Hey everyone!
I have a very annoying issue on my 2001 S60.
Whenever I brake at highway speeds (60 mph and above) I can feel a nasty vibration throughout the entire car, except for the steering wheel. I suspect the rear brakes. They are less than a year old though, and the reason that I replaced them was due to the same kind of vibration. I replaced the front brakes (pads and rotors) about a month ago since I initially thought it was because of the front brakes, but that obviously didn't fix the issue.
To rule some things out:

Tried different rims with different tires, no difference
Can't feel a difference in heat left/right after a few hard braking runs both front and rear
Inner and outer tie rods have been replaced
Sway bar endlinks have been replaced
Engine mounts have all been replaced
Calipers all move freely
Sometimes (so not always) a slight back and forth pulsation can be felt when braking at very low speeds
A "droning" sound can be heard while the vibration occurs
All lug bolts are tightened to spec in a star pattern (140nm)
Properly cleaned the hubs using a wire wheel
I found out that one of the front control arm bushings is torn, could this be the cause?

I'd really love to hear some input from others who might have experienced the same. Do I just need a new set of control arms? I am going to replace them anyways since I found the torn bushing.

 

I'd probably still suspect the brake rotors or possibly a wheel bearing. Worn control arm bushings typically lead to vague steering or the feeling of the car going in/out of alignment but not vibrations. Vibrations come from things that rotate (wheels/rotors/axles) or the engine (motor mounts). Have you jacked up the rear and spun the wheels by hand to see if you can feel any high spots on the rotors?

 

I haven't tried that yet, what exactly would I be feeling/looking for? I did notice that the rear rotors have worn in an odd way, atleast on the surface facing away from the car. It seems like the outer part of the disc has less material compared to the inner part (with inner part I mean the part of the friction surface closest to the hub/lug bolt holes, sorry if it sounds a little vague, I'm not sure how to properly describe it but I hope you get the point), which would suggest that the upper part of the outer brake pad is pushed against the rotor with more pressure compared to the lower part of the pad. And this is the case on both rear rotors, is it normal for them to wear like that?