[Dustydogs]

I thought I'd share the troubleshooting I went through to finally cure my Gran Coupe of chassis vibration in the hope it'll point someone else in the right direction.

The car is a 2013 640D with 75km (50k miles?) on the clock. I dont know if the n57 diesel is sold in America but it's an amazing car that can get up to 1400km (850miles?) on a tank while still showing 240kw.

I've only had it 3 months old and when I test drove it, I thought the wheels just needed balancing or the run flats had been sitting too long so thought nothing of it.... That was just the start. I was feeling a heavy vibration mainly through the seat from the rear, and only faintly through the steering wheel unless I rested hands on the paddle shifter then I could feel it there as well. It was pretty much through the entire speed range from in town speeds up to highway but the resonance would change. Sometime it'd be rythmic, sometimes buzzing, sometimes just bumpy. n hindsight, I had several different types of vibrating components that would sometime cancel each other out, sometime amplify each other so there was no smoking gun and it turned out to be a range of issues.


In short the following is the process I went down in order, largely thanks to this forums pointing me to different solutions:

- Tyre shop balance. Feedback that I had 3 buckled wheels
- Had the offending wheels rounded/fixed. Seemed to solve the problem but 2 days later it was back and worse than ever.
- Took it back to the used car dealer for warranty repair, they replaced left engine mount & Trans mount. There was a modest improvement (huge improvement in handling however) but the vibration was still there.
- Had the wheels road force balanced. Was advised the right rear tyre was way out and was able to be remedied by re-seating it further around the rim. This also remedied an abs sensor code I was sometimes getting on the wheel too. As a result the Rear felt a bit better but the vibration through the seat was largely there so I focused on the drivetrain.
- Replaced rear Guibo/Flex disc (had minor cracks), Centre Bearing (this didn't need doing but I did it anyway) & rear Diff bushing (was split at the top). Again an improvement, it settled things down and tightened up the acceleration response but the vibration was still there.
- I then looked at the brakes. Pulled all wheels off and popped of the brake rotors, swapping Left to Right and sanding the surface off the pads. Here I noticed the rotors weren't centering on their own so I took the time to centre them well and made sure they spun true. Big improvement was had here, the minor vibration through the wheel was totally removed but some vibration was still there.
- At this point I noticed at stationary idle the car would shudder a little similar to the vibration I was feeling at speed. Gave it some injector cleaner and this suppressed the vibration noticeably.
- I took the engine cover off and noticed oil pooled around injectors so I replaced valve cover gasket, injector seals and cleaned injectors. This effectively removed the vibration entirely so clearly the majority of my vibration issues were engine related.

I know the n57 gets clogged intakes so this will be my next job on the car to smooth it out even more but it's finally driving the way it should.

The prior drivetrain and wheel repairs definitely had an impact though so I'm guessing the chassis in these cars are highly sensitive and as the car gets on in age, bushings etc wear out and the car vibrates its arse off...

Sorry for the long winded post but hopefully someone else can benefit if they're having vibration issues. cheers