[ouderkirk]

Hello everyone,

I had an odd issue come up on my 06 325xi today.

I just got back from visiting family yesterday and the car was riding great. One hour in mountains and one hour on freeway after running around the small town all day. No sounds, warning lights and the steering/suspension felt fine.

I even took the wife and dogs out for a ride later after getting home and didn't notice anything odd or "bouncy/sway-ish"

This morning I got up checked coolant (had a water pump go out a couple months or so ago so I'm watching the cooling system like a *&$# hawk) ..... looked good.... checked under to make sure the trip didn't spring up any kind of leak anywhere. Everything looked normal/good.

I didn't notice anything on surface streets (like a bounce or a noise) got on the belt route and as soon as I merged left and got settled in my lane, my car started gently swaying .... like the wind was blowing but felt almost rhythmic. What is odd is I was and still am hearing NOTHING, which has me wondering if it even could be a sway bar issue. Most the time if there is a sway bar issue you hear something.

It isn't constant, and once the energy is dissipated it stops. Which is to say its the bumps not the acceleration causing it.

But when I hit a bump or uneven section of the road.... instead of a up and down shock adjustment that you would expect, it feels to be swaying left to right. It also feels like it is getting lower when it sways to the right compared to the left. (Kind of feels like it wants to fishtail)

The weather has been all over the place and with recent temp changes I have been playing around with tire pressure.... letting a bit of air out and checking levels..... however I am a bit confused about the tire pressure. My car has info for 16" rims but mine has 17" .....

I checked the owners man and it says for 30F/36R for 17" ..... I thought maybe I did something stupid with the tires, but I just went over all the tires and it is still doing it.

No warning lights, no banging or thuds or grinding, tires are in great shape and now at 31F/36R

I get to work from home tomorrow so I was going to slip away and try to get it on jacks, but I would love to know what the community thinks might be going on.

FYI: In case someone saw my post in the AWD transmission section about a "shimmy" my car is doing when stopped at red lights.... lol not the same issue.... my car just wants to shake its rear end I guess

Thanks in advance

[Boony]

So I just got an alignment. I’ll post the specs in a bit, and ultimately my rear is shimmying left and right over everything now as you describe. It was not before. The most major thing they did was set my rear camber both at -3.2
I am on probably beyond blown stock sport struts on what seems to be sagging h&r sport springs. Will be changing most major bushings in the rear as well as putting on coils soon to try and correct this issue.

[ouderkirk]

Hey Boony!

Thank you for the reply and it kind of ties into my update.

I am still an "aspiring" DIY'er and I am waiting for a set of Schwaben jack stands. So I have just been crawling on the ground pulling on everything solid I can grab.

On the last wheel I found a problem, hopefully it is THE problem... but I can only see so much.

The rear passenger side trailing arm snapped in two.

I am guessing that an alignment needed after replacing? I would think this could affect camber.

But if not please let me know so I don't waste money getting one done lol

I'll update if I find something related.

[Boony]

Okay so almost 99% of the time the second you touch anything suspension-wise, you ideally need to get an alignment.
Now when it comes to stressing for an alignment... there is definitely a difference between being a forum-stickler and swearing you need to get an alignment every time you gain 5 lbs for exact OCD level specs (which is many people on here lmao), and the contrary, being normal, and only getting an alignment after a substantial adjustment.

For example;
I once had an annoying issue of the car tracking to the left when the steering wheel was straight. I got an alignment to no avail, shop told me replace the front driver lower control arm and then come back. I went home and swapped to a new control arm in the drive way.......took it for a drive and the alignment was spot on perfect after my swap and I didn't have to get another alignment as the car felt fantastic. That is WAY different than your situation though with a full on break, which you totally should get an alignment for after you swap the trailing arm.

just my .02

As for my situation, the shop said I need to replace the right lower control arm inner bushing. Apparently that is causing my steering wheel to not be centered at various speeds and part of causing significant issues in keeping the car level on acceleration/deceleration, and probably coupled with sagging/blown suspension causing my shimmy.