Driveline hum/noise - diagnosing? RESOLVED
 

Guys, what's a good procedure to diagnose driveline humming?

Accelerating up to 50, it starts to make a bit of noise. It's a muted humming that changes with acceleration and deceleration, becomes unoticeable below 40 or so.

Subjectively, the car does not "roll" on the road as smoothly as I would like.

No driveline vibration, it's more of noise.

Sound does not seem to vary when doing side to side transitions so it doesnt seem to be wheel bearings.

Any other checks to do to rule those out?

How about the diffs/propeller shafts, what's the best way to see if those are the problem?

X5 3.0 on staggered 19" sport package wheels and tires, tires are OE Bridgestone Turanzas.

RESOLVED: Rear wheel bearings

Have u notice this noise after changing the tyres?
I had the same noise with a set of Bridgestone tyres. After replacing them, the noise go's away!

When the tires were new there was no noise so I am not sure if it's the tires. Still very thick tires, definitely more than half tread life left on the fronts, maybe 70% rear.

I am saying that, on my case, a new set of Bridgestone tyres was the problem. The tyres been in warranty, I replace them after a week with Goodyear and the noise was solved!

sounds like wheel bearings ,I had the same thing.

If it's above 40 mph, and unnoticeable below, probably wheel bearings. Tell tale sign is taking turns above 40, it will quiet down depending on what side the bad bearing is, and which way you are turning.

I would replace in pairs if it is wheel bearings, as good practice.

Ah, gotcha!


Ugh...saw that wheel bearings are not the easiest to do on these.

Yup, if these are it, will change in pairs definitely.

EX5, did you change front, rear, or all wheel bearings?

RB, I took a long sweeper at speed and I did not notice a change though. Will have to make a test run to be sure.

Any other ways to confirm its the bearings?

Update:

On the road, the "driving on a metal bridge" sound starts at about 40-50mph, then gets speed dependent.

Very noticeable at decel at around 50mph or so, then progressively gets less noticeable. Below 40 it's pretty much gone.

Seems to be from rear, while driving I tilted my head back between the front seats and the sound gets a bit more distinct.

Tried swerving left to right and taking sweeping turns at speed to unload bearings, no change in sound.

Update 2:

Put the car on stands and spun and shook all the wheels.

Fronts were fine, found a few issues at the rear.

There was movement when shaking the rear driver side tire and we thought we found our damaged bearing...turned out to be a failed upper wishbone ball joint though. Both l/r upper locating link ball joint boots were torn as well. So l/r upper wishbones and upper locating links are being replaced. These would not be causing the "running on a metal bridge" sound though.

Spinning the rear wheels there was a bit of clicking that seemed to be coming from the diff. Nothing obviously wrong with the bearings. Decided to replace them anyway as a best guess first step.

Bearing removal was pretty unremarkable considering the horror stories, unbolted from the rear of hub and pulled right out.

Spun the removed bearings by hand and not obviously worn at first, but putting a bit of pressure on it while spinning I could feel a slightly rough portion of rotation on on the passenger side bearing. It was nit picking though, they both felt serviceable to me.

Pressed the old flanges out to be transferred to the new wheel bearing assemblies. The bearing covers of the old bearing fell off during the process and got to look at the bearing's guts. Balls looked fine and there was still grease inside.

I got SWAG brand bearing assemblies. They use Koyo Japan-made bearings. For reference, the original bearings were Koyo's as well but made in the USA.

Rear discs were off so adjusted the parking brakes as well, they were getting a bit loose.

TL;DR: nothing obviously wrong with rear bearings but replacing both to start. Busted left rear wishbone ball joint, torn ball joint boots on l/r locating links, so replacing both parts in pairs. Adjusted parking brake.

Final Update:

So replaced upper wishbone, upper locating link, and wheel hub bearings in pairs.

Alignment was performed. I had the alignment checked when I first got it at 25,000 miles and the rear camber was at 1.5deg or so, which progressively got steeper over time to a bit over 2 deg. At my last alignment at 40,000 or so (after front suspension work), the best we could get rear camber to was 2-ish deg.

I was glad to see we could now get rear camber back to 1.5deg. Toe front and rear was set to around .05 or so.

Went out for a test drive and I'm glad to hear (or not hear) the "running on a steel bridge" sound is gone!

Looks like it was the rear wheel bearings as many have shared.

Glad to hear it was resolved! For me I only had to do the front bearings for now which were a bear of a job. Rear bearings definitely are easier as long as you have the right E14 socket for those retaining bolts!

Thanks RB!

Yeah, I read your front bearing job write up and it's making me dread mine! Visual inspection shows my front control arm bushings are starting to deteriorate, so will be getting ready to replace the arm assy with ball joints, torsion strut arm ball joints, and front wheel bearings (the only front end parts still not replaced).

Bumping an old thread, I am starting to hear a humming noise that sounds like it's coming from the front. But in my case its 0-40mph speed dependent. Cruising on the highway, I do not hear it at all. Accelerating to 40 its an increased hum, and decelerating from 40 its a decreased hum.

I'll try and measure the tire trend depth first and report back.

My initial thoughts were:
Tires
Something rubbing
Slight wheel bend
Alignment issue.

I have an issue like that with my 4.4. If you're under 20 and listen carefully you can hear this hum. Depress the gas pedal hum goes away. Press it hum continues. After 20 no sound. This is the second x5 that has this issue, still don't have a clue.


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Fronts have about 4/32 left surprising because they are stamped 2015 while the rears look to have way more meat and they are stamped 2010.

Similar noise here. If you slow down gradually I can actually hear something like grinding. Will be changing all four wheel bearings in two weeks. I'll report back on results because so far I know one front and one rear have play in them.

No grinding noise here. It's just faint humming noise that wasn't there a few weeks ago. Last time i heard a similar noise was on my E39 M5 and it turned out to the those rubber grommets that hold the oil filter housing and power steering housing to the chassis of the car. They were deteriorated and the housings were rubbing up against the vehicle causing this harmonic noise. I'll check those out because it could very well be the same thing!

Same problem here - thrumming is definitely louder over the last few months. I thought I had it narrowed down to a front wheel bearing (there's a tiny amount of play when I jack up the wheel and do the 9-3 test) but when driving, it sounds more like something at the rear, not the front.

Just plain :dunno:

Will probably wait until something falls off... ;)

Update: my noise was a wheel bearing. Just weird I've had two types of wheel bearing noises. M5 was a clicking noise, X5 was horrid humming/vibration noise.

Congrats on the resolution solution and thanks for the update!

It was the right rear - finally got loud enough to be sure. Bearing race was badly pitted.

I cannot believe the fronts bearings are harder to change than the rears. At the rear there is very little clearance to work on anything, even once the driveshaft is removed (which is a mission in itself!). At least on the front the access is better, even there is all the bearing driving to be done.

I guess I might find out one day - I hope it's not any day soon. :bustingup