[shadowx360]

Originally Posted by feuer

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.

Yep, he already told me the options for INPA and I've used INPA/NCSEXPERT for years for other stuff. Saved me $1200 when the dealer wanted to replaced the FRM module even though all it needed was a reset with INPA and $2000 for coding in a new TCU unit.

Originally Posted by ajaye

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.

No, I did not press the brakes at all after I turned it off. I just jacked it up and pulled the caliper brackets off. I was able to use a C clamp to easily push in the front and back pistons to get them to slide back onto the rotors.

As for the comment about the brake lines, I pumped the brakes till the pistons were entirely pushed out of the boots, and then popped the pistons out for an overnight clean. When I woke up the next day, I saw that the master reservoir didn't have any liquid above the filter and my brake pedals were super numb even after filling with 1L and then flushing with another 2L. I was thinking about the ABS module since I couldn't feel any pumping of the brakes even though I slammed the pedal as hard as I could, though I thought it could have been just the soft pedal not giving any feedback. Like I said before, I flushed it with another 3 liters a week later and I've had the same pedal feel (including the pulsing of ABS/automatic windshield wipers) since then. I often check the brake fluid levels and they never went down any, so I would guess that no air (if present), has escaped since that time.

Originally Posted by ajaye

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.

Yes, I do not know where to attribute this phenomenon. My friend has both an E9X and an E6X and he told me that my brakes are "super weird." The first inch has no absolutely no effect, but as soon as the pedal turns hard, the brakes turn into straight clamps. It makes creeping up in traffic/slow parking impossible, I either have locking-up-the-seatbelt grip or zero grip. However, the combination of HPS pads, slotted rotors, and Michelin PSS tires allow my car to to 60-0 in a shorter distance than his GT500.

[feuer]

Originally Posted by ajaye

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.

Alright, not to start a fire but let me copy past and high light some thing else for you:
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?

Respectfully Ajaye, even if you are right the OP still need to start by bleeding the brakes properly and that is by activating the ABS pump, period.
Since all the brake fluid was drained.

Back in the day when I lived in Europe and didn't have access to computers to work on cars we were tricking the ABS system by "driving" the car up on the lift so the ABS would think the wheels are loosing traction and kick in. That way all the air trapped in the pump will be pushed to the calipers.

Honestly, is nothing new.

Let the OP try it out. If that doesn't help next would be looking into the pads he has and lastly what you are talking about.

[shadowx360]

Originally Posted by feuer

Alright, not to start a fire but let me copy past and high light some thing else for you:
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?

Respectfully Ajaye, even if you are right the OP still need to start by bleeding the brakes properly and that is by activating the ABS pump, period.
Since all the brake fluid was drained.

Back in the day when I lived in Europe and didn't have access to computers to work on cars we were tricking the ABS system by "driving" the car up on the lift so the ABS would think the wheels are loosing traction and kick in. That way all the air trapped in the pump will be pushed to the calipers.

Honestly, is nothing new.

Let the OP try it out. If that doesn't help next would be looking into the pads he has and lastly what you are talking about.

I finally got around to bleeding the brakes using INPA. I saw a few air bubbles on the rear brakes. Ran the cycles twice just in case and in the end all the fluid that came out looked fresh, meaning all of the fluid was replaced. I'm afraid the top bit of the brake pedal still has no effect, but the initial bite from the pads is even greater now, so it's literally become impossible to park or creep forward without jerking the car or getting that grinding sound towards the end of coming to a stop, when the pads are almost locked on, but not quite. I threw on as much CRC Disc Brake Quiet lube as I can on the contact surfaces. The small bit of squeak I used to hear is gone, but now I hear that grind at the end unless I tap the brakes a little bit harder, at which point the car feels like it crashed into something. I'm not sure what to do, I don't want to downgrade to crappy pads just get that smoothness and the grind out.

I also verified all the pads and calipers aren't stuck nor are they retracting in ward.

[feuer]

Originally Posted by shadowx360

I finally got around to bleeding the brakes using INPA. I saw a few air bubbles on the rear brakes. Ran the cycles twice just in case and in the end all the fluid that came out looked fresh, meaning all of the fluid was replaced. I'm afraid the top bit of the brake pedal still has no effect, but the initial bite from the pads is even greater now, so it's literally become impossible to park or creep forward without jerking the car or getting that grinding sound towards the end of coming to a stop, when the pads are almost locked on, but not quite. I threw on as much CRC Disc Brake Quiet lube as I can on the contact surfaces. The small bit of squeak I used to hear is gone, but now I hear that grind at the end unless I tap the brakes a little bit harder, at which point the car feels like it crashed into something. I'm not sure what to do, I don't want to downgrade to crappy pads just get that smoothness and the grind out.

I also verified all the pads and calipers aren't stuck nor are they retracting in ward.

Oh, wow, that's not good. You had some air in the system but although is properly bled know that didn't affect the dead pedal travel.
Only think I can think off is either the brake pedal itself or the master cylinder.

[PhaseP]

It makes me think something wrong with brake booster. It is not getting boost for the first inch and then comes in full effect, locking up the brakes. Though if it was not touched why it would start acting up after some other work...

[feuer]

Originally Posted by PhaseP

It makes me think something wrong with brake booster. It is not getting boost for the first inch and then comes in full effect, locking up the brakes. Though if it was not touched why it would start acting up after some other work...

I think that something might have happen when the brake pedal was pressed continuesly with the brake lines disconnected. It will definetely require more investigation. A competent shop should be able to diagnose it

[feuer]

Originally Posted by shadowx360

I'm afraid the top bit of the brake pedal still has no effect

Any updates on this issue?

[ajaye]

I am also curious. I didn't think anyone would wanna punish themselves by letting the system run dry so sorry for incorrect assumption. I just finished the same job and I was getting pretty excessive knock-back (swapped on different wheels/tires at the same time) causing similar excessive pedal travel. A proper balance cured it immediately but if it happens even when you're crawling/parking that's not your issue.

Replacing the springs on all four calipers vs. re-using my 80k mile springs also made a noticeable improvement in pedal feel for me. My fronts were especially deformed/under-sprung. Hope you can get it figured out.

[feuer]

Originally Posted by ajaye

Replacing the springs on all four calipers

What? Bushings and slide/guide pins you mean?

[ajaye]

Originally Posted by feuer

What? Bushings and slide/guide pins you mean?

See description for #2 were its referred to as "retaining spring" yet move down to #12 and its "clip"

http://www.realoem.com/bmw/enUS/show...diagId=34_2249

[PhaseP]

The main mechanism for the pads to retract after application of brake is the square cut o-ring seal around the piston. Very simple yet effective solution:

[feuer]

Originally Posted by ajaye

See description for #2 were its referred to as "retaining spring" yet move down to #12 and its "clip"

http://www.realoem.com/bmw/enUS/show...diagId=34_2249

that is just a atni rattle spring. has noting to go with the OP issue not retracting the brakes pads

[feuer]

Originally Posted by PhaseP

The main mechanism for the pads to retract after application of brake is the square cut o-ring seal around the piston. Very simple yet effective solution:

I know and some high tech calipers have actual springs behind the piston. Brakes need to be fast on and fast off. BMW OEM brakes have non of that.

[ajaye]

Originally Posted by feuer

that is just a atni rattle spring. has noting to go with the OP issue not retracting the brakes pads

I know you know everything, but if the caliper slides on pins, the pins attach to the carrier, and the spring is exerting force on both the caliper and the carrier, then physics would beg to differ with you.

Anti-Rattle Clips: Heating and cooling cycles can weaken springs and anti-rattle clips. Weak parts can result in excessive caliper/pad movement or binding causing noise and other related problems. This can lead to uneven and premature pad wear, rotor wear and pulling. On some floating calipers, the most neglected piece of hardware is the clip in the bridge. - See more at: http://www.knowyourparts.com/technic....1Y0Ah93Z.dpuf

http://www.bimmerforums.com/forum/sh...chanic-stumped

I wanted to resurrect this thread to hopefully help others encountering this problem.


I was experiencing the same issues after a recent caliper swap out. Excessive pedal travel. Similar spongy feel. I had plenty of braking power when the pedal finally engaged. I also noticed that the car was not pulling to one direction or the other while braking, which I have noticed in the past when dealing with air in the brake system on pervious non-BMW vehicles.
It turned out that the problem was actually quite simple and perhaps easy to overlook. The SPRING CLIP on the new caliper was not installed correctly. Apparently there are two ways you can install it and have it stay in. The way it was incorrectly installed did not provide enough tension to prevent the caliper piston from retracing too far back inside the caliper. This caused all the symptoms and I could visually see excessive movement while my helper engaged and released the brakes. Reinstalling the spring clip correctly solved all the issues and the car was back to normal at no cost.


I hope this helps someone else down the line. It can really boggle your mind for quite awhile thinking of all these complex possible problems that may or may not fix it. I felt foolish for installing the clip wrong but overjoyed when discovering how easy it was to fix.

[feuer]

Originally Posted by ajaye

I know you know everything, but if the caliper slides on pins, the pins attach to the carrier, and the spring is exerting force on both the caliper and the carrier, then physics would beg to differ with you.

The spring forces are radial and the caliper movements are are lateral, so whether I know everything or not is moot argument since the physics would disagree with you.

[techwhiz]

Originally Posted by feuer

The spring forces are radial and the caliper movements are are lateral, so whether I know everything or not is moot argument since the physics would disagree with you.

Agree with you.
It's just a rattle reducer. You can run without that thing.

[ajaye]

Originally Posted by feuer

The spring forces are radial and the caliper movements are are lateral, so whether I know everything or not is moot argument since the physics would disagree with you.

This is quite possibly the most idiotic thing I've read all week. For one, to say forces applied in different directions have no effect on one another is just plain asinine. Furthermore, there IS lateral force created by the spring on the carrier, its called FRICTION. For someone that did there first brake job in the 90s or whatever, you have a frightfully poor understanding of how these parts work in conjunction with one another.

Originally Posted by techwhiz

Agree with you.
It's just a rattle reducer. You can run without that thing.

Your own response is a contradiction. How would rattle happen without the clip present? Answer: Improper clearance created from the lack of RETAINing spring. What happens when there is additional clearance between these parts when you step on the pedal??? Riiiiiiight, increased pedal travel to take up that clearance. But how about you do me a favor, take all four off, go for a spirited drive and report back.

[Cloud9blue]

The retainer clip holds the position of the sliding caliper in place, so to prevent any pad movements, which can causes rattles and excess noise. A loos clip could cause a soft pedal as well, but that also means your brake guide and the guide bushings are getting a little too loose. I would check with that as well.

From my experience, if you are sure that your lines are properly bleed with no air in the system, a soft pedal can only be two things, unevenly worn/tapered brake pads and/or worn brake guide bushings.

For example, I replaced the stock rubber guide bushings with solid brass ones this year, which drastically improve the pedal feel and eliminated the so called few mm of "dead-zone" at the top of the pedal travel. However, with the crappy stock sliding caliper system, I would still end up with a slightly softer pedal if my track pads are more than 1/2 worn. With single piston sliding calipers on our car, pads tend to develop a slight taperer shape relatively to the rotor surface, when it is subjected to repeated hard braking like my car sees on the track. As a result, the brake pistons have to travel a bit more than before the entire pad surface come in contact with the brake rotor, which translate to a softer top of the pedal feel when you apply the brake.

Hope this helps.

[feuer]

Originally Posted by ajaye

This is quite possibly the most idiotic thing I've read all week. its called FRICTION. For someone that did there first brake job in the 90s or whatever, you have a frightfully poor understanding of how these parts work in conjunction with one another.

friction force vs pressure force. I will not be a condescending jerk and will let you decide which one is applied and whether it will retract the piston back.

[juld0zer]

I noticed OP mentioned they applied CRC brake quiet 'lube' on all contact surfaces.
That is not a lubricant, in fact it is quite the opposite and works quite well as an adhesive.

OP can you please clarify where you applied this compound? In the caliper carrier/bracket, under the ears of the pads or just the back of the pads only?

[shadowx360]

Originally Posted by ajaye

I am also curious. I didn't think anyone would wanna punish themselves by letting the system run dry so sorry for incorrect assumption.

Helpers and I spent too much time eating and drinking and sun went down before we could finish the job. But yes, for future reference, don't leave the system dry overnight, brake fluid will corrode through your wheels if you do.

Originally Posted by Cloud9blue

For example, I replaced the stock rubber guide bushings with solid brass ones this year, which drastically improve the pedal feel and eliminated the so called few mm of "dead-zone" at the top of the pedal travel.

I will do that when I do my brakes again this summer. Thanks. I found some on EBay but they say ATE calipers only. Mine are stock. Did the ones you use say ATE calipers only?

Originally Posted by juld0zer

I noticed OP mentioned they applied CRC brake quiet 'lube' on all contact surfaces.
That is not a lubricant, in fact it is quite the opposite and works quite well as an adhesive.

OP can you please clarify where you applied this compound? In the caliper carrier/bracket, under the ears of the pads or just the back of the pads only?

Back of the pads where the back of pads and carrier/bracket touched. Tried my best to limit it to where it contacted the carrier/bracket so my calipers wouldn't look orange afterwards.

Originally Posted by feuer

Any updates on this issue?

It's been two years and issue didn't go away. Brakes saved me in quite a few spots so I don't think it's a safety issue but still annoying. I'm planning on doing them again this summer and replacing all rotors, pads, and retaining clips, and replacing guide bushings with brass ones. I'll probably just bleed it with INPA this time.

[JJaber]

I'm having this issue as well. Had my fluid flushed @ the dealer and that didn't really help. I honestly didn't think it was that bad until I drove my dads 535 the other day and felt how smooth and gradual the braking was. My brake pedal is beginning to feel more like an on/off switch (okay, not that bad but definitely not as linear as the 535).