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      09-06-2011, 07:48 PM   #1
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Help! Soft brake pedal after pad change.

Changed all 4 pads out (to Pagid-19s) yesterday for track event next weekend and now have soft brake pedal--actually, feels like mostly more travel to floor, not necessarily spongy, but feels terrible! I did NOT bleed this time, having done a full flush last month for track day. Brake fluid reservoir is topped off at max level with Motul 600.

It's the bleed isn't it? I should just do it, right?

But there's no way I could have intrduced air into the system by just changing the pads. It's definitely different than before though. I also haven't bedded them in yet.

Anything else it could be?

Thanks.
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      09-06-2011, 08:13 PM   #2
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I would start with a bleed, its most likely the problem. At the very least its probably the best place to start when looking at brake issues. Bedding shouldn't affect pedal travel - it will change the bite and release.
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      09-06-2011, 08:29 PM   #3
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Do a proper bed in on the pads.I usually find that after a pad change that my pedal is not as good as when they have been bedded in properly.Failing that a good bleeding might be the fix.I usually do a bleed every 4-6 weeks during the track season.
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      09-06-2011, 08:34 PM   #4
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Thanks, those were the two things on top of my list, bleed and bed. We'll see...
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      09-12-2011, 12:34 PM   #5
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Sleeper519: How'd you make out w/the soft pedal? I just changed my brake pads this weekend to Cool Carbon pads and installed ATE Blue fluid. Pad install went smoothly, no rattles or squeaks, and the bedding process went well, also (great pad transfer onto the rotors w/good uniformity). However, after two very careful sequences of bleeding w/a Motive pressure bleeder, which has always produced great results...at least on my Porsche Cayman, I have a slightly soft pedal. It firms-up w/a few quick taps, so it appears to be air. Looking into it now, but was wondering your end results.

-Brian
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      09-12-2011, 03:48 PM   #6
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Quote:
Originally Posted by Sleeper519 View Post
Changed all 4 pads out (to Pagid-19s) yesterday for track event next weekend and now have soft brake pedal--actually, feels like mostly more travel to floor, not necessarily spongy, but feels terrible! I did NOT bleed this time, having done a full flush last month for track day. Brake fluid reservoir is topped off at max level with Motul 600.

It's the bleed isn't it? I should just do it, right?

But there's no way I could have intrduced air into the system by just changing the pads. It's definitely different than before though. I also haven't bedded them in yet.

Anything else it could be?

Thanks.
I run Pagid yellows and actually have a set on my car right now (was at track event last weekend). I'm not sure what you are feeling is abnormal especially if you are changing from stock BMW pads. Stock pads as soon as you depress the brake pedal it's firm/hard. Track pads (I've changed them in and out at least 6 times) always feel a bit spongy after you install them and this does not go away even with bleeding though it sounds like you should do this anyway. What I experience is the first 1/3 of the pedal travel is "spongy" and then it firms up, but it's never as rock hard as the stock pads. THE PEDAL SHOULD NOT GO TO THE FLOOR (OR CLOSE) HOWEVER. This is even when sitting in the garage, on the street you'll find that the braking is adequate, but when on the track and nicely warmed up you'll find that you have a nice, easy to modulate pedal (it still feels a bit spongy though). I think this is normal with these pads and I've never had a hard pedal with these pads and I've changed and flushed my brake fluid 3 times in the past 2 years, no change in pedal feel. Braking performance however is really excellent and consistent.
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      09-12-2011, 06:36 PM   #7
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Quote:
Originally Posted by Sleeper519 View Post
Thanks, those were the two things on top of my list, bleed and bed.
That's what she said...

Seriously, in regards to the brakes, bed first and then bleed.
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      09-12-2011, 08:25 PM   #8
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Quote:
Originally Posted by VictorH View Post
I run Pagid yellows and actually have a set on my car right now (was at track event last weekend). I'm not sure what you are feeling is abnormal especially if you are changing from stock BMW pads. Stock pads as soon as you depress the brake pedal it's firm/hard. Track pads (I've changed them in and out at least 6 times) always feel a bit spongy after you install them and this does not go away even with bleeding though it sounds like you should do this anyway. What I experience is the first 1/3 of the pedal travel is "spongy" and then it firms up, but it's never as rock hard as the stock pads. THE PEDAL SHOULD NOT GO TO THE FLOOR (OR CLOSE) HOWEVER. This is even when sitting in the garage, on the street you'll find that the braking is adequate, but when on the track and nicely warmed up you'll find that you have a nice, easy to modulate pedal (it still feels a bit spongy though). I think this is normal with these pads and I've never had a hard pedal with these pads and I've changed and flushed my brake fluid 3 times in the past 2 years, no change in pedal feel. Braking performance however is really excellent and consistent.
Thanks for that, Victor. I'm glad to know the Pagids can be that way. That describes pretty accurately what I experienced. BTW, were you at Road Atlanta this weekend for the HPDE?

I bedded the pads (3X) with some improvement. Then pressure bled them with Motive with also slight improvement. I've since been told that the old fashioned way of "friend-with-foot-on-the-pedal" bleeding provides better pressure for getting small air bubbles out.

Anyhoo, I ran great at the track event, had a blast, and proceeded to melt (seriously) my stock rotors from the heat. So I'm using my Search button to research BBKs... I see one in my near future, but damn $$$$!

This will certainly be my next thread. To be continued...
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      09-13-2011, 12:24 PM   #9
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Yes, was at Road Atlanta, nice weather and great time.

I think you and I have the same experience with the pads, it's not abnormal, it just feels different. I bet when you remove these pads and put your stock pads back, the pedal will again be as firm as you remember it. I really doubt you have any "micro-bubbles" or any air in your system for that matter.
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      09-13-2011, 12:33 PM   #10
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I would definitely recommend the old fashioned way of brake bleeding with someone pressing the pedal over the pressure bleeder.

When you replaced the pads, did you crack open the bleeder to let the brake fluid out?
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      09-13-2011, 02:15 PM   #11
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Z K, No, when I change pads I just muscle the piston back open, but never open the fluid system unless I'm going to bleed or flush (with the system pressurized).

Victor, Yes, great time at RA. Never saw so many E92 M3s at one event before! I saw your SC tag and meant to come over and meet you. Maybe next time.
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      09-13-2011, 03:56 PM   #12
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Yes, there sure were a lot of late model M3s. I was parked over by the registration shed next to Brian in a blue E90 M3, then a white '11 GT3 (driven by Steve a Road Atlanta regular) and a silver E92 M3 (that wasn't you was it?).

How did you fry your brakes (I've done it with stock pads but never Pagids and I've gotten those stinkin' hot before)? I never got mine all that hot that weekend and my instructor was encouraging me to "brake a little sooner and softer" for which I was not a good student and ignored.
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      09-13-2011, 04:30 PM   #13
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Quote:
Originally Posted by Sleeper519 View Post
Z K, No, when I change pads I just muscle the piston back open, but never open the fluid system unless I'm going to bleed or flush (with the system pressurized).

Victor, Yes, great time at RA. Never saw so many E92 M3s at one event before! I saw your SC tag and meant to come over and meet you. Maybe next time.
With ABS brakes, I would always open the bleeder when pushing the brake piston in. This makes sure you aren't forcing old and dirty brake fluid back through the ABS system valves and back to the master cylinder. I have noticed that the brake pedal will be mushy and low brake pedal engagement when I don't open the bleeder when pushing the piston in. Since then I have always opened the bleeder.

Google and you'll find a lot of articles regarding ABS system damage from pushing the piston in without opening the bleeder.

Here's one:
http://autorepair.about.com/library/a/1i/bl836i.htm
Another:
http://www.brakeandfrontend.com/Arti...irst_time.aspx
Quote:
There are a couple of things that are critically important when performing brake system service not only on Hondas, but on any car equipped with ABS. The days of pushing pistons back to replace pads without opening the bleeder valves are gone. The risk of pushing dirty fluid back into the ABS modulator is just too great to take the chance. Besides, you wouldn't perform a brake service without flushing and bleeding the system, so the bleeders will have to be opened anyway.
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      09-13-2011, 05:26 PM   #14
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Quote:
Originally Posted by Z K View Post
With ABS brakes, I would always open the bleeder when pushing the brake piston in. This makes sure you aren't forcing old and dirty brake fluid back through the ABS system valves and back to the master cylinder. I have noticed that the brake pedal will be mushy and low brake pedal engagement when I don't open the bleeder when pushing the piston in. Since then I have always opened the bleeder.

Google and you'll find a lot of articles regarding ABS system damage from pushing the piston in without opening the bleeder.

Here's one:
http://autorepair.about.com/library/a/1i/bl836i.htm
Another:
http://www.brakeandfrontend.com/Arti...irst_time.aspx
Thanks, Z, I will keep that in mind.

I'm not sure how that would lead to a soft pedal though, unless you are doing some permanent physical damage to the master cylinder. Most everybody I've talked to on this subject either uses a piston retraction tool , a large C-clamp, or slow manual traction (muscle). No one has mentioned opening the bleed valve. There seems potential to suck back air into the lines unless you've pressurized the system.
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      09-13-2011, 05:33 PM   #15
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Quote:
Originally Posted by VictorH View Post
Yes, there sure were a lot of late model M3s. I was parked over by the registration shed next to Brian in a blue E90 M3, then a white '11 GT3 (driven by Steve a Road Atlanta regular) and a silver E92 M3 (that wasn't you was it?)...
I was on the back row of the main paddock with 2 other local M3s (Jamie) and 2 more from TN. One was my instructor, who had a space gray coupe with the Dinan stroker engine in it. Rode with him a couple of sessions. What a beast! Plus he had Dinan stage 3 suspension, Dinan exhaust, ST trophy BBK, etc. Talk about a "sleeper"! He was seriously chewing an some of the GT3s there.
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      09-13-2011, 05:47 PM   #16
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Quote:
Originally Posted by VictorH View Post
...How did you fry your brakes (I've done it with stock pads but never Pagids and I've gotten those stinkin' hot before)? I never got mine all that hot that weekend and my instructor was encouraging me to "brake a little sooner and softer" for which I was not a good student and ignored.
Long story short. I was running Carbotech SP-10s on the rears and new Pagids RS19s on the front. Pagids bedded in great with beautifully burnished rotors. As the day progressed, felt increasing fade and brake judder (bad) so I started to ease off a little. They were literally smoking when I came in and the rotors had melted around the cross drilled holes. Instead of bing circles they were like crecent moons, partially filled in with molten metal from the rotor face. Driving home they felt and sounded terrible. I'm not sure if you can turn or lathe the face of these rotors or not, but if I have buy new ones, they will come in a BBK.
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      09-13-2011, 06:22 PM   #17
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Quote:
Originally Posted by Sleeper519 View Post
Thanks, Z, I will keep that in mind.

I'm not sure how that would lead to a soft pedal though, unless you are doing some permanent physical damage to the master cylinder. Most everybody I've talked to on this subject either uses a piston retraction tool , a large C-clamp, or slow manual traction (muscle). No one has mentioned opening the bleed valve. There seems potential to suck back air into the lines unless you've pressurized the system.
You open the bleeder valve and then push the piston in with the piston tool/c-clamp/muscle. You'll find that the piston will move very easily with little resistance and the extra fluid will come out the bleeder - make sure to attach your bleeder bottle. Tighten back up the bleeder when done pushing the piston and you're set. It is a good idea to bleed afterwards. Air won't get sucked in as you are pushing the fluid out by compressing the piston.
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      09-13-2011, 06:39 PM   #18
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Quote:
Originally Posted by Sleeper519 View Post
Long story short. I was running Carbotech SP-10s on the rears and new Pagids RS19s on the front. Pagids bedded in great with beautifully burnished rotors. As the day progressed, felt increasing fade and brake judder (bad) so I started to ease off a little. They were literally smoking when I came in and the rotors had melted around the cross drilled holes. Instead of bing circles they were like crecent moons, partially filled in with molten metal from the rotor face. Driving home they felt and sounded terrible. I'm not sure if you can turn or lathe the face of these rotors or not, but if I have buy new ones, they will come in a BBK.
You're going to be okay. Clearly you got your rotors hot, but the rotor holes are filled in with pad material. You can spray them with your garden hose and they'll look round again. The other problem, the brake judder, I've had before but that's due to pad deposits. Leave your track pads on for another week or so (I'm assuming you're using this car as your daily driver), then change back to the street pads. The pad deposits will be ground off over the course of the week and the street pads will feel just fine and you'll be good to go for another event (assuming these are not old, high mileage rotors).
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      09-13-2011, 09:28 PM   #19
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Air can get stuck in ABS pump/valves that's why BMW has a test plan on the gt1 for bleeding brakes. Just did this on a 645i u put pressure bleeder on the reservoir then run the bleeding procedure. Witch runs the ABS pump and pluses the valves a each wheel individually. Runs a couple times then tells u to move to the next wheel. Works great bt scan tool might do it not sure but having the gt1 is a huge help. You can do some awesome stuff to the old smg trans
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      09-13-2011, 11:45 PM   #20
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I find the same with race pads. They always feel a bit soft, but firm up just fine on the track. When I put the stock pads back in the pedal is immediately firm again. Been this way with all of my cars.

Do you install the race pads in the same position in the caliper each time? If you are rotating them (which can be done for longevity) you will also experience what you are describing because the pads wear differently and may not mate completely flush with the rotor. I number my pads to keep track of where the pads are positioned. My last track day was not a TT event so I rotated my pads and it took 3 sessions to get good brake feel back.

Everything you described sounds normal to me and I wouldn't worry about it.
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      09-13-2011, 11:56 PM   #21
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Quote:
Originally Posted by Sleeper519 View Post
Changed all 4 pads out (to Pagid-19s) yesterday for track event next weekend and now have soft brake pedal--actually, feels like mostly more travel to floor, not necessarily spongy, but feels terrible! I did NOT bleed this time, having done a full flush last month for track day. Brake fluid reservoir is topped off at max level with Motul 600.

It's the bleed isn't it? I should just do it, right?

But there's no way I could have intrduced air into the system by just changing the pads. It's definitely different than before though. I also haven't bedded them in yet.

Anything else it could be?

Thanks.
A proper bed in should take care of it. You are mating up two fresh surfaces, until they mate up perfectly, you will get a sensation of a soft peddle. It's from pad compression on a leading edge most likely.
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      07-21-2018, 10:20 PM   #22
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i realize it's an old thread that i'm bumping, but I've had the same experience - swapped out what I assume were stock pads, which had a linear bite right at the top for Ferodo DS2500s, increased pedal travel immediately after. I did open the brake fluid reservoir to let out some fluid since the pistons were getting pushed back a decent bit. Right after, no braking force until a third of the way down and then it bites relatively hard.

Bed & bleed?


Update - swapped the OEM pads back on, pedal firm again. Then swapped back to the Ferodos, and immediately lost that top 1/3rd firm pedal. I've no idea what the reason for this is.

Last edited by kyoo; 07-23-2018 at 11:06 PM..
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