Is it safe to drive? Serious problem with vibrations at speed...

[SamuelL421]

Hi all, wish I could be making my first post under better circumstances , I need help from a z4 guru...

Here's my problem - My 2003 3.0i (daily driver, 93k on the clock) is experiencing some bizarre vibrations and noises this past week. It feels as though they are coming from under the car and I can feel it in my seat and slightly through the wheel. The vibration is very very subtle until 20-30+ mph and below that all I can hear is a faint noise. The noise sounds like wub wub wub... or whir whir whir... depending on speed and gets louder until 40-45mph. Its easily heard but not very loud. Above 45-50mph the vibration is hard to notice and the sound gets drowned by road noise.

What I've checked already -

• wheel balance - had this done last weekend, didn't help the problem.
• wheel bearings - these are all fine.
• engine - everything seems fine, I'm replacing the belts soon as one occasionally squeals for a few seconds every few starts. Otherwise the engine is perfect/well maintained.
• brakes - Not a stuck brake.

Problems I know of with the car -

• passenger front rim has a small bend - There is a bent spot on the inside lip not sure how long its been this way but I believe its been a lot longer than the past few weeks (when the vibration/noise started). Rim balanced fine when I took it in last weekend.
• Differential has a slow leak? - Not sure if this is my doing (overfilling?) or if there is just a very slow leak. I usually can see tiny damp spots around the differential or on the gasket of the CV joints after driving long distance (200+ miles). I've replaced this oil once in the past 20k miles and again last week. Last week I replaced gear oil again just in case and the "old" oil in there was still close to full and looked new. Not sure if this could be a sign of some other issue? CV joints maybe?

Any ideas guys? I am at a complete loss, I've worked on my own vehicles for years and none of the obvious answers seem to be the culprit. Unless I'm overlooking something obvious? Do you think the car is safe to drive? I was supposed to attend an event this weekend and was looking at a roughly 300 mile round-trip drive which seems extremely risky right now...

[pmmjarrett]

I would look at the driveshaft Ujoints, CV joints and check the pinion bearing on the diff first. If everything's right and tight there, I'd drain the diff and look for signs of a bearing going bad inside the diff.


I won't tell you if it's safe to drive or not. She's already talking too you, it's a matter of if you want to take on the risk.

I always follow and plan for Murpheys law. Nothing ever breaks at a convenient time, safe place or close to home.

[Shipkiller]

Have you checked the rubber 'guibo' on the drive shaft?

Number 1:

http://www.realoem.com/bmw/showparts...93&hg=26&fg=10

[seank]

So, did you check the diff fluid? Its pretty easy to check. There are too many things that it could be with the information given.

It could be harmless to drive or damaging. It just depends what it is.

[pmmjarrett]

Originally Posted by Shipkiller

Have you checked the rubber 'guibo' on the drive shaft?

Number 1:

http://www.realoem.com/bmw/showparts...93&hg=26&fg=10

Interesting drive shaft setup.

I didn't know these cars had a 2 piece driveshaft. Learn something new every day. Something that's not common on RWD domestics (where most of my experience as a mechanic is) unless it's a longer wheelbase like a pickup or van.



Definatly take a look at center mount and bearing... 8 & 9

What you are describing is about exactly what my 04 Dodge crew cab dually was doing when my carrier bearing went out at 200k because of a siezed U-joint.

Vibration was mostly felt on initial accleration but not braking and smoothed out with speed. It had me baffled for a while as I looked at everything but overlooked that carrier.