I purchased my 850 at (~40k miles) knowing that it had a warped rotor problem, as there would be a little pulsing & vibration from the pedal whenever it was braked from high speed - & hardly ever from slow. No big problem there. The rotors were heavily lipped and the pads were down to almost nothing anyway, so time for a change.

I didn't fix the problem straight away as it wasn't too bad & I was waiting for parts from the best source. The thing was, I did need a tyre rotation and front alignment, as the car was scrubbing out the passenger side front tyre (on the outside) - and an almost new Michelin was rapidly biting the dust (on Volvos that's a pun) thanks to uneven wear. So I got the rotation and alignment.

Not the expected result- after 15 mins or so of driving (whenever the pads were heated), terrible vibration occurred upon every brake application, from high or low speed. This wasn't a vibe that shook the steering wheel, nor did it really pulse the pedal. It felt like applying the brake was pushing a few dozen rough rocks into all four alloy rims to stop it (the Lada method?). Needless to say it was virtually undrivable. Who knows what parts I could shake loose?

My auto tech friend said it was like nothing he had ever felt in severity, and half suspected the rear brakes, even though the fronts were so worn, because of the way that the car felt. He changed the front discs and pads (more OEM) and the problem was fixed. At the time checked the rear discs & pads which were little worn, running true, and the pads had the volvo shims behind them. We left the rear alone.

It seems I received a few lessons from my story which partially contradict bits & pieces of info on the stories that I have archived on Ozbrick. (I have about 5 archived threads on my site which talk about various aspects of warped rotors &/or sticky brake calipers. This one is going on next.)

One lesson is that the front discs can be the culprit in brake shudder even though the steering wheel doesn't shake. That is maybe because the power steering (or other FWD stuff?) isolates the wheel from the shudder.

Number two lesson- It doesn't necessarily mean it's a stuck brake caliper when it takes until warmup before braking starts with the bad vibrations.

And lastly, a simple & brief removal of a wheel can make a minor rotor problem into a very significant one. Maybe when the rotors warp they are held back from warping as much as they can because of the pressure of the wheels, and then they are allowed to "spring out" when a wheel is removed? I noticed one recent post where someone had a wheel off and then had problems with brake shudder. Or maybe the wheels were originally torqued carelessly, and setting them back on evenly brought the problem out.

Does anyone have any experience with this wheel removal problem, or any other theories?