Cobra4B

Spend the day re-doing my brakes after finding them all leaking due to new powdercaoted calipers w/ powdercoat in the are where the AN iftting seals.

Bled the system w/ ATE super blue and went for a spin.

Car drives great and will engage ABS even w/ the ceramic pads.

However... sitting at a light iding I can push the pedal to the floor... is this due to some pad tapering, is this normal?

I have no fluid leaks and the master doesnt leak on the vaccum booster at all.

With the car off the pedal gets nice and hard, but if I really push on it it will go down a little... could this be due to pad tapering too?

Thanks,
Brian

PS... if the vaccum booster was bad then I'd have an ultra firm pedal when driving correct?

If the master was leaking I'd see it on the vaccum booster right?

Just double checking everything.

rcr162

One possibility is that you still have some air in the system, bleeding again might help. It is also possible to have a bad master cylinder without leaking being apparent.

Maineiac

Not normal.....

c4cruiser

It sounds like there is still an air bubble somewhere. Re-bleed the system and see if that makes a difference. Make sure you follow the correct caliper bleeding sequence.

varkwso

you have air or a bad component somewhere - pad taper does not go to the floor without piston knockback..

Cobra4B

With the car off the pedal is rock hard... I re-checked last night... it doesn't move so I hightly doubt the master is leaking internally.

This is only w/ the car on and running that I can slowly push it all the way down when trying... I guess some air could still be in there, but the car stopps like normal w/ the ceramics.

We'll see.

BrianCunningham

With the car off so is the ABS unit.
You could have air in it.

Cobra4B

No... master cylinder reservoir has never gotten low and sucked air in, I'm always very careful of that.

No way for air to be in the ABS... I simpy changed the calipers and bled the system.

I need to drive a buddy's C5 and see what it does. I really think it's the nature of the ceramic pads.

Whenever I put my race pads in the pedal is far harder.

pipeliner1

If the race pads are making the pedal harder then you are magically compressing your ceramic pads. You have air somewhere in your system.

Next time when you bleed the brakes tap the calipers with a rubber mallet to see if theres air in the top of them.

gkmccready

How? For the pedal to go down you're either compressing something, or leaking somewhere, right?

The only way two pad sets should be different when you push down while stationary is if the pads are a different thickness?

Tintin

It is impossible for a brake pad to cause the pedal to sink to the floor. The nature of a hydraulic system is that the fluid is incompressable. Unless the pad is 2 inches thinner than the one you took out the pedal will not sink to the floor ,you are compressing air.

You have air in the system and I will guess that it is in the master. You may have to remove the master to bench bleed it to solve this. I have tried to do this with a compressor driven bleeder in the past , but it does not always work. Remove the master and gravity bleed it. That always works. I had this problem with GM ABS brakes on a 1LE Camaro, which is essentially identical to the Corvette system.

Cobra4B

I'll re-bleed the system and see what happens. I don't see how I could have ever gotten air in the master or the ABS. I have never let the fluid get low so as to suck in air, I am always very careful of that.

Aardwolf

Was that you that posted about one of your caliper lines leaking? Maybe some of the other ones are leaking to, or draw air in. Perhaps there is really just a whole lot of air in there now.

Cobra4B

Nevermind... all is well... I went out and checked it today, the pedal goes down 3 to 4 inches then stops and is rock solid 3+ inches from the floor. Last night it was dark and for some reason I thought it was the floor I was hitting... it wasn't.

W/ the car off the pedal is rock solid... and the fluid level is exactly where I marked it when finishing up last night.

I re-did all the brakes, all 4 were seeping, but only one was leaking badly. I removed the powdercoat from the needed areas w/ brake cleaner and q-tips then used new copper crush washers.

sothpaw2

Yes, I have the ceramics and I can attest that it shouldn't go to the floor.

Note that the ceramics have major brake fade--your first couple of stops will be ok but after that --watch out!! Never to be used in auto-x and don't go within 100 mi of any road course.

Tintin

All racing Porsches have Ceramic brakes... they are the cat's pyjamas..

The 911 Turbo road car has them as well... The Turbo is the only car I have ever been a passenger in that made me carsick because of the forces in braking (and the ham handed student)

Ceramic has superior heat disapation so in fact there is far less fade than other materials. It also is less prone to deform at high temperature and load which is why F1 cars have composite ceramic pistons and engine blocks.

Maybe the fade is because the brakes were not up to temperature? Or the wrong fluid? Not due to the material, it is bleeding edge.

B-ras

I believe the high-end Porsches etc. run ceramic rotors, as opposed to the ceramic pad some guys here run on the street to cut down on dusting.

Cobra4B

I run ceramic pads on the street only... ceramic pads are way different than carbon-ceramic rotors.

Again.. all is well.

Tintin

Dusting? You mean there are some people who would change their brake pads to keep down brake dust? WTF for? That is almost unbelievable, don't they have car washes where they live? Wow...


I naturally assumed they were using PCCB brakes to stop better... I can't imagine buying any aftermarket piece for a car that did not make it drive better....

Anyway , it is good that you don't have to bleed the master, it is a drag-a-roo.

Aardwolf

Even worse, there are many that will not USE a car wash.