[shadowx360]

Hey guys, about a year ago I replaced my rotors, pads, and caliper piston seals. That involved leaving the brake lines drained overnight so the next day I filled the master reservoir and pulled about 2 liters of brake fluid through. The brakes felt mushy and soft, so the next week I manually flushed another 3 liters of fluid through the system by pressing the brake pedal, applying a vacuum to the end of the bleeder screw, and loosening the screw, and repeat.

It's been a year since then, and I'm still having a problem with the top 1 inch of the brake pedal feeling very soft. That top 1" does not actually brake at all, my car does not slow down. After that portion, the pedal gets rock solid and my 60-0 stops today are shorter than they were before I did all this brake work. Does anyone have any ideas on what is causing this softness? Like I said, I've flushed over 5 liters of fluid so I don't think flushing any more is going to help.I was very careful in not letting any air back inside the screws when the pedal was released, and I didn't see any air at all for the last 2 liters of fluid.

[feuer]

Bleed the system by activating the abs pump. You will need BMW software for that. INPA has that feature and is inexpensive.

[feuer]

Additionally, initial bite depends from the pads. OEM have great initial bite. Aftermarket not so much.

[Stream]

Have the same problem (with oem bmw pads)
My brake system was bleeded 2 years ago by pressing brake pedal method. I hope next time activating ABS pump will help.

[zero2sixtyZ]

Originally Posted by feuer

Bleed the system by activating the abs pump. You will need BMW software for that. INPA has that feature and is inexpensive.

Is there a DIY on this? Similar to the automatic coolant bleeding? Wondering how babysitting the reservoir works.

[feuer]

Originally Posted by zero2sixtyZ

Wondering how babysitting the reservoir works.

I'm not sure what exactly do you mean by babysitting?

[Volasko]

Originally Posted by zero2sixtyZ

Is there a DIY on this? Similar to the automatic coolant bleeding? Wondering how babysitting the reservoir works.

The automatic coolant bleeding is done through a series of pedal inputs and timing steps. To activate the abs module you need IPNA software and the proper coding cable. I'm having the same problem with pedal feel and hope that getting a proper shop bleed the lines with the abs module activated will help.

[Jeff@TopGearSolutions]

Originally Posted by feuer

I'm not sure what exactly do you mean by babysitting?

I think it was an auto correct for bypassing. Cell phone life haha.

To the OP, if bleeding doesn't work, initial pedal feel also has to do with the pads and the lines. Consider upgrading to stainless steel braided lines, that will improve pedal feel for sure.

Originally Posted by Jeff@TopGearSolutions

I think it was an auto correct for bypassing. Cell phone life haha.

To the OP, if bleeding doesn't work, initial pedal feel also has to do with the pads and the lines. Consider upgrading to stainless steel braided lines, that will improve pedal feel for sure.

He might have meant "how do you go through the INPA bleed procedure and make sure the abs reservoir doesn't go dry?" Hence, babysitting.

[shadowx360]

Originally Posted by feuer

Bleed the system by activating the abs pump. You will need BMW software for that. INPA has that feature and is inexpensive.

I have INPA, and I found the thread:
http://www.e90post.com/forums/showthread.php?t=598994

The info is a bit confusing though, which option/jobs do I execute? There are tests, pre-bleeding, etc.

Originally Posted by Jeff@TopGearSolutions

To the OP, if bleeding doesn't work, initial pedal feel also has to do with the pads and the lines. Consider upgrading to stainless steel braided lines, that will improve pedal feel for sure.

I've thought about that, but I'm running Hawk HPS ceramic pads and they feel fine in a friend's E92.

[feuer]

Originally Posted by Jeff@TopGearSolutions

if bleeding doesn't work, initial pedal feel also has to do with the pads and the lines.

I already brought the pads factor up in post #3

Originally Posted by shadowx360

I've thought about that, but I'm running Hawk HPS ceramic pads and they feel fine in a friend's E92.

also depends of the rotors your friend is using the the way the brakes were broken in, bedded in.

[feuer]

The info is a bit confusing though, which option/jobs do I execute? There are tests, pre-bleeding, etc.


PM'ed

[zero2sixtyZ]

Originally Posted by FCobra94

He might have meant "how do you go through the INPA bleed procedure and make sure the abs reservoir doesn't go dry?" Hence, babysitting.

This is what I meant. Making sure the fluid stays in the reservoir while the ABS unit vibrates/bleeds the air out.

I've used the Motive bleeder but I feel like the pedal isn't as firm as before.

[feuer]

Originally Posted by zero2sixtyZ

This is what I meant. Making sure the fluid stays in the reservoir while the ABS unit vibrates/bleeds the air out.

I've used the Motive bleeder but I feel like the pedal isn't as firm as before.

You don't have to do nothing but activating the abs pump and bleeding the calipers one by one. Just like old fashion pump the brake pedal procedure to bleed the system

[ajaye]

Sorry guys but if the reservoir was kept full and no one was stomping on the big pedal while the lines were disconnected, I'm not seeing any way the ABS bleed procedure is going to make a difference in the deal travel issue OP is having.

OP, If you replaced the caliper seals and/or, specifically, the dust boots, that would be where I would look next. I've read of people installing boots that were for whatever reason not to spec (even though they were the correct part), and they were actually pulling too tightly on the piston and drawing it back into the caliper too far at rest. The result is dead travel in the pedal until the piston reaches contact with the pad again, then completely normal operation.

If this ends up being your issue, you might consider just replacing the calipers. The Centric premium re-manufactured are like $50 after core charge on Rockauto, they rebuild the original BMW/ATE casting and use a new piston. I would just be concerned that driving around in the elements with the piston staying significantly drawn back from the pad may have allowed a bunch of crud to collect inside the piston cylinder and on the piston face/rim. Hope this may help.

[feuer]

Originally Posted by ajaye

Sorry guys but if the reservoir was kept full and no one was stomping on the big pedal while the lines were disconnected, I'm not seeing any way the ABS bleed procedure is going to make a difference in the deal travel issue OP is having.

OP, If you replaced the caliper seals and/or, specifically, the dust boots, that would be where I would look next. I've read of people installing boots that were for whatever reason not to spec (even though they were the correct part), and they were actually pulling too tightly on the piston and drawing it back into the caliper too far at rest. The result is dead travel in the pedal until the piston reaches contact with the pad again, then completely normal operation.

If this ends up being your issue, you might consider just replacing the calipers. The Centric premium re-manufactured are like $50 after core charge on Rockauto, they rebuild the original BMW/ATE casting and use a new piston. I would just be concerned that driving around in the elements with the piston staying significantly drawn back from the pad may have allowed a bunch of crud to collect inside the piston cylinder and on the piston face/rim. Hope this may help.

let me copy paste and highlight some of the text for you :

Top of Brake Pedal Soft
Hey guys, about a year ago I replaced my rotors, pads, and caliper piston seals. That involved leaving the brake lines drained overnight so the next day I filled the master reservoir and pulled about 2 liters of brake fluid through. The brakes felt mushy and soft, so the next week I manually flushed another 3 liters of fluid through the system by pressing the brake pedal, applying a vacuum to the end of the bleeder screw, and loosening the screw, and repeat.

[shadowx360]

Originally Posted by ajaye

OP, If you replaced the caliper seals and/or, specifically, the dust boots, that would be where I would look next. I've read of people installing boots that were for whatever reason not to spec (even though they were the correct part), and they were actually pulling too tightly on the piston and drawing it back into the caliper too far at rest. The result is dead travel in the pedal until the piston reaches contact with the pad again, then completely normal operation.

Hey, I understand this, but when I took apart my brakes a few weekends ago for a quick inspection after leaving it overnight, all the calipers were still pretty tightly clamped to the rotors and I needed a rubber mallet to remove the bracket. I assume that means the calipers aren't retracting too far inward?

[feuer]

Originally Posted by shadowx360

Hey, I understand this, but when I took apart my brakes a few weekends ago for a quick inspection after leaving it overnight, all the calipers were still pretty tightly clamped to the rotors and I needed a rubber mallet to remove the bracket. I assume that means the calipers aren't retracting too far inward?

...and they will not retract that far inward. I did the first brake job in the early 90's and I'm yet to see a caliper piston do that and have done many brakes since.
If that is happening I would explain the brakes as slow not soft. Brakes need to be fast on and fast off. I hope you understand.

Anyhow...

Try the INPA. I was the the very first guy who installed F30 Brembos on all corners.

Also first guy who swap the master brake cylinder with a unit from an m3

Search and you will find some of my posts (many were deleted though)

If the INPA helped me why it should not help you?

Not properly bled system and pads with low initial bite are main reason for soft pedal.

[shadowx360]

Originally Posted by feuer

...and they will not retract that far inward. I did the first brake job in the early 90's and I'm yet to see a caliper piston do that and have done many brakes since.

Anyhow...

Try the INPA. I was the the very first guy who installed F30 Brembos on all corners.

Also first guy who swap the master brake cylinder with a unit from an m3

Search and you will find some of my posts (many were deleted though)

If the INPA helped me why it should not help you?

Not properly bled system and pads with low initial bite are main reason for soft pedal.

Thank you so much for your advice. I'm just waiting on getting some free time next weekend so a friend can come over and help me bleed the brakes. Don't reckon one person can possibly work both INPA and the brake screws at the same time?

[feuer]

Originally Posted by shadowx360

Thank you so much for your advice. I'm just waiting on getting some free time next weekend so a friend can come over and help me bleed the brakes. Don't reckon one person can possibly work both INPA and the brake screws at the same time?

You can but takes a lot of running around the car. Besides, is good reason to hang with your friend and get the grill going and open few cold beers.

Cloud9blue help me twice.

When I installed the f30 brembo brakes and then again when I installed the master brake cylinder.

Genuinely nice guy. Reach out to him if you need help with the INPA since I'm not the most computer savvy person.

[ajaye]

Originally Posted by shadowx360

Hey, I understand this, but when I took apart my brakes a few weekends ago for a quick inspection after leaving it overnight, all the calipers were still pretty tightly clamped to the rotors and I needed a rubber mallet to remove the bracket. I assume that means the calipers aren't retracting too far inward?

Probably not, but did you by chance push the brake pedal at all after you shut the car off but before checking? You checked the rears right? All 4 pistons still moving freely?

Can you also clarify the bold in the excerpt of your original post above? Did you actually remove the calipers, drain the brake system, leave it overnight, then fill a completely empty MC reservoir? I kind of just assumed by "leaving the lines drained overnight," you mean "draining" like disconnected.

[ajaye]

Originally Posted by feuer

...and they will not retract that far inward. I did the first brake job in the early 90's and I'm yet to see a caliper piston do that and have done many brakes since.
If that is happening I would explain the brakes as slow not soft. Brakes need to be fast on and fast off. I hope you understand.

Lemme copy paste and highlight some of the text for you

That top 1" does not actually brake at all, my car does not slow down. After that portion, the pedal gets rock solid and my 60-0 stops today are shorter than they were before I did all this brake work.