Spongy Brake Pedal - Please help

[TJ Jim]

So back to the original post? Since he is sure the system is bled, master cylinder?

 

[KennethS]

Was always curious if the scrap bottle was necessary. Haven’t done it often enough to confirm it one way or the other.
Next bleed I’ll omit the scrap bottle.

I use one so brake fluid doesn’t end up all over the garage floor.

 

[olysan]

A few things for you. The reason we call it "bench bleeding" the master is because it really needs to be done in a vise. The circulating hose method tells you nothing. You need to do the plugged port method and all your corner bleeding needs to be done with the ignition on so you can watch for the brake light to come on if the shuttle valve gets shifted.

But, before we get there, when is the pedal spongy and what are you comparing that to? You said the problem is pre-existing, what and when was it doing the spongy pedal thing?

FYI- no, not the booster, a bad booster produces the opposite of spongy, the pedal will be high and hard since there is no vacuum assist.

The pedal is spongy when the vehicle is running. The braking force is also very weak. I’m running 32” tires. The brakes were weak compared to my 2023 daily driver SUV before the rebuild and they’re worse now.

 

[macleanflood]

I usually just gravity bleed my brakes. Make sure there's enough fluid in the reservoir and let it drip out one wheel at a time. Slow and easy. Get all the old contaminated fluid out. I thought that was what @TJ Jim was describing.

Usually need a repeat a day or so later too.

-Mac

 

[TJ Jim]

I usually just gravity bleed my brakes. Make sure there's enough fluid in the reservoir and let it drip out one wheel at a time. Slow and easy. Get all the old contaminated fluid out. I thought that was what @TJ Jim was describing.

Usually need a repeat a day or so later too.

-Mac

Nope. Pump the pedal just like a two man bleed. Gonna try the gravity bleed someday

 

[mrblaine]

Was always curious if the scrap bottle was necessary. Haven’t done it often enough to confirm it one way or the other.
Next bleed I’ll omit the scrap bottle.

No, you need the collection bottle to keep the fluid from going everywhere, you just don't need to start with the end of the hose under fluid. And, if it wasn't that way, we'd never be able to fill empty calipers by gravity bleeding.

 

[speeding_infraction]

The pedal is spongy when the vehicle is running. The braking force is also very weak. I’m running 32” tires. The brakes were weak compared to my 2023 daily driver SUV before the rebuild and they’re worse now.

You need to bench bleed the master cylinder using the method below. I had this I exact issue on my jeep and was able to fix it by bench bleeding my MC using the plugged port method.

https://wranglertjforum.com/threads/brake-questions.91383/#post-1955534

 

[olysan]

You need to bench bleed the master cylinder using the method below. I had this I exact issue on my jeep and was able to fix it by bench bleeding my MC using the plugged port method.

https://wranglertjforum.com/threads/brake-questions.91383/#post-1955534

I’m going to give this a shot next week.

You need to bench bleed the master cylinder using the method below. I had this I exact issue on my jeep and was able to fix it by bench bleeding my MC using the plugged port method.

https://wranglertjforum.com/threads/brake-questions.91383/#post-1955534

 

[TJ Jim]

Keep us in the loop

 

[dbbd1]

Did we ever determine if the bleed port is at the top of the caliper (correct) or at the bottom of the caliper(incorrect)?

 

[olysan]

Did we ever determine if the bleed port is at the top of the caliper (correct) or at the bottom of the caliper(incorrect)?

Bleed ports at the top. Today I pulled the Master Cylinder and did a bench bleed. Then I reinstalled and bled the entire system. It’s definitely drivable now, but I’m still not happy with where it’s at.