I have a 2000 Disco II. I have searched through the threads but haven't found anything that matches what is going on exactly. After it had sat for awhile, the battery was dead, so I jumped it to get it going. No problem there. Shortly after the three amigos popped on. My braking power has been lack luster since I got the thing but I never thought much of it. The pedal feels very solid but at low speed in a parking lot I can't panic stop. It slows down but doesn't come to a quick stop even at 5-15mph. There is a fraction of a second delay. I checked the fluid level and it is full. I checked the pads and they have plenty there. There are no fluid leaks anywhere. I'm thinking about replacing the vacuum line that runs to the manifold as a first step. Is there something else I should be looking at?

 

It's probably a leaking booster. You can check the vacuum line from the manifold/throttle-body to the booster, but you'll probably have to replace the booster. D2 booster is different than D1, so get advice on a source from D2 people. I can only point in the general direction of Rover's North.

 

What you are describing could also be bad brake fluid. Now to flush or change the brake fluid is a 1.5 hour fix and will cost 200 bucks at the shop or about 25 bucks if you do it yourself. If you change the booster you will have to bleed and flush the brakes anyway. But you may want to try flushing the brake fluid first because if it works it will be cheaper.



What Brake Fluid Does
Brake fluid is what's called a "hydraulic fluid." Most people have heard the term "hydraulic" before, but many don't know exactly what it means. It means moved or powered by fluids. That's exactly what brake fluid does: it moves components in your vehicle's braking system. Brake fluid is special because the job it does is especially hard. It has to work perfectly under high pressures and temperatures. That's why it's so important to maintain your brake fluid under good repair, because as it ages it doesn't work as effectively.
Brake Fluid and Moisture
It's necessary to flush and replace your brake fluid periodically, because brake fluid is hygroscopic, meaning it readily absorbs moisture. That means that you should always take special care to protect your brake fluid from contact with water, especially when topping off the fluid. Brake fluid will even pull moisture in directly from the air. Over time brake fluid becomes too saturated with excess moisture, which causes it is degrade. Once moisture content reaches a certain level the brake fluid is no longer able to function properly in the brake hydraulic systems.

 

"at low speed in a parking lot I can't panic stop. It slows down but doesn't come to a quick stop even at 5-15mph. There is a fraction of a second delay"

Why this may happen is the mositure when you put pressure on the pedal is absorbing, the pressure a little. Not transfering that pressure to the brakes like fresh brake fluid would.

 

find a used brake booster... i paid $40 for mine, and now I can stop as well as a disco can. Or you can spend $500 on a new one from AB.