[spta97]

I often get a thump when it goes into reverse cold coming out of the garage.

It doesn’t make noise at other times.

Is this a symptom of the problem in this thread or just “normal” M behavior?

[silver_metallic]

Originally Posted by spta97

I often get a thump when it goes into reverse cold coming out of the garage.

It doesn’t make noise at other times.

Is this a symptom of the problem in this thread or just “normal” M behavior?

Does it still make a noise when reversing out of your garage once the car is fully warmed up? If not, then you're probably good. For me the noise was there all the time, irrespective of operating temperature.

I still hear a small, low pitch and acceptable one-time "thump" (not a loud metallic clunk/click) when the car is cold but i can tell that is coming from the rear brakes tackling the higher cold-idle torque versus the middle of the differential.

[spta97]

Originally Posted by silver_metallic

Does it still make a noise when reversing out of your garage once the car is fully warmed up? If not, then you're probably good. For me the noise was there all the time, irrespective of operating temperature.

I still hear a small, low pitch and acceptable one-time "thump" (not a loud metallic clunk/click) when the car is cold but i can tell that is coming from the rear brakes tackling the higher cold-idle torque versus the middle of the differential.

Thanks. Mine is a thud (you can feel and hear) only when cold after disengaging the parking brake and putting it into reverse.

Once warm it is fine and it happens a lot more when the ambient temp is low and not so much when warm.

After that initial this it does not happen again.

I wonder if it’s just the brake sticking?

[X3M11]

Hi Steven,

Any more updates on ur car?

I think ive had the same thing your going on about. Been in to the dealer way too many times to get fixed. I could upload a video just not sure how on the forum here.

Have they fixed it yet?

[RoWoX3M]

Following bc mine still does a thud (or what sounds like brake calipers releasing) when accelerating from a stop

[harperium]

https://x3.xbimmers.com/forums/showthread.php?t=1837347

I posted this thread and I also found this document from the BMW TIS site.

The sound and behavior I'm hearing in my '21 X3MC does seem to match the BMWTIS document on the F90, F82, F83 and F87. I've printed it out and will take it to BMW Service tomorrow.

For me it's not a thud per se, but more of a CLICK, as described in the BMWTIS:

A clicking noise is noticed from the area of the rear axle differential, either when:
 Transitioning from driving forward to backing up
 During load reversal while driving (i.e., engine load to overrun, etc.)

They said this happens between 37 and 73 lb-ft of torque, which also matches what I've seen....

[harperium]

For my issue, which may not be the same, BMW service said the tech advisory for the M2/3/4/5 is the same issue and they are updating it to include the X3M. They had to order parts to fix, but it's not a "safety issue" so I can drive in the meantime. Car will be fixed next week.

[dkhm3]

I think I have his issue. Clunk at low speeds, sometimes the car is in park and I can hear it clunk. Sounded like something was loose. Just 3-4 times in a row clunk clunk clunk. Scheduled for service next week. Ugh. 14k miles 2020.

[Bufford T]

If it happens all the time just take it to your stealer so they can hear/feel it.

Could be something simple, like your parking brake not fully disengaging or something more serious.

Either way, make your stealer work for the premium you have paid for your luxury vehicle

[moff]

My car is at my dealer’s today with this exact issue. I took the TIS with me and gave it to the master tech - he wasn’t impressed. Basically told me that he’s not seen this across any M5 or X (M) or M3/M4 and that the document was US and that US cars are built to a different spec to UK cars.

I’m not holding out much hope…. They will also likely try and blame my aftermarket tow hitch which worries me too!

Car left with them for the whole day so will update later.

[OEMJumper]

i know someone who had this issue. it was the crankshaft bolt not being tight and leaving space for it to move on initial movement of the vehicle and creating the thud

[scops]

I finally got this sorted and have pasted the fix to this problem. It was a battle to get the dealer to acknowledge problem, sales guys were pathetic, its normal they said. Not on my watch. 10 visits later i lost my cool and the whole dealership heard me. Clunks/thumps on cold starts are NOT normal let alone in drive and reverse. Good luck all, stand your ground.

[Jnat]

I have this clunk...
The question i have is if left alone what is the repercussion if any?
It's basically a one time event for me on initial engagement.

[joebie3]

Originally Posted by Jnat

I have this clunk...
The question i have is if left alone what is the repercussion if any?
It's basically a one time event for me on initial engagement.

The fall out from the noise will depend on what the source of the noise actually is. If it's something like the splines having excess space between them causing them to "knock" in start/stop situations, it's possible that eventually the splines will either degrade and get worse or end up sheering at some point. This could leave you stranded destroying both the diff and the driveshaft. If this is your issue, it will inevitably get worse with time.

If, let's say, the noise was from the diff carrier bolt and it finally lets lose it can take out the diff/t case/drive shaft as well as cause some amount of damage to the underside of the car depending on how much the back half of the diff flails around.

IMO It's hard to say what the exact damage would be in any situation because each failure is a little bit different. Some are very spectacular and others mundane lol.

[Jnat]

Originally Posted by joebie3

The fall out from the noise will depend on what the source of the noise actually is. If it's something like the splines having excess space between them causing them to "knock" in start/stop situations, it's possible that eventually the splines will either degrade and get worse or end up sheering at some point. This could leave you stranded destroying both the diff and the driveshaft. If this is your issue, it will inevitably get worse with time.

If, let's say, the noise was from the diff carrier bolt and it finally lets lose it can take out the diff/t case/drive shaft as well as cause some amount of damage to the underside of the car depending on how much the back half of the diff flails around.

IMO It's hard to say what the exact damage would be in any situation because each failure is a little bit different. Some are very spectacular and others mundane lol.

i should have worded my question differently. Your correct and i agree with that completely along with assuming what you describe... I guess stated better: i think this is exactly my noise and i'm bothered by the fact that the tolerance is such that it allows for this and furthermore that the answer is friggin lock tight... wow.

[joebie3]

Originally Posted by Jnat

i should have worded my question differently. Your correct and i agree with that completely along with assuming what you describe... I guess stated better: i think this is exactly my noise and i'm bothered by the fact that the tolerance is such that it allows for this and furthermore that the answer is friggin lock tight... wow.

Agreed on that for sure! It's kind of unbelievable honestly LOL

[PNW_F10]

Hey guys, I'll chime in but not coming from me curious to see you you think. I went for a ride a few weeks ago in my car to discuss the slight "thud" when i pull out of my driveway and down a slight curb.
He explained that these rotors on these cars "float" and when you first pull out they can "set" into place and that's the noise.
I'm not sure if I buy it, but I'm also not that concerned about it. Doesn't happen every time.

Thought I'd share,

[Jnat]

Originally Posted by PNW_F10

Hey guys, I'll chime in but not coming from me curious to see you you think. I went for a ride a few weeks ago in my car to discuss the slight "thud" when i pull out of my driveway and down a slight curb.
He explained that these rotors on these cars "float" and when you first pull out they can "set" into place and that's the noise.
I'm not sure if I buy it, but I'm also not that concerned about it. Doesn't happen every time.

Thought I'd share,

I guess it's possible.