Brakes suddenly very spongy while driving

jackdog1

New Member
This isn't something I need solved, I'm just posting this in case anyone else has the same problem.

I had replaced my front rotors and pads a month ago, but had accidentally undone the driver's side brake line connector bolt, spilling a bit of brake fluid and apparently letting some bubbles in to the line. I bled the affected line, pumping the brakes several times, and several bubbles came out, but the brakes never felt quite as tight as before.

Earlier today, I was driving when the brakes suddenly became very spongy and the brake pedal had to be pushed almost all the way to stop the car. I bled the same brake again, and an air bubble immediately came out. Afterwards, the brakes were as tight as when I first bought it. What I figured out later was that the last bubble was trapped in the piston, and worked its way into the line while I was driving, causing the sudden pressure drop.

So if anyone has a similar issue with the pressure dropping in the middle of driving, instead of assuming something like a cracked piston or ruptured break line, just try simply bleeding the brake again (pump it at least 4 times, topping of the fluid in between).

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Last edited:

Diana Nam

Respected
Registered VIP
This isn't something I need solved, I'm just posting this in case anyone else has the same problem.

I had replaced my front rotors and pads a month ago, but had accidentally undone the driver's side brake line connector bolt, spilling a bit of brake fluid and apparently letting some bubbles in to the line. I bled the affected line, pumping the breaks several times, and several bubbles came out, but the brakes never felt quite as tight as before.

Earlier today, I was driving when the brakes suddenly became very spongy and the brake pedal had to be pushed almost all the way to stop the car. I bled the same brake again, and an air bubble immediately came out. Afterwards, the brakes were as tight as when I first bought it. What I figured out later was that the last bubble was trapped in the piston, and worked its way into the line while I was driving, causing the sudden pressure drop.

So if anyone has a similar issue with the pressure dropping in the middle of driving, just try simply bleeding the brake again (pump it at least 4 times, topping of the fluid in between).

Sent from my XT1064 using Tapatalk
thats usually why you bench bleed those first before putting it on.
 


HeX

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These are the basics of brake (nit break) bleeding, so you're nit posting anything new. This is pointless.
 

jackdog1

New Member
These are the basics of brake (nit break) bleeding, so you're nit posting anything new. This is pointless.
I just thought it might be helpful to anyone who had their brake pressure drop right in the middle of driving for no apparent reason.

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HeX

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Well, there was an obviously apparent reason that just a brief search online wouldve answered.
 

jackdog1

New Member
Well, there was an obviously apparent reason that just a brief search online wouldve answered.
Alright, sorry for posting a "pointless" post. Just trying to be helpful.

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