New brake rotors, pads & steel braided lines - pedal needs tapping to be firm...

[wjburken]

Well crap.

If a new Master cylinder is inexpensive then I'll just eliminate this issue with a replacement.

/facepalm/

The question asking if you put anything behind the pedal was asked last week. When folks ask questions here, there is usually a reason so it helps if you answer them so they can help you figure out what is going on.

I believe you are in the right path. Just make sure you properly bench bleed the new master cylinder.

 

[OR VietVet]

The other thing to remember is this, what we are saying about being careful to not bottom out the master cylinder, is not to say that the problem from doing that always happens. IT CAN HAPPEN but NOT ALWAYS. It happens, that is why so many people know about that possibility. But it does not always happen.

 

[Dustin Jackson]

When I bled my brakes recently my pedal was going to the floor and not firming up and I suspected I had damaged my master cylinder seal but in the end I was able to get it rock solid, so don't give up yet.

I would recommend the bottle and hose method, just make sure you aren't opening the bleeder too much, just enough to leak brake fluid out at a restricted flow.

I did mine laying on the ground with the Tahoe RUNNING pressing the brake pedal with a broom stick because I wanted to be the one physically controlling the brake pedal and be able to see the fluid flow.

 

[ivin74]

I would recommend the bottle and hose method, just make sure you aren't opening the bleeder too much, just enough to leak brake fluid out at a restricted flow.

X2

 

[Tozan]

I have replaced rear brake lines several times in the last few years because I was breaking the lines when off road... Every time I replaced the rear lines I was by myself. I filled the M/C put a clear hose on the bleeder and put the hose in a bottle. Cracked the bleeder a little bit and went back up front pumped the brakes a few times checked the M/C filled and repeated... After the pedal started to firm up it would pump up and get a little soft after sitting...

At this point I would accelerate to around 35 mph in loose sand and try to lock it up. The ABS would do its thing and stop then I would repeat that several times until things were normal again...

I guess this is not the normal way but it seems to work for me... lol

 

[donjetman]

Everytime it rains around here (rarely) I take all of our vehiles out and slam the brakes a few times to pump some fluid the the abs unit.

 

[sniper_x]

SO, I replaced the Brake Master Cylinder with a Genuine GM unit.
I even had a GM shop install it and power bleed the system.

The pedal is still softer than my similar Yukon with the same brake setup.

I took it to a brake shop and I said "I just bought the thing and felt that the pedal was soft."
They drove it and said that they thought it was good.

So maybe I have unrealistic expectations, but surely there is a way to get these brakes to be more solid.

Should I proceed with replacing the calipers with upgraded units as planned, and then maybe I'll see a firmer pedal?

I welcome opinions. My goal is to get this 100% and I will do whatever i have to to get this right.