bmw 2001 330xi intermittent vibration
 

I have a 2001 330xi. 130k miles. I have had a intermittent vibration since I bought the car. It happens at 60 and faster under load. it last 5 seconds then goes away for 5 second. Also if its vibrating and I let off of gas it stops. I have replaced both front axles, driverside pedastal(complete kit), front diff, rear diff. rear driveshaft joints feel good. front driveshaft looks ok but front yoke on transfer case seems to have play. I'm assuming this would be similar to having a bad u-joint but what confuses me is it comes and goes in cycles under load. i have had bad u-joints before and know the faster u go the worse it gets and isn't intermittent.

Welcome to bimmerfest! :D

Can you tell whether it originates in the driveline, or somewhere in the steering hardware ?

its def in the driveline. its not really bad but enough to where its annoying. you can hear and feel the vibration.

Center diff/transfer case
 

I had a similar issue with my '01 330xi, starting around 130K miles. Very subtle drivetrain vibration, sometimes visible on the gearshift lever. Got gradually more noticeable as mileage ran up to 145K. However, it was noticeable only at very light throttle in 4th/5th at 45-65 on level ground. My indy eventually traced it to the transfer case (center diff). I never had it replaced and traded it in. The car was only worth $9500, and I would have been in around $4K in parts for the transfer case and clutch (if you're gonna drop the tranny might as well at that mileage).

I read somewhere about the center support for the rear driveshaft possibly causing vibration when worn but still why would the vibration come and go every 5 seconds. Weird

Sometimes "low-tech" gives the best results. There`s a device called a "Reed Tachometer", which the technician brings along inside the car as it is driven, and the device records the specific frequency at which the vibration occurs. That reading is cross-referenced to a chart listing the various possibilities for that particular frequency.
If all else fails, you might want to seek out an old-school shop that has one of these things.

I had a bad vibration on my 2001 330ci above 75mph. Turned out to be the rear differential bushing. Changed it just a few weeks ago and car is rock solid again. Worn bushing was allowing the rear dif to twist causing the half axles to tweak/not be square with the wheel hub / bearing.

Think about it...if the dif twists the CV joints on your half shafts are now loaded up and the car will vibrate at high speed....not good for dif or axles.

Get under the car and look at the bushing attached to your rear differential cover. Mine had a visible crack in it from 11 to 3 oclock position. Does the differential look to be straight up at 12 or is that huge bolt going through the dif bushing/dif cover pointing down a bit, toward the driver side, now go in reverse and look at it...the dif will be tweaked the opposite way.

Check out Pelican parts. I installed the OEM Lemfoerder brand...quite inexpensive but a mother to install without the proper removal and insertion tools.

Thanks I will take a look at it. Was your vibration intermittent or constant?