2011-01-04 01:01:31 +0000 #1
Now that my differential whine problem seems to be resolved, I thought I would create a thread that summarizes the issue in case there is anyone else with a similar problem. In short, my brand new 2011 328i (August 2011 build date) exhibited a classic differential whine as is characterized in technical discussions/write ups. (Google “differential whine” or “differential preload whine”)
Having had the car for only a few weeks, I was naturally concerned. My concern was significantly raised when I was put into a 2010 328 loaner that had the exact same problem. Although the loaner was not quite as loud as my 2011, it was definitely the same issue. I took away from my discussions with my dealer’s service department that this is a well-known problem and that BMW differentials are prone to make noise. The dealer has been very forthcoming with me about the issue and I should note that my experience with the dealer and BMW regarding this problem has been very positive thus far. The service department’s shop foreman immediately heard the noise during the first test drive. We agreed that is sounded as though the sound was in the rear end. After some time and some interfacing with BMW, my SA advised me that they were replacing the differential. She stated that my rear end whine was about twice as loud as other cars that had the noise.
I picked up my vehicle this morning and drove it to work. There was no noise coming from the rear end; the noise is definitely gone.
My understanding with a differential is that they will make noise if they are not setup correctly. I had also read that “machining variations” of the ring and pinion gear set can also result in a whine. As an engineer with no experience with setting up or building a diff, all I can say is that this sort of makes sense when the gears are not properly aligned or a bearing is loaded improperly. Perhaps an expert could comment on this or elaborate on the types of noises a differential should or should not make.
Although this issue seems to be resolved for me, something still concerns me about the problem based on my very limited understanding here and based on my discussions with the service manager and the service advisor. They both implied and even stated that this is a common problem, but since mine was louder than normal (“twice as loud”), they agreed to fix it. It seems to me, however, that the whine noise that I had was in no way normal or good.
Perhaps there are others here that could share their experience, assuming of course that my car and the loaner car are not the only vehicles with this issue. I have made several good audio recordings of my car before the fix and of the loaner from inside of the cabin. If there is interest, I could produce a compilation video of the recordings. Using a very simple filter on the recording, the differential whine can be isolated. It has a very definitive pitch.
Having had the car for only a few weeks, I was naturally concerned. My concern was significantly raised when I was put into a 2010 328 loaner that had the exact same problem. Although the loaner was not quite as loud as my 2011, it was definitely the same issue. I took away from my discussions with my dealer’s service department that this is a well-known problem and that BMW differentials are prone to make noise. The dealer has been very forthcoming with me about the issue and I should note that my experience with the dealer and BMW regarding this problem has been very positive thus far. The service department’s shop foreman immediately heard the noise during the first test drive. We agreed that is sounded as though the sound was in the rear end. After some time and some interfacing with BMW, my SA advised me that they were replacing the differential. She stated that my rear end whine was about twice as loud as other cars that had the noise.
I picked up my vehicle this morning and drove it to work. There was no noise coming from the rear end; the noise is definitely gone.
My understanding with a differential is that they will make noise if they are not setup correctly. I had also read that “machining variations” of the ring and pinion gear set can also result in a whine. As an engineer with no experience with setting up or building a diff, all I can say is that this sort of makes sense when the gears are not properly aligned or a bearing is loaded improperly. Perhaps an expert could comment on this or elaborate on the types of noises a differential should or should not make.
Although this issue seems to be resolved for me, something still concerns me about the problem based on my very limited understanding here and based on my discussions with the service manager and the service advisor. They both implied and even stated that this is a common problem, but since mine was louder than normal (“twice as loud”), they agreed to fix it. It seems to me, however, that the whine noise that I had was in no way normal or good.
Perhaps there are others here that could share their experience, assuming of course that my car and the loaner car are not the only vehicles with this issue. I have made several good audio recordings of my car before the fix and of the loaner from inside of the cabin. If there is interest, I could produce a compilation video of the recordings. Using a very simple filter on the recording, the differential whine can be isolated. It has a very definitive pitch.
