Where is the 3rd differential bolt?? And clunking noise.

Ateam · 11-20-2011, 12:19 PM

Ok so I read through every darn thread both e92 and e46 last night I could find on the topic and to be honest I left more confused than when I started.

My car never had any diff noise other than the gear chatter I have read about when shifting gears at a standstill but otherwise was quiet until yesterday.

Have had my car for almost a year now and never had this.

The problems I have read about including diff noise when making slow tight turns which seems to resolve with the additive you can get bmw to put in the diff fluiid.

The other common one is a "clunking" noise when coasting at slow speeds or low speed acceleration and then taking foot off. With some mild turning sound. This seems to be where many people find broken diff bolts etc.

So I checked the 2 bolts that go through the exhaust hanger and one was indeed loose enough that it was easily tightened with a hand wrench and the other was pretty tight but not so much it was not easily torqued further. So I tightened these and the sound improved somewhat but was still there.

I looked around for the "third" bolt that apparently is the main one holding the diff in and there are so many damn bolts under there I just could not see which bolt this is. If someone could explain or beter yet post a picture of where this bolt is that would be great!

Also a fair number said this noise is "normal" Does anyone else have a small clunk noise when letting off on the gas at slow speed/coasting and absolutely no sound when driving normally or hard. Perhaps some degree of sound is normal? I just wanna make sure my diff is not falling off! How can bmw again do this with so many people after the problems with the e46! I have dct by the way.

Ateam · 11-20-2011, 04:54 PM

Found it for those that interested. When facing the rear of the car, it is on the left side of the diff. It is a bolt hidden in a little round "cave" that you cannot really see that well. Its a 21 hex bolt and you need a slight extender to get to it.

I have never launched, never had wheel hop and have no exhaust or mods and one of my bolts was quite loose. THe one on the left exhaust hanger. The other two turned out to be fine. This signifigantly cured my clunk to the point it is much more mild and now I feel relieved my diff is not going to break like so many others.

I would reccomend anyone with this car check them quickly. You dont need to lift the car or anything if you are relatively thin and can simply slide yourself under the car to get to the bolts on the red exhaust hangers and the 3rd one at the left-rear is much less deep into the car so is accessible. Worth it to torque nice and tight if anything is loose.

11-20-2011, 12:19 PM	#1
Ateam Banned 88 Rep 1,105 Posts Drives: M3 Join Date: Sep 2011 Location: USA iTrader: (0)	Where is the 3rd differential bolt?? And clunking noise. Ok so I read through every darn thread both e92 and e46 last night I could find on the topic and to be honest I left more confused than when I started. My car never had any diff noise other than the gear chatter I have read about when shifting gears at a standstill but otherwise was quiet until yesterday. Have had my car for almost a year now and never had this. The problems I have read about including diff noise when making slow tight turns which seems to resolve with the additive you can get bmw to put in the diff fluiid. The other common one is a "clunking" noise when coasting at slow speeds or low speed acceleration and then taking foot off. With some mild turning sound. This seems to be where many people find broken diff bolts etc. So I checked the 2 bolts that go through the exhaust hanger and one was indeed loose enough that it was easily tightened with a hand wrench and the other was pretty tight but not so much it was not easily torqued further. So I tightened these and the sound improved somewhat but was still there. I looked around for the "third" bolt that apparently is the main one holding the diff in and there are so many damn bolts under there I just could not see which bolt this is. If someone could explain or beter yet post a picture of where this bolt is that would be great! Also a fair number said this noise is "normal" Does anyone else have a small clunk noise when letting off on the gas at slow speed/coasting and absolutely no sound when driving normally or hard. Perhaps some degree of sound is normal? I just wanna make sure my diff is not falling off! How can bmw again do this with so many people after the problems with the e46! I have dct by the way.
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11-20-2011, 04:54 PM	#2
Ateam Banned 88 Rep 1,105 Posts Drives: M3 Join Date: Sep 2011 Location: USA iTrader: (0)	Found it for those that interested. When facing the rear of the car, it is on the left side of the diff. It is a bolt hidden in a little round "cave" that you cannot really see that well. Its a 21 hex bolt and you need a slight extender to get to it. I have never launched, never had wheel hop and have no exhaust or mods and one of my bolts was quite loose. THe one on the left exhaust hanger. The other two turned out to be fine. This signifigantly cured my clunk to the point it is much more mild and now I feel relieved my diff is not going to break like so many others. I would reccomend anyone with this car check them quickly. You dont need to lift the car or anything if you are relatively thin and can simply slide yourself under the car to get to the bolts on the red exhaust hangers and the 3rd one at the left-rear is much less deep into the car so is accessible. Worth it to torque nice and tight if anything is loose.
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