Front suspension rattly knocking noise over bumps

[Newbers]

I know there is often chat on here about changing front sus bushes so I don't necessarily want to dig up what's already been said (although I couldn't find the answer searching).

At 48k miles my car Coupe with 17" Continentals runflats, has recently developed a knocking from the front suspension. I notice it more going over bumps in the road than potholes.

Any thoughts about most likely cause? i.e. where should I be looking first - or is it more a case of all the bushes go at about the same time?

I don't need a performance upgrade but I hate noises that shouldn't be there!

 

[hopz121]

Front Rear Wishbone bushes i would say (Lollipop Bushes) get them changed and you shaould be all good again.

Dont buy cheap replacements as they wont last and if you fancy an upgrade go for Meyle or Powerflex.

Goood Luck

 

[cj10jeeper]

At 50k it could be any one of half a dozen items including lollipops. Car need jacking up to see what is moving, bushes, droplinks shock mounting, etc.

If changing the lollipops I'd do a whole front refresh of lollipops, wishbones, drop links and ARB bushes

 

[Bing]

I have this in my car right now. My indie has been all over it and can't find the cause, only stopping when the next step,was to spend some serious time taking the suspension apart up front. It's like a hollow tube wobbling about and knocking against something, like you say only really noticeable over uneven road surfaces. He reckons it is the top mount(s) or something else to do with the suspension that they can't get without disassembly. From what I've read on here the top mounts are not the best on these cars - certainly on the M's. I'd take yours to a garage to have them rule out all the stuff mentioned above. Oh, and check your firewall braces are secure - you can get a knocking if the nuts slacken off a little, as they have a tendency to do over time.

 

[simonlpearce]

It does very much sound typical of rear wishbone bushes. These are usually the first thing to go.

 

[Newbers]

Thanks for the feedback chaps. Am I right in thinking the Z4 uses the same front wishbones as the E46 3 series? I seem to recall having to change them on my old coupe at about 50k miles.

Bing: sounds similar - almost the sort of noise where you'd imagine something has moved quite a long way before making contact - more than the sort of movement you could believe possible.

cj10jeeper: I do think there is something to be said for swapping everything although I feel that at 50k that seems a bit overkill (particularly given that I'm not really looking for a performance upgrade). There may well come a time when I change all of the springs & shocks and that would the opportunity to swap everything.

I'll jack it up and see if anythings obvious.

On a seperate note I'm wondering if I should be kicking myself - I've just built an extension with new garage. The floor is beam and block with a reinforced concrete screed. Perhaps I should have stood my ground with the structural engineer and used a concrete slab with an inspection pit (wine cellar/ nuclear fall out shelter........) It would be nice to be able to have a quick look without lying in the dirt....

 

[cj10jeeper]

I think you misunderstand. I only meant the parts I listed, not shocks and springs.
All the nits I suggested will be tired at 50k especially as the front set up is so sensitive.

Once jacked it's as easy to replace the lot as mess about eg do lollipops and wishbones instead of trying to put new lolipopd on old wishbones

 

[Toe-side]

Probably worn suspension as above but have you checked that your strut brace fasteners are torqued correctly? This causes a front end knock!
E46 parts are the same.
Wear on the Z wishbone parts can be rapid if cheap OEM lollipops have been fitted previously. Some are very poor quality.

 

[Dean'o]

I have same problem with my z4 e85, have replaced strut mounts control arms and, drop links but still have a rattle sound. It also rattles when when you kick the front wheels. Am think anti roll bar bushes? Any ideas. Would start a new thread on this but can't find how to.!!

 

[Rich8]

The last comment is one to check - strut braces can knock/rattle louder than you would think if they are loose.

 

[Dean'o]

I get the rattle sound when you kick front wheel. My pads are low and my brake discs are not good.

 

[skelters]

Front Rear Wishbone bushes i would say (Lollipop Bushes) get them changed and you shaould be all good again.

Dont buy cheap replacements as they wont last and if you fancy an upgrade go for Meyle or Powerflex.

Goood Luck

This and also get all the bushes and suspension checked.

 

[Dean'o]

I have re newed control arms top strut mounts drop links.

 

[kis]

Do you hear it when driving?

If you kick the wheel it could be the brake dust shield? That would rattle. You might not hear it when driving.

Only other thing it could be related to is the sway bar? Seems like you’ve replaced everything else…

 

[Dean'o]

Hi thanks for the reply. I have just replaced front discs and pads. Never thought to check dust shield for play. I thought it was the pads rattling. Everything was in a poor shitty state. I did check front sway bar bushes seemed OK but I suppose the weight of the car and bumps in road can exaggerate it more. Will replace front bushes and see how we go.

 

[Dean'o]

Can't hear rattle sound when driving. But knocking sound.

 

[kis]

The dust shield is pretty notorious for corroding away. Most of our cars are between 15 and 20 years old...
Just unsure whether it would rattle. It should be more a scraping sound. But one to check out before you look at forking out any more money?

 

[Dean'o]

Dust shield looks ok, it definitely at the wheel on both sides. Can't hear it when driving. Just the knocking sound. Going to sort sway bar bushes out next week. Have renewed control arms drop links and strut mounts. I have a got a wheel wobble through steering wheel, whether the two are linked not sure, been told front wheels are slightly buckled,

 

[kis]

I'm doubtful that you would get that from a sway bar? Bushes are cheap. And should be easy to install. So you will know shortly.

If that fails, what about the wheel bearing?

 

[HGoward]

If it was a constant rattle whilst driving, I would say top mounts. But I'm unsure if you can't hear it when driving.