HELP E85 strange knocking noise

[Tommy_hf]

Hopefully someone has had this problem and solved it.
My Zed developed a weird knock, it's like using a wooden mallet hitting somewhere on the bottom of the car. It's most noticable when the car is up to running temp and I'm on slight uneven surfaces jiggling the car a bit.
That said, bigger undulations and potholes don't create the noise.

So far things I could think of:

Stabilizer droplinks (they're new Meyle HD items)
Shock tower topmount (is new already)
Lower control arm bushings (checked, no play in them and are Meyle HD items)
Couldn't replicate the noise by kicking the exhaust.
Rear diff bushing (is new) and the noise doesn't vary with applying some throttle. It depressing the clutch doesn't vary the noise.
And yes, when the car isn't up to temps it doesn't make the noise.
I've retorqued the strut tower bolts.
What could be wrong? The car just had a check up at the dealer and nothing on suspension seem to have play.

I run track pads in Alcon 4 pot calipers, but didn't have the noise earlier on, so I figured it shouldn't be related to the brakes. Mounting bolts also torqued to spec.

TIA

 

[Tommy_hf]

guess nobody has a clue

 

[Toe-side]

"I run track pads in Alcon 4 pot calipers, but didn't have the noise earlier on, so I figured it shouldn't be related to the brakes" ?
When did the noise appear, when you fitted the brakes?
Noise from the Front or back of the car?
"And yes, when the car isn't up to temps it doesn't make the noise". So it only makes a noise when engine hot or Brakes have warmed up?
Engine mounts? http://www.z4-forum.com/forum/viewtopic.php?f=9&p=575766

 

[Tommy_hf]

The sound appeared recently, the brakes have been on the car for years
I was thinking about the engine mounts, looked at the exhaust mountings yesterday and jiggling the engine sometimes gave some knocking noises. The mounts still look ok but maybe they're worn out. Thnx

 

[wilbo]

Does it happen when you move forward or backwards slightly? If so, does it sound like it could be coming from the diff? I had a knock like this for ages and after researching on here concluded that it was the lube, or lack of, where the prop shaft meets the diff. This thread below explains in a bit more detail, but I had mine sorted at the weekend by a mechanic and the noise has gone.

http://www.z4-forum.com/forum/viewtopic.php?f=2&t=20865

 

[Tommy_hf]

There was a slight click from the diff carrier bushing, that was already replaced. But the sound kept coming back after a drive. The right side engine mount was a bit excentric and torn, so it got replaced with M3 items which are a bit more solid It actually did help a bit as there was less knocking from the right side. But there was still another knock. And there was only the left front topmount left to inspect. As the right one was already renewed. At first it didn't show, but the noise increased and after a small roadtrip the tears appeared in the topmount. New one is already in, hopefully that will solve the problem (the xenon leveler linkage was creaking like an old granny as well ) Apparently a compilation of things producing knocking noises. Oh well, fresh Z4 E85 in the end

 

[bedminsterbob]

I had a similar noise turned out to be a faulty new droplink, try turning the wheels to full lock so you can hold the droplinks in turn and get someone to push down and rock the car at same time. When I did this I could feel the knock as well as hear it.

 

[Tommy_hf]

Droplinks were already changed

Just went out to swap the topmount and retorque the chassis braces. Test driven it and all noises are gone, the car feels a lot more connected as well In the end it was the left topmount cracking which knocked random and the right engine mount which led to knocking on spirited drives