[CSBM5]

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.

Crazy prices. The BMWNA MSRP for the diff, 33-10-8-686-989, is $4126. You can get it discounted 24% at bmwpartsworldwide site (Ziegler BMW), $3131. With a lift, it's likely not a difficult DIY, but guessing a good indy could do the swap in 3 hrs labor.

[Ramos]

3 threads on the main page about this topic, I am thankful others are having the same issue, so that we can collectively find a solution.

I am not buying into this whole premise of "normal behavior", a loud clunk/thud from the diff is NOT normal behavior.

I would love to know if anyone has found a fix for this other than replacing the Diff which one member seems to have been able to get BMW of EL Cajon to do for him under warranty.

[JacobM340i]

Hopefully soon I’ll get up under the car and take off the exhaust and heat shielding and take a good look at everything, see if any is loose or worn. I’ll keep y’all updated.

[hayko_M340]

I believe someone mentioned a Differential Ground Strap in a different thread? Anyone try looking into that or changing it out? Maybe it gets worn out over time causing the noise? Just throwing out ideas.

[noname]

I just dropped mine off this morning for a check engine light and this.

[Ramos]

Please keep us posted if and how it gets fixed

[noname]

Annnd it didn't get fixed. DTLA BMW drove it for less than 2 miles and said they couldn't reproduce the issue.

[jxz01]

So, I just made an appointment with “Performancetechnic” the best Indy shop specializing in Bmw i can find in the Bay Area to check out this issue. Just wanna make sure bolts are tight and torqued to spec and see if anything needs replacement. I am not too concerned about it because my friend’s brand new g80 has the exact same noise and people having this issue seem to have no mechanical failures. Might just be a matter of annoyance.

[dustwhyn]

Originally Posted by jxz01

So, I just made an appointment with “Performancetechnic” the best Indy shop specializing in Bmw i can find in the Bay Area to check out this issue. Just wanna make sure bolts are tight and torqued to spec and see if anything needs replacement. I am not too concerned about it because my friend’s brand new g80 has the exact same noise and people having this issue seem to have no mechanical failures. Might just be a matter of annoyance.

Any update on this?

[RD85]

I just bought a 2020 M340i and have this issue as well. Does BMW still have Guibo problems? (former E36 owner having flashbacks.)

[dustwhyn]

Originally Posted by RD85

I just bought a 2020 M340i and have this issue as well. Does BMW still have Guibo problems? (former E36 owner having flashbacks.)

My guibos were toasted but that wasn’t what was causing the clunk for me. I replaced them and the issue was still there. I actually ended up replacing my entire driveshaft assembly with an upgraded one and I still have the issue.

But I did notice that while I was tightening the nut that holds the input yoke onto the diff (I had to swap it to a different one for my driveshaft upgrade), I was able to reproduce the sound by putting a load on the input yoke, which leads me to believe that it’s something inside the diff, most likely a preload issue. I recall another user saying that BMW “tightened” their diff and the issue went away. My guess would be that they adjusted the preload to be back within spec. I’ve thought about attempting to do this myself, but I have zero knowledge on what tool(s) I would need to make the adjustment, what I need to adjust to, and whether or not the diff needs to come out of the car.

[G30M]

before i had my M340i i had an Audi S4 with diffs galore and DCT

that car had so many different clunks it wasn't funny

one day i tried to do a wheelspin take off from a 90 degree junction it gave me a mighty clunk and i felt a whack and then all the diff clunks went away, left me only a DCT clunk

not sure that it helps here but these things might be referred to as drivetrain lash or driveline lash - it it could be anywhere along the drivetrain

but if you suspect the diff, just drain the oil, but put a coffee filter between the diff and the collecting pan, and then see if there are any metals filtered

[dustwhyn]

Originally Posted by g21

before i had my M340i i had an Audi S4 with diffs galore and DCT

that car had so many different clunks it wasn't funny

one day i tried to do a wheelspin take off from a 90 degree junction it gave me a mighty clunk and i felt a whack and then all the diff clunks went away, left me only a DCT clunk

not sure that it helps here but these things might be referred to as drivetrain lash or driveline lash - it it could be anywhere along the drivetrain

but if you suspect the diff, just drain the oil, but put a coffee filter between the diff and the collecting pan, and then see if there are any metals filtered

This was the first thing I did when I suspected it was the diff. Fluid came out perfectly clean.

[jxz01]

Originally Posted by dustwhyn

Any update on this?

Yes, I went to the shop for spark plugs replacement and figured why not just try replacing the diff fluid and see if it fixes the issue because my car is at 30k and I don’t follow the 60k spark plugs & diff fluid guideline on the manual. Anyways, replacing the diff fluid seem to be my solution, I don’t experience the the clunk like I used to. The symptoms of my car is on my another post, you can check it out. I asked the tech is the diff fluid bad or something but he said not really.