[commodore90]

Hi All! This is my first post here, on this forum, which I find very useful.
Two weeks ago, I have become a proud owner of G30, 520d mild hybrid rear wheel drive, 2021. The car has 54k km and is exactly 3y old.

When I tested the car during purchase, I missed to drive it on wet conditions, as it was not rainy, but, as soon as the rain fell, I noticed one strange thing:
Only when accelerating hard from stationary and on straight direction and on slippery surface, the car has strong lateral shaking (bouncing)

This is especially noticeable in shopping centers parking lot, as the surface there is usually very slippery and smooth concrete.

So, I went to official BMW service shop, they checked the whole car for 2h...there was only one thing: slight signs of ware on one of universal rubber joints, so I replaced it with original one.

To sumerize : the car has 0 vibrations when its driven on highway at any speeds. It has 0 vibrations when accelerating hard on dry conditions, it even drifts nicely on wet surface without any hassitation or vibration, but when the conditions of surface are slippery or wet, and direction is straight forward, the car has strange and hard lateral shaking. I feel like something is bouncing and kicking almost like metal on metal.

To mention: all rims are BMW original 18" with brand new tires, all straight in good condition.

Please share your thoughts about this issue as it drives me creazy

[commodore90]

To try one more time to get some info:
Nobody else experienced this kind of car behavior?

[lnxguy]

Oh wow, I have never heard of this one before. I'd say transfer case but obviously you don't have one. Are you getting any sort of wheel hop? Can you get someone to watch while you drive?

[tsbrown]

Originally Posted by commodore90

Hi All! This is my first post here, on this forum, which I find very useful.
Two weeks ago, I have become a proud owner of G30, 520d mild hybrid rear wheel drive, 2021. The car has 54k km and is exactly 3y old.

When I tested the car during purchase, I missed to drive it on wet conditions, as it was not rainy, but, as soon as the rain fell, I noticed one strange thing:
Only when accelerating hard from stationary and on straight direction and on slippery surface, the car has strong lateral shaking (bouncing)

This is especially noticeable in shopping centers parking lot, as the surface there is usually very slippery and smooth concrete.

So, I went to official BMW service shop, they checked the whole car for 2h...there was only one thing: slight signs of ware on one of universal rubber joints, so I replaced it with original one.

To sumerize : the car has 0 vibrations when its driven on highway at any speeds. It has 0 vibrations when accelerating hard on dry conditions, it even drifts nicely on wet surface without any hassitation or vibration, but when the conditions of surface are slippery or wet, and direction is straight forward, the car has strange and hard lateral shaking. I feel like something is bouncing and kicking almost like metal on metal.

To mention: all rims are BMW original 18" with brand new tires, all straight in good condition.

Please share your thoughts about this issue as it drives me creazy

How many miles on the car? Shuddering under acceleration can be from a worn flex disk. I did preemptive replacement on mine at about 45k miles as it was showing wear/cracking.

[commodore90]

Hi All!

Apologies for the late response on all the answers.

The car has only 55k km.
It drives excellently on highways in all suspension modes: Adaptive/Comfort/Sport as it has the adaptive suspension.

The problem is noticeable significantly in wet conditions, full throttle when the rear end slides due to slippage. the whole car shakes in the lateral direction.

Both, the repair shop and Dealer confirmed that everything is ok with the car...

[arkhi]

This sounds normal to me. Try putting the car in SPORT TRACTION mode and see if it goes away.

[lnxguy]

This is traction control cutting in.

[adhrp]

Yeah sounds like not so great wet performance tires and traction control setting in.

[G30M]

Originally Posted by commodore90

To try one more time to get some info:
Nobody else experienced this kind of car behavior?

2 words

TRACTION CONTROL

[commodore90]

Ok I didn't point out that of course the problem is present in Sport individual mode where all the traction controls are disabled (both of them).
So it's not traction control.

I have also tried both suspension configurations: comfort and sport.

Tires might be the issue, even though I bought a new winter set.
The car is currently on an 18" OEM rims.
I need to try with a summer rim set which will be either 19" or 20".

[G30M]

your traction control is fully disabled?

then it's called "wheel hop". your car don't have enough power to do a proper wheelspin burnout whatever the stunt it is you are trying to do.

the power to the wheels is at near the limit of breaking traction. sometimes it's powerful enough to break traction so the wheel slip, but then at some stage the tires grip and then that sends a big shock to your drive train. (in reality this is cause by a combination of flex in your drive train and bouncing of the suspension, regardless, the end result is a repeated loss and regaing of traction leading to something breaking into many pieces)

do it enough times and your drivetrain will literally snap into pieces.

don't do it.

[lnxguy]

Originally Posted by commodore90

Ok I didn't point out that of course the problem is present in Sport individual mode where all the traction controls are disabled (both of them).
So it's not traction control.

I have also tried both suspension configurations: comfort and sport.

Tires might be the issue, even though I bought a new winter set.
The car is currently on an 18" OEM rims.
I need to try with a summer rim set which will be either 19" or 20".

Traction control is never completely disabled, even in sport mode.

[G30M]

Originally Posted by lnxguy

Traction control is never completely disabled, even in sport mode.

lol how misinformed

[CnSky]

Rear subframe mounts maybe? Check my old posts have pictures of how they can tear.