Hello, I have a very soft brake pedal feel still, after having bled the brakes like crazy. New master cylinder, new brake lines and flex lines, new calipers and pads on the rear. Good pads on the front (1/4 inch of meat per pad.) Rotors all good it seems...

I've even used the ABS relay "jump" idea to activate the modulator in the bleed sequence.

They only seem to "grab" or "bite" after they've gotten hot.

Maybe the pads should of a type that bite better?! The new rears are metallic ...Not sure what's on the front.

Any suggestions?

 

Further...

I've just done the "Decent Control" in low thing. I could hear the ABS kicking in a lot....

I guess I have to bleed the brakes again to see if the module expelled any air?

 

Had a buddy fighting his for weeks, turned out to be a bad booster, not completely failed but leaking enough he could not get a hard pedal.

 

...Interesting.

How do I determine the booster is at fault? Vacuum test?

 

Oh, and another thing...I replaced all the lines with that copper/nickel brake tubing and replaced all but the front right flex line with new braided flex lines. The reason I didn't change the front right one was that the brake line was in good shape and the rubber flex line looked good too. Might this remaining rubber flex line be too old? It doesn't seem to swell with brake pressure applied. Perhaps it's damaged inside?

 

Yes, you should rebleed after doing running the HDC in low range. It should help a lot.

 

Did you properly break in the brake pads? Could be a vacuum leak at the intake, line, or booster.

 

I am curious about the vacuum leak thing. When I first start the truck after its been off for a few hours, the brakes seem almost not existent. They are spongy and then after a few minutes, though still spongy, they begin to "bite."

I've always understood brake booster fails to result in a hard pedal and poor brake power....

What specifically should I check with the vacuum?

 

Try the tests at this site https://axleaddict.com/auto-repair/B...-Booster-Check all brake boosters are basicly the same as far as operation is concerned

 

If the brakes seem to bite eventually after they’ve warmed up are you using ceramic brake pads?? They can sometimes depending on the brand & ceramic feel glazed or take more effort to stop until they’re warmed up. That’s why properly breaking them in is very very important. If you don’t they’ll act glazed.