Hum/rumble/resonance at 45 MPH

**CgdR** · 02-14-2013, 01:01 PM

Hello. As the title says, I have an unpleasant low-frequency cabin resonance, only audible at 45 MPH. The car is a hand-me-down, and I suspect that the problem has been there for years. I can't tell where the sound is coming from, but it stays the same when coasting in neutral or when applying the brakes lightly. Therefore, I assume that what is driving the vibration is downstream of the gearbox. What could it be?

The guibo looks to be in good condition and all 4 wheels spin smoothly. I tried to inspect the CSBearing, but it is hidden behind a stiffening beam, the exhaust, and a shield. Do I need to disassemble all of that to inspect the CSB, or can I bend the shield out of the way?

I would appreciate any other thoughts that you may have.

1997 528i Auto 120,000 miles

**edjack** · 02-14-2013, 01:21 PM

How much tread is left on the tires? As they wear out, some tires become noisy. Try a front-to-back rotation to see if the noise changes.

Can you grasp the driveshaft anyplace along its length? Maybe you can shake it up and down to check for play.

**CgdR** · 02-15-2013, 08:52 AM

Tires are good, but I will try a rotation.

Does anybody know if it is necessary do remove exhaust & shields to inspect the CSB? I can only reach the portion of the driveshaft next to the guibo or near the differential. Both places are too far to feel if there is any play in the CSB.

**Justin517** · 02-15-2013, 10:21 AM

does it get louder when turning left or right?

hows your tire pressures and tread?

how is your alignment?

**528canyonrot** · 02-15-2013, 10:28 AM

I had to remove the exhaust and the shields to check/RR my csb. It was torn about 80% around

**CgdR** · 03-13-2013, 07:49 PM

I am making progress: by running the car in gear with one wheel off the ground (ASC off), I have found that the noise is coming from the rear right wheel. The vibration is the same whether the wheel is on or off the car. I can only feel/hear the noise when the wheel is turning relatively fast (abut 40+ MPH). The only anomaly I see is that the axle may be wobbling a bit on the wheel end. However, when it is stopped, everything feels tight an smooth. What in the rear wheel/CV joint can cause this vibration that resonates throughout the cabin?

**joekeefer** · 03-14-2013, 01:45 PM

When I'm cruising at 45 in D. I get an awful droning noise. But I'm sure it's the exhaust on my car.

**larrym3711** · 03-14-2013, 02:21 PM

Joe,

Why are you so sure your "droning noise" is exhaust? Did you "custom" the exhaust? If "no" then you have a problem somewhere else as my E39 is very quiet at 45 mph. Usually the "noise" is from the tires as they wear. Quiet at first, but then becoming noisy as they wear. Is this noise new?

larrym3711
2001 540iA Sport

**Nick Bain** · 03-14-2013, 02:41 PM

I am getting the same ghost hum cabin resonance but its happening at random speeds from 45-80 can't drive my car past 80 as it drives poorly even though I had it alighned and made them double check it. I am suspecting a front left steering linkage as the car makes noise in that area over bumps and I can hear something loose in there when I crank the unlocked steering wheel when the car is off. So I just bought the inner and outer tie rods for that side. As the whole front has all new control arms thrust arms and shocks. I think there may still be a problem in the rear as it sounds like a drivetrain noise but with these cars having a lot of aluminum parts and tight cabins its hard to diagnose where the sound is coming from.

**joekeefer** · 03-14-2013, 08:11 PM

Originally Posted by larrym3711

Joe,

Why are you so sure your "droning noise" is exhaust? Did you "custom" the exhaust? If "no" then you have a problem somewhere else as my E39 is very quiet at 45 mph. Usually the "noise" is from the tires as they wear. Quiet at first, but then becoming noisy as they wear. Is this noise new?

larrym3711
2001 540iA Sport

Because as soon as my rpm's raised or drop the pitch, tone and noise level change. I was cruising on a hwy with slight incline, on throttle just enough and at 40-50 while in throttle the noise was there. It's the stock exhaust. My car is an 03 530i with 98k miles. I assume original parts are still there and probably getting close to time for replacement.

**Coal** · 03-18-2018, 10:32 AM

My 2011 328xi had a resonant vibrating hum from driver side dash at about 25 mph light throttle pressure. Was fixed by replacing fuel vent valve under warranty. This was 2 years ago now its back.

**rdl** · 03-18-2018, 02:50 PM

Originally Posted by CgdR

I am making progress: by running the car in gear with one wheel off the ground (ASC off), I have found that the noise is coming from the rear right wheel. The vibration is the same whether the wheel is on or off the car. I can only feel/hear the noise when the wheel is turning relatively fast (abut 40+ MPH). The only anomaly I see is that the axle may be wobbling a bit on the wheel end. However, when it is stopped, everything feels tight an smooth. What in the rear wheel/CV joint can cause this vibration that resonates throughout the cabin?

From the symptoms, one of the half shaft's CV joints has bit the dust. Feeling tight while stationary isn't proof of being in good condition.
I'd try having a helper turn the wheel while feeling & listening for any roughness in the CV joints. It's similar to a wheel bearing or suspension ball joint - even the tiniest hint of a minuscule movement or click means it's failed. CV joints are precision assemblies, on the same level as ball bearings; any deterioration in the balls or races in the joint will cause a jolt as the joint is rotated. That little jolt becomes a noise as the speed/frequency increases. I wouldn't be surprised if you were to find one of the boots with a tear, which will have allowed road dirt into the joint and ground away at it until the damage starts making noise.