that might be the axle....on mine with all four wheels on the ground. if you go under and grab the front left axle you can try to move it from left to right as in from wheel to the transfer box so left (towards out side of car) and right ( towards the inside of the car) if that makes sense either way just wiggle it and see how much play you have....i hear it when sometimes going over bumps and its not the trust arm bushings....so i saw a post on youtube some guy with a 330xi replaced his axle and joint cuz of vibration but that was cuz he had a torn boot and never fixed it. now who knows mine is definitly worn cuz when compared to the right axle the right axle has almost no play at all just a hairline and thats with all your weight....so take a look at yours. BC i tried to move the tierod also and it didnt wiggle so steering is not the main cause of the vibration.....possible to not as severe.

I've just skim-read this thread, so I don't know if anyone has suggested this already, or indeed if you have done this....

I had a skyline a few years back and had similar to what you have described. It was the 3-piece alloy wheels that were buckled.

Basically I took it to a skyline specialist and he suggested swapping the front wheels with the back. The wheels were NOT staggered so we did. I took it for a drive and BINGO! It WAS the problem.

I'm assuming your wheels are the one piece standard, and that they are staggered as standard, so obviously it wouldn't be a good idea to do what I did, but perhaps borrow a set of wheels, all 4 to be sure, and then go for a run. This would at least elliminate the wheels/tyres, so you can then look at other sources if its not the wheels/tyres...

Forgot to add, the way we found out was to put the car on the ramp jacking it under the chassis so the wheels could turn. We started the car, put it in gear and saw all 4 wheels turning, and could physically see the wheels out of true. If you can't borrow another set of wheels, then just simply go to a garage that can do this.

Sounds very plausible. Most definitely worth the effort to see if this is the problem or not.

If you don't have access to an extra set of wheels you could put the spare on, that would let you test one corner at a time. Come to think of it, I might do that myself !

I have some shaking through the steering but it's not consistent. Sometimes it's quite bad by the time I get to 65mph, sometimes it's barely noticable all the way through to 80mph. Its peak is always about 70mph.

I will try that too...but when they balance the tires they barely added any weight to them....usually when its a bad rim they add and add and finally say its bent...but not a bad idea i have 4 jack stands too so will try...

on a second note about the bad CV causing some issues here are some vids on youtube that have the same sound as min...

1) YouTube - bad inner CV joint noise on driveaxle

2) YouTube - Clicking axle? Maybe this is your problem...

3) YouTube - BMW DIY #7 E-46 AWD FRONT AXLE SWAP

and 3rd is on a 330xi so same as our X's and he had bad cv that was causing vibration under acceleration. Now when im driving i feel the vibration but right when you floor it its realy bad...and the speed has not increased drastically thus i am going to replace my left front axle and joint. its only 80 bucks form partsgeek.com same part as ECS tunning (124) so ill do that then tierods then alignment and see how it goes.

Balancing a wheel is the balancing of its centrifugal forces using weights, not the shape and roundness of the wheel, which is what is in contact with the ground (albeit with a lump of rubber wrapped around it).:stickpoke

Imagine an egg that has been 'balanced' using weights. Roll that egg along a flat surface.... get the picture? Its exactly the same, as it was exactly the same for my skyline which I too had the wheels balanced time and again....until I got to the specialist!

Ohh dont get me wrong i know what you are saying...but i have a going bad cv joint and i had put new tierods (cheap) and 6months later i have a bad alignment....I can assure you i have not hit any potholes so i think the smart thing will be to replace the going bad cv joint then tie rods and get new alignment then do the balance but with roadforce and as you said...i mean thats all i have left...but yea i agree with you...thats what had happened to the goodyear tires after 3K miles they were egg shaped.

OK UPDATE!!!!

After a new left axle with new CV joint from parts geek (empi company) I noticed a huge reduction in vibration under acceleration. Also since i was going to do an alignment i decided to change out the whole tierod assembly and old ones were not worn out after inspection once it was removed so that was extra but better do it before alignment so i did. afterwards i went to butler tire and had them do the alignment and balance and i can say there is no more vibration. Its baby smooth and i feel a little "humming" but went up to 120mph and nothing so im finally happy. YAYAYAYAYA but will drive for a week or so and see if it stays this way.....

I hope this helps others.

GREAT NEWS!!!!
Thank's for share!

I had bad vibration when braking from 50-60 mph. Bentley service book says it's more likely to be worn front suspension components, not brakes. So I jacked up the front end, put in jackstands, and wiggled the wheels. Most motion occurred holding the driver's side wheel at 10:30 and 4:30, and pulling the wheel back and forth. (1:30 and 7:30 on the passenger's side.) So I got a friend to shake the wheel back and forth at those locations, while I laid under it with my hand on each of the 4 link ends - two are bushings, two are ball joints, on each side (8 total). There was detectable motion on all four bushings, and the two ball joints on the control arms. (The trailing link ball joints were OK.) So I replaced the two control arms, which include the bushings and the ball joints, and the two bushings at the forward ends of the trailing links. Problem went away.
You mentioned replacing the control arms, which include the respective ball joints and bushings, but you didn't mention the bushing on the trailing link. Jack up the car, and check for play in those bushings, at the forward end of the trailing links, while somebody shakes the wheels as described above.