Hi, I tried searching for an answer to my questions on brakes, didn't find anything useful so here I am.

When braking the car I've noticed that I need to put much more pressure on the brake pedal to bring the car to a stop. The brake pads and steel brake tubing was replaced last year and it's worked well till now. I'm wandering about couple of possible suspects, the booster check valve, booster or maybe some of the calipers are seized. Any diagnostics this forum can recommend?

Thanks in advance.

 

Too much air in the brake system will cause that. Do a search for 'brake bleeding'.

 

Read the first few pages of this brake system manual if you haven't performed brake bleeding yet:

http://www.nicoclub.com/FSM/maxima/1998/BR.pdf

 

Quote: The brake pads and steel brake tubing was replaced last year and it's worked well till now.
I don't think he would have original fluid after that job.

Does your pedal feel spongy and go to the floor, Or is it stiff at a fairly high position? Have you gotten your brakes hot enough to glaze them. Ive seen brakes destroyed by heat to the point that the discs and pads were there, but the coefficient of friction was all but gone.

 

The brake fluid was replaced when the brake piping was replaced of course. They bled very well and performed good for about a year. After the brake piping replacement, the car spent a day at a test track doing some advanced driving lessons. All was fine until about a year later. Now it's hard to stop the car, meaning that a lot of foot pressure needs to be applied. I've tested the booster by pumping it with the car turned off, and the brake pedal does go hard once the residual boost pressue is released. When I start the car while pushing on the brake pedal, the pedal does drop once the car starts. This to me at least means that the booster side works fine. Meaning either that the calipers are seized, or rotors are galzed. Is there a method to test calipers or rotors for glazing?

thanks.

 

Pull the calipers and check the pads for glazing, and the pins for sticking. Youll probably need to turn the rotors and replace pads. I dont get into fancy pads myself, but if you race/drive hard look at hawk or EBC green stuff IIRC. If the brakes have gotten that hot you might have the fluid flushed as well.

 

Brake booster going bad maybe? Can't say I've seen a Maxima have a brake booster fail but its possible. Thats what assists you when you press the break pedal and if its taking a lot of force, chances are its bad or perhaps one of the vacuum hoses connected to it are loose or disconnected.

 

prolly jus air in the lines. bleed lines and report back

 

If he has air in his lines, then he more than likely has a leak somewhere. He has his brake lines replaced and new brake fluid as well as a good bleeding as he described. If all of a sudden he got air in the system out of nowhere then his master cylinder is bad.

 

This too.

 

If his pedal is coming up hard its not air in the lines. Booster or possible check valve, just my educated opinion.

 

I vote for check valve, booster and master, in that order. The seized caliper theory doesn't make a lot of sense since it would be a long shot indeed for both calipers to seize at the same time and if one seized, you would get a pull.
After a quick look at the brake section of the FSM, you might check the proportioning valve also since it is a shared component between right and left.

 

I'm thinking pads and rotors are glazed up.