My '84 Berlinetta has an LG4 and a 700r4. When I press the brakes, I hear a sound almost like someone breathing out loudly from my brake pedal. When the car is running, it causes my rpm's to drop considerably, almost to the point of stalling. Could this be a bad brake booster? It takes a lot of pressure to stop in a hurry, and fortunately I haven't needed more than they can give me yet. Any ideas?

 

Sounds like a vacuum leak inside brake booster. New or rebuilt booster is a good idea.

 

Ya you need a new brake booster.

 

Would that require a new master cylinder? Probably not right?

 

Don't be so quick to blame the booster just yet. Does your car have cruise control? If so, you have a combination brake light/cruise control release switch like in the picture. In the top view, do you see that vacuum hose nipple on the left side? Hitting the brake pedal activates the switch and breaks the vacuum connection with the cruise unit. That's how the brake pedal switches off cruise control. Those switches can go bad and will leak open vacuum when you hit the brake pedal. I've had it happen, only after after finding out the hard way that it wasn't really my booster making the hissing noise. Pull the hose, plug it and try the brakes again. If your vacuum leak noise goes away, it's the switch. Not saying it absolutely is, but it's the easiest and cheapest thing to check first.

 

No I don't have cruise control, so I don't think that would be it. Is there any way to test the booster first?

 

Hmmmm....read what the Berlinetta came equipped with: http://www.thirdgen.org/1984-chevy-camaro
I would look under the dash just for the fun of it. If you want to test the brake booster, remove the large vacuum line, plug the hose from the engine, and listen again for a brake pedal hiss.