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      01-22-2013, 04:12 PM   #1
Daveyc
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Adaptive suspension: knocking sounds over minor bumps

Since I got the car end of December, I noticed a mild knocking sound when going over minor bumps on the road. It sounds like a loose exhaust mounting, or even like worn ball-joints on an old car, albeit quieter than that.

Took my car in to the dealer today for them to look over, expecting it to be a case of a missing exhaust mouth or two. The drew a blank on that and want the car back in two weeks to look at suspension.

Not worried, as I'm sure they'll fix it but has anyone else heard of this or experienced it?

Last edited by Daveyc; 01-23-2013 at 01:44 PM. Reason: Typo
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      01-23-2013, 01:45 PM   #2
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Any thoughts folks?
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      01-23-2013, 02:35 PM   #3
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Not here personally, sorry to not be of more help
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      01-23-2013, 02:36 PM   #4
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Quote:
Originally Posted by Daveyc View Post
Any thoughts folks?
I wonder what it is? Maybe Highlandpete will have an idea.
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      01-23-2013, 08:31 PM   #5
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Interesting. I noticed recently that on mine that there was a slight knock on smallish bumps. And only sometimes. I did think it was luggage in boot but tonight thought that it appears too prominent for that (I havnt emptied the boot to check yet, havnt had chance...

You mention adaptive suspension. Does it only do it ok a certain mode?

On another note, how do we know of we have adaptive or not...? Mine seems former in sport compared to comfort but didn't think it had adaptive (or do they all seem firmer?)
I know we can look at VIN checkers but what physical signs are there?
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      01-24-2013, 04:52 AM   #6
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I'd be looking at all the obvious things first, loose gubbins in the boot. Anything moving about under the boot floor? Even the boot lid itself, (although unlikely) could be a source of knocking, something like the wire loom not fitted and tied down sufficiently.

The comment on modes is valid, is it the same in all modes? What if there is someone sitting in the back, does it change? Can they sense where it comes from? Like in the car, under the car.

Many times something like this has caused 'scratching of heads', when it is something obvious, once tracked down, but not necessarily the suspension. Even how one of the rear doors shut, most unlikely, but could be the issue. Exhausts and heat shields are clearly an obvious source, but not always easy to see how from a static test.

If the issue is identified as being in the suspension, it still may need a bit of head scratching to find the source.

As to identifying the 'physical' adaptive suspension, swing the steering to one side and you should easily see the proportional valve sticking out from the strut with wire attached.



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      01-24-2013, 09:52 AM   #7
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I have adaptive suspension and had a similar knocking sound when I first got my F30, and spent some time looking around the boot/exhaust area for something loose as that's where it sounded like it was coming from. I was planning on taking it into the dealer, but it's gradually lessened to the point where I'm now only very occasionally aware of it (after 2000 miles). No idea why that should be, but I shall leave it for now unless it gets worse again.
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      01-24-2013, 03:12 PM   #8
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Quote:
Originally Posted by Daveyc View Post
Since I got the car end of December, I noticed a mild knocking sound when going over minor bumps on the road. It sounds like a loose exhaust mounting, or even like worn ball-joints on an old car, albeit quieter than that.

Took my car in to the dealer today for them to look over, expecting it to be a case of a missing exhaust mouth or two. The drew a blank on that and want the car back in two weeks to look at suspension.

Not worried, as I'm sure they'll fix it but has anyone else heard of this or experienced it?
Yes! I get that noise over speed bumps - appears to be coming from front right wheel area but doesn't seem to have any impact on drive other than this knocking noise - now you have mentioned it I'll likely take it in and have it looked at
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      01-24-2013, 06:41 PM   #9
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Thanks for the replies. I checked for stuff in the boot and underneath the boot liner - nothing.

The sound is pretty telling of what the source could and could't be. Slightly wooden in sound, too heavy and solid to be something in the boot, trim or a door and, most certainly, coming from underneath the car. The weight is about right to be the the exhaust, but the dealer ruled that out firmly (they even checked for marks on the underside of the car).

The sounds comes mostly from rear left, a little less from front left and slightly from front right. It's very clear when rolling over even minor bumps, such as on roads through city, with a few surface repairs. To say it sounds like worn ball joints on an old car would be the most accurate description - bang on in tone and weight.

No sign of it diminishing as I approach 1,600 miles, but it's less prominent in Sport mode, almost as if the tightening of the dampers damps the knocking.

The dealer talked about it potentially being an issue with the top mounts. I've no concerns (yet) about their attitude, as they're taking it seriously. Get the feeling they might have seen it before, as they jumped to suspecting suspension immediately after ruling out exhaust mounts.

I read online somewhere (can't remember where) a comment from a magazine about an Audi with adaptive suspension that had similar knocking sounds and that the dampers were eventually replaced to fix the problem.

Car is due in the dealers for the day week after next. Meantime, it's fantastic to drive and seems to be getting better with miles. The grunt is just grin-inducing and it feels so positive and talkative in Sport. Love it, knocking or not.
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      02-09-2013, 12:46 PM   #10
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Well just to revive this one...

Oh dear. Only picked up the car on Wednesday. Suspension 'clonking' loud enough for my wife to comment.

I really do hope this isn't the start of something. Again.
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      02-09-2013, 03:55 PM   #11
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Hi Rich,

Erm, that sounds like it could be same as my problem. Does the sound seem to be kicked off by minor bumps in the road? Quite a rapid wooden clonking sound from some or all of the wheels ...?

May car is due to go in for attention on this problem next week. It'll be interesting to see what they make of it. I can't help thinking BWW may have some faulty adaptive damper units out there ...

Hope you're not in that situation, although I'd guess BMW will put it right as soon as they know how. They won't want issues like that spreading too widely.

Strangely, apart from the clonking, my car seems to handle just fine.
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      02-09-2013, 04:43 PM   #12
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Certainly minor bumps, not so much bad road surfaces. And the noise appears to come from the nearside rear. Your original description is spot on. The sort of noise you'd hear riding in the back of a badly maintained mini cab.

To be honest I noticed it within half an hour of picking up the car but just couldn't believe it. Not after everything I've been through to get into this car. I've also tried emptying everything out of the boot to no avail.

When is yours in?
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      02-11-2013, 05:16 PM   #13
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I'd like to bump this thread again.

All those with Adaptive Suspension, who gets noises over bumps at low speed? There's a definite 'clonk' on mine. The suspension is certainly noisy and not what I'm used to after a couple of months in the non-AS F31 Sport. The demo non-AS F31 M Sport on 19s like mine didn't make this noise either.

I could scream about this for two reasons

1) I've finally got into another car after 18 months in an E91 that BMW seemed unable to fix

2) I've given up smoking and I might kill somebody. For fun.
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      02-11-2013, 05:48 PM   #14
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Quote:
Originally Posted by rich1068 View Post
Certainly minor bumps, not so much bad road surfaces. And the noise appears to come from the nearside rear. Your original description is spot on. The sort of noise you'd hear riding in the back of a badly maintained mini cab.

To be honest I noticed it within half an hour of picking up the car but just couldn't believe it. Not after everything I've been through to get into this car. I've also tried emptying everything out of the boot to no avail.

When is yours in?
Hi Rich,

That's spooky - you're describing exactly what I get. The nearside rear makes clonking noises over fairly minor bumps (e.g. slightly recessed manhole cover at 30mph in town). Nearside front seems to be second most easily provoked by bigger bumps but, if I go over sustained bumps across the whole road surface, I can clearly hear the sound coming independently from all four wheels. In my book, there's no way the car should make this sound - I think we have faulty AS ... :-)

My car is being collected by the dealer from my office tomorrow and they're going to have it for the day. I'll let you know if they come up with anything, although I fear them reporting that 'there is no issue, sir ...' That will make me an unhappy customer and I'll have to take the car in myself and take the service manager out for a ride.

Anyone else?
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      02-12-2013, 03:35 AM   #15
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An update when you get the car back would be much appreciated.
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      02-13-2013, 02:18 PM   #16
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Any news Daveyc?

Mine's booked in for tomorrow.
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      02-13-2013, 04:14 PM   #17
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Hi Rich,

Sorry for the delay - had it in my head that the car was going in Tue, but it was today.

Not a good outcome, I'm afraid. I went up to the dealer and took one of the technicians out for a drive first thing this morning. He agreed completely about the noise - in fact, he heard it before we even got off the dealer premises when we went over a couple of quite abrupt speed bumps. We got onto some backgrounds and the guy could clearly hear that all four dampers were involved in the percussion party (nearside rear being by far the most easily provoked). I left the car with them, as agreed, and the head technician then spent some time with it, including back-to-back road test comparison with another car with adaptive.

Guess what? The head techie decided that my car was perfect, with no unusual noises. Needless to say, I wasn't delighted with the outcome, but I was in and out of meetings when the dealer rang to give me the news this afternoon. I've agreed on taking it back in a week or so for them to keep for a few days, but I think the fundamental problem is that some of these guys just don't have the driving experience and, perhaps, that they don't give the customer enough credibility (hence hurling the car round bends and running engine diagnostics, in spite of a very clear written brief about low speeds and straight lines).

To say the sound is obvious to anyone who is tuned into their car would be an understatement (my not-into-cars mate spotted it in seconds). Rear nearside sounds like a well worn ball joint on an old car, while the other three wheels sound like mildly worn ball joints. The noise is most apparent in a straight line at town speeds. I hear that the head techie put the car through lots of 'changes of direction' and, bizarrely, did an engine test well.

Nosy suspension isn't the ownership experience I expect at 42k, so I'll talk to my sales guy tomorrow and see what he thinks. I'll see if I can take him out for a spin this weekend and go from there.

This is a techie comment, but I've played with suspension on a few cars and bikes, and I think this is a case of the dampers being significantly under-damped on the rebound stroke (no problem on compression), resulting in them over-extending and hitting the end-stops at times.

I've never been called Sherlock, but there are several pointers toward this being true:

1. Driving over a speed pump at 5-10mph: no sound as the wheel hits and starts to climb the leading edge, but a distinct 'clonk' as it drops off the steep trailing edge (at which point the wheel is briefly airborne).

2. Driving in town at 20-30mph: if a wheel drops into quite a deep manhole depression at 20-30 mph, I get a clearly audible clonk. One for each wheel that travels over it. No rebound going on here of course: just a damper extending under drive of the spring until the tyre finds tera firma.

3. Cornering progressively at speed: Clonks are less frequent in this situation, but I get them on the inside wheels (i.e. the lightly loaded side of the car) if the inside wheels run over small potholes. In this situation, I get front and offside corners giving clonks (where it's generally limited to NS rear in town). So in my book, this is a case of lightly or unloaded inside dampers (i.e. poised somewhere around the middle of their travel range) which suddenly find a few centimetres of air under the tyre, provoking the over-extension again (driven simple by the springs wanting to extend fully, as there is little or no rebound going on from mid-stroke).

Another thing that I think is significant is that switching between comfort and sport has no impact on how much provocation is needed to cause clonking. This points even more strongly towards a damper fault, as I'd expect at least some rise in rebound damping rate in Sport, which ought to slow the speed of over-extension or stop it happening completely.

BTW my car has done this since mile one and the behaviour hasn't changed significantly since then, with nearly 2,700 miles on the clock now.

Anyway, this is just a theory and I could well be talking bollocks, being on my second beer. But ... does anybody fancy a wager on BMW UK acknowledging a problem with some batches of active dampers in a few weeks' time? Whether I succeed or fail in getting traction with my dealer, my wager is on the table :-) It will take quite a few tuned-in and persistent owners to get there, but it has to happen in time.

Rich, I'd be really interested to hear how you get on tomorrow. Not sure if you're experience mirrors mine but, if it does, tell them to drive the car at town speeds in a straight line and find a few bumps, potholes and manhole covers.

Good luck,

Dave
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      02-14-2013, 03:26 AM   #18
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Well I'm off there in a few minutes. Thanks very much for the reply. You could be describing my car. Unfortunately you could also be describing my experience of the early stages of a fault on a car.

Take car in first thing>dealer rings at the end of the day>says car's fixed>drive out of car park>noise returns>repeat process for ever.

Anyway, we'll see.
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      02-14-2013, 04:27 AM   #19
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Quote:
Originally Posted by rich1068 View Post
Well I'm off there in a few minutes. Thanks very much for the reply. You could be describing my car. Unfortunately you could also be describing my experience of the early stages of a fault on a car.

Take car in first thing>dealer rings at the end of the day>says car's fixed>drive out of car park>noise returns>repeat process for ever.

Anyway, we'll see.
No such problems with mine, but I be listening when going over bumps, keep us posted.
I have written to BMW complaining of the "Poor quality control", and said they need to address this problem before it's plastered all over the internet, these faults should not be there, look at all the supposed testing they do
before the release of the cars.
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      02-14-2013, 06:07 AM   #20
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Quote:
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Not a good outcome, I'm afraid. I went up to the dealer and took one of the technicians out for a drive first thing this morning. He agreed completely about the noise - in fact, he heard it before we even got off the dealer premises when we went over a couple of quite abrupt speed bumps. We got onto some backgrounds and the guy could clearly hear that all four dampers were involved in the percussion party (nearside rear being by far the most easily provoked). I left the car with them, as agreed, and the head technician then spent some time with it, including back-to-back road test comparison with another car with adaptive.

Guess what? The head techie decided that my car was perfect, with no unusual noises........


This is a techie comment, but I've played with suspension on a few cars and bikes, and I think this is a case of the dampers being significantly under-damped on the rebound stroke (no problem on compression), resulting in them over-extending and hitting the end-stops at times.....
Sounds the typical response when the garages don't know what is wrong. There is clearly nothing obvious.

I'm not sure this is exclusively an adaptive issue, (but could be in this case) as it appears some of the F25 1-series users have had rear suspension issues and clunking sounds. And not tied to adaptive suspension. Just this past couple of weeks it seems BMW are sorting it, after many months of drivers waiting. Have read the solution is with dampers, top mounts and bushes, (possibly revised).

Also I've read of some rear suspension thumping noise on 5GT models, again not directly linked to adaptive suspension.

I understand your thinking, but I'm not sure you really get to the endstops, that would be some pretty aggressive dynamics and you'd be tossing the car all over the place to lift off the wheels. You can't rule anything out, as it is all supposed to be in tolerance. But how you describe it, in an aging setup I'd be looking at loose top mounts with the clonking you describe.

As you appear to have the same/similar clonking front and rear the common 'parts' are, from my thinking, damper internals, damper control (software/sensor related) and wheel/tyre combination. I read that one 1-series user rid his car of the rear clunking when he changed wheel sets for winter use, 16" moving to 17", so some very unusual suspension behaviour involved in that case.

I do tend to agree the issue looks likely to lay with faulty dampers, but 4 on one car makes me scratch my head. Possibly some control module common to damping strategy may be involved. One bit of thinking... as if the rebound valving is slow to respond and goes to full closure, too late to cushion the rebound, but makes it abrupt with resulting clunk. Vertical motion sensing faulty?

Has you dealer opened a PUMA case, or at least checked with BMW for others with the same issue, already on record?

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      02-14-2013, 06:48 AM   #21
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Just taken another look at your comments after posting my thoughts, and note your observations.

Quote:
Originally Posted by Daveyc View Post
.......The nearside rear makes clonking noises over fairly minor bumps (e.g. slightly recessed manhole cover at 30mph in town). Nearside front seems to be second most easily provoked by bigger bumps but, if I go over sustained bumps across the whole road surface, I can clearly hear the sound coming independently from all four wheels. In my book, there's no way the car should make this sound - I think we have faulty AS ... :-)
Some odd reactions and sequences it seems, but are they? Could be pointers at the problem. Are you 'driver only' most of the time? Better or worse, when you have a passenger(s)?

More I think on this, the more I'm minded it is in the 'sensing' of the car. Would be interesting if you have a passenger in the n/s rear and try roads you know well and how it clunks, see if the reactions are different.

I know you shouldn't have to bother and the garage should fix it, but always helps to have reasoned observations to add weight to your case. Could help others get a quicker fix, if it can be identified.

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      02-14-2013, 08:09 AM   #22
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When I got down there one of the techs came out to have a drive around with me. He's a good guy and I know him from when I had my E91.

Anyway we went for a drive around and even though I thought it was noisy he didn't. So we swapped seats and tried again. Again, he didn't think there was anything unusual. So then we jumped in the service manager's F30 330d M Sport with AS. I drove and to be honest at first it didn't sound too different to mine but then we tried a different road surface, got back, jumped in mine again and went the same route. In my opinion my car was significantly noisier. Mine 'clonks', his didn't.

So my car's still there.
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