[BMWM.D.]

Anyone noticed this on their M240? Since day one, I’ve noticed a hollow thump or knock type noise from the rear of the car at lower speeds (<30 mph) on bumpy roads. Almost sounds like it could be a shock or mount. Since I haven’t had the opportunity to drive any other G42s, I figured I’d ask.

I wouldn’t call it loud, but it’s noticeable. Sounds like maybe the right rear, but noises can be deceiving and hard to track down. Anyway, just wanted to see if anyone else noticed anything they thought to be out of the ordinary.

[steelatx]

I know this may be a silly answer, but it might be the exhaust burbleing and popping. Some of the reviews said bmw removed a lot of the burbles, but i assure you they are there. I hear a similar thumping noise and it's 100% the exhaust. Usually hear it when I let my foot off the gas to coast or when i up shift under harder acceleration.

[hermiti]

I hear the same thing. I'm not sure what it is. Sounds like a faint version of empty luggage in the trunk going airborne then landing.

[CTGT2005]

The way to test if it's exhaust is switching between comfort/eco and sport plus. If the sound intensifies then then it's probably exhaust related.

[MattM240eye]

Similar sound in mine. Not the exhaust. Only on bumpy roads like stated above

[Roadwar]

At 500 miles here. I hear it also. It's not exhaust. Seems isolated to right rear suspension over some bumps. That is the lightest corner of the car....I'm just waiting it out at this point. This suspension is fairly stiff even in the comfort setting so I'm hoping it will soften up as it wears in.

[MattM240eye]

Originally Posted by Roadwar

At 500 miles here. I hear it also. It's not exhaust. Seems isolated to right rear suspension over some bumps. That is the lightest corner of the car....I'm just waiting it out at this point. This suspension is fairly stiff even in the comfort setting so I'm hoping it will soften up as it wears in.

Agreed. I'm at 500 as well, It's definitely the right rear. It's not super annoying, and it's mainly on large bumps ( we have plenty here in New England ). .

[P_Chris]

I noticed this as well.

[BMWM.D.]

Glad to hear it’s not just me. And I also thought maybe it was the exhaust at first. It does it at steady throttle while moving along at low speed. There are definitely exhaust burbles as mentioned, but that’s not what I’m hearing.

[MattM240eye]

Originally Posted by BMWM.D.

Glad to hear it’s not just me. And I also thought maybe it was the exhaust at first. It does it at steady throttle while moving along at low speed. There are definitely exhaust burbles as mentioned, but that’s not what I’m hearing.

I think it's just the stiffness of the suspension. Since it's clearly not a isolated thing.. might just need time to break in more, and hopefully some filled potholes. :-)

[BMWM.D.]

I believe I can hear the same noise when coasting along at 5-10 mph on roads that aren’t smooth. It’s a more constant type of noise — almost more like a groaning — but I’m pretty confident it’s from the same source as the more isolated “thump” sound.

Either way, it sounds like it’s probably some type of engineering or widespread parts issue. What I’m hearing definitely isn’t normal sport suspension noise. Since others seem to have it, it clearly isn’t a fluke thing.

I’ll be keeping an eye out for any info from BMW engineering. This is one of the drawbacks of getting a brand new model; you get all the teething issues.

[SN1P3]

I have this noise as well. I originally thought it was the trunk liner but I've confirmed that it's not. Sounds suspension related as others have said.

It seems to only happen to me when the car is cold. I don't notice it after about 10mins of driving. Anyone experience the same?

[MattM240eye]

Originally Posted by SN1P3

I have this noise as well. I originally thought it was the trunk liner but I've confirmed that it's not. Sounds suspension related as others have said.

It seems to only happen to me when the car is cold. I don't notice it after about 10mins of driving. Anyone experience the same?

I think I hear it warmed up too. It's pothole hell right now, but it's not super annoying, I've heard worse thumps in other cars. When the road is smooth/smoothish it doesn't happen.

[BMWM.D.]

Originally Posted by SN1P3

I have this noise as well. I originally thought it was the trunk liner but I've confirmed that it's not. Sounds suspension related as others have said.

It seems to only happen to me when the car is cold. I don't notice it after about 10mins of driving. Anyone experience the same?

I thought the same thing. I’ve actually been planning to remove the trunk lid liner for testing, but I don’t really think that’s it. I’m thinking it’s something in the suspension, but what I’m not sure. If I try to chase it down, I’ll probably start with disconnecting the sway bar end links.

[kkgriss]

I noticed the same in mine that I picked up in November. In December, I had it investigated and was told that it was a "loose valve" within the right rear shock. In January, the replacement shock finally arrived and was replaced. I immediately noticed improvement and that the "thump sound" was significantly reduced but did not go away completely. In fact, it seems to me to have gotten slightly worse since the replacement, though still not anywhere near the level it was when I first got the car. I intend to put a few more miles on the car to see what happens.

I could be incorrect, but based on my experience, I believe there could be something faulty in the design of the shock. Especially after seeing the number of other people who are experiencing the same.

[Roadwar]

Today we had the warmest day here since I got my car. It was 75 degrees. I took it out for a 30 minute drive and for what it's worth, the "thump" wasn't present. So at least in my situation warmth seems to help. Anybody else had the same thing happen?

[BMWM.D.]

Originally Posted by kkgriss

I noticed the same in mine that I picked up in November. In December, I had it investigated and was told that it was a "loose valve" within the right rear shock. In January, the replacement shock finally arrived and was replaced. I immediately noticed improvement and that the "thump sound" was significantly reduced but did not go away completely. In fact, it seems to me to have gotten slightly worse since the replacement, though still not anywhere near the level it was when I first got the car. I intend to put a few more miles on the car to see what happens.

I could be incorrect, but based on my experience, I believe there could be something faulty in the design of the shock. Especially after seeing the number of other people who are experiencing the same.

That’s good info. I do find it hard to believe that this many of us got defective right rear shocks, but it is a unique part number from what I remember. So I guess it’s possible a big run of that part number weren’t built to specification or something.

I don’t think I’m going to do anything about my car at the moment, though I may check the availability of that shock and mount. I feel like I should put some more miles on mine before I start replacing parts. I’m at about 600 miles right now.

[Golddog]

I would be curious as to what the build dates are for all that are reporting this problem.

[Roadwar]

Originally Posted by Golddog

I would be curious as to what the build dates are for all that are reporting this problem.

Mine was built week 51 (week before Christmas).

[BMWM.D.]

Originally Posted by Golddog

I would be curious as to what the build dates are for all that are reporting this problem.

Mine is a 12/21 build

[kkgriss]

Originally Posted by Golddog

I would be curious as to what the build dates are for all that are reporting this problem.

Mine is 9/21.

[steelatx]

12/8/2021 here