328i heavy vibration at lower speeds

[Beer+Oversteer]

Just got finished changing out all 4 wheels as I suspected a balancing issue, and to my terror it has made no difference. There was no sudden action or event that started the vibration, it just happened after getting off the expressway last night.

It is at lower speeds (15-50 mph)
Coasting in neutral it is very present
Accelerating past 4000 rpms it is slightly less present
Decelerating it is very present
Higher speeds after 50 it seems to even out and be less present
Steering doesn't seem to make a difference whether I load it left or right

When I jacked up the car there wasn't any play in the driveshaft. All 4 wheel bearings are tight.
Motor mounts are newer. I will check the transmission mounts later today. Both rear axles were tight.


The vibration is very violent, I won't be driving the car until I can diagnose the problem.

Any ideas before I start throwing parts at it?

Edit:

Here is a video of driving. It is worse when I'm accelerating, only slightly

https://streamable.com/ss11e

Second video is rolling in neutral.
https://streamable.com/n38xv

[Eric93se]

push down with your body weight real quick on each fender to see if the suspension recovers quickly and the same at all four corners. Problem could be also the guibo or the center support bearing.

[Beer+Oversteer]

push down with your body weight real quick on each fender to see if the suspension recovers quickly and the same at all four corners. Problem could be also the guibo or the center support bearing.

Would a blown strut give this kind of issue? The car is unfortunately on cut springs from the previous owner. I am going to order coilovers soon.

[Eric93se]

Usually at higher speeds a bad suspension will get scary. From what you said it's more at lower speeds (55 is not really low speed though). Cut springs are not a good idea, lowered springs are inexpensive, so that's a bit ghetto.

You have to try and isolate where it's coming from.

[Beer+Oversteer]

Usually at higher speeds a bad suspension will get scary. From what you said it's more at lower speeds (55 is not really low speed though). Cut springs are not a good idea, lowered springs are inexpensive, so that's a bit ghetto.

You have to try and isolate where it's coming from.

I completely agree. I purchased the car a week ago. I have a ton of parts en route. The car is completely solid at all 4 corners with the suspension, even with the cut springs. Anything I can check or any tips for diagnosis? What is evident in the case of a bad flex disc or center support bearing?

[Eric93se]

Well the bad CSB can cause a vibration, the bearing can go bad and the there is a rubber bladder that can tear off completely. Not too sure about the flex disc symptoms other than noise, not to sure if it tears itself apart. The rubber in my guibo dryed out, and its meant to absorb shock, so it was due.

[Beer+Oversteer]

Well the bad CSB can cause a vibration, the bearing can go bad and the there is a rubber bladder that can tear off completely. Not too sure about the flex disc symptoms other than noise, not to sure if it tears itself apart. The rubber in my guibo dryed out, and its meant to absorb shock, so it was due.

Here is a video of driving. It is worse when I'm accelerating, only slightly

https://streamable.com/ss11e

Second video is rolling in neutral.
https://streamable.com/n38xv

My further diagnosis:

Car will shake in neutral revving the engine around 2-3k rpms, but not nearly as much as when moving. This is evident of potentially transmission mounts or engine mounts?

Let me know. Thanks for your help so far.

[Eric93se]

Yeah I mean, that's bad stuff you've going on their. To be sure I would replace trans/engine mounts, guibo, CSB. It's inexpensive and they're all probably due.

[Crazy Dave]

My car has a vibration like you describe, just not quite as intense. I haven't lifted it up to check around, but my past car had something slightly similar and it was the CSB/guibo. So I just ordered new ones for this one and plan to swap them out this weekend. I'll report back and let you know if it fixes it.

[Beer+Oversteer]

Okay great. My coilovers just shipped, so I will be starting with suspension, and if that makes no difference I will move to motor mounts and transmission mounts. This car was a swap and the owner responsible for the swap claimed "everything" was replaced, which I am having a hard time believing.

[MtekJosh]

I had a similar violent vibration on a vert I recently bought, pulled the driveshaft to check things out and turns out the u joint between driveshaft and diff was seized up. Id pull the driveshaft and look at everything down there

Sent from my SM-N920T using Tapatalk

[Beer+Oversteer]

I had a similar violent vibration on a vert I recently bought, pulled the driveshaft to check things out and turns out the u joint between driveshaft and diff was seized up. Id pull the driveshaft and look at everything down there

Sent from my SM-N920T using Tapatalk

Were there any other significant noises or signs of this? I do here some banging around underneath the car if I cut the wheel, but it could be the exhaust. The noises that I have really point to transmission mounts, including that when in gear there is significantly more vibration.

[Beer+Oversteer]

Hey guys, I have great news! I believe I found the source of my vibration.
IMG_1520.JPG
IMG_1522.JPG

That would be my flex disc missing precisely 2/3 bolts connecting to the transmission.

At least the transmission mounts are good?

What in the hell would have caused this

Bolts are en route, will update to confirm it was the source.