[ab1]

Hi all,

i have just picked up a brilliant m6 with 120,000km on it and most of the prevantative maintenance has been carried out ie rod bearings etc. Im ironing out some minor issues such as stalling when left idling (probably ionic sensors) and this driveline vibration.

it occurs under load at any speeds over about 80/90km/h. smooth at a constant speed. the other thing is sometimes the smg shifts produce a bit of a thud (i have done the reset with the paddles)

I first thought would be the guibo however upon a brief inspection i could only spot hairline cracks which imo would lead to harsh vibrations. Could anyone advise what the best diagnostic procdure would be.

TIA

 

[Garfunkgrin]

Hey ab1, welcome.

I had some vibration issues last year and had a diagnostic thread on the go. Quite a few suggestions on items to check within:

Driveline Vibration - Help for Diagnosis Ideas

Vibrations can be tricky!

 

[TassieBMW]

Hey mate, good to see another Aussie on the forum, what neck of the woods are you from?

In my personal experiance 'driveline vibrations' very frequently turn out to be wheel/tyre issues, particularly wheels that are buckled and/or have balance issues.
Although you might be correct that it's coming from the driveline, I'd definitely rule this out first as Australian roads and BMW wheels seem to be a recipe for damage.

 

[Garfunkgrin]

As an echo to the above, my vibration turned out to be a flat spotted tire, tucked in the inside camber where I didn’t find it until they came off the car

 

[ab1]

Hey mate,

I'm in Melbourne and can agree for sure the roads here are woeful. I drove it back from Adelaide and it was quite harsh stiff edc mode. I've just had new contis put on and the vibration was noticeable before and after. Granted I am yet to have an alignment so I need to rule that out first.

I would've thought that if it's only under acceleration it would rule out tyres but could be wrong

 

[TassieBMW]

If you've just had wheels balanced with new tyres and they didn't report any issues with the wheels then I'd say you can probably rule those two things out. Suspension issues are another thing to rule out so an alignment is definitley a good next step. The thrust-arm bushings and ball joints are somehwhat common failures and could create a similar feeling.

The vibration happening only when under acceleration does sound like it would have to be driveline, just make sure that if you're sitting at higher speed (140kph+) that it is not present. Often these things can hide themselves at low speed but if you sit are higher speeds with a buckled wheel or dodgy suspension components you usually feel the steering wheel shaking in your hands or a shimmy travelling through the entire car.

Let us know how you go tracking it down.

 

[platii]

If the tires are new and balanced the vibration could be coming from the drivetrain.

Ball joint and wishbone bushings wear may not cause vibration, if it does it will be felt in the steering wheel. You can test holding the front wheel with both hands apart at 3 and 9 o'clock position and push pull against each side and also at 12 and 6 position and look for play.

Flywheel damage could start to show vibration at 1500 rpm and oscillates with engine speed, but also when car is standstill, this vibration will be felt in the chassis.

 

[ab1]

thanks will test both of those when i am in melbourne next week. i would hope flywheel damage is not the case as that has already been replaced prior to my ownership. there is some engine movement when idling and revving it but very minor.

 

[platii]

May not be the flywheel then.

 

[ab1]

i ended up finally getting around to looking into this while i was having smg issues. The guibo looks completely fine however the centre bearing looks cracked especially when pulling on it if i am no mistaken?