just out of curiosity i was wondering how Lexus designs the brake system to work on my second gen IS and the reason why is sometimes when im driving i notice at lower speeds it sometimes almost feels like the brake pedal dips down before it starts to do the work. not sure if its a part in the system that causes this or if i should check something for an issue but its been like that since i bought the car so i just always thought thats how its supposed to work but any input or insight would be appreciated

 

Sounds like either your brake fluid is low/ has a leak....or your brake master cylinder is going bad.

 

in that case its gotta be one of the ports in the master getting clogged up because my fluid level is always pretty good

 

Yup. But depending on the milage of your car, the fluid is probably passing the seals inside the master cylinder. Not leaking out side the system, but leaking internally.

 

Fluid needs replaced every 3 to 4 years max. as it attracts moisture and degrades.

Even at that, yours sounds like it has air in it. Air leads to excessive pedal travel as unlike fluid, it does compress.

Also, if the rear caliper(s) are not sliding (aka stuck floating caliper), the pedal will gain travel and feel mushy. Pull off the highway with minimal braking and check the rotor temperatures. They should be luke warm at best if didn't use the brakes in the last 10 min. If not, I suggest service is due/past due.

 

Given his symotoms....he is past servicing....It really sounds like a bad Brake booster. When he changes that out, he can do a full fluid flush anyways.

 

Duplicate post. Deleted content...

 

JM2C - there is not enough information from OP to make this decision. Based upon what???

If the booster had an internal leak, the post would have read something like "I have to use both feet on the brake pedal to start the car." But it doesn't.
The pedal travels too far before braking is felt to be effective. Two vary different problems.

 

i think it’s gotta be the master internally leaking because when I have the excessive pedal travel before the brakes work it’s not a lot of travel it’s slight, also sometimes at red lights I’ll have my foot on the pedal hard enough to keep the car stopped but it will sometimes slowly start to inch forward and I’ll really have to press on it so I would think it would be a bad deal inside the master internally leaking

 

Be specific, how far does it move? And when stopped, are you saying the pedal continues to move to the floor to keep the car from moving?

If yes, then stop driving it and get the MC replaced. Do a complete fluid flush, and get all the pads and hardware looked at. It sounds like its been neglected and never had the fluid changed or it wouldn't fail in this manor.

What color is the fluid?

Driving w a failing MC is a good way to die.