Auto trans 325i
When I drive my car normally and calmly (Engine stays below 3000 rpm for each gear) I do not have any noticable sounds or vibrations, but when I manually shift the automatic and hold it in gear such as holding it in "2" or "3" I will notice that when I am around 3500-4500 rpm that there will be a low frequency rumble which is heard in the cabin more than it is actually felt. Higher RPM will remove the rumble as does lower RPM so I am guessing that it is a harmonic vibration type issue from a loose/worn rotating part such as a shaft inside the transmission, or the driveshaft itself.
At 194k I have never touched the CSB or Flex-disk. The trans and diff fluids were changed 2 years / 8k miles ago.
I DID replace my engine mounts (with OEM mounts) prior to the noise exposing itself. I also have a low rumble in the rear end which is faint when driving straight, loudish when turning left, and disappears when turning right. I am certain this is a wheel bearing noise and have already purchased bearings to take care of that. I don't imagine it is related but it is some background info in case it might be related.
So I am thinking something with the driveshaft is worn out. What do a bad flex disk and CSB typically behave like when they go bad? Searching threads reveals clunking noises but I am not seeing much about a rumble like mine.
Oh and I wont be devastated if anyone suggests that my transmission is about to poop the bed. I have probably done over 20 full throttle acceleration runs in the past 2 months for testing and experimenting some things that I was working on, among other abuse (no neutral drops, just just a strong healthy M20 spinning it at full power through shifts). The shifts are very solid, no slipping beyond what a healthy automatic feels like.
When I drive my car normally and calmly (Engine stays below 3000 rpm for each gear) I do not have any noticable sounds or vibrations, but when I manually shift the automatic and hold it in gear such as holding it in "2" or "3" I will notice that when I am around 3500-4500 rpm that there will be a low frequency rumble which is heard in the cabin more than it is actually felt. Higher RPM will remove the rumble as does lower RPM so I am guessing that it is a harmonic vibration type issue from a loose/worn rotating part such as a shaft inside the transmission, or the driveshaft itself.
At 194k I have never touched the CSB or Flex-disk. The trans and diff fluids were changed 2 years / 8k miles ago.
I DID replace my engine mounts (with OEM mounts) prior to the noise exposing itself. I also have a low rumble in the rear end which is faint when driving straight, loudish when turning left, and disappears when turning right. I am certain this is a wheel bearing noise and have already purchased bearings to take care of that. I don't imagine it is related but it is some background info in case it might be related.
So I am thinking something with the driveshaft is worn out. What do a bad flex disk and CSB typically behave like when they go bad? Searching threads reveals clunking noises but I am not seeing much about a rumble like mine.
Oh and I wont be devastated if anyone suggests that my transmission is about to poop the bed. I have probably done over 20 full throttle acceleration runs in the past 2 months for testing and experimenting some things that I was working on, among other abuse (no neutral drops, just just a strong healthy M20 spinning it at full power through shifts). The shifts are very solid, no slipping beyond what a healthy automatic feels like.
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