This is the alloy bar that bolts across the front suspension turrets and also to the firewall in the middle, which cuts down on chassis-flex as the front wheels move around. The E39 didn't have one and the E60 doesn't need one, but it's there and if one of the bolts come even slightly loose then it produces a rattle inside the dashboard like no other. It is not easily identifiable as a loose component in the engine-bay by ear as the noise is so internal and you may find yourself, as I did, spending forever adjusting panel fit inside the dashboard and cable-tying wire connectors with no joy. Rest assured it is a loose bolt on the strut-brace.
The problem is steel bolts going into alloy threads on the strut-tops, which become loose easier and are more prone to damage if overtightened or the strut-brace is removed and refitted a lot. BMW are aware of the problem and they're official fix is detailed in this PDF [http://5series.net/forums/attachments/e60-discussion-2/37844d1190387791-cracking-sound-e60-dashboard-sib_511304.pdf], but they will charge a premium for this and probably replace the brace.
The strut-brace attaches in three places, with two bolts in the centre joining the firewall and one either side on the strut-tops. They have E10 double-hex heads. Two of my four bolts were loose - one of the centre ones, which just kept spinning and needed coaxing out, and the O/S strut-top. This would get near tight then skip and go finger-loose again. The strut-brace was so loose this side that it could be moved around by hand at the end with the bolt in place.
Quick Repair Options:
- Heli-coil - This is the recommended or 'pro' way. You can get a hell-coil kit for £10-£20 and it basically winds a new stainless-steel thread into the old one so the original bolt tightens straight back in.
- Drill out and re-thread - This is cheaper and dirtier as it just involves boring out the hole with the damaged thread to a larger size and using a die to re-thread it to accept a larger bolt. This is what I did, drilling the offending hole in the O/S strut-top out to 9.5mm and threading it using an M10 tap. I then used a short M10 bolt (17mm) with a large knurled collar to keep that end of the brace nice and tight.
This did NOT fix the rattle?
If you're strut-brace is not loose and the noise is still there then it could be two other things:
- Axial tie-rod / Track-rod end failing - Yes, when the axial tie-rod / track-rod ends start to fail it does produce a rattling / cracking noise from behind the dash, just like a loose strut-brace. No one would ever guess this defect would make this sound where it occurs, but there you go. I suspect this was the cause of the rattle in my E60 after all, though never had chance to replace the part before I sold it and the guys buying it both agreed the noise was something steering-rack related.
- Loose trim - If the sound is definitely originating behind the dash then loose trim or structure is likely your culprit, though this is quite rare. E60s use alloy design and the body absorbs a lot of flex, so when stuff behind the dash does become loose the sound is amplified in the cabin. I am sure when this does happen, every case is different so there is probably a lot written about it online. Best of luck tracking it down.
This is a common fault and there is plenty of information on the forums:
This comment has been removed by the author.
ReplyDeleteI've had this horrible rattle for 5 straight months now, only recently i've realized it was this stupid strut brace.
ReplyDeleteIs it safe to drive without one ?
I can't imagine it is dangerous to drive without the brace, or that it would fail a UK MOT. It might be worth running the car with it removed just to see if the noise goes away. If it does, you could always try refitting the brace bolts with a load of 'Stud-lock' and see if that helps...
Delete