S211 suspension rattle.

[saff]

Hi. I know this is a well-discussed subject but this is a puzzler.

Front o/s knock/rattle over rough road surface but not large bumps.

Recently replaced the lower suspension arms c/w balljoints and ARB droplink.

The odd thing is that it goes away when the car has been driven a while, as if the offending part 'warms up' and rattle stops.

When cold the noise returns.

It's just passed an mot so it cant be something too dreadful.

I'm thinking maybe the strut itself or perhaps the upper strut mount bearings but obviously I don't want to replace bits willy-nilly if I can help it.

Any suggestions please chaps?

 

[W1ghty]

Brake disc shield ?

 

[Nicebutdim]

I had a similar problem. Front offside. I removed the strut to examine it. The action was smooth when compressing the strut but when allowing it to then extend under its own steam the last two inches of movement had no damping and so shot upwards with a clack. A new pair of struts solved the issue.

Having said that, on the w211, tracing the source of suspension noises is really difficult and frustrating. Like you, i have replaced most of the front suspension components over the last couple of years but i still get an annoying low fluttering sound a bit like a loose exhaust hanger or a flapping under-tray when slow driving on rough surfaces.

 

[saff]

Brake disc shield ?

Thanks for the reply W1ghty. I did have an issue with these when I replaced the pads and discs recently but used washers to secure them. The noise is a bit 'heavier' than that would be. A pain in the bum.

 

[saff]

I had a similar problem. Front offside. I removed the strut to examine it. The action was smooth when compressing the strut but when allowing it to then extend under its own steam the last two inches of movement had no damping and so shot upwards with a clack. A new pair of struts solved the issue.

Having said that, on the w211, tracing the source of suspension noises is really difficult and frustrating. Like you, i have replaced most of the front suspension components over the last couple of years but i still get an annoying low fluttering sound a bit like a loose exhaust hanger or a flapping under-tray when slow driving on rough surfaces.

Thanks for the reply. Yeah my suspicions are towards these or the top mounts. I don't suppose replacing both on both sides would break the bank but compressing the long coil springs is a PITA, ask me how I know this? Cheers

 

[Nicebutdim]

Thanks for the reply. Yeah my suspicions are towards these or the top mounts. I don't suppose replacing both on both sides would break the bank but compressing the long coil springs is a PITA, ask me how I know this? Cheers

Yes. I had to buy a hydraulic spring compressor to do mine. Here it is in action

 

[saff]

Yes. I had to buy a hydraulic spring compressor to do mine. Here it is in action

View attachment 124356

 

[saff]

That looks just the job!

 

[saff]

Hi, an update to this.
I'm a bit red-faced but happy at the outcome nonetheless.

I finally got to the bottom of the rattle, it was the plastic under tray which is broken I'm sure due to a stupidly severe hump at the local tip which I grounded on.

Anyway, my local garaged repaired/secured it for the princely sum of £20 +vat.

All quiet, no knocks, sheer bliss

 

[bolidemichael]

Thanks for the update. Your embarrassment may save someone else the same fate in future!

 

[JamDebs]

I had a similar problem that was driving me mental. Turns out it was the rubber/plastic dust cover protecting the shock absorber. It had slipped down allowing it to jump around when going over bumps. Put it back in place. No knocking.

 

[TimmTurner]

Hiya guys,

I’m having this issue but I’m no where near as technically minded so took mine to the garage. (They mot’d and serviced a week ago) They can hear the rattling as clear as day when going over bumps ect, but cannot find the cause?

It happened when I had full lock oncoming out of a carpark and went over a speed bump, not fast though? From then it rattles from the front end? With the garage stumped i don’t know what to do? Any advice?