So I thought my weird driveline noise was caused by my failing guibo and other things. But I replaced my guibo, center support bearing, trans output seal, selector shaft output seal, tranny mounts, and all my shifter bushings. And I STILL have this noise. It increases with the speed of the driveshaft, and gets louder when I let off the throttle. I don't know how to explain it, it sounds sort of like, "rut rut rut ruh ruh ruhruhruhruhruhruh" when you are accelerating. Now my driveshaft WAS rubbing on a heatshield when we took everything apart. I thought that the new center support would not sag like the old one and keep the driveshaft away from everything. Everything looked good when we put it back together so I am 90% sure it is not that. The trans and diff fluid were replaced with royal purple a few thousand miles ago, but I am wondering if the trans could be underfilled? We had the car level and filled it until the fluid ran out of the fill hole when we did it. The trans leaked from the rear output shaft seal, but not enough to make drops on the ground or anything, so I don't think it leaked a significant amount. I do not have an LSD, and there is no vibration at this point, just noise. Any advice would be great, I am taking the car autoXing on Sunday, so we will see if anything blows up at that point. :shifty
Anyway, everybody loves pics, so here are some of the old guibo, trans mounts, and center support bearing. (yes it was in pieces)
http://img.photobucket.com/albums/v236/Racerhoze/IMG_1033Small.jpg
http://img.photobucket.com/albums/v236/Racerhoze/IMG_1034Small.jpg
http://img.photobucket.com/albums/v236/Racerhoze/IMG_1037Small.jpg
http://img.photobucket.com/albums/v236/Racerhoze/IMG_1032Small.jpg

its poss that the driveshaft is still rubbing... how were the motor mounts? i know we have different motors but my mounts were both blown and under hard acceleration would cause the driveshaft to hit the heat sheild, just an idea but that noise is more high pitched...another would be your wheel bearings / tire noise, wheel bearings will deff make that noise you are describing and change with accel and decel left and right movements

Dunno what's actually causing the noise, but motor mounts could cause the works to be misaligned. When I replaced the trans and engine mounts, the trans ones looked like yours, but the right engine one was compressed a good centimeter or two more than the left, or the replacements. Given the direction our torque monsters spin (and that they're already leaning to the right), that's not all that surprising. Replacing them made a big difference in idle and takeoff smoothness, and might fix your noise as well.

The sound does not seem to change when I turn left or right, so I am not sure if that rules out the wheel bearings. And now that I think about it, when I did my suspension, I think I remember the driveshaft looking like it was rubbing the rear subframe. (what would cause that?) And as far as motor mounts, the only reason I was holding off was because the motor mounts are so expensive! At least I think 40 dollars per mount is expensive... :shifty

It's entirely possible you've got a failing joint in your driveshaft. Motor mounts I'd pretty much rule out. I could see them being misaligned and causing something to rub, but then you'd have a shiny spot from the rubbing. Wheel bearings are a possibility, so are diff bearings. Remember, new fluid doesn't keep old parts from wearing out.

There is a shiny spot on the driveshaft from rubbing, but I just figured it was from the center support bearing sagging badly. Could my diff mounts be shot?

Just noticed I misspelled replaced in my thread title... derrrrrr :(

With that much damage to the guibo and centre bearing I would expect one of the U-Joints to be shot. Did you check the play in them. If it's isn't that then I would also wonder about input shaft bearing (diff) and output shaft bearing (tranny)

**Edit** Geez I realized I just basically said the same thing as Binjammin

I would consider not doing the autox tomorrow. Have you ever seen a driveshaft come loose?

The U joints were solid and had no play in them. Where would the driveshaft come loose? I am now just thinking it is rubbing on the rear subframe but I have no idea why...

My guibo looks worse than that :(

When you figure it out let us know, please

I just read your post again man, I thought you had an accompanying vibration. You've only got a rubbing noise? Pull your rear wheels and inspect your ebrakes.

Louder on decelleration could be the input bearing of the diff. I put a 3.73 LS into my car and that stopped my noise that I could only hear when my foot was off the throttle. You ought to put that guibo and center bearing up on your wall - they are in collectable condition.

The U joints were solid and had no play in them. Where would the driveshaft come loose? I am now just thinking it is rubbing on the rear subframe but I have no idea why...

How are your subframe and diff bushings? If the diff is out of place, it could rub the subframe, but it would have to be fairly drastic.

How are your subframe and diff bushings? If the diff is out of place, it could rub the subframe, but it would have to be fairly drastic.

My subframe bushings were just replaced. I took this picture with the rear of the car on ramps and the driveshaft looks pretty centered. How bad is that input bearing on the differential to replace?
http://img.photobucket.com/albums/v236/Racerhoze/IMG_1057Small.jpg

Edit: Oh and my car survived some sweet autocross action today :stickoutt
http://img.photobucket.com/albums/v236/Racerhoze/IMG_1044Small.jpg

Shaft looks nowhere near anything.

Didn't you recently have problems with rubbing brakes?

Input bearing is not an easy task since you have to deal with the pinion bearing issue, but since you're not changing the input shaft you should be able to mark where it's currently torqued. You still have to remove the bearing and such, which may be difficult if you don't have the tools.

Shaft looks nowhere near anything.

Didn't you recently have problems with rubbing brakes?

Input bearing is not an easy task since you have to deal with the pinion bearing issue, but since you're not changing the input shaft you should be able to mark where it's currently torqued. You still have to remove the bearing and such, which may be difficult if you don't have the tools.

I did have a problem with a caliper.. but that was because it was missing a bolt. :shifty Benjammin suggested that it may be something to do with my e-brake, but I drove around and pulled it up varying amounts with no change in sound. What tools are required to remove the bearing?

Edit: Dang nice ninja edit

I did have a problem with a caliper.. but that was because it was missing a bolt. :shifty Benjammin suggested that it may be something to do with my e-brake, but I drove around and pulled it up varying amounts with no change in sound. What tools are required to remove the bearing?

Edit: Dang nice ninja edit

http://www.realoem.com/bmw/showparts.do?model=HD23&mospid=47408&btnr=33_0073&hg=33&fg=10

You're going to have to remove what you see above. You'll probably need the diff secured into something strong, then with a slide hammer yank it out.

I can't imagine it's you're bearing that's giving you issues. Bearings are more of a constant sound than a wur-wur-wur sound. You should be able to get the car up on stand and put it drive (be careful) and listen for the sound.

That's how I diagnosed my rear, among other things.

I had a similar problem and it ended up being a bad tire. Belt was separating and almost blew out. Changed tire and noise went away.

I guess it will be the jackstand method for me as far as diagnosis. And I don't think it is a bad tire, because it seems to be coming from the center of the car, and it is too metal on metal sounding to be a tire IMHO

If you get someone standing outside the car when you pull away they might be able to diagnose the location of the sound a bit better.

The sound insulation is so good in these cars its really hard to do it from inside the car.

First response in the thread at the time :confused lol
I did have a problem with a caliper but that was because it was missing a bolt.

First response in the thread at the time :confused lol

Well its not like I was driving around knowing it didn't have a bolt. It had worked its way out after I installed my suspension. And then the bottom of the caliper was grinding against the outside of the rotor.