Knocking coming from the rear

[crustyclown777]

Hi guys,
Hoping some of you can point me in the right direction as there is a heap of experience on the forum.

I have a slight knocking noise (sounds like when the boot is slightly open and you're driving over a rough surface, and its bouncing on the latch, like a metal on metal noise, but damped/insulated.) coming from the rear left area of the vehicle.
Going over speed bumps and larger undulations the knock is not present, but when travelling over a rough surface with plenty of tiny bumps, its pretty obvious.

I have replaced the rear trailing arm bushes (powerflex) and the noise is still present, any ideas? i have also checked the tyre to fender distance and it is slightly lower than the RHS, so could be a broken spring?

I was thinking of replacing the rear anti roll bar bushes next?

Thanks!

 

[srhutch]

Def check your springs, very common weak point.

 

[dannytheduck1985]

Def check your springs, very common weak point.

Stes on the money
snapped spring

 

[exdos]

Did you have this noise before you started doing any work on the rear suspension?

If not, I would suggest that one of the bolts you undid is not tight enough. Most of the OEM nuts and bolts used by BMW are self-locking because they have very close tolerance. Once they have been undone, they never retighten as they do on first use and can work loose. If you don't use new nuts and bolts for the suspension parts, You need to use thread locker when refitting. Hope this helps.

 

[ph001]

Broken spring or top mounts on rear shocks.

 

[hopz121]

Rear Top Mounts I would suggest.

 

[Jembo]

Check your ARB drop links as well

 

[crustyclown777]

Woah, good feedback!
I’ll try and narrow it down and report back when it’s solved.

 

[Spaniarduk]

Antiroll bar link (-s).

 

[crustyclown777]

Finally solved it.
Anti roll bar drop link had completely sheared. Luckily nothing bad, and they’re cheap to replace.