Sorry, but this is a non Volvo question. I also have a 1992 Acura Integra with abs. The brake petal sinks to the floor. I see no leaks, and assume it is the brak booster, because the petal doesn't do anything when I start the car. I was reading in the Haynes manual when you change out the brake booster with a new one or a master cylinder you must measure the brake booster piston and put it in a equation to figure out clearances. I do not have a vacuum pump to put 20 in in hg to the brake booster to measure it! I guess what I was getting at is can I skip the equation by buying a brake booster and master cylinder already together in the junk yard? I don't have the money for the vacuum pump, because I just started a new job. Any advice is appreciated!!