Help. Sounds like .....?

[Sean Hamilton]

I only noticed a new noise in the last couple of days.
It's been a while since I've driven with the roof on.

A noise that sounds like a deep (locomotive) rumble emanating from the rear.
Most noticeable 50mph plus and still there at 85mph only louder.

Engine?
Chuck it in neutral, clutch out, engine idling back down to normal.
Vehicle speed coasting and noise is definitely there.
Coast down to 45mph and noise is gone. Well, not anything that I can hear as abnormal.
So it seems not engine speed related.

Tyres?
They're worn and on their last legs, so :-
Try different road surfaces at the above varying speeds.
Noise seems consistent irrespective of speed and type of road surfaces - from glassy smooth to rough bitumen.
So I doubt it's tyres related.

Transaxle?
Crikey! Hope not!? $$$ What's in that? Gearbox and CV joints. Anything else.
This seems to me to be rotative related. Most noticeable at higher motion speeds.
Vehicle has 200,000 k's on the clock and I'd reckon still on it's original CV joints.
So, ...... I dunno.

Any clues???

TIA.

[stealthn]

exhaust?

[Sean Hamilton]

Doesn't seem to be exhaust/engine related, Bob.
Noise (rumble) is constant, irrespective of engine (revs) speed.
BUT varies in intensity - noticeable only above 50mph.

[slakjaw]

maybe a bad wheel bearing

Kyle
71 911

[Jupiter]

wheel bearings?

[Tim L]

My guess, it's a rear wheel bearing. Jack up the rear and rotate the rear wheel very slowly, it should be perfectly smooth. If you feel any roughness at all it's the bearing. If it is the bearing it will get louder with time.

Tim

[Sean Hamilton]

Okay, I'll give that a go.
I didn't think about wheel bearings.
In my experience when a wheel bearing is shot, it'll usually emit a high pitched squealing sound.

Still, I should check, so I'll report back.
THANKS.

[Tim L]

In my experience it sounds like a low pitched hum. You can usually tell what side is bad by going around long sweeping turns. The loaded outside wheel will make the hum.

Tim

[n8marx]

I just replaced both of my rear wheel bearings because they were making the exact same sound. Definitely wheel bearings. One of them was bad enough that 1/2 of it locked up causing my hub to spin in the bearing race. Chewed up my hub very badly. Luckily I found a used one for $165US. Moral: replace your wheel bearing/bearings ASAP.

[Sean Hamilton]

Well the wheel bearings are silky smooth. Spun the wheels freely, no roughness - to me at least.
The only sound was the pads against the rotors.

Fairdinkum! - Whilst jacked I noticed that the tyre treads are knackered!
They're Goodyear Eagle F1's with bugger-all tread in the centre but plenty enough on the outside. Usually a sign of over inflation but the pressures are spot on.
Shameful - dangerous!! I'll replace them, pronto.

Maybe the "rumble" speed related noise is the half slicked out tyre tread, after all??

Still, given your similar experiences I'm not discounting that Wheel Bearings is in fact the problem.

[Superman]

Change tires, if they're worn out. Re-evaluate. Don't fix stuff unless you find they are indeed broken. Still, my guess is wheel bearings too. I've made advice about wheel bearings on a number of occasions, but I often forget the word that best described the sound. I remember it now. The word is "growl." Bad wheel bearings growl. The faster you go, the louder they growl. Typically, the growl is accompanied by a rumble as well.