Brake issue
May 30, 2018 | 08:34 AM
#1
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From: Frederick, MD
Brake issue
I have an inconsistent pedal that is driving me nuts. I don’t seem to be losing fluid so I don’t think I have a leak anywhere.
Some stops the engagement is high in the pedal travel and a quick stop. Other times it engages about 1/3 of the way down and has a softer linear grab. It is inconsistent when these occur so I don’t think its vacuum loss. I could be on the highway for 20 minutes and hit the brakes for an off ramp and get near immediate heavy braking like nothing is wrong and on the return have a soft pedal.
Ive bled all corners. The front calipers are newer 8/17. The rears are close to being adjusted. I recently tore down and swapped the rear axle housing using the same brake assemblies and had the issue before and after.
Some stops the engagement is high in the pedal travel and a quick stop. Other times it engages about 1/3 of the way down and has a softer linear grab. It is inconsistent when these occur so I don’t think its vacuum loss. I could be on the highway for 20 minutes and hit the brakes for an off ramp and get near immediate heavy braking like nothing is wrong and on the return have a soft pedal.
Ive bled all corners. The front calipers are newer 8/17. The rears are close to being adjusted. I recently tore down and swapped the rear axle housing using the same brake assemblies and had the issue before and after.
May 30, 2018 | 11:30 AM
#4
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From: Alaska
I have seen master cylinders do this, it's not very common though, either the front or the back piston inside doesn't seal every time you hit the pedal. it is far more common that it just doesn't seal anymore and makes it easy to diagnose a bad master cylinder. but when it seals sometimes or most of the time it's tough. you could try this: stab the brake pedal every time you hit the brakes, I don't mean mash it to the floor, I mean slap your foot on it hard and fast at first then go slow (get an impact on the pedal but with no force behind it). if it is the same every time and doesn't play wishy washy bs then I would say for sure it is the master cylinder.
Jun 1, 2018 | 08:08 PM
#6
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From: Alaska
Jun 2, 2018 | 08:18 AM
#7
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From: Frederick, MD
So the pedal is completely normal, firm, and stops every time once you get thru half the travel. The intermittent issue is whether the pedal squishes down thru the first half of the travel or wether I get stopping power thru the first half. That is the inconsistency.
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Jun 2, 2018 | 11:22 AM
#8
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Joined: May 2009
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From: Moscow, ID
My 83 pickup used to do this with the clutch. The longer I drove it, the less pedal response I had. Turned out the rubber section of line attached to my firewall heading to my slave cylinder was breaking down inside, causing fluid to enter the layers of the hose without fully engaging my clutch. fluid levels looked fine, but there wasn't enough pressure to move the slave cylinder because it was easier for the fluid to expand inside the rubber. Take a look at all of your brake lines and look for obvious wear, unusually soft brake hoses, and places where they look like the rubber has been stressed, stretched, and damaged. It might not be the issue, but worth looking.
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