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Discussion Starter · #1 ·
Alright guys, I’m going to describe this in as much detail as possible, so please bear with me…

2003 330i by the way, auto transmission (recently replaced)

This morning I was enjoying a rather spirited drive, going about 85 mph in a low gear with the music up a little bit louder than it should have been (essentially being a jackass), which is something I do almost every morning before class. As I’m slowing down for an upcoming stop sign, I realized that the worst sound I’ve ever heard coming from any car was coming from what seemed to be the rear of the car, almost like a bearing failure. After a little bit of driving and feeling and testing and stuff, I found out:

1. It isn’t coming from the engine (redundant?), RPM’s don’t affect the sound. If I’m at speed and put the car in neutral I can rev the engine with no effect on the noise, even changing gears doesn’t change anything as far as that god-awful sound is concerned.
2. It becomes audible (although barely) at around 20 mph. As speed increases beyond that, the noise becomes louder and whinier, to the point where it’s almost overwhelming.
3. When any sort of torque is applied, I mean even BARELY tapping the gas pedal, there is this grinding sound that kicks in momentarily and the sound gets WAY louder and whinier, but when I let off the gas and coast it returns to normal.
4. I can’t feel anything going on wrong with performance or anything that I’m aware of, aside from the quick grinding sound when I hit the gas.
5. It is quickly getting worse and worse.

Logic dictates that it has something to do with the driveshaft bearing (I think?) but I searched around for a little bit and wanted to see if there is anyone with a very similar problem before I start ripping stuff off of my car. I have DIYed a fair amount on it but most of it had to do with the cooling system and stuff directly under the hood, never really anything in this area and therefore have no clue what I’m getting myself into.

What do you guys think it could be, and how much time and money are involved in a DIY if that’s something worth DIYing?
 

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2001 325i 5mt. 2009 535xi Touring 6mt.
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Good job isolating it from different gears, as you say it must be somewhere in either the driveshaft or differential. I would checkout out that center support bearing on the driveshaft. I recognize it is annoying to get to, but such is life. Perhaps it would be easier for you to jack the rear end up, disconnect the driveshaft from the differential, put the transmission in neutral and see how the driveshaft feels as you turn it by hand. At the same time while it is disconnected, you could spin your wheels by hand and see if there is friction. Your hands will never supply as much torque as the engine so it's possible this won't help, but I think you'll be able to identify a bad bearing.
 

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Sounds like you have it pretty isolated to the d/s bearing. I am going through the same thing, well, almost. Vibration after 60mph and upon deceleration. Started squeaking also just now as I went to Chipotle. A word of advice, replace the guibo while you are under there also. If you do not want to wait for it to be shipped, I recommend NAPA. Got my guibo there, it's a billstein of all things, and my center support with bearing, a meyle.
 

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Discussion Starter · #4 ·
Thanks guys. A little more research (and a call to the indy) I think I have confirmed that it is that driveshaft bearing. I'm about to order the parts today.

BUT while I'm down there, I was wondering if there's anything not incredibly extensive else I should repair/clean/fix/replace. I did a little bit of skimming through a few DIYs and it seems like I've gotta drop the exhaust and cat to get to it, should I go ahead and replace (or just clean... Wait is that possible or even a good idea?) post cat sensors? And anything else?


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I had vibrations at low speed (1st and 2nd gear) in the rear end that vibrated all the way to the armrest. Felt as if I was driving on those highway reflectors. It turned out to be the giubo (guibo?). I had my center support bearing changed out at the same time. When I picked up my car from the mechanic he showed me the old giubo and center support bearing, both were toast at 98K miles.
 

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Discussion Starter · #6 ·
I don't feel this except when I first begin accelerating, and as I drive it now I'm beginning to doubt my original conclusions. Could be that I'm just being paranoid but I'm picking up the parts now, I'll keep you guys posted on how tomorrow goes.


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