[JacobM340i]

Hey guys, I just bought a 2020 M340i rwd with 60k. Love the car but noticed after I bought it that when let’s say you slow down to about 4-5mph then as soon as you hit the gas to accelerate there is a slight clunk coming from the rear diff. It feels like drivetrain “slop”, it doesn’t always do it either you have to catch the speed and everything just right for it to do it. Here’s the catch though, it only does it when the rear diff/fluid is cold, as soon as I drive it 10ish miles, it won’t do it at all. You think changing the fluid will help?

Then something completely different, is it normal for these engines to vibrate at idle a little, sometimes mine is perfectly smooth other times you can feel it vibrate a little. Definitely doesn’t idle as smooth as my mk7 GTI that I had previously.

Thanks!

[seccsc]

It won’t hurt anything if you did. At least you would validate the differential isn’t low.
I had mine replaced and the second one modified by BMW to fix the vent leaking issues.
I am not aware what type of fluid it takes.
It is an LSD, so make sure to validate the fluid type.

[sikotic]

I had the same thing on my 2020 M340i, they said the rear diff was loose and needed to be tightened.

They also sprayed some detection powder to see if its leaking at all, so I can update the next time I take it in. But the car did feel much better afterwards

[JacobM340i]

Originally Posted by sikotic

I had the same thing on my 2020 M340i, they said the rear diff was loose and needed to be tightened.

They also sprayed some detection powder to see if its leaking at all, so I can update the next time I take it in. But the car did feel much better afterwards

The diff mounts?

[JacobM340i]

If anyone has the vibration problem it was fixed with fuel system cleaner

[peelerec]

Originally Posted by JacobM340i

Hey guys, I just bought a 2020 M340i rwd with 60k. Love the car but noticed after I bought it that when let’s say you slow down to about 4-5mph then as soon as you hit the gas to accelerate there is a slight clunk coming from the rear diff. It feels like drivetrain “slop”, it doesn’t always do it either you have to catch the speed and everything just right for it to do it. Here’s the catch though, it only does it when the rear diff/fluid is cold, as soon as I drive it 10ish miles, it won’t do it at all. You think changing the fluid will help?

Then something completely different, is it normal for these engines to vibrate at idle a little, sometimes mine is perfectly smooth other times you can feel it vibrate a little. Definitely doesn’t idle as smooth as my mk7 GTI that I had previously.

Thanks!

Perfect way to describe what I’ve had for the last 3k miles. I am currently at 25k miles with several track days. It doesn’t appear to be a huge issue but definitely a lag when going slow and car not warmed up. I have a differential fluid flush and replenishment scheduled with my Indy shop next oil change.

[JacobM340i]

Originally Posted by peelerec

Perfect way to describe what I’ve had for the last 3k miles. I am currently at 25k miles with several track days. It doesn’t appear to be a huge issue but definitely a lag when going slow and car not warmed up. I have a differential fluid flush and replenishment scheduled with my Indy shop next oil change.

Please let me know if it helps haha, thanks!

[FishMuffins]

I’ve been having this problem for about a year now, starting at around 42K miles. Took it to the dealer then and they couldn’t replicate the noise but they changed the diff bushings, but the noise is still there. I recently changed the diff fluid at an Indy and the noise and the thud is still the same- happens when it’s cold and goes away when warmed up. Did anyone find a cause or a fix to this?

[JacobM340i]

Originally Posted by FishMuffins

I’ve been having this problem for about a year now, starting at around 42K miles. Took it to the dealer then and they couldn’t replicate the noise but they changed the diff bushings, but the noise is still there. I recently changed the diff fluid at an Indy and the noise and the thud is still the same- happens when it’s cold and goes away when warmed up. Did anyone find a cause or a fix to this?

Nope, changed my fluid, no help, I’m thinking maybe the output shaft on the transmission or diff might be loose, that’s what I’ve heard other people say fixed there’s, idk.

[Ramos]

I have the exact same issue and it's driving me mad.
Replacing the Diff fluid does not help.

Of course dealer could not replicate even though I drove around with the Tech and he could hear then clunk with me in the car.

Any updates or fixes for this?

[Ramos]

Originally Posted by JacobM340i

If anyone has the vibration problem it was fixed with fuel system cleaner

Can you share the product you used? I also get intermittent engine vibration at idle.

[JacobM340i]

Originally Posted by Ramos

Can you share the product you used? I also get intermittent engine vibration at idle.

Actually it didn’t fix it haha, I also recently changed both motor mounts and still no dice even tho it is a lil smoother now. Still not as smooth at idle as my buddys supra but I guess I can live with it.

[jxz01]

Originally Posted by JacobM340i

Actually it didn’t fix it haha, I also recently changed both motor mounts and still no dice even tho it is a lil smoother now. Still not as smooth at idle as my buddys supra but I guess I can live with it.

Hi Jacob, I have read a lot about the rear diff clunking issue, and I think I am experiencing the same thing. Is this something normal or should i send it to the dealer?

[BMW11]

wow suddenly multiple people with the same diff issue; this sounds troubling to me. This is a bummer. How much approx. is a new diff installed at BMW out of warranty?

[peelerec]

Originally Posted by BMW11

wow suddenly multiple people with the same diff issue; this sounds troubling to me. This is a bummer. How much approx. is a new diff installed at BMW out of warranty?

After consulting extensively with a couple Indy shops that have worked on BMW’s and raced for many, many years. They both independently confirmed this is normal and shouldn’t be of concern.

[peelerec]

Originally Posted by JacobM340i

Please let me know if it helps haha, thanks!

Transmission and diff fluid drain done 2k miles ago. The thunk remains, but as I mentioned on another post, both my Indy shops believe this to not be of concern.

[hayko_M340]

Originally Posted by JacobM340i

Hey guys, I just bought a 2020 M340i rwd with 60k. Love the car but noticed after I bought it that when let’s say you slow down to about 4-5mph then as soon as you hit the gas to accelerate there is a slight clunk coming from the rear diff. It feels like drivetrain “slop”, it doesn’t always do it either you have to catch the speed and everything just right for it to do it. Here’s the catch though, it only does it when the rear diff/fluid is cold, as soon as I drive it 10ish miles, it won’t do it at all. You think changing the fluid will help?

Then something completely different, is it normal for these engines to vibrate at idle a little, sometimes mine is perfectly smooth other times you can feel it vibrate a little. Definitely doesn’t idle as smooth as my mk7 GTI that I had previously.

Thanks!

I have been having this clunk/thump issue for a well over a year if not two. Mostly happens when cold or slowly accelerating from a stop. I am nearing 50K miles, still on original fluid. My differential has also been leaking or "Sweating" as the dealers and BMW calls it. Just got it back from service for the second time and nothing has been done about it. Took Shop Foreman and technician on test drive and verified noise/concern after apparently they "Could not verify customer concern. Upon visual inspection it was found that the differential is sweating per sib 330321 and is deemed normal." Basically they threw it back at me after I sat them in the car and proved to them it was making noise saying they will not do any more work forward regarding the issue as the vehicle has aftermarket wheels and tires installed therefore considered outside influence. Surprised they didn't blame it on tune or bolt-ons rather the tires

[hayko_M340]

Originally Posted by jxz01

Hi Jacob, I have read a lot about the rear diff clunking issue, and I think I am experiencing the same thing. Is this something normal or should i send it to the dealer?

Dealer won't do anything will either say can't replicate customer concern or throw it back and say it's normal until you sit them next to you and take them on a test drive. Shop Foreman at dealer was telling me BMW is becoming very stingy with warranty work and they are really hovering over their shoulders when it comes to warranty work.

[hayko_M340]

Originally Posted by BMW11

wow suddenly multiple people with the same diff issue; this sounds troubling to me. This is a bummer. How much approx. is a new diff installed at BMW out of warranty?

Here you go. Dealer quote after BMW refused to warranty it.

Don't mind the sunroof quote that's a another issue.

[jxz01]

Originally Posted by peelerec

After consulting extensively with a couple Indy shops that have worked on BMW’s and raced for many, many years. They both independently confirmed this is normal and shouldn’t be of concern.

Good to hear, at least I am not the only one suffering from this “feature”. I guess it takes time to adapt coming from Lexus to BMW

[jxz01]

Originally Posted by hayko_M340

Here you go. Dealer quote after BMW refused to warranty it.

Don't mind the sunroof quote that's a another issue.

Lol, that’s straight day light robbery
Btw, I am guessing it is the sunroof rattle you got. I already accepted mine the way it is

[JacobM340i]

I just don’t see how this is normal, have a friend with a supra with same diff and trans and it doesn’t do this.