Vibrations/oscillation.

ManiacGT · 03-21-2013, 05:09 AM

From the moment I had this car I've felt a subtle bounce/oscillation from the rear on smooth roads between 25 and 35 mph. It's like you're running over a slightly ribbed road.

Anyhow I put this down to stiff suspension and either a slightly out of shape rear tyre or wheel.

When I had the tyres changed a year ago I really hoped it would go and it didn't this slight bounce at a certain speed was still there.

So I recently changed wheels thinking it must be a wheel. No. It's still there. Took it to the dealer and got a 'that's how this car is' response.

Still not happy. I over inflated the tyres tonight and I could really feel this bounce, reduced the pressures and it got less but is still there.

At this point I'm thinking wheel bearing (but there's no discernible bearing type noise) or final drive / diff / etc but again no noise (though I do think I can hear a very faint rotational thump but it could be my imagination).

So before I spend good money on diagnosis to be told there's nothing wrong, does anyone have any thoughts what this might be?

FYI I have the adaptive suspension. I've also had this car on a Dyno and you could see the rear of the car bouncing up and down around 1cm at 30mph but as you slowed or speeded up the car settled down.

A) it's bugging me and B) I'm worried something might fail...

Thoughts?

nicknaz · 03-21-2013, 11:22 AM

I think you are right on and it is due to short wheelbase, relatively stiff suspension and stiff 19" tires.

My "fix" is to drive the z4 in sport+ and make the mild oscillation an actual deliberate suspension movement.

Might as well own up the the tradeoffs required by owning a car like the z...

rking117 · 03-21-2013, 11:54 AM

i would take it to an indendent indy shop. it will cost you a buck but you will know for sure if there is truely an issue. then if there is you might be able to get the issue warrantied through them too if they are an authorized repair facility. I owuld bet there is something going on with something being out of balance. rotor warped etc. You could alos try to have a facility balance the tires on the vehicle. i have seen where that fixes some issues too. They problem with that is you cannot rotate your tires afterwards as they are balanced to the location they were balanced. mine does not have any bounce to it at any speed. but i am very particular with who balances my tires etc.

HpDellNestle · 03-21-2013, 12:00 PM

My experience with BMW dealer: when they told you "that is how the car is", that is when you know something is not right. Go find someone that can solve the problem. Keep the receipt from dealer stating your complaint, and their "that is how the car is" respond so you can ask BMW to pay up later. Good luck.

ManiacGT · 03-21-2013, 12:01 PM

Its definitely not wheel/tyres as they've been replaced, and, re-balanced. I can drive the car at 40/50/60/70+ and its smooth as glass. Driving around at 30mph I can feel this slight bounce.

nicknaz · 03-21-2013, 12:23 PM

Are you able to test drive a dealer's Z4 with same wheels and suspension? That would be a relatively easy way to sort this out.

I think this is a case where it really might be the way the car is.

Road probably isn't perfectly smooth and at lower speeds the imperfection is transmitted, versus at higher speeds it is damped, just based on the extra force from hitting the same imperfection at a higher speed.

ManiacGT · 03-21-2013, 12:44 PM

It's definitely not a road surface issue either as I've had the car on a Dyno/rolling road and it bounces but not enough to determine why...

SgtGigglebox · 03-21-2013, 12:58 PM

Mine is relatively new, but I haven't felt anything like that. If its "just the way the car is", I would imagine that others would be chiming in with theirs doing the same. What about trying to get them to put their diagnosis in writing? Whatever the next steps are, that would seem to be a useful thing to have handy.

I took my 2006 si in several times, complaining of a ticking sound and they always said nothing was wrong... now I see a full thread on the old Z4 board talking about a faulty cylinder head that BMW has known about.

nicknaz · 03-21-2013, 02:46 PM

Quote:

Originally Posted by ManiacGT

It's definitely not a road surface issue either as I've had the car on a Dyno/rolling road and it bounces but not enough to determine why...

The only remaining explanation / excuse I can think of is the way the car was strapped to the dyno (not by the control arms I hope...)

Is your car out of warranty?

Maybe it is time to pack it in and sell the thing while it still looks good and doesn't have obvious issues.. Seems like you've hard more than your fair share of minor annoyances.

ManiacGT · 03-21-2013, 03:40 PM

Quote:

Originally Posted by nicknaz

The only remaining explanation / excuse I can think of is the way the car was strapped to the dyno (not by the control arms I hope...)

Is your car out of warranty?

Maybe it is time to pack it in and sell the thing while it still looks good and doesn't have obvious issues.. Seems like you've hard more than your fair share of minor annoyances.

It's under insured warranty..

I refuse to give in on this car, I've been thru too much and it's cost me a lot.. Not having someone else benefit from all that.

nicknaz · 03-21-2013, 03:53 PM

Quote:

Originally Posted by ManiacGT

It's under insured warranty..

I refuse to give in on this car, I've been thru too much and it's cost me a lot.. Not having someone else benefit from all that.

I recall hearing something about not letting sunk costs influence future decision making ....

Go get a Porsche instead man

jparnes1 · 03-21-2013, 03:55 PM

Quote:

Originally Posted by nicknaz

I recall hearing something about not letting sunk costs influence future decision making ....

Go get a Porsche instead man

That's not totally bad advice. He may have a lemon and sometimes you have to cut your losses.

R1robot · 03-21-2013, 04:37 PM

First, I would follow nicknaz's idea and test drive a 35i with the same setup. I imagine these small bumps at certain speeds has to be engine related, everything else should have been sorted out regardless of speed. I assume the sounds and vibrations are consistent during these speeds.

If you have the time and perhaps a buddy or someone who has a shop to lift your car and replicate the scenario, go under the car and try to locate the sound and if need be with a stethoscope since you know how fast the vibration sounds. If the car can't replicate that sound when its wheels are off the ground, try finding a flat spot on the differential and basically rule out anything else you may think it can be. Be thorough for peace of mind and good luck.

BuckarooVT90 · 03-21-2013, 06:06 PM

Shocks? Have they been checked?

ManiacGT · 03-22-2013, 04:30 AM

There is actually no sound to speak of. I just think from time to time I can hear a very soft rhythmic thump. But its that quiet its hard to tell over road noise.

The bounce effect is between 25-35 mph on very smooth road. When sat in the car you can just feel yourself bouncing in the seat ever so slightly, in a rhythmic way. When it happens, if you hold out your hand, you can see a 2/3mm up/down motion at your fingertip. But as roads here aren't that smooth for long, it happens for say 10 seconds and then its gone. Its always on smooth road though and feels very much like the natural rebound of the car after you've hit a small bump in the road.

BuckarooVT90 · 03-22-2013, 05:41 PM

springs bounce... shocks or dampers are supposed to limit the bouncing or oscillations. I would have your shocks inspected. My doesn't do that its rock steady from 0-120mph... maybe a loose shock mount?

SgtGigglebox · 03-22-2013, 05:49 PM

I think that the Funky Bunch said it best, "Come on Come on, Feel the Vibration"

ManiacGT · 03-23-2013, 11:41 AM

Its so slight.. I know its there but few others can feel it. Anyhow its going in on the 6th to be checked over... I'll let you know what they find... If I'm not sick of it by then and have sold it!

ManiacGT · 04-06-2013, 05:41 AM

Back from the indy.. Feel reassured its nothing sinister or requiring immediate action.

No issues in drive or suspension. However on the ramp at 30mph a 2mm oscillation could be seen in the NS rear. Looks like damaged bearing or hub possibly due to impact (pot hole) damage or a manufacturing defect.

Car seems good otherwise.. Which has improved my mood a bit.

03-21-2013, 05:09 AM	#1
ManiacGT Major 85 Rep 1,448 Posts Drives: Z4 sDrive 35i Join Date: Jan 2011 Location: Manchester, UK iTrader: (0)	Vibrations/oscillation. From the moment I had this car I've felt a subtle bounce/oscillation from the rear on smooth roads between 25 and 35 mph. It's like you're running over a slightly ribbed road. Anyhow I put this down to stiff suspension and either a slightly out of shape rear tyre or wheel. When I had the tyres changed a year ago I really hoped it would go and it didn't this slight bounce at a certain speed was still there. So I recently changed wheels thinking it must be a wheel. No. It's still there. Took it to the dealer and got a 'that's how this car is' response. Still not happy. I over inflated the tyres tonight and I could really feel this bounce, reduced the pressures and it got less but is still there. At this point I'm thinking wheel bearing (but there's no discernible bearing type noise) or final drive / diff / etc but again no noise (though I do think I can hear a very faint rotational thump but it could be my imagination). So before I spend good money on diagnosis to be told there's nothing wrong, does anyone have any thoughts what this might be? FYI I have the adaptive suspension. I've also had this car on a Dyno and you could see the rear of the car bouncing up and down around 1cm at 30mph but as you slowed or speeded up the car settled down. A) it's bugging me and B) I'm worried something might fail... Thoughts?
	Appreciate 0 Tweet Quote

03-21-2013, 11:22 AM	#2
nicknaz Lieutenant General 3187 Rep 10,509 Posts Drives: C6Z Join Date: May 2008 Location: NorCal iTrader: (0)	I think you are right on and it is due to short wheelbase, relatively stiff suspension and stiff 19" tires. My "fix" is to drive the z4 in sport+ and make the mild oscillation an actual deliberate suspension movement. Might as well own up the the tradeoffs required by owning a car like the z...
	Appreciate 0 Quote

03-21-2013, 11:54 AM	#3
rking117 Lieutenant Colonel 118 Rep 1,668 Posts Drives: Z4 3.0i & 320i Join Date: Aug 2012 Location: USA iTrader: (0)	i would take it to an indendent indy shop. it will cost you a buck but you will know for sure if there is truely an issue. then if there is you might be able to get the issue warrantied through them too if they are an authorized repair facility. I owuld bet there is something going on with something being out of balance. rotor warped etc. You could alos try to have a facility balance the tires on the vehicle. i have seen where that fixes some issues too. They problem with that is you cannot rotate your tires afterwards as they are balanced to the location they were balanced. mine does not have any bounce to it at any speed. but i am very particular with who balances my tires etc. __________________ Enjoying an E89 Z4, F30 320i and Fiat Abarth // E85 Z4 (sold), E82 128i (sold), Fiat Pop 500 (sold)
	Appreciate 0 Quote

03-21-2013, 12:00 PM	#4
HpDellNestle Private First Class 1 Rep 141 Posts Drives: Z4 Join Date: Jan 2011 Location: US iTrader: (0)	My experience with BMW dealer: when they told you "that is how the car is", that is when you know something is not right. Go find someone that can solve the problem. Keep the receipt from dealer stating your complaint, and their "that is how the car is" respond so you can ask BMW to pay up later. Good luck.
	Appreciate 0 Quote

03-21-2013, 12:01 PM	#5
ManiacGT Major 85 Rep 1,448 Posts Drives: Z4 sDrive 35i Join Date: Jan 2011 Location: Manchester, UK iTrader: (0)	Its definitely not wheel/tyres as they've been replaced, and, re-balanced. I can drive the car at 40/50/60/70+ and its smooth as glass. Driving around at 30mph I can feel this slight bounce.
	Appreciate 0 Quote

03-21-2013, 12:23 PM	#6
nicknaz Lieutenant General 3187 Rep 10,509 Posts Drives: C6Z Join Date: May 2008 Location: NorCal iTrader: (0)	Are you able to test drive a dealer's Z4 with same wheels and suspension? That would be a relatively easy way to sort this out. I think this is a case where it really might be the way the car is. Road probably isn't perfectly smooth and at lower speeds the imperfection is transmitted, versus at higher speeds it is damped, just based on the extra force from hitting the same imperfection at a higher speed.
	Appreciate 0 Quote

03-21-2013, 12:44 PM	#7
ManiacGT Major 85 Rep 1,448 Posts Drives: Z4 sDrive 35i Join Date: Jan 2011 Location: Manchester, UK iTrader: (0)	It's definitely not a road surface issue either as I've had the car on a Dyno/rolling road and it bounces but not enough to determine why...
	Appreciate 0 Quote

03-21-2013, 12:58 PM	#8
SgtGigglebox Lieutenant 100 Rep 494 Posts Drives: '13 Atacama 35is Join Date: Sep 2012 Location: Washington D.C. Area iTrader: (0)	Mine is relatively new, but I haven't felt anything like that. If its "just the way the car is", I would imagine that others would be chiming in with theirs doing the same. What about trying to get them to put their diagnosis in writing? Whatever the next steps are, that would seem to be a useful thing to have handy. I took my 2006 si in several times, complaining of a ticking sound and they always said nothing was wrong... now I see a full thread on the old Z4 board talking about a faulty cylinder head that BMW has known about.
	Appreciate 0 Quote

03-21-2013, 04:37 PM	#13
R1robot Private First Class 5 Rep 111 Posts Drives: 2003 Z4 2.5i Join Date: Jan 2013 Location: Texas iTrader: (0)	First, I would follow nicknaz's idea and test drive a 35i with the same setup. I imagine these small bumps at certain speeds has to be engine related, everything else should have been sorted out regardless of speed. I assume the sounds and vibrations are consistent during these speeds. If you have the time and perhaps a buddy or someone who has a shop to lift your car and replicate the scenario, go under the car and try to locate the sound and if need be with a stethoscope since you know how fast the vibration sounds. If the car can't replicate that sound when its wheels are off the ground, try finding a flat spot on the differential and basically rule out anything else you may think it can be. Be thorough for peace of mind and good luck. Last edited by R1robot; 03-21-2013 at 07:10 PM..
	Appreciate 0 Quote

03-21-2013, 06:06 PM	#14
BuckarooVT90 Private First Class 10 Rep 189 Posts Drives: '13 Z4 sDrive35i DCT Join Date: Sep 2010 Location: Virginia iTrader: (1) Garage List 2020 Z4 M40i [8.00]	Shocks? Have they been checked?
	Appreciate 0 Quote

03-22-2013, 04:30 AM	#15
ManiacGT Major 85 Rep 1,448 Posts Drives: Z4 sDrive 35i Join Date: Jan 2011 Location: Manchester, UK iTrader: (0)	There is actually no sound to speak of. I just think from time to time I can hear a very soft rhythmic thump. But its that quiet its hard to tell over road noise. The bounce effect is between 25-35 mph on very smooth road. When sat in the car you can just feel yourself bouncing in the seat ever so slightly, in a rhythmic way. When it happens, if you hold out your hand, you can see a 2/3mm up/down motion at your fingertip. But as roads here aren't that smooth for long, it happens for say 10 seconds and then its gone. Its always on smooth road though and feels very much like the natural rebound of the car after you've hit a small bump in the road.
	Appreciate 0 Quote

03-22-2013, 05:41 PM	#16
BuckarooVT90 Private First Class 10 Rep 189 Posts Drives: '13 Z4 sDrive35i DCT Join Date: Sep 2010 Location: Virginia iTrader: (1) Garage List 2020 Z4 M40i [8.00]	springs bounce... shocks or dampers are supposed to limit the bouncing or oscillations. I would have your shocks inspected. My doesn't do that its rock steady from 0-120mph... maybe a loose shock mount?
	Appreciate 0 Quote

03-22-2013, 05:49 PM	#17
SgtGigglebox Lieutenant 100 Rep 494 Posts Drives: '13 Atacama 35is Join Date: Sep 2012 Location: Washington D.C. Area iTrader: (0)	I think that the Funky Bunch said it best, "Come on Come on, Feel the Vibration"
	Appreciate 0 Quote

03-23-2013, 11:41 AM	#18
ManiacGT Major 85 Rep 1,448 Posts Drives: Z4 sDrive 35i Join Date: Jan 2011 Location: Manchester, UK iTrader: (0)	Its so slight.. I know its there but few others can feel it. Anyhow its going in on the 6th to be checked over... I'll let you know what they find... If I'm not sick of it by then and have sold it!
	Appreciate 0 Quote

04-06-2013, 05:41 AM	#19
ManiacGT Major 85 Rep 1,448 Posts Drives: Z4 sDrive 35i Join Date: Jan 2011 Location: Manchester, UK iTrader: (0)	Back from the indy.. Feel reassured its nothing sinister or requiring immediate action. No issues in drive or suspension. However on the ramp at 30mph a 2mm oscillation could be seen in the NS rear. Looks like damaged bearing or hub possibly due to impact (pot hole) damage or a manufacturing defect. Car seems good otherwise.. Which has improved my mood a bit.
	Appreciate 0 Quote