I have a 2007 V70R (with 114k) which began to have this problem late this summer. Specifically after about 30 minutes of driving, after being stopped, the transmission (Geartronic 6 speed) would thunk when shifted from P, N, R, D. Afterwards, sometimes when the car shifted from 2nd to 3rd, or from 3rd down to 2nd (when slowing and braking), the shift would be harsh and clunking.
But both these problems were sporadic. Ninety-nine % of the time the trannie was just fine.
After reading many posts, suggesting everything from new trannie, fluid flush, software upgrade, coolant contamination, failing valve bodies, etc., I decided replacing that the lower transmission torque mount, a known defect, was the place to start. It was the cheapest fix. I had already replaced the upper engine mount, another known defect. If the upper engine mounts were under-engineered, then likely so was the lower transmission torque mount. As the car needed to be warmed up before the problems occurred, this could be explained by the fact that the torque mount’s rubber bushings softened up with heat from the engine.
I ordered IPD’s HD Billet & Polyurethane Transmission Torque Mount and had my mechanic install it. WOW what an immediate difference! The original torque mount was a mess. It’s just a metal frame. The bushings were seriously degraded. About 95% of the front-end clunckiness was gone: I had been thinking I was overdue for serious suspension work.
(It’s just possible that this fixed also resolved an intermittent “Chassis Service Settings” warning light I had been getting.)
I am not an engineer, or even a mechanic, but it’s just common sense that if the transmission housing is not firmly anchored to the subframe, it’s not going to do its job very well.
On the editorial side, it seems ridiculous that Volvo is going to all the expense of setting up a 4C suspension system, with all the sensors and so on, and then so seriously under-designing something as fundamental as the torque and engine mounts. It’s like building a mansion on a sand foundation.