Knocking noise

[SGRG]

So after 4 months of ownership and doing all manners of preventive work, my car has decided to make the infamous knocking noise which seems to be coming from the rear from what I can hear. I jacked the car up to see if I can spot anything loose but couldn’t spot anything from a brief look. However upon lowering the jack, instead of the rear settling quickly the massive gap between the wheel and arch seems to stay put.

Immediately after removing the jack:


After 10 minutes:


Is this normal?? Thanks in advance.

 

[RedUn]

Did you let the handbrake off so it can settle?

When is the knocking? Driving slowly, turning, over bumps etc

 

[SGRG]

Did you let the handbrake off so it can settle?

When is the knocking? Driving slowly, turning, over bumps etc

Hi @redun, ah nope. Never knew this but coincidentally I did start the car up to drive it up and down the drive but now that I remember at the point I released the handbrake it did go down. Just never knew this, learn something new today.

Right the knock started short distance from home so it was under 35 mph and seemed like when it was going over bumps. However I just got back from a short test drive after the suspension settled and now no knocking noise.

Might go for a drive again later to see if it comes back again.

 

[RedUn]

The handbrake stops it settling its normal

Ref knocking, have you checked for broken rear springs whilst you had it jacked up? It's quite a common issue, I'd start there first before opening pandoras box

 

[dhobbs]

Rear top mounts can knock if they have been replaced by Meyle versions. Not an easy thing to visually check though.

Springs first.

 

[SGRG]

The handbrake stops it settling its normal

That is reassuring RedUn

Ref knocking, have you checked for broken rear springs whilst you had it jacked up? It's quite a common issue, I'd start there first before opening pandoras box

Rear top mounts can knock if they have been replaced by Meyle versions. Not an easy thing to visually check though.
Springs first.

Yep i checked the springs and all looked fine when i pulled on it as well as visually. I went on two test drives since i heard the noise and surprisingly didn't hear it at all on both runs. Might go for a longer drive sometime this week.

On positive side i had my B12 kit delivered last week. Now I am just waiting on RBM to schedule installation. I will also be changing front top mounts with OEM mounts including OEM reinforcement plate and rear with rogue engineering. So hopefully Ross can check for any anomalies while he has the car up on the ramp.

Appreciate the feedback guys. Hopefully the "noise" doesn't come back.

 

[beanie]

I’ve been chasing a light knock in the rear of mine for a while. Still no closer to solving it.

RTABs changed for gen BMW - done for other reasons but no change in noise.

Springs are fine

Rogue Engineering top mounts - no change

Checked other bushes at two specialists - no joy

Stripped out rear in a desperate search - no change

It isn’t noticeable on larger or more extreme hits but only when trundling along over broken or ‘jiggly’ surfaces :lol:

My sneaking suspicion is that the rear toe and camber bushings are worn as the car is more prone to hunting out cambers on hard acceleration than it used to be. New tyres helped but haven’t resolved it so perhaps there’s some noise originating from there

I am going to look at it again soon and may change some other bushes/shocks so hopefully I’ll get rid of it. If you have any luck please let me know!

 

[SGRG]

I’ve been chasing a light knock in the rear of mine for a while. Still no closer to solving it.

RTABs changed for gen BMW - done for other reasons but no change in noise.

Springs are fine

Rogue Engineering top mounts - no change

Checked other bushes at two specialists - no joy

Stripped out rear in a desperate search - no change

It isn’t noticeable on larger or more extreme hits but only when trundling along over broken or ‘jiggly’ surfaces :lol:

My sneaking suspicion is that the rear toe and camber bushings are worn as the car is more prone to hunting out cambers on hard acceleration than it used to be. New tyres helped but haven’t resolved it so perhaps there’s some noise originating from there

I am going to look at it again soon and may change some other bushes/shocks so hopefully I’ll get rid of it. If you have any luck please let me know!

that must be so frustrating, hopefully you find the cause mate. Fingers crossed mine seems to have resolved it self or i just imagined the noise in my head. Anyway I will ask the RBM team to check for anything that might have caused it. Lets see if it stays that way after new suspension refresh.

 

[beanie]

It’s a minor annoyance really and I don’t notice it in normal driving so I haven’t been particularly inclined to throw money at it. Thinking about it now, I may go a bit further with the stripping things out to see if it’s something stupid that I overlooked.

Hopefully yours will stay that way.

 

[SGRG]

Just to conclude this thread, I took the car to PMW in Chelmsford Essex for CSL geo setup. They took a look at this issue but didn’t find anything obvious. However, the main man did say that sometimes the strut bar can cause this for reason I can’t remember (this was done in October 2021). Long story short he made some minor adjustment to the strut bar and no more noise since. Just happy it wasn’t anything bad.

 

[XMetal]

What "strut bar" are you referring to? The only struts in the rear are the ones propping up the hatch (on the coupe)...are those the ones that you're referring to?

 

[BMWZ4MC]

The two front strut tower to firewall braces need to be torqued correctly or they creak over uneven surfaces (mine have needed tightening on a couple of occasions over the last 13 years). Perhaps that’s what the OP is referring to?

 

[XMetal]

Perhaps, But OP's complains were knocking noises coming from the rear?

 

[05_3.0i_zoom]

I usually hear a knock when I shift from 1 to 2 to 3. I never investigated

 

[XMetal]

I usually hear a knock when I shift from 1 to 2 to 3. I never investigated

Same here. I will need to look into this further the next time I have the car in for service.

 

[SGRG]

The two front strut tower to firewall braces need to be torqued correctly or they creak over uneven surfaces (mine have needed tightening on a couple of occasions over the last 13 years). Perhaps that’s what the OP is referring to?

This i believe was it.

@XMetal, the sound sort of seemed to travel i.e. sometime from underneath the driver seat, sometimes behind so I could never place it. Anyway they did some tightening up and all fine now.

 

[Tom2207]

The mot boys over here are not long in finding such things , unlike the rest og GB in NI mot testing is done in big centers government run , like PSV stations in England , the idea is that its a fair system thats well monitored and fiddle free . Part of the test is to put the vehicle on a computer controlled vibrating plate , basically the wheels go on a set of plates the computer gives them a shake , then waits for knocks or vibrations to be felt and then a print out gives you the information ,, its an amazing system for finding knocks , bush wear , joint wear etc but ye gods its merciless.

 

[05_3.0i_zoom]

The two front strut tower to firewall braces need to be torqued correctly or they creak over uneven surfaces (mine have needed tightening on a couple of occasions over the last 13 years). Perhaps that’s what the OP is referring to?

This i believe was it.

@XMetal, the sound sort of seemed to travel i.e. sometime from underneath the driver seat, sometimes behind so I could never place it. Anyway they did some tightening up and all fine now.

Any pictures lol

 

[BMWZ4MC]

The mot boys over here are not long in finding such things , unlike the rest og GB in NI mot testing is done in big centers government run , like PSV stations in England , the idea is that its a fair system thats well monitored and fiddle free . Part of the test is to put the vehicle on a computer controlled vibrating plate , basically the wheels go on a set of plates the computer gives them a shake , then waits for knocks or vibrations to be felt and then a print out gives you the information ,, its an amazing system for finding knocks , bush wear , joint wear etc but ye gods its merciless.

The test centre used the same machine during the last MOT my car had before I shipped it to Aus. That was more than five years ago and in the SE of England. I suspect it’s a standard part of the MOT everywhere.

 

[Tom2207]

The mot boys over here are not long in finding such things , unlike the rest og GB in NI mot testing is done in big centers government run , like PSV stations in England , the idea is that its a fair system thats well monitored and fiddle free . Part of the test is to put the vehicle on a computer controlled vibrating plate , basically the wheels go on a set of plates the computer gives them a shake , then waits for knocks or vibrations to be felt and then a print out gives you the information ,, its an amazing system for finding knocks , bush wear , joint wear etc but ye gods its merciless.

The test centre used the same machine during the last MOT my car had before I shipped it to Aus. That was more than five years ago and in the SE of England. I suspect it’s a standard part of the MOT everywhere.

Ah it may have changed since Ive been away , it used to be local garages could do mots in england and scotland , it wasnt uncommon for guys here to pop over on the ferry t get an mot quickly

15 mot test centers in NI
23,560 test centers in England
233 '' other '' test centers , the rest are private , we dont have any private test facilities at all.