This is a bit like a recent thread by Invar on spongy brakes, but I'll start another thread as there are a few differences and I've done basic testing.

This is a 940 with ABS. Brake pedal effort is quite a bit more than should be required, especially when compared to another 940 and a 740. Pedal travel is too far (confirmed by noticeable hiss on releasing pedal). Pedal goes to hard stop more gradually than it should. Initially this smelled like a classic booster and/or master cylinder problem, but now I'm not so sure as the tests don't totally confirm this. If anything, problem is the front brake system rather than rear. Maybe front pad hardness? Proportioning valve? A combination of things? Your thoughts appreciated as this is not my area of expertise (as if anything is).

Basic tests and info: Caliper pistons seem to be extending and retracting okay. Pad wear is even. Did pressure bleed (twice) -bled normal, absolutely no improvement. No visible leaks or hose problems. Rear pads near new and front pads are at 70%. Front pads may be a harder composite (I haven't really done a proper comparison).

Master cylinder checks: Continuous hard pressure on brake causes some initial minor sinking, but stops hard long before bottoming. Master cylinder is extremely clean and may not be original. Fluid was also very clean.

Booster checks: Check valve in good shape -lots of residual vacuum when removed. Tests okay against pedal effort upon starting (pedal sucked down, but possibly not as much as it should). After stopping engine there is no additional pedal back pressure.

Theory #1: Master cylinder starting to go, but not totally gone. Front section leaking around plunger into rear section.

Theory #2: Booster starting to go. Booster diaphragm damaged by sustained fluid leakage in past.

Theory #3: Master cylinder starting to go and booster also starting to go.

Theory #4: Master cylinder has been replaced, but connecting rod to pedal was not properly adjusted (no history -only had car a few months; other service records indicate non-Volvo shop was used and/or user maintained).

Theory #5: Front pads simply too hard. 85% of braking is front brakes so too much effort required.

Theory #6: Unbeknown to me, right leg has atrophied and seat is too far back.

Your vote?