Bahnzii

I recently installed a 4 wheel bbk on my C6 Z06 and ran it at Reno-Fernley for its' maiden voyage this last weekend.

Fun track

I performed a Pressure bleed (motive) with Motul 600 and then a quick speed bleed after that. I'm running Cobalt CSR pads frt & rear for the track and the Centric pads included in the kit for the street.

Overall I was kind of impressed but I have some questions for those more experienced than myself

1. I bedded the Centric pads and I immediately noticed that the pedal travel before bite was much longer than stock. The stock Z06 brakes started engaging in what felt like the first 1/3 of pedal travel, the Stoptech's on the other hand felt the opposite, it feels like they engage on the bottom 1/3 of the pedal travel - - and this was after bedding them.

2. When I got to the track and started pushing I immediately noticed that I had to give the brake pedal a quick 1/2 pump to have a firmer pedal otherwise it felt like it went all the way to floor with very little bite from the pads. I did observe that on the first few turns of the session this was less noticeable. Is it possible I still have some air in the lines? Or possibly am I getting pad knockback?

I'm not on R-Compounds, I am running Nitto NT-05's.

I also installed the Quantum brake duct adapters, so the fronts are finally getting some good air

I have seen some comments in other threads (I did search) that wheels bearing might be the culprit, but I find that hard to believe, considering it is an '09 Z06 with only 6500 miles on it now.

Any tips or tricks you can throw my way??

I would like to have a higher/firmer pedal on the first push of the pedal for my next trackday

Thanks...

glenB

Sounds like you still have air in the system

John Shiels

knock back should not feel like the pedal is going to the floor.

Dreamin

Todd Z

4th on air in the system. Initial pad grip varies on the pad. I like the Hawk DTC70 in front and DTC60 in the rear.

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0RAAMaudio

Yep, air, highly likely.

MySR71

I too would suggest rebleeding the system but don't use a pressure bleeder. Use the two person method. I say this because when I installed my StopTech 4-wheel BBK on my car, I had trouble bleeding it with the Motive power bleeder. Actually, I was unable to bleed the front calipers. That is, right after putting on the calipers and lines, I pumped up the power bleeder to around 20-25 psi and opened the bleed screws. Nothing came out. And I mean nothing. At first, I wondered if something was mismanufactured or misinstalled. That wasn't the case. Instead, the power bleeder didn't have enough pressure to get the system going and I needed someone in the driver's seat pushing on the pedal. StopTech confirmed this (that pressure bleeders don't always have enough pressure and the 2-person method is best). After doing that, I can now use a pressure bleeder. Now, I presume that Speedbleeders would be ok as the important thing (as I understand it) is that someone pushes on the pedal the get the high pressures.

The fact that you can pump up the pedal suggests air in the system. Also, be sure to bleed via the order that StopTech recommends. I think they say the outside bleed screw then the inside but double check. Best of luck.

Edit: My car is a C5Z06.

Bahnzii

That's interesting, I had the exact same problem when I installed them!!

Nothing out of the right front caliper with the Motive. Installed the speed bleeders and all was good. I will go back and re-bleed with the just the speed bleeders and see how it looks.

Bleeder screws are outside and then inside.
I bled them in order from RR, LF, LR, RF.

Thanks all, I will report back if I get a lot of air out or not...

longdaddy

i believe you are supposed to bleed the inside screw first

shifter77

BLEED those babies AGAIN.

H1ghlndr

I installed a ST BBK last month and I have always used the Motive pressure system.

The first bleed was not bad, but foot definitely went down. I ran the car around and bed in the pads and rotors on the street. I then re-bled and had a great pedal. You need to make sure to get the ABS active when you are bedding in before a bleed.

I spent 2 days at Watkins Glen with the best feel I have ever had. Pedal was hard all day even when hot. I never had that with stocks....

I also use the Quantum kit.

haikun

I installed front calipers 2 weeks back, We used a rubber hammer to "knock" on the caliper to get the air out (had to repeat that a few times. No problems after that. Brakes engage immediate :-)

/Hakan

MySR71

From the StopTech install instructions:

Vicious-Z06

BLEED! I have the Stoptechs, and they can stop a freight train!

UstaB-GS549

If pumping the brakes before a corner helps at the end of a long straight, that would be knock-back. You could check rotor run-out as a cause, but you would normally feel that as pedal pulsation. The other cause for knock-back is rotor wobble due to loose bolts on your wheel bearing cartridge. For me, one of 3 bolts were finger tight on OEM bearing with 22,000 miles on it.

If you need to pump up the brakes after a relatively short straight, then most like cause is air in caliper, lines or master cylinder.

flink

Yup. I've found that if there's gas in the lines (air or the fluid has boiled) then pedal-pumping doesn't help. Which makes sense - pressing the pedal compresses the gas and it expands straight back as soon as you release.

Whereas if the pedal pump does help, it's some mechanical problem. Usually knockback, but I've found that the effects of pad taper can also be reduced by a double-pump or a left-foot-tap.

punz

I thought bleed order is: RR, LR,RF,LF. I've always blead the inside side of the caliper first, then the out side with someone working the brake pedal.

Bahnzii

The sequence I mentioned was taken straight from the '09 Service manual and then the outside / inside for the bleeders is straight from Stoptech

The order for the brakes appears to be based on how the brakes are in a circuit because of ABS, I assume. Otherwise, the old skool method of furthest to closest would then fit the order you listed.

As for bleeder order it makes sense (to me) to do the outside first in the hope of getting air out the furthest point and then work inward.

By the way, car is up on jacks and I will bleed them tomorrow. I can solo bleed them with my speed bleeders but I won't really be able to tell if there is a lot of air in the lines since I can't watch it

Bahnzii

I had to pump every corner fwiw. This is my first time with semi-floating rotors so I guess it could be knockback but I would be amazed that I am already pushing hard enough now to cause knockback - - I guess that's both good and bad

Bahnzii

Pulled the track pads, put back street pads and did a 4 corner speed bleed, then gave the calipers some good whacks with a rubber mallet and did one more pump on each caliper.

Pedal feels nice and firm now, but the caveat is there is no heat in the system, just street driving.

I have a track day Friday, so that will be the true test