Rattling from rear on a 52-reg M3 convertible

[DrDaveWatford]

I'm getting strange (and irritating) metallic rattling sounds which seem to be coming from the rear passenger side of the car. Sounds a bit like a small spanner or bearing shaking about in a metallic compartment, and makes metallic rattling sounds every time I go over a bump. I've closely examined the car inside and out, including inside the roof comparment and boot for any loose metallic object. Also the roof mechanism works fine and everything seems suitably tightened. Totally mystified. Any ideas ?

[m12_nathan]

Got a similar metallic noise from the back of mine, new exhaust going on early next week, loose baffles apparently, rear shock top mounts are also a common cause of rattles.

[DrDaveWatford]

Oh well, looks like a trip to the dealership then.

:-(

Thanks for the suggestion, anyway.

[john_p]

Hehe I had exactly this problem!

I took out the electronics from the boot, the roof box, passthru, subwoofer, loads of stuff. Didn't solve it.

Eventually discovered it was where the rear seat backs clip onto the chassis - it uses a u-shaped metal clip each side which rubs against the metal and causes a clicking noise. Get someone in the back and see if they can pinpoint it.

Easy DIY fix due to the lack of roof. Remove the rear bench (pulls up from the front, then out) this will reveal two nuts which hold down the rear seat backs. Undo these, and the seat back pushes up. I put some cloth tape and some additional padding where the clips are, and it has been squeak free ever since!

Other possibilities:
- CD changer / nav unit / TV unit / bluetooth (if fitted) the latter two are on a flimsy bit of metal that can move about too much
- suspension damper loose (rubber perished inside perhaps) probably difficult to check without dismantling, you can see the top if you open the roof cover with the roof up and remove the two plastic covers
- diff / exhaust etc?

>> Edited by john_p on Thursday 9th June 20:05

[xm5er]

I've had a similar problem on all my BMs and all have been traced to either hand brake drums or brake calipers.

Is the sound louder outside? (Open the window and drive past some walls.) If so then try driving along and gently press the brake with your left foot, if it stops the its your caliper. If not then try driving along with the hand brake pulled on gently. If it doesnt stop then at least you've eliminated two possibles.

[z3stu]

I had the same problem and it was the rear Suspension Springs on both sides had broken there top rings. The one making the noise on the passenger side had the broken part stuck there rattling between the bodyshell and spring.

Stu

[ferrari355gtb]

Had the same on my CSL, booked it in to be checked and then driving home heard something fall off the car and bounce along the road - the noise has now gone.