Sensation of mass shifting in engine bay - mounts replaced

Hullo My '96 850 Estate gives a sensation of having a large mass at loose under the bonnet. All engine mounts have been replaced, with the main mount found to have failed after 18 months and replaced again. There is at times a repetitive wheelbearing type noise when on sharp loaded left turn, and on slow walking pace dowhill over road surface there is a sensation of weight shifting as I go over irregularities, it is felt through the brake pedal as a sort of loading unloading as I go over the irregularities of our well maintained roads. (Similar to walking with a box with a loose bottle of wine in it) All shocks and front top mounts were replaced recently (2 months) and for a while the car felt very taut. If I break/accelerate in 2nd gear there is a feeling 'clonk' like a mass shifts and hits a stop and at one time if I had braked sharply to stop and pull away, there was a sound a faint whirring that seemed to be take in play - lasting say half second. Sometimes there is a sensation of faint vibration coming through the floorpan when driving without accelerate or brake, but it never lasts. Having replaced main mount twice, viewed the play on the failed part the 2nd time by someone demonstrating the movement of the engine with a strong bar whilst it is on the hoist, does anyone think I have missed the real cause? Is there a chance the mounts have been installed badly - or did I hit a batch failure (gen. volvo through nordic)? I am sure the problem will emerge but I want to reduce the financial meanderings.

knocking 

it may be that the mounts on suspension havent been fitted properly. have you changed the drop links? they would have the same effect, and are cheap enough/easy to do yourself. another thing you can try is jacking up one wheel at a time and running the car in gear , only the raised wheel will turn, but chock all other wheels for safety. if you hear the clonking when revving with in gear, then i would suspect the driveshaft. keep me posted. anyone else any suggestions?

Movement of mass 

Thanks for the suggestions, are drop links different to anti-rollbar links (replaced after service)? Has anyone else had repeat failure of the main mount, this seems strange to me? Thank you for the input.

if your car is front wheel drive look at the drive shafts with the wheels in the air it could be a partaliy broken c.v joint causing the movement i had a pegiut 106 where it was like it and it was narrowd down to how the drive shaft had failed allso look at the bottem engine mount as it could be that one

I have been through 2 top mounts in 18 months that's why I went for a poly top mount. No problems since. The car is starting to creak and clunk a bit now. My cars done 105K and I'm gonna try the drop links (anti role bar links) first. Oh,,,,, and greasing the end stops cures most creaking in these cars for anyone with creaking on full lock.

This sense of mass moving...............would it be the mother in law in the boot of the car, and you forgot to let her out ??????

and the lime and shovel:waffen093: