Transmission Rattle? Help Pls

[SoCalRPM]

Over the last few weeks I've started noticing a somewhat subtle rattling (?) sound, which I believe may be coming from the transmission.

2011.5 e92 DCT ZCP

I tried searching but couldn't find much of anything that pertains specifically to what I'm hearing. I can only describe the sound as how a junky old car's transmission rattling might sound when they apply acceleration.

The sound is mostly only noticeable under relatively heavier loads (not flooring) around the 3-4k RPM in 3rd & 4th gears.

I'll try to get some video soon!

Anyone have any similar experiences? Fixes? I'm hoping it's something simple.

**Updated with Video**
Still hard to tell with the wind noise...

[MightyM3]

So this could be a ton of things, I would recommend posting a video. This could be exhaust shield smacking against the exhaust, could be driveshaft related....

[SoCalRPM]

I agree. I'll work on getting that video! Difficult to replicate the circumstances where it's noticeable and safely get a video, though.

I did watch some driveshaft noise related videos but nothing seemed close.

[MightyM3]

I get some pinging/clunking on occasion at the RPM range you mentioned. For next season I will be replacing the drive shaft with a CF one, hopefully that takes care of the issue.

[Rajmun340]

insufficient clues, could be many things. to narrow it down, does it sound like a coiled spring rattle ? If so suspect dual mass flywheel, not the transmission. Happened to mine.

[SoCalRPM]

Updated the first post with video, here it is again!

[buldogge]

I get the same thing when running in "auto" mode, even in 4 or 5...I think it's a bit of pre-detonation, personally.

When I am shifting manually (and since I do not let it load up) I do not seem to have the same issue.

-Mark in St. Louis

[SoCalRPM]

Originally Posted by buldogge

I get the same thing when running in "auto" mode, even in 4 or 5...I think it's a bit of pre-detonation, personally.

When I am shifting manually (and since I do not let it load up) I do not seem to have the same issue.

-Mark in St. Louis

Thanks, Mark. This has only been happening when manually shifting - although I haven't tried it in "auto" mode yet. I will try to replicate though. It only recently started.

[Redd]

If it's happening as you accelerate/decelerate, it might be your engine mountings need replacing. Mine died at 42k kms (26k miles).

[SoCalRPM]

Originally Posted by Redd

If it's happening as you accelerate/decelerate, it might be your engine mountings need replacing. Mine died at 42k kms (26k miles).

Does not happen on deceleration. Only relative to throttle (load) input. Had the engine mounts replaced a few thousand miles ago when I did RB.

[pbonsalb]

Easy enough to test the detonation theory. Clear adaptations and add enough octane booster to increase octane to 95.

If the ionic knock sensing is working properly, you should not get pinging type light detonation. The system works through the plugs and coils rather than knock sensors bolted to the block. Coils don’t seem to be a failure item. How old are the plugs?

Does a high level scan tool show any stored or pending faults?

[buldogge]

Originally Posted by SoCalRPM

Thanks, Mark. This has only been happening when manually shifting - although I haven't tried it in "auto" mode yet. I will try to replicate though. It only recently started.

What RPM/speed is it occurring at?

I haven't done any "testing" per se...but...it only seems to occur when the revs are too low for the given speed (ie short shifting), brought on by the auto programming, in my case....generally below 3k.

-Mark

[SoCalRPM]

Originally Posted by pbonsalb

Easy enough to test the detonation theory. Clear adaptations and add enough octane booster to increase octane to 95.

If the ionic knock sensing is working properly, you should not get pinging type light detonation. The system works through the plugs and coils rather than knock sensors bolted to the block. Coils don't seem to be a failure item. How old are the plugs?

Does a high level scan tool show any stored or pending faults?

Thanks for the feedback. Plugs were replaced about 25k miles ago so it's getting close to time but shouldn't be an issue yet I would think

[SoCalRPM]

Originally Posted by buldogge

What RPM/speed is it occurring at?

I haven't done any "testing" per se...but...it only seems to occur when the revs are too low for the given speed (ie short shifting), brought on by the auto programming, in my case....generally below 3k.

-Mark

Mostly at the 4k range but some on either side of that. It could be happening a little more at the top end but if it is the engine/exhaust noises are drowning the sound out to know for sure

[SoCalRPM]

A few quick updates - still looking for some help!

I took the car out with a friend the other day so we could try to narrow down what might be going on.


- the sound doesn't seem to change whether the car is cold or full temp.

- when revving to neutral, no rattling sound so doesn't seem exhaust related (maybe?)

- you can hear a hint of it if you put your foot into it while in reverse

- we jacked the car up but can't find anything loose or obvious.


The mystery continues...

[Theodore]

It's probably worth taking a look at the driveshaft center mount / support bearing, part # 26122283046.



Video Example of Failing Center Mount

[De_Cruelz]

SoCalRPM I have the same issue and it certainly sounds like detonation. Also exactly what the OP experienced in this post: https://www.m3post.com/forums/showth...1532390&page=6

His solution was replacing the O2 sensors and new x-pipe. I have a pair of O2 sensors on order now hoping it would fix it for me too.

[SoCalRPM]

Originally Posted by De_Cruelz

SoCalRPM I have the same issue and it certainly sounds like detonation. Also exactly what the OP experienced in this post: https://www.m3post.com/forums/showth...390&page=6

His solution was replacing the O2 sensors and new x-pipe. I have a pair of O2 sensors on order now hoping it would fix it for me too.

Thanks for the feedback. Interesting thought. I looked through that thread but couldn't find any good audio/video clips. Do you have any recordings of your car making these sounds?

I haven't found a solution yet but will report back when I do!

[SoCalRPM]

Originally Posted by Theodore

It's probably worth taking a look at the driveshaft center mount / support bearing, part # 26122283046.

[IMG]https://c1552172.ssl.cf0.rackcdn.com/548620_x450.webp[/IMG]

Video Example of Failing Center Mount

This is a strong lead. I've seen other driveshaft videos that don't sound anything like what I'm experiencing but this seems more plausible!

[bmwm3s65]

Originally Posted by SoCalRPM

Over the last few weeks I've started noticing a somewhat subtle rattling (?) sound, which I believe may be coming from the transmission.

2011.5 e92 DCT ZCP

I tried searching but couldn't find much of anything that pertains specifically to what I'm hearing. I can only describe the sound as how a junky old car's transmission rattling might sound when they apply acceleration.

The sound is mostly only noticeable under relatively heavier loads (not flooring) around the 3-4k RPM in 3rd & 4th gears.

I'll try to get some video soon!

Anyone have any similar experiences? Fixes? I'm hoping it's something simple.

**Updated with Video**
Still hard to tell with the wind noise...

Hi SocalRPM,

i Have the exact same noise! I am running alpine stage 2 93 octane tune. I have not tried going back to stock yet. I read your replies in the pre-detonation thread. I hope its not that, i rather it be a noise csb. Have you researched this any further or ever figured out what the noise was?

[SoCalRPM]

Originally Posted by bmwm3s65

Hi SocalRPM,

i Have the exact same noise! I am running alpine stage 2 93 octane tune. I have not tried going back to stock yet. I read your replies in the pre-detonation thread. I hope its not that, i rather it be a noise csb. Have you researched this any further or ever figured out what the noise was?

I haven't precisely nailed it down yet but I have come across two other forum members with the same/similar sound who also have an Alpine tune.

This is a recent discovery so I haven't contacted Alex directly yet. I may try removing the tune first to see if that removes the sound.

[Scharbag]

Originally Posted by SoCalRPM

I haven't precisely nailed it down yet but I have come across two other forum members with the same/similar sound who also have an Alpine tune.

This is a recent discovery so I haven't contacted Alex directly yet. I may try removing the tune first to see if that removes the sound.

Yup - try removing your tune and go back to 241E. If that helps, then another test is put the tune back in and get yourself some E85 and throw that in the tank. If you do not get noise with a tune and E85, it is a timing issue.

Also, if you can find someone with a "knock-box" type device, you can see if it is knock really quickly. And FYI, there is a handy place on the bottom of the block near the crank pully to mount the sensor - it is a bit of a pain because you have to take off the big skid plate but I could not find any other easy spot to install the sensor.

As for the tune options, Alex gave me a "winter" tune that seems to be WAY better but still put down 382.7HP on the dyno.

Hope this works our for you. Please let us know what the solution is.

Cheers,