My brake pedals don't feel great anymore. It feels mushy and not as firm as when I first got my new brake kit. Would a brake fluid flush help?
Brake pedal feel
- Thread starter Seraphitia102
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nyuk98gt
15 Year Member
Seraphitia102:
Your technician/mechanic probably knows to do this but the master cylinder should be bled (2 bleed screws on the engine side) after the four corners are bled. A brake system flush every 2 years is not a bad idea, imho.
HTH,
Chris
Your technician/mechanic probably knows to do this but the master cylinder should be bled (2 bleed screws on the engine side) after the four corners are bled. A brake system flush every 2 years is not a bad idea, imho.
HTH,
Chris
Thanks 
I'm going to a mechanic today to get this done. I'll inquire as to whether or not the master cylinder is bled as well.
I'm going to a mechanic today to get this done. I'll inquire as to whether or not the master cylinder is bled as well.
Thanks
did the flush solve the mushy feelings?
my car does this , but not all the time. pedal feels spongy and can actually hear it creaking. still stops fine but doesnt feel as firm.
Unfortunately it only made a modest difference. I do notice a slightly better pedal feel but sadly it wasn't what I was looking for. When I had my 2 piston Cobra brake kit, the pedal firmness was much better. My SSBC 4 piston kit had an excellent pedal feel when I first got them but 3 years later... the pedal feels mushy.
warment
Founding Member
trinity_gt
10 Year Member
A few thoughts:
A "mushy" pedal can generally be brought on by three things:
You've bled the lines and hopefully have gotten all of the air out of the system ruling out point 1.
An external leak would be obvious and evidence by brake fluid on the ground. Assuming you don't see any you can rule out that. Internal leaks are trickier because they don't leave any evidence with the exception of reduced braking feel and performance. A leak occurs across the seals of the master cylinder, for instance, where fluid from the high pressure side leaks past an O-ring and gets back into the reservoir. This generally results in a pedal that is soft but also one that sinks slowly as pressure is maintained. The cause is often bad seals or corrosion in the bore of the master cylinder. This can happen if water gets into the fluid and it's left there for extended periods (e.g. winter storage months...)
Mechanical deformation occurs when parts give and bend. Pressure that would have gone into pressing a brake pad against a rotor instead goes to deforming something. Modern brake systems are pretty robustly constructed (though it's worth inspecting brackets, sliders, mounts and the like) but one thing that can "give" is brake lines. They can expand when pressure builds, resulting in a mushy brake pedal feel. It may be a sign that a brake line is on the verge of bursting so get it inspected... Other parts can mechanically deform too: The hydroboost and master cylinder mount to the firewall. Make sure it's not deforming or bending in response to pedal pressure.
One other thing that can mimic mechanical deformation is bad wheel bearings. If the rotor is wobbling due to a worn wheel bearing it can push the pads away from the rotors a bit, leading to an initially mushy feel and extended pedal travel when you get on the brakes.
A "mushy" pedal can generally be brought on by three things:
- something compressible in the lines (like air)
- internal or external leakage
- mechanical deformation in response to hydraulic forces
You've bled the lines and hopefully have gotten all of the air out of the system ruling out point 1.
An external leak would be obvious and evidence by brake fluid on the ground. Assuming you don't see any you can rule out that. Internal leaks are trickier because they don't leave any evidence with the exception of reduced braking feel and performance. A leak occurs across the seals of the master cylinder, for instance, where fluid from the high pressure side leaks past an O-ring and gets back into the reservoir. This generally results in a pedal that is soft but also one that sinks slowly as pressure is maintained. The cause is often bad seals or corrosion in the bore of the master cylinder. This can happen if water gets into the fluid and it's left there for extended periods (e.g. winter storage months...)
Mechanical deformation occurs when parts give and bend. Pressure that would have gone into pressing a brake pad against a rotor instead goes to deforming something. Modern brake systems are pretty robustly constructed (though it's worth inspecting brackets, sliders, mounts and the like) but one thing that can "give" is brake lines. They can expand when pressure builds, resulting in a mushy brake pedal feel. It may be a sign that a brake line is on the verge of bursting so get it inspected... Other parts can mechanically deform too: The hydroboost and master cylinder mount to the firewall. Make sure it's not deforming or bending in response to pedal pressure.
One other thing that can mimic mechanical deformation is bad wheel bearings. If the rotor is wobbling due to a worn wheel bearing it can push the pads away from the rotors a bit, leading to an initially mushy feel and extended pedal travel when you get on the brakes.
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