Resonance/noise

[Riggie]

An interesting one this...... I have just done a round trip over 4 days to Germany and back, clocking up around 1400 miles. I noticed on the way over at 60mph, a sort of thrumming noise which isn't constant it sort of 'beats' or pulses. It's very difficult to describe, but drop below or above 60 and it goes. It almost sounds like some sort of resonating.

I tried varying the tyre pressures which helped to reduce it. I've been searching the web but no joy, except a post about a recall on a 3 series for some sort of damping material to be fitted to the driveshaft to stop the sort of thing which I've described. Anyone come across anything like this?

My car is a 35d with 58k miles, running well otherwise.

Thanks.

[Horizon]

Is it a 2010 MY, if so have the front driveshafts been inspected RE 2013 recall/ service inspection ?

[Riggie]

Its December 2009, so probably doesn't qualify. What was the reason for that recall?

[Riggie]

Just Googled the front driveshaft recall thing. Interesting, I'll have to get it up on a ramp and check them.

That driveshaft, according to RealOEM was fitted from 03/2010, so doesn't apply to mine and the part number for mine is different, so maybe this was a particular manufacturing problem for that shaft?

[Horizon]

[quote="Riggie"]
Its December 2009, so probably doesn't qualify. What was the reason for that recall?
[/quote] backlash in universal joint on front driveshaft, symptoms of vibration around 60 MPH, some drive shafts failed totally coming apart.
Suspect driveshafts were fitted between March and Dec 2010 I think . So your build date ids prior to that.

[Riggie]

[quote="Horizon"]
[quote="Riggie"]
Its December 2009, so probably doesn't qualify. What was the reason for that recall?
[/quote] backlash in universal joint on front driveshaft, symptoms of vibration around 60 MPH, some drive shafts failed totally coming apart.
Suspect driveshafts were fitted between March and Dec 2010 I think . So your build date ids prior to that.

[X5Sport]

Underbody shield loose?  Tyre pressure change might affect ride height and therefore wind path/standing wave pattern under the car.

[Riggie]

[quote="X5Sport"]
Underbody shield loose?  Tyre pressure change might affect ride height and therefore wind path/standing wave pattern under the car.
[/quote]

I can have a look at that as well when it's up on the ramp. Maybe the answer is not to drive at 60 !

[X5Sport]

Another check is what tyres are you using?  Could be tyre noise resonating with something, or possibly one of the diffs droning due to a tyre issue if non-'*' tyres in use, or even just a single bad tyre perhaps?  Changing pressures having an effect could point to one corner being the source.

I am of course assuming the rhythmic drone doesn't include 'you're driving too fast/slow/close <insert alternative word here> noises'  O:-)

Chances are it's something really simple..

[Riggie]

[quote="X5Sport"]
Another check is what tyres are you using?  Could be tyre noise resonating with something, or possibly one of the diffs droning due to a tyre issue if non-'*' tyres in use, or even just a single bad tyre perhaps?  Changing pressures having an effect could point to one corner being the source.

I am of course assuming the rhythmic drone doesn't include 'you're driving too fast/slow/close <insert alternative word here> noises'  O:-)

Chances are it's something really simple..
[/quote]

The tyres are non star, non runflats, as I don't like RFT's.  They are Kumho X3s which were fitted as a set around 10k miles ago. All have 5-6mm tread left. I have read many posts about non star tyres and those who have had no problems with them and others who have.  If it was a diff drone, would it not be constant?  Buying a new set of star rated would be an expensive way of proving or disproving the theory......The only non RFT which are star marked appear to be Michelin Diamaris. Any experiences of these?

[X5Sport]

The non'*' tyre issue does seem to be inconsistent I agree hence suggesting it might also only be a single tyre for some reason.

The 'diff drone' may only occur at certain speeds as it will vary according to speed, and may only 'couple' to give a resonant note at a certain frequency/speed.  Is there any difference between wet or dry surfaces?  Given wet roads would allow more wheel slip, that might eliminate that issue and push it back to something simpler.

It might even be an exhaust note?  Finding where it's loudest would help.  Chances are it's going to be a trim/cooling/airflow flap 'sirening' at a smal range of wind speeds.

Diamaris were standard fit to many E53s. 

[Riggie]

[quote="X5Sport"]
The non'*' tyre issue does seem to be inconsistent I agree hence suggesting it might also only be a single tyre for some reason.

The 'diff drone' may only occur at certain speeds as it will vary according to speed, and may only 'couple' to give a resonant note at a certain frequency/speed.  Is there any difference between wet or dry surfaces?  Given wet roads would allow more wheel slip, that might eliminate that issue and push it back to something simpler.

It might even be an exhaust note?  Finding where it's loudest would help.  Chances are it's going to be a trim/cooling/airflow flap 'sirening' at a smal range of wind speeds.

Diamaris were standard fit to many E53s.
[/quote]

Thanks for this, certainly food for thought. I will check today if there is a difference between wet or dry surfaces. I'm planning on keeping the car for a while, so if it is the tyres then I will replace them with star rated. It's odd that it has only started after they have done 10k and they have worn evenly.

[celica]

Where is the resonance and beats pulse noise coming from, does it sound like interior, exterior, left or right?

[Riggie]

Difficult to tell, central I wold say.

[celica]

I have a pulsating resonance noise on certain temps on the climate control unit

It sounds like it's coming from behind the dash but could be the auto fan

Try switching off the climate control unit to check not same issue as me