Can I come crawling back to this board for some real expertise? Tough vibration!

[Tiger]

Not only that... his car is a 2001 too... Costco wheel balancer are rarely ever calibrated. I still think it is wheel balance issue. You don't need roadforce balancer... but a good balancer.

My uncle got a new machine and everytime I go there, I manually calibrate his machine before I do any balancing. He and his crew never calibrate the machine. Before this machine he had a good Coat wheel balancer but something was seriously wrong with it. We could never calibrate the machine... I would run like 5 or 6 calibration and the result are horrible. The machine would read zero but if I keep spinning it to check it, it would throw new weight readings... never ending.

[DanDombrowski]

Hey all, its been awhile since I've sold my E34 and posted here. Since I've been very much lacking stimulating automotive conversation beyond clear corners, wheels, and oil type discussions on the other board, and because I have an extremely confusing vibration problem, I've come here to throw myself at your guys feet for help. Since you all actually work on some of your cars, I was hoping someone could shed some light on this. This is for my E46 (which has a driveline very similar to the small 6 E34 525i, actually). The E46 is a 2001 330Ci with a 5spd manual.

Okay, holy crap, I am completely, thoroughly, and utterly confused. I've been having a rear end vibration for some time that I asked about here but didn't get any responses. I did my test of lifting the car and running the engine tonight, and I got very strange results.

With the wheels on - MEGA vibration, way worse than driving the car. Nothing until about 40, then a pretty big peak (probably the biggest) at 45, then a little less at 50, then another peak at 70, slows down a bit at 80, and then gets progressively worse from 90mph +. Heres an odd thing - when driving the car, the worst vibration is at 82mph, where there is the least with the wheels off. When driving, there is very little vibration at 45mph.

With the wheels off - very, very, very little vibration, but I can still feel something slightly. I can also notice what I THINK is a slight bit of runout on the rotors radially, then seem to be not rotating perfectly round, but its not completely obvious. Could be an optical illusion.

Now, here's the part. I put the car in 5th, let off the clutch, and let it idle at 20mph. With the wheels off, there is a noise like what you would think the inside of a windmill sounds like. Its a clinking, clunking, metal gear noise thats rythmic, but random, if that makes any sense. I had my GF rev the car up to 40-50, and it does SEEM to get a little worse, but its very hard to tell. If you put your ear directly next to either wheel hub, it seems to come from the hub. If you stand behind the car, it seems to come from the differential.

As crappy as a busted differential sounds, I'd rather pay $200 for a used diff than $400 for a rebuilt driveshaft. I am just at a complete loss, I'm very confused by these symptoms.

A little more information about the tires. I got a flat a little while ago, Costco finally got my new tire in. The flat was on the LR. I had them put the tire that was on the RR on the LR, and the new tire went on the RR (to balance out the camber wear and because the RR wears the fastest). Both wheels balanced to 0.00 on their 2 position machine, but it wasn't a roadforce machine. Also, the vibration in the car didn't seem to be affected by this tire change at all.

Any ideas? I'm thinking either the differential is all sorts of broken, the wheel bearings are shot (although there is no play in the wheels that I can tell), or the CV axles are messed up somehow. I want to throw tools at the wall at this point. Thanks for all the help.

[Blitzkrieg Bob]

How's the subframe?

Did you check to see if it has torn out on the body? (common problem for some e46s).

Bad rear end makes more noise then vibration, so I'd go for the wheel bearings

[DanDombrowski]

Yeah, I know about the subframe problems. Theyre not typically known to cause vibrations, and I've inspected for tears several times. There are no tears in the subframe that I see. Thanks for the response. I'm thinking it has to be either wheel bearings or a bad diff.

[Blitzkrieg Bob]

Yeah, I know about the subframe problems. Theyre not typically known to cause vibrations, and I've inspected for tears several times. There are no tears in the subframe that I see. Thanks for the response. I'm thinking it has to be either wheel bearings or a bad diff.

Change the fluid in the diff and look for metal flakes

[winfred]

i can't think of anything that i've seen on a e36/46 that would vibrate in the assend, the axles can get a little clunky when running on stands as they are at a bit of a odd angle so don't let that fool you, the wheel bearings suck in e36/46s but generally make no more then noise or a buzz, e46 diff mounts seem to suck but so far i've not seen more then a nasty clunk when going from forward to reverse or on/off the power, brakes are not really going to effect anything unless you are using them, have you tried rotating the tires from front to rear? that if it is a issue will change the problem

[DanDombrowski]

Bob,

Yes, I was thinking this as well. Didn't have time to get to it today, but this is next on my list. If the differential is the one making the noises I'm hearing, then there would be LOTS of metal. I wish I could have taken an audio clip or something. I think this test will tell me a lot.

Thanks.

[DanDombrowski]

Wow, thank you so much. This is solid information. So when the rear wheels sag, this throws the CVs at an odd angle and they vibrate more? I never thought of that. Is this a consistent thing, or "some do, some dont" ?

I suppose to check this I could jack up the rear trailing arm and put another jack stand underneath it. This is very meaningful, although I would still be confused as to what is causing my vibration.

I've posted a lot of information in other threads on the other boards about work I've done/need to do that I didn't include here. My rear diff bushing is indeed cracked, and I do need to get that fixed, as I am getting a clunk, but youre right, I wouldnt expect that to cause any vibration.

As for the wheel bearings, I have another symptom. Between 20 and 40 mph, I get a woomp-woomp-woomp noise from the rear. It doesnt vibrate, but it makes the noise. I've tried leaning the car left and right, but haven't noticed any difference in the noise depending on which direction I'm turning, so I had a tough time thinking it was the wheel bearings. The grinding noise in the rear though might also be a part of it.

I can't rotate the tires, because the rears are wider than the fronts. Best I could do is mount the fronts on the rears when spinning the car stationary on a lift.

I have tried fitting the spare (not voluntary, had a flat) and that didn't change the vibration much at all.

So you think the fact that I was getting a big vibration with the rear end lifted is false because of the axle hang?

[DanDombrowski]

This is interesting. I have 2 costco locations close to me. One is on the way to work, one is close to home. The one that is close to home has 2 Coats machines, one the "2 position" one, and one older style you see in most shops that has the older display (not sure if thats a good description or not).

The costco by work is brand new (less than 3 months old) and has all new machines. I would THINK that they've been calibrated not too long ago, but they may very well be off. The Coats machines with the 2 postion balancers are the XBR1800 IIRC.

The reason I never thought it was a wheel balance issue is 1- I get the woomp woomp noise at 20-40, and 2- I swapped around tires all over the place and the vibration didnt change much if at all. Also, I had a bit of vibration before I even got these tires, which I bought because I found the old ones were cupped, which I attributed the vibration to, but was wrong.

I will take it by the costco next to me and have them give it another try. Thanks tiger!

[Sixdown]

From my experiences, the woomp woomp noise came from the tires. It may be the new one you had put on the rear. In my cases it has been faulty tread or uneven wear on the front or rear tires. It can be wheel bearings too. Anything uneven can cause the noise.