OVER 400 SOLD! Ships for FREE today! Part: New Vacuum Power Brake Booster Fits: Lexus LX450 Years: 1996 • 1997 Part Number: 4461060792 | 44610-60790 | 44610-60791What is it for? A brake booster is to braking what power steering is to steering. A brake booster uses a stored vacuum to overcome the high fluid pressure in a car's braking system. With a brake booster, the driver does not have to exert much force on the brake pedal when applying the brakes. A brake booster is also sometimes called a "vacuum brake booster" for this reason.How do I know it's time to replace it?