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Clunking noise when going over bumps

Posted: Wed Nov 22, 2017 6:02 am
by ChristopherEmmanuel
Hi all, sorry for the long waffle ...................
But I hope this will help others as the dealers really do not have a clue. I purchased my i3 back in August 2017 and when test driving noticed a clunking noise from the nearside suspension, dealer said he would sort out before delivery.

Well several visits to the dealer resulted in them not fixing the problem and throwing many new parts to rectify the issue and they did not succeed.
After my own investigation i found that the steering column shaft was loose and the dealer fitted a new column, clunking still present the second dealer then had it in four more times to rectify the problem and could not, then told me they all do that?

I went to a third dealer who threw all new suspension parts on again in case of faulty new parts and still no joy.

I being really pissed at this stage had a look myself and found the front sub-frame bolts at least 1.5 turns loose. I tightened them up and guess what, The clunking noise stopped!

I went to the third dealership to see if the bolts were stretch bolts and they are. BMW recommends 104Nm torque setting but at this setting it still clunks a bit.

The tech told me that the 104Nm is because the bolts screw into the carbon fiber tub, but looking at the drive module chassis, it bolts directly to this so do not understand why such low torque settings.

I hope this will help someone who has this problem as it seems to be a limited problem with others I have spoke to who have a clunking noise on their car.

Re: Clunking noise when going over bumps

Posted: Wed Nov 22, 2017 7:05 am
by theothertom
Thanks for tracking this down and posting.

Re: Clunking noise when going over bumps

Posted: Wed Nov 22, 2017 9:38 am
by jadnashuanh
FWIW, that's the same spec for tightening the wheels. Aluminum is probably the limiting factor. The ultimate strength can be overcome somewhat by using a larger diameter and/or longer fastener so there's more area. Overstressing could cause the aluminum threads to be damaged.

Re: Clunking noise when going over bumps

Posted: Wed Nov 22, 2017 2:47 pm
by ChristopherEmmanuel
your welcome, and agreed, not really room for a large washer, wish there was. I am also going to check the shock absorber bolts tomorrow as I am sure these will not be tight enough also. Will post my findings as soon as I can

Re: Clunking noise when going over bumps

Posted: Sat Nov 25, 2017 9:51 am
by ChristopherEmmanuel
Well BMW had the car in to change the bolts on the subframe as some of them were not where they are supposed to be (oops maybe i tightened them to much) and they said they had torqued them to 104Nm.

in the mornings when setting off when car was cold the clunking started again but almost went away when driving for a while.

I was not satisfied with this and was sure the bolts needed to be tighter.Mmmmmm

OK I decided that the problem had to be with the sway bar as the clunking was drop link clunking.

I found the sway bar was solid in the bushings and would not move up or down. Nailed it!

The sway bar could not move up or down with the shocks and was acting as a big torsion spring, I am surprised the drop links did not snap under the stress.

Sprayed WD40 on the bar in the bushes and the noise has disappeared completely even when cold. BMW do not sell bar separately so £200 for the privilege. No Poly bushes from Powerflex either?

So there you have it. Clunking may not be drop links check sway bar bushes first. Three dealers have thrown thousands of pounds of parts and labor and all it needed is a bit of lubrication.

Hope this helps a lot of people with this new and innovative car and the new problems we all have yet to encounter :D

Re: Clunking noise when going over bumps

Posted: Sat Nov 25, 2017 1:39 pm
by theothertom
In the US we have a saying for your determination....bird dogging. A bird dog focuses on the matter at hand and cannot be swayed one way or the other until the task is complete. Thanks for "bird dogging" this one!

Re: Clunking noise when going over bumps

Posted: Sat Nov 25, 2017 4:01 pm
by Toalmar
Very good that somebody did sort this out. I've got this clunking issue since February this year. My dealer has tried every think. when they changed the shock absorber and the guide support on top of the shock absorbers the noise was gone, but just for about 1500 km.
I had my car to the dealer last no on Friday and they told it was nothing more to do. I've been looking around for this issue long time, and I'm happy to find somebody that probably sort out the problem. Please make some pictures of the bolts very you did the modification it's easier to find them then. I'm not sure what you mean with Subframe bolts since I'm from Norway and we use different names.

Re: Clunking noise when going over bumps

Posted: Mon Nov 27, 2017 12:01 pm
by ChristopherEmmanuel
Hi Toalmar ... Id=31_1051

item number 2

Also check first sway bar bushes as mine were seized and would not let the bar move with the drop links,

Re: Clunking noise when going over bumps

Posted: Sun Dec 03, 2017 1:19 pm
by Toalmar
When I check this little bit more I find out that the Subframe is mounted with 6 bolts, 2 in front M12 x 98mm), 2 in middle (M12 x 60mm) and 2 in rear (M12 x 98mm).
The torque for these bolts is a little different. Middle and rear 104Nm, front bolts 96Nm and then 90° rotation if I understand the document from BMW right
Last picture of this page show the bolts: ... 1VnXrmLD63

On this page you see the torque for the bolts at the subframe: ... 1VnXqb7ZMd

Re: Clunking noise when going over bumps

Posted: Mon Dec 04, 2017 5:15 am
by ChristopherEmmanuel
Thanks for that,

Yes mine were very loose, and were tightened to the right torque by the dealer. I have had a fairly quiet car for a couple of weeks now since lubricating the sway bar bushes, but the odd heavy knocking when going over big pot holes. am hoping the dealer will replace the sway bar bushes to completely eliminate the knocking noise.