I flew from JFK this Saturday in a 748 and was sitting pretty much above the center of the wingbox. There was a very loud rattling noise and strong shaking / vibration for about 30 s before lift-off that stopped a few seconds later at what felt like a height of only a few meters. After that, the engines were immediately surprisingly quiet for such a full plane in climb.
The take-off was towards the South, and the plane was about 98% full. I have taken off in a 748 from JFK before and don't remember this noise/vibration but was sitting further in the back. I believe I have experienced a similar noise, but not as loud and without the vibration sometimes in A330 and A340s.
There were two flight attendants in backwards facing crew seats who acted completely unconcerned so I decided there wasn't any need for concern
What was that noise? Poor runway surface? But then why did it seem to stop only at a height of a few meters?
Same for damaged or poorly balanced tire.
Could it be the turbines? But it is normal to throttle back immediately after lift-off?