a stone hitting the engine guard on the bottom. Take a stone, or for that matter, screw-driver or something metallic and bang the bottom plate.

    See if you think that's the sound. For me, what I've heard while riding and what I hear when I tried this, is pretty close.

    So, that's what I think and hope is happening with me.

    Let me know what you think.... It would be nice to get a confirmation or otherwise.

    Regards,

    KHK
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  10. Ralph Leavsey-Moase

    Ralph Leavsey-Moase Adventurer

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    Funny this noise (like yours) just started this week (top box off) mine has clocked just over 11,000 kilometres! will look into wheel etc. It is not the drive line slack as I have been on postive throttle
    orange1
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  11. VDRZANE

    VDRZANE Salty Adventurer

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    If the 'stone hitting the engine guard' is the sound you are referring to, that is simply fuel pinging/detonation. Bad gas or even a slug of air/water with your gas is the culprit there. I have the same thing on my '03 R1150GS Adv, and get the "pinging" after I get some crappy gas from the middle-of-nowhere. It sounds EXACTLY like little rocks/stone hitting the underside of my engine guard or the gas tank itself. Again, it is hard to tell where the sound was coming from initially due to wind noise etc.

    Hope this helps and I hope this is all the problem really is!
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  12. AMAL

    AMAL Virtual Poseur

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    It is nothing like backlash from the drivetrain. As was said by Kirby; for it to be that loud, something sounds like it has broken. It sounds like something snapped or broke apart. The first time it happened; I was waiting to go down since I was sure a frame weld had snapped, or a major fastener of some sort. I shrugged it off and kept going...maybe not the most intelligent approach. I got away with it the first time; so I let it go the other three times so far.

    It always happens under a positive engine load; usually when I am accelerating moderately. The bumps I mentioned could be incidental. It is possible a rock has been thrown up into the skid plate, but I doubt it. It sounds like something has snapped loose, or broken. It is a difficult sound to describe, but it is something you don't really want to hear, because you get the feeling it can't be good.

    I will be pulling, pushing, and tugging parts this weekend looking for this thing. Hopefully I will find it. I looked around some today, but didn't have time to get into it real deep. I will let you guys know if I find anything...one way or another.

    AMAL
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  13. Humungus

    Humungus no it doesn't

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    Backfire....??
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  14. kirby

    kirby Adventurer

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    Well, let's hope that VDRZANE is right. But, if it was bad gas, one would expect it to be a bit more regular through out the duration of the fuel in the tank. Maybe it is the H2O/AIR thing. Hopefully that is it.

    For those who are wondering what the sound is like, imagine the following. Find a water pipe somewhere in your home. Take a hammer and hit it as hard as you can.
    What you'd hear (without the reverbration) is about the sound that you could expect to hear.

    So, you could understand why AMAL and I have this sinking feeling in the stomache when we hear this sound.

    AMAL, chip in here, if this not analogous. And again, this happens irregularly, and only once at a time. BTW, on the few times I've heard this, I was pulling very hard on the throttle.

    Whatever it is, I've ridden close to 7000 km in 8 days, heading out to Nova Scotia and back to Toronto.

    So..... based on the law of large km (numbers), I am thinking that whatever the cause, it is not critical.

    Anyways, good luck with your bike !

    KHK
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  15. Humungus

    Humungus no it doesn't

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    Kirby...not wanting to insult your intelligence but have you heard a GS backfire before ? Thats exactly what they sound like with a small backfire...a very metal sounding knock. Just a thought...i hope for your sake thats what it is.

    OOps...wrong post...ment to mention it to amal
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  16. STUFF2C

    STUFF2C We Ain't Left Yet!!

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    It could be water in the thingamajig from to much washing.
    It's under Warranty! Ride the crap out of the thing! If it breaks, get it fixed.

    Just a Thought.
    16,800 trouble free miles on mine:D Hard ones too.
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  17. AMAL

    AMAL Virtual Poseur

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    I will keep an open mind about the backfiring. I am curious why my bike would backfire though?

    I once had a leaking exhaust header on an 87' Jeep Cherokee. The header pipe had a crack at the manifold braket. It had a bad weld. The noise was metal-to-metal sounding...like a push-rod and rocker-arm tapping together. The noise became fainter as the metal heated, and the crack had closed some from the metal expansion. I understand that sounds are not always what they seem to be.

    The noise is accompanied by a feeling in the saddle that something has been impacted/jarred/broken loose from within the bike. That is why I said earlier that; "I thought I was going down." It felt like something within the drivetrain or frame had broken free, and the bike geometry had shifted slightly...that kind of thing :eek1. Of course, it didn't do that...but I processed it as that initially.

    The hammer and water pipe analogy is pretty close, except you are sitting on the water pipe when you strike it!

    I have yet to do my inspection this weekend regarding this. I have only made it as far as coffee this morning. I'll post later on this weekend sometime about what I find...if anything.

    Thanks for the responses.

    AMAL
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  18. AMAL

    AMAL Virtual Poseur

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    It hasn't been wet yet. It still has all of the bug guts I have collected from several hundred miles of riding at night in the countryside. It might get a bath on Saturday once a month, but that would be optimistic.

    AMAL
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  19. slide

    slide A nation with a future

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    Let's see if we can eliminate the backfire. Is this something that occurs during throttle changes? if it's a steady throttle, I doubt the backfire idea. I'm also skeptical that your description of banging on a water pipe as hard as you can could possibly be pinging. Also pinging, if intermittent would only occur under added load which you don't mention.

    Is there anyway this can be the loose side panels decorating your gas tank flapping about? When I examined a GS12, I noted that these panels were rather loosely attached to the bike. Could it be the sidestand banging? I read you eliminated the center stand.
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  20. AMAL

    AMAL Virtual Poseur

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    My recollection is that it has only occurred during acceleration. My accelerations have been moderate, and I shift at about 4000 RPM. This is suggested in the manual for "Running-In". It has only happened four (4) times.

    I looked things over a bit more today and could not find anything loose. I am not as concerned with it now after having looked at what I have, and keeping an open-mind regarding "backfire".

    It has happened so infrequently, and not being reproduceable, leaves me a bit bewildered obviously. I have never heard a BMW backfire. Perhaps that is all it is. If I get it again; I will keep that in mind and see if it seems to click for me.

    It seems to be coming from the collector portion of the exhaust pipes (catalytic converter?) under the bike. That is why I thought it may have been a drive-train or frame issue perhaps since it originated there, and I was accelerating at the time I first noticed it. This first occurance was the most intense, and disconcerting. I thought something had come apart from the stress of acceleration. I seem to recall that I had left a stop sign, shifted to second gear, accelerated...and...THWACK!

    I will just keep riding it and see how it plays out. This is in no way sour grapes here! I really like this bike! Maybe it just didn't like the gas I was feeding it. Although it has only gotten the highest grade pump gas; usually 93 Octane (with 10% Ethanol), I have bought some of it from some seeding looking establishments (better than running out of gas!). Maybe there was some water in the holding tanks?

    Thanks all for the input here. I will post later if I find out something. In the meantime; I will just enjoy the bike.

    Best,

    AMAL
    #20