[NoSole]

I have an '08 335xi that has a weird vibration. I'm at about 145k miles so I'm at the perfect age and wear for just about everything to be failing on this car. I feel a vibration when driving that I can't, for the life of me, figure out. I've read a bunch of different threads looking at possible causes and so far, nothing conclusive. I'll try my best to describe it as accurately as possible.

Symptoms:

• For all intents and purposes, the car rolls smoothly. Wheels are balanced and aligned).
• Vibration ONLY occurs when I'm in gear and on the throttle/under load.
• Vibrates through the whole car (feel it through the seat), not just the steering wheel
• Taking my foot off the gas, regardless of speed, car rolls smoothly w/no vibration
• Shifting to neutral and revving engine (whether fast or slow)... no vibration. It feels smooth.
• The frequency of the vibration is directly related to speed.
• At slow speeds (20-40pm) it feels like a wobble like my wheels are way out of alignment
• At highway speeds (50-80mph) it feels like a high frequency vibration. The speed/intensity of the vibration is directly proportional to the speed of the car. (I hesitate to say "intensity" because I don't mean that it is amplified with mph, just that the vibration is faster)

Recent maintenance (whether notable or not):

• brake flush
• new engine oil and filter
• new transmission pan/filter and oil
• new transfer case fluid
• all ignition coils changed ~19k mi ago (due to misfires)
• new tires ~10k mi ago
• new spark plugs yesterday.

Known issues:

• Engine oil leak from oil pan gasket
• Slow transmission oil leak from mechatronics sleeve
• Very slow rear differential leak (basically just enough to make the case very dirty over time, but not actually drip)
• Changed the plugs due to slow, inconsistent cranks. Now it starts quickly and smoothly.
• When changing plugs, #3 was covered in oil, so at the very least my valve cover gasket is shot. I don't recall if there was oil on the electrode, but I have an inspection cam and will pull plug to check again soon when I have time and will also inspect the cylinder.
• While it's all open again, I need to check the serials on the fuel injectors anyway to see if they fall in the recalled batch. Will clean injectors, and will not be surprised if #3 is fouled.

As of now, it's just sitting in my driveway, not being driven. It breaks my heart cuz I love this car and have been through a lot with it, but it's getting so damn expensive to maintain compared to it's residual value.

[robthewrench]

A guess, drive shaft or axle shaft u-joint or CV joint. Both these components turn at the same speed as the wheels. So if not the wheel's balance, could be one of these.

You seem to have narrowed it down being related to wheel speed and not engine speed. At 145K have any of the axle shafts been replaced? I see you own an xi, so either front or rear could be the issue.

[NoSole]

Yeah, that's what I'm thinking too. I spoke with my neighbor last night and he was thinking driveline or broken motor mount possibly. Gonna take it too his shop and throw it on the lift to take a look so I don't have to crawl around in the street and inspect everything from 6 inches away with the car on jack stands!

Thanks Rob. Will report back on my next move and the result

[NoSole]

The problem is failing CV joints. Both the right and left have some play in them.

[Aode06]

Its usually the center transfer case bushing. And man is it a pain in the rear to do. I just remove the entire transfer case and have a specialty shop press it in and out. Most shops don't have the expensive bmw tool.

[Suvorovo]

Good advice from everyone, but if it's the transfer case bushing there are some $90 tools you can buy to press it out yourself. There are some threads on this.

Here's some advice when I replaced my driver's axle:

1. PB Blaster the axle nut, control arm nut, tie rod nut, wishbone nut overnight.
2. Unstake and Remove the axle nut with an impact. Quite a breeze.
3. Start hammering out the axle maybe about .5cm-1cm just to get it going. This made life so much easier since the strut dangles once the control arm/wishbone/tierod are removed.
4. The control arm was difficult to remove due to the care I took to keep the ball joint intact. I used one of these ball joint separators https://www.fcpeuro.com/products/bal...cta-tools-4013 and hammered it into place very so slightly without damaging the ball joint rubber. Buy a 24mm crowfoot adaptor to properly torque down the control arm nut. The CV boot is in the way and there is no way to fit a socket and a torque wrench. If you keep the crowfoot and the torque wrench on the same plane (perpendicular) the torque values don't change and you can safely torque down the nut to the correct spec.
5. The wish bone was removed with a two jaw gear puller. Quite a breeze. No need to smack the knuckle and risk damaging something else. Ball joint is in good condition.
6. Hammering the axle was pretty easy with about 3 medium strength smacks with a chisel on one of the protruding edges of the CV axle. Keep a oil container underneath as some fluid leaks out.
7. DO NOT HAMMER YOUR AXLE into the differential! It's enough to use your hand to smack it into place until an audible click is heard.
8. DO NOT HAMMER YOUR KNUCKLE ASSEMBLY to get the axle into the knuckle. I used 2 inches of wood and a dead blow hammer to lightly tap the axle into place. It will take a lot of taps, but you do not want to transfer the force of the hit to the differential. Once you can get the axle nut in on 2-3 threads, tighten it lightly until the axle is completely pulled into the knuckle. Since an Axle has telescopic features, you don't risk pulling the axle out of the differential.
9. Don't rebuild your axle, just dish out the extra money for a new axle and save time. The axle nut was staked pretty hard from the factory which caused damage to the threads when trying to unstake.
10. If you have auto leveling headlights, the suspension will sag and make attachment of the leveling sensor arm difficult. You'll need to put the car down, drive around for a bit so the suspension settles and then lift the car up to attach the leveling sensor arm.