Air in brake system still?

[pontiacgp]

Yes break in the pads so they bedded in properly, that will help them to last longer and brake better but I'm not sure how critical that is with a ceramic brake. I have EBC Yellow pads and I brake them in by their directions. The Yellows work ok when cold but once hot they grab.

As for your booster they can last as long as a car is on the road so no need to change it until it goes bad.

 

[roger1]

Thanks.
Here's the instructions:

5 moderate to aggressive stops from 40 mph down to 10 mph in rapid succession without letting the brakes cool and do not come to a complete stop. If you're forced to stop, either shift into neutral or give room in front so you can allow the vehicle to roll slightly while waiting for the light. The rotors will be very hot and holding down the brake pedal will allow the pad to create an imprint on the rotor. This is where the judder can originate from.


Then do 5 moderate stops from 35 mph to 5 mph in rapid succession without letting the brakes cool. You should expect to smell some resin as the brakes get hot.

After this is complete, drive around for as long as possible without excessively heating the brakes and without coming to a complete stop (Try for about 5 minutes at moderate speed). This is the cooling stage. It allows the heated resin in the brake pads to cool and cure.


After the brakes have cooled to standard operating temperature, you may use the brakes normally.

I wouldn't think the driving I've done today would have been detrimental to the pads. I did the lock up test a few times on that first drive but I really don't think enough to heat the brakes and done anything to that resin they mention.
I'm going to go out do this now. I know of a good place to where I should be able to do it all without any traffic lights. An old country road with hardly any traffic on it too and it's not far away.

 

[roger1]

Nah, I still have an issue.
I was pretty sure it was OK coming home from the alignment shop but when I did the pad break-in procedure, I now think it wasn't really any better than before.
It still feels like I have air in the system. Pedal travel distance is just too far. On the aggressive 40 to 10 mph part, I tried to lock them up. I couldn't and it feels like the pedal is pretty much to the floor. Pumping does not raise the pedal at all so now we have an answer to that.
Even with the car stopped and off the pedal will go down to that same almost to the floor position and pumping doesn't change that either. I'm thinking the piston in the master is bottomed out with the pedal just off the floor.
What to do next?

 

[pontiacgp]

The rear brakes gives you your pedal height but if the brakes felt good after you left the shop and deteriorated after that I think you may have a defective master cylinder. If it was air in the system the pedal should become firmer with a few pumps as you are compressing the air which makes the pedal firmer. When you shut the car off does the pedal feel hard as a rock as you pump the pedal?

 

[roger1]

The rear brakes gives you your pedal height but if the brakes felt good after you left the shop and deteriorated after that I think you may have a defective master cylinder. If it was air in the system the pedal should become firmer with a few pumps as you are compressing the air which makes the pedal firmer. When you shut the car off does the pedal feel hard as a rock as you pump the pedal?

No. It feels kind of hard but not rock hard. More pressure makes it go down further and further until it's just off the floor.

 

[pontiacgp]

I think the master is defective. Did you have a problem with the master you took off?....but you probably used the old one for a core...

 

[Bonnewagon]

Are the brake lines original? Rear cylinders? There might be a tiny leak and as air gets in your pedal deteriorates.

 

[Longroof79]

I was also going to suggest adjusting the rear brakes. That could certainly affect your overall pedal height and firmness.
I was almost thinking the brake booster, but it would give you a hard peddle and brake fade when you try to stop.

 

[roger1]

Yes gp, I did have a problem with the master I took off.

I need to tell you the whole story.
I did a front and back with new master brake job on this car back in early 2013. 5 years ago but very few miles. I'd guess just a couple of thousand. Pads, shoes and rotor/drum turning were the only things needed but I put a new master too only because of the age of the original. New Bendix hoses too. I bought the parts from Rock Auto. Master was a remanufactured Wagner.
That Wagner master was bad. It wouldn't bench bleed (so I never installed on the car) Just kept blowing bubbles and wouldn't stop. I went to Napa locally and bought another. I believe it was new and not rebuilt but don't remember for sure.
That master bench bled fine but when on the car, it made a funny noise when stepping on the brake.
I thought the pedal didn't feel quite right either but not as bad as it does now. I could lock them up but the pedal travel still seemed a little far and it also felt like I had to put more pressure on it than I should to keep the car from creeping especially when it's at a cold faster idle.

I decided to buy this new PowerStop kit and a new AC Delco master. To get rid of what I didn't like plus get an upgrade to the ceramic pads and slotted/drilled rotors.

Another question here. Could I be damaging the master by holding the body in my vise when I bench bleed them? I was afraid to hold it in the vise by the mounting flange for fear of breaking since it's aluminum.

 

[roger1]

I was also going to suggest adjusting the rear brakes. That could certainly affect your overall pedal height and firmness.
I was almost thinking the brake booster, but it would give you a hard peddle and brake fade when you try to stop.

I certainly can try that tomorrow to try and rule out an issue there. Btw, I replaced the cylinders with the new shoes I put on back in 2013. They are Bendix. Shoes are Wagner Thermoquiet.