soldier4life

Part 1 - Bought my car used and 1st thing i noticed were the brakes weren't what you'd normally find on a C6 Z06. Can anyone give the some info on them? Says PBR Performance on the caliper.

Part 2 - My pedal has been a bit mushy even after new bleed/flush, pads, rotors and NEW master brake cylinder. pedal has some travel but then bites. Car stops really hard and an improvement from stock rotors/padlets After a trip to the track (PBIR) the pedal travels even more. Really bad but when it bites it bites hard. Everything leads to me thinking air in system, but the car was bleed and flushed manually and using a Tech 2 for ABS. Also like i said earlier new master cylinder. Could the seals in the caliper be bad at the cylinder?

I wanna get back on the track but not like this. Was thinking to buying new OEM calipers as i know the car previous too me owning it was tracked some or Wilwood calipers. A BBK isnt an option for me at this time.

See pic below

cruzin2

My experience with non abs cars that exhibit this phenomenon is that the pads are to "hot" for the track you are running. Meaning that the mu for the coefficient of friction comes in too high in the temperature range. I.e. There no brake until you get enough heat into the pad and then all of a suddenly the brakes lock up. We had this happen when a supplier accidentally sent us high temp circle track pads and we ran hpde. It was freaky.

Normal track pads should still work on the street at least minimally.

If you decide to change calipers and can't step into a brembo/stoptech, I would consider the wilwoods. Not too much better than the stockers but you have more pad options and you also don't have to worry about the bolts backing out.

0SpeedFreaksUSA

Sounds like there is still have air trapped in there somewhere and it may require a few bleed cycles to get everything out.

What pads are you running now? Do you have SS or the stock brake lines?

-Matt M.

RX-Ben

And when (brakes hot or cold) is the pedal mushy?

Those look like C6Z calipers with different lettering.

JRitt@essex

If your pedal is mushy, you almost definitely have air trapped somewhere in the system. A hydraulic system is closed, and fluid just gets pushed around, pushes out the pistons, etc. That is all based on the brake fluid not being compressible. In simple terms, the fluid won't squish! It basically just slides around. Air on the other hand is very easily compressible. So if your pedal is soft, you either have a leak somewhere in the system, or you have air in the system.

For leaks, have someone else sit in the car and depress and hold the brake pedal while you take a peek at all of these areas with a flashlight (after first checking these areas for brake fluid and wiping them down):

As for air, sometimes it takes several bleeds to get all the air out of the system, particularly if you bled it totally dry for a new master.

• Another weird one...but I've seen it happen...air gets trapped in the caliper and only comes out when the orientation of the caliper is changed. In other words, the caliper is unbolted (but still attached to the brake line), and it is moved from a vertical to a horizontal position, etc. Gravity does it thing and dislodges the air bubbles. Again...not the most likely scenario, but it does happen.

One last question...was the new master cylinder you put into the car an OEM unit? If you put in a different type/size of master, that can negatively impact the pedal travel if it's not sized properly.

Hopefully that helps.

0Randy@DRM

Check for leaks like everyone said. If you can push the pedal to the floor, you have a leak. If it holds a pedal even if it's down, no leak.

With both bleeders open tap on the caliper with a rubber mallet. Not super hard or anything but can help with any trapped air pockets.

I got 10 bucks on there is air in one of the rear lines. Open those bleeders up and start pumping!!! Then finish it off with a pressure to open, closed to up position aka the old fashion way.

Just because a part is new doesn't always equal perfect. Some masters come less then perfect, they can be junk from the get go. I have new stock masters here at 1/2 price if you think it's maybe internal.

My money is still on either a leak or air in the rear lines.

Randy

0Todd TCE

Wrong post. Sorry!