BMW e39 528 rear end noise

Well, it's been almost a full 2 months without something going wrong!
I noticed a few days back that at 70mph, particularly on smooth roads, there seems to be an odd noise coming from what i think sounds like the
rear of the car (but you can't really tell....as ever).
Sounds almost like tyre noise...
It's a sort of low pitched humming.
Doesn't do it at any other speed other than 70mph - coud be that over 70 the wind noise dulls it out.
It's not really loud, I mean, even the stereo on very quietly means you can't hear it. There's no vibration through the car at all either.
I've got new tyres on, and the car's been lowered and aligned properly.
I don't *think* it was doing it before I lowered it, but then i don't do motorway driving that often, and if I do, it's normally the same 85mph as everyone else.
It doesn't make the noise any quieter or any worse when you turn.
I've jacked up the car and there's no play at all in the rear wheels.
Any suggestions chaps?
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----- Original Message -----
Newsgroups: alt.autos.bmw Sent: Wednesday, February 22, 2006 8:30 AM Subject: BMW e39 528 rear end noise

Is it possible it could be early signs of a wheel bearing despite the lack of play? I have the same symptoms on my car and I was pretty convinced it was the wheel bearing, although it passed the MOT and I made the tester aware of it. My car only hums at high speed too 70mph 80mph etc, it might be that the noise only becomes sufficient that you hear it at that speed, but it's really there all the time but too soft to detect, but even at those speeds it's certainly not loud, stereo drowns it easily. I found it was more noticeable when I go over really good tarmac, and the road is very quiet, even at lower speeds I could just about hear it straining.
I'd be interested if there are any other suggestions to this one myself..
******DAM REPLIED TO SENDER SORRY **********
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Are the tyres the same make and type as you had before? Some can make a humming noise at certain speeds due to tread design. Are they an OEM to BMW?
Could be a wheel bearing or the final drive itself. Final drive noises often change slightly if the car is accelerating or decelerating. But I think the driveshaft bearings can also sometimes fail.
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Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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Hi Dave
Yes, the tyres are all the same - got 235's on the front and 255's on the rear.
They are Kumho KU31's and have been on for a few months now.
The car's also had a new gearbox fitted last year.
The sound doesn't change at all with acceleration or decelleeration - only that if you you slow down (or speed up) the sound goes away (or at highers speeds you don't hear it for the wind noise?).
By driveshaft bearings, I presume you mean the prop centre bearing?
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Russ (www.e36coupe.com) wrote:

I would say the most likely thing is tire noise, especially since you put wide(r) tires on the rear and lowered the suspension (which screws up the camber).
Have you had the alignment checked yet (especially rear)?
--
-Fred W

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yeah, it's had a 4 wheel alignment, and the only bit that was slightly out was the front drivers wheel - the castor was slightly out of limits. This may have settled down again now the springs have been in for a while since.
The rear camber, etc were within tolerance.
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....what settings should I have told them to use for the Hunter 4 wheel alignment machine, by the way? I'd said it was on Mtec suspension setup - which I understand is a similar ride height to what I have now.
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No - the differential driveshaft bearings - ie those at either side of the differential. Prop bearings tend to cause vibration first as it runs at a higher speed.
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*Caution: I drive like you do.

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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