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Thread: Sounds like...

  1. #1
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    Sounds like...

    First one: This noise is sharp (2 pieces of metal clinking), comes from the rear (pretty sure) when I let go of the clutch after a downshift into second. The very last 1/2 inch of the clutch travel does it, and it does it particularly if I let go of the pedal fast. Relevant piece of info: while coming to a complete stop or at a complete stop, if I let go of the clutch pedal fast (in neutral), I can hear what has been described as the "throughout bearing" rattling in rhythm with the rpm of the engine. However, if while coming to a stop or at a stop, I let go of the clutch pedal reaaaally slowwwly, the throughout bearing noise doesn't happen at all.

    Second one: Another noise (?) is also coming from the rear, is a tad louder than the first one and just as sharp. Comes in ones or twos (quickly after first) backing up, or accelerating forward up a driveway.

    Car: 2005 325i, Sports package, 61K miles, 5 spd.

    Sorry, but I search this e46 forum for "clunking downshifting" and only pulled up stuff for autoshmatics (a nice story about the clunk in the trunk and a bowling ball...).

    Any ideas?

  2. #2
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    Bump for the manual guys...

    by Dane Wilson, on Flickr

  3. #3
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    Bump for the ones driving stick...Maybe it is a clunk?
    I was wondering if this could be related to the throughout bearing?
    I think it can also happen downshifting to 3rd (but less loud).

    Any ideas? Even fun ones...

  4. #4
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    not a clue... wish i could help

    maybe there is a rodent in the transmission?

    or maybe youre driving an autobot?

  5. #5
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    ok

    Try checking the THROWOUT (that's how you spell it), bearing in the following manner:

    Stopped, idling, in neutral, foor off clutch pedal.
    Now, depress clutch pedal normally but slowly and listen carefully for any rotational spinning-dry bearing type of noise. Let the pedal out and depress again and keep listening. Do the test cold as well as after you have been driving for awhile; stopped, in neutral, not rolling.

    Jack the car safely, as always. Check the rear floorpan where the diff carrier bolts up to the floor with large bushings. Use a good, bright light.
    There are pics of what area to look at as well as examples of floor sheet-metal cracking somewhere here.
    While under there, inspect the driveshaft U-joints for dryness, rusty-looking drool, looseness of any kind. Roll forward and inspect the Guibo... the flex-coupler for cracks, nylon cords showing, etc.

    Rear wheel bearing? Rear half-axle, c.v joint bearings? Brake problems? Rear suspension pieces/bushing problems? Transmission mount problem?

  6. #6
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    Thanks rowdy lee,

    I will try to hear the throwout bearing grinding will pushing the clutch in. I am pretty sure though, that the noise is present (car stopped, idling, in neutral) only when I have taken my foot off the clutch pedal too quickly.

    I am going to go look under there tonight and look for all the good things you mentioned (there are a lot of them, whats the Guibo?)

    Sorry about the sp mistake, I'm a ferner.

  7. #7
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    The guibo or more commonly known as "flex disc" is a rubber disc about 6" in diameter between the transmission and driveshaft, it's purpose is to absorb vibrations.

    I don't think this is your problem, although it's always good to inspect things. When the guibo does start going, and gets really bad and begins to fray, it will deflect and thump in the drive tunnel under acceleration.

    If you have a grinding noise with the clutch disengaged (pedal pushed in) you most likely have a bad throwout bearing.

  8. #8
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    Thanks Phillips, I have a grinding noise matched perfectly to the RPM when the clutch is engaged in neutral (pedal out). No noise with clutch disengaged.

    Doesn't sound like the Guibo, you are right, and perhaps I should describe the sound better. Got the car only ~ 1 month ago and still learning the noises (I think I go it now).

    Imaging hitting a bell with a hammer but your other hand is on the bell (preventing the resonance from occurring). It would sound like 2 pieces of metal "tinging"-right? So its sharp and metallic, not a thump and I don't think its a clunk either.

    Here is how I can produce the sound reliably:

    Driving in 3rd slowly, then downshifting to 2nd to take a left turn (or right), no noise yet, wait for it...there, as soon as I FULLY released the clutch pedal, the very last bit that really torques the differential (perhaps and transfers the slowing inertia of the engine onto the wheel) : "ting"....

    Accelerate slowly and within 2-3 sec : "ting"... no more noise into 3-4-or 5th. Down to 4th (can't hear it), down to third: "ting" but if it did it in 3rd, it will not do it again into second.

    After a complete stop if the noise occurred while downshifting to second, it will "ting" (sometimes twice in rapid succession) while accelerating slowly in first, but once its done it, never again does it happen in 2,3,4 or 5th.

    The noise is much more noticeable when driving slowly.

    So it seems to be that the noise occur when there is a change in acceleration/deceleration. Differential?.

    I hope that a better description will help you gurus help me!

  9. #9
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    still thinking...

    Have you looked at the driveshaft universal joints yet? Also, jack the rear onto jackstands (safely/properly... look it up), and grab a wheel and try rotating it back and forth a few times... just a few inches back and forth with great strength. Trying to listen for constant-velocity joint clicking at the differential/axles.

    Also, roll under the rear of the car and look for any floor cracking at the mounts for the differential carrier... left fwd one, mainly. There are some pics in a sticky somewhere, probly, on the site. Need super bright light to inspect well or, BMW dealership will inspect n/c due to legal settlement...

  10. #10
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    No I have not looked under there yet. I plan on inspecting all that with a bright light (problem is that I don't know the name of the parts-but I can describe what I see).

    This morning I turn the engine off, put it in 1st gear, removed the hand brake on a flat surface and rocked the car bar and forth a few inches. I could hear a noise that resembled the "ting" but was much subddoed. Does that help? is that the constant-velocity joint clicking at the differential/axles?

    With everyone's help, I am going to figure it out. I can also take it to a local German auto mechanic and post results of our conversation (his diagnosis)...

  11. #11
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    Ach!

    German... mechanic. A real German?

    The magic words; German mechanic. lol

  12. #12
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    I don't think the subframe failure could be the culprit here either, but anything is possible. I think they remedied the infamous subframe failure in the later models. Earlier E46 models had the failure. I'm not sure of the dates that this was addressed.

    It is also uncommon for the Universal joints to fail, especially in only a 5 year old car. I hope for your sake this isn't a problem because the entire driveshaft must be replaced and it's rather expensive.

    Go here: www.realoem.com and enter the last 7 digits of your VIN to help you identify/isolate parts.

    Is your car an Xi model?

  13. #13
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    Quote Originally Posted by rowdy lee View Post
    German... mechanic. A real German?

    The magic words; German mechanic. lol
    No no, he is American, he just works on German cars...we'll see what he thinks and I'll report back here.

    Phillips, thanks, I will take a look at that website and learn some part names

    Car is not an XI.

    Its strange that no one has ever experienced these symptoms...

    Man, there are lots of parts at that realoem.com site! I learned the names of some parts but I am not sure which one is the driveshaft universal joints. Is it #1 here?: http://www.realoem.com/bmw/showparts...29&hg=26&fg=10

    Again, tonight, I turned the car off, put it in first, removed the hand brake and got it to clunk loud and clear with several push from behind. It only did it once even after I pushed again from the back or the front, but it was the same noise. The problem is that I can't both push the car and be under there looking and listening.

    Going to stop by the mechanic tomorrow...(no, not the German one, the American one that fixes German cars )

    As for the subframe failure, I guess after 2000, BMW says there is a less than 0.1% chance of having this problem in the vehicle. See here http://www.e46subframeclassactionset...f/bmwn1faq.pdf
    It does go on to cars built as late as 2006...

    The phenomenon is not uncommon and seems present in other BMW models including "the infamous M clunk" and some 7 series models.

    Some sites speak of a software upgrade
    Last edited by Oli77; 05-13-2010 at 09:59 PM. Reason: Automerged Doublepost

  14. #14
    nathancarter is offline Stretch Haters Club #1 BMW CCA Member
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    Don't have anything really helpful to post, but please keep us updated.

    The software upgrade would be applicable to automatic transmissions... not really relevant to your issue, I think.

  15. #15
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    So Dr. German Auto Mechanic (he has an engineering degree) is putting the money on ....drum roll please.... either the Universal joint (AKA Guibo I guess, congrats to Phillips and rowdy lee!), or, the Center mount.

    He came to this conclusion because after I described the noise and situation, he looked under the car and asked me the following question: "when downshifting at higher rpm, rev matching -or trying too, do you ever get a vibration back there?" I said: "well yes, as a matter of fact, I have heard a little shimmy back there at higher rev and I drive a little hard around corners", and he said: "say no more".

    If I look here, its #1 or #7-8-9 right?

    He thinks the cling, ting clunk is the drive shaft getting thrown off center because of torn rubbery plates/mounts. I will bring the car to him and will post on the results probably later next week. You guys had your finger on it though !

  16. #16
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    The Guibo is part #1 in the above diagram, the center bearing is #9 that goes into the center bearing carrier, which is #8.

    I hope he doesn't guess on it being the guibo or center bearing because I still don't see how it could make this noise; unless of course the center bearing itself was loose...

    How about the transmission mounts? Part #2 in the diagram below.


  17. #17
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    He does think that either of those is at fault. I wondered too, that the shaft would have to get off-center (a lot) to hit another piece of metal down there-right? Unless, as you suggest the center piece id loose. We'll see...

    I am not familiar with the underneath of the car at all but will ask him to keep it up there until I pick it up ....

    As for you idea about the transmission mounts, the noise is more towards the center of the car. When I drive slowly, it sounds like it comes from the back. But when I make it clunk with engine off (see above), the noise sounds dead center under car, not forward....but i will keep you posted.

    Now, onto those droopy socks syndrome pillars...

    Also, the extra vibrrrrrrration when I downshift (perhaps a little too hastily). Could that be the transmission mounts?
    Last edited by Oli77; 05-14-2010 at 07:13 PM. Reason: Automerged Doublepost

  18. #18
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    So I spent about an hour with the mechanic this morning. After pulling tugging turning and prying under there, he found nothing wrong with the drive shaft. A little grinding noise in the differential but that's it. Gear box and differential both have oil. All is OK, all bushings, transmission mounts, center mount, Guibo, all check out fine. No play at all in the drive shaft and the Guibo was apparently replaced recently.

    He now thinks its the throwout bearing (back to the beginning of the thread). He thinks that it might get a little cockeyed when you let go of the clutch pedal completely. My clutch is fine right now, he recommends I keep driving and when clutch goes, I'll get a new throughout bearing I guess.

    Do you guys think this diagnosis is appropriate? I realize its a guessing game, but you all know quiet a bit, and your expertise is appreciated...

  19. #19
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    Rowdy, Phillips and Dane, I finally went under there and took a look around. Here is what I did.

    Put the car in first, chucked the wheels, removed hand brake, and lifted right rear tire way off the ground. My 17 year old would move the wheel back and forth, while under there, I would feel for the metal on metal sound. We have the original jack and could not reproduce the sharp loud clunk but here is what I found out. Correct me if I am wrong please:

    Guibo is totally clean (new looking), it moved with the drive when we move the wheel (duhh). The tranny mounts look very good to me. So I moved toward the back of the car.

    I feel no metal on metal vibration or ting or clunk in or around the center mount, or the plate under it... so I moved back some more.

    Now at the front of the diff. Nothing, no leak at intake, noise is, however, getting clearer, like I'm comin'to getcha' close (my son, by now, is asking how much longer this will take...).

    Ok now, back side of the differential (no leak on that sucker). That big back side bushing in pic below with question mark, well, it moves with just the back and forth motion of the right wheel turning. I can see it, the big center nut (axis of bushing) moves!!!



    So, I jammed a large screw driver hard between the metal part of the bushing (not the one attached to chassis) and the diff. In the pic above, I inserted the screw driver at the blue dot and it was mightily stuck. And I took it for a ride.

    Clunk still there, I drove up 4 houses and back and the screw driver was about to fall off when I got back home.

    Is that bad? could that be the culprit (rather than the throwout bearing?). Your help, input, ideas are greatly appreciated....

    Also, forgot to mention, there is rust inside bushing, you can see it fall onto that arm in the pic

    Is it OK to bump my own thread? (I guess I'll find out)
    Last edited by Oli77; 05-23-2010 at 11:43 AM. Reason: Automerged Doublepost

  20. #20
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    Le bump de la bump

    Bump for my question above please

  21. #21
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    How can a urethane bushing make a clunk? Bump bump to myself I guess...

  22. #22
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    Of course it's ok to bump your own thread.

    Nice detective work. Since you can see rust beginning to form on the bushing, it's most likely torn and deteriorating. That bushing is a royal PITA to change too, when I changed mine, it took the better part of the day. I changed all mine.

    The clunk you're hearing is probably the clunk of the bushing/differential moving.

  23. #23
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    Thanks Phillips, so you concur that the axis through that bushing should NOT move when you put torque on it (gently).

    Is that the rear differential bushing?

    I read in this forum and others that its a PITA indeed, and I will hire the help of a mechanic to have that changed and will post if this gets rid off the annoying clunk.

    Any idea how much this will set me back?

  24. #24
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    Yes, any lateral/radial deflection of the bushing means it's bad.

    However, I don't know how much this will set you back; I used home-made tools from work to install mine. If I were to speculate, anywhere from $100-$500? Don't quote me because I'm not certain.

    While you're in there, you should replace them all. I would, I did. Do it once and forget it.

  25. #25
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    I feel better already

    Awesome! I hope this is the culprit and I will let you all know if this indeed stops the dreaded clunk. Its amazing how many forums and people have described a clunk under the car, and there are so few definitive solutions proposed (its a guessing game for sure), or so many dead threads are out there (including a 7 pager at e46Fanatics with the guy simply selling his car at the end).

    Thanks again, I will post back when its done...

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