A thumping 540i

[Eric540i]

Under anything other than very mild acceleration I’m hearing/feeling a rattle (or a nasty thumping when accelerating hard) that seems to be coming from under the rear seat. It appears and disappears around 40km/h (25 MPH). At first I thought a broken exhaust mount might be responsible but everything seems Ok there. Any ideas?

[markus]

rear u-joint or center bearing

[Ross]

Ditto

[Eric540i]

Thanks for your insight.
A rear u-joint or center bearing?
That sounds like major $$$
I had considered these as culprits but I expected vibration at any speed, which I'm not feeling.

I realise that the question is relative but how difficult is it to replace either of these parts?

Thanks.

[mattyb]

centre bearing not hard, rear uni can be a pain as it was never meant to come out and be replaced. it was intended that the whole drivesahft was replaced if the uni was stuffed.

centre bearing only shows its ugly head under load and at slower speeds.

[Eric540i]

Thanks!
You were right, my centre-bearing was at fault.
I appreciate your help.
Eric