So i have been having brake issues. and about 15 min ago.
i was driving down the highway, cars stopped in front of me. i slammed on the
brakes and the pedal was hard nothing happened for about a second then slowly started to grab on and stop the car. it was such a weird sensation.
after being scared half to death. i proceed down the rd and tried to repeat the problem. if i pump the brakes it does it sometimes, then kinda normal braking. but that hard pedal is there. I feels like the vacuum isnt there.
the brakes in the xjr iv noticed havnt been the best since iv had the car, feels like im getting only 80% braking power. My xjs feels much more grabby.
Anybody have any idea?

 

Shawn,

My first suggestion is to STOP using the car until its sorted.

Brake fluid being OFF is my usual suspect. Brake fluid absorbs moisture from the atmosphere, and as it does so it reduces its efficiency, and goes "dark" in colour. This causes a "rock hard" brake pedal, and very little stopping power. Brake fluid should be flushed and changed every 2 years or so.

Rubbish brake pads, also known as "el cheapo" pads can also give this issue.

At the opposite end is these fancy "super spec" pads. They usually require significant heat to get "grabby". Great for the race track, but not so great in normal driving conditions.

Of course you could have a booster issue, or a master cylinder issue. However the simple things are easy to do and just might sort it.

 

Thanks for the help.
Checked fluid all is ok.
idk what the deal is.
Anyone know where i can buy the blue break fluid.

 

The X300 brake boosters are sometimes faulty and leak vacuum. I have a stack of X300 boosters in boxes that have vacuum faults, mostly 'SQUEAK' noise when brakes first applied but some that have faulty internal valves.

Make sure the hose/pipe to the booster is leak free and the check valve is OK.

It could be an internal valve fault.

bob gauff

 

Great.
how would i check to see if the check valve is working ok?
its such a strange feeling normal braking works fine but i feel could be better but i may need new pads.
pumping totally renders it hard then slowly pushes in. i really would like to track this down on my own.