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Quote from: Irish_Alley on June 12, 2018, 09:51:37 AMbd do you think the old MC and new MC could have the same problem? i mean i know stuff can be bad right out of the box but couldnt the problem lay in the brake lines/hosesI'm not there to make firsthand observations, so must draw from experience with the posted symptoms balanced against how the system functions while doing the best I can to filter out assumptions that have been made. Based on what has been posted, I suspect an adjustment issue and/or residual air trapped in the system or a simple lack of familiarity with the "feel" of GM power brakes to be the most likely cause(s). Don't make the mistake of believing that any particular symptom has only one cause. The original symptom may have been repaired only to be replaced by a similar substitute having a different cause. Hence, all we can do at a distance is make suggestions for checks to be performed and evaluated in the hope that it is sufficient for the OP to discover the truth and resolve the issue. Do you disagree?There are two wrong decisions to make: one is to do nothing, the other is to "overthink" the symptoms rather than just looking. Filter out that which you can definitively through observation and what remains is probably the cause.
bd do you think the old MC and new MC could have the same problem? i mean i know stuff can be bad right out of the box but couldnt the problem lay in the brake lines/hoses
Checking the hoses while the petal is applies id a good suggestion.I have noticed that the rear brakes will lock up when sufficient pedal force is applied.I had not mentioned this earlier because until I replaced the shoes and drums, the shoes and drums had been contaminates with brake fluid or grease, which will cause the drum brakes to grab.So, new drums and shoes, adjusted (parking brake as well) and rear braking is balanced side to side,but still will lock up earlier than the discs in front.Possibly a hose or hoses have some give which they should not.As the pedal is rock solid without engine vacuum, maybe manual only force is insufficient to cause a hose to swell, but vacuum assist may provide the force to do so.On to this step.......
it might reduce the line pressure and it might stop straight but im not sure, never dealt with this issue. im almost on the line of "thats a gm brake system for you" but want to eliminate anything we can. much like my sig says "When you have eliminated the impossible, whatever remains, however improbable, must be the truth" ~Sherlock Holmes
seams as if your very knowledgeable and know what youre doing but did you bleed your brakes according to the "Brake system and diag."?
I didn't see any comments about the dash light. If the system is off balance, would the proportioning valve switch not cause the light to come on? And if it is tripped, it would prevent whatever system is an issue from being bled since the piston in the valve blocks the line between the m/c and that part of the system.