So Wednesday I'm driving home. It's about 90F out, some pretty curvy roads for the first half of the drive. Second half is all freeway. About 3/4 of the way home I have to slow down and the brakes are soft/mushy. The car slows well, but brake feel is way off. I get her home and have to let things cool down. Check fluid levels, all is good. No leaks, lines look good. I drive the G about 2 hours later and the brakes feel a bit better, but still soft. The next morning, the brakes are normal.

The fronts were replaced about 15K miles ago with EBC Yellow stuff pads and rotors turned. Did EBC's recommended bed-in process. Took rear wheels off, pads still in good working order, rotors are in great shape.

So, is this a MC issue?

The fluid hasn't been changed since I've had the car (about 2 years) and who knows when/if it had been changed before. Could the fluid be the problem? Not that I would mind replacing with some high temp fluid.

Just trying to get some ideas on what might be going on.

Thanks,

2009 G37xS with about 125K miles.

 

I hope it's not your pistons - You can always take them off and build the pressure again while pumping the pedal and leaving the cap open on the break fluid

Takes about half an hour to do all 4 but I think it's super worth it

 

might need to bleed the brakes, you probably have air in the system.

 

Should be flushing/bleeding the brakes every 2 years regardless of mileage.

What kind of half @ss brake job does not include a brake fluid flush....

 

Would think air would give you that feeling all the time.

The brakes were still okay, but had lots of judder. Turned the rotors and got new pads to see if that would get rid of that problem. Was going to do a flush when I got new rotors and pads all around. So the other half of the half-@ss brake job was coming up.

I'll start with the flush. Though I haven't felt it mush out on me again, it's brakes, so I'm gonna head it off at the pass.

Thanks!

 

Get the right tool and it'll be nothing more than a 20 minute (or less) job to do all 4 corners. Look up motive power bleeders. Completely eliminates the need for a helper.

Also, back to your original issue. It's possible a piston is sticking, generating excessive heat, cooking your brake fluid. If that's the case, that could explain the soft pedal. Did you check both sides of each rotor for signs of overheating?

 

Change over to steel brake lines. The stock brake lines tend to wear out and give you a mushy feeling because of expansion.

 

Did a flush on the brake fluid. Had 2 different colors of brake fluid in the lines. Brakes feel tight. Will keep an eye on things. Thinking about the steel brake lines when I change out the rotors on all 4. Thanks all!