Continuous spongy/low brake pedal
#1
Team Owner
Thread Starter
Continuous spongy/low brake pedal
My car has had this minor issue since it was brand new. My GF at the time had an '05 TL so when I bought my '06 in Dec of '05 I was used to the way the TL drives. I immediately noticed the brakes on mine had a different feel. The pedal was lower and with more slop. It seemed like once this slop was taken up it was relatively firm with little travel once the brakes were applied. It's slightly different than the traditional air in the lines spongy feel. I lived with it for all these years because its not too bad.
I've adjusted the rod length at the pedal to its max to raise the pedal to no avail. I've run two different big brake kits both with braided stainless soft lines with no change to the problem. At that point the caliper and lines are eliminated.
I've run different fluids from stock to very thin (Motul 5.1) to thicker than stock (Motul RBF600) with little change. I've flushed the system almost every year, followed the factory sequence as well as my own sequence.
Every once in a while if its been a long time since I've hit ABS I'll hit it a few times and pedal height and firmness is back better than stock for a day or two. I should mention that as part of the bleeding process I would bleed, cycle the ABS several times and bleed again.
Now I'm ready to begin replacing parts. I hated when I would track the car that I had the additional travel and slop in the system. It's equally annoying on the street especially when I need a quick response. I'm guessing it might be in the ABS pump but I'm probably going with the master cylinder first since its cheap.
So the question is, is there any known problem with the brake system that causes air in the system like problems that are impossible to get rid of? I seem to remember a very old thread where a guy had this problem and eventually lost his brakes and totaled the car but I can't find it yet. It's not a bleeding or fluid issue and its not a caliper or soft line issue. The problem is somewhere above that.
I've adjusted the rod length at the pedal to its max to raise the pedal to no avail. I've run two different big brake kits both with braided stainless soft lines with no change to the problem. At that point the caliper and lines are eliminated.
I've run different fluids from stock to very thin (Motul 5.1) to thicker than stock (Motul RBF600) with little change. I've flushed the system almost every year, followed the factory sequence as well as my own sequence.
Every once in a while if its been a long time since I've hit ABS I'll hit it a few times and pedal height and firmness is back better than stock for a day or two. I should mention that as part of the bleeding process I would bleed, cycle the ABS several times and bleed again.
Now I'm ready to begin replacing parts. I hated when I would track the car that I had the additional travel and slop in the system. It's equally annoying on the street especially when I need a quick response. I'm guessing it might be in the ABS pump but I'm probably going with the master cylinder first since its cheap.
So the question is, is there any known problem with the brake system that causes air in the system like problems that are impossible to get rid of? I seem to remember a very old thread where a guy had this problem and eventually lost his brakes and totaled the car but I can't find it yet. It's not a bleeding or fluid issue and its not a caliper or soft line issue. The problem is somewhere above that.
The following users liked this post:
jon2000 (02-13-2013)
#3
Team Owner
Thread Starter
That's what I'm worried about except it's been 115,000 miles since and I can't say it's gotten worse. Was it the seals in yours? Also, was the pedal reasonably firm once you got the slop out?
#4
Moderator
iTrader: (1)
I changed the master cylinder; as you recall, I DIDNT WANT ANY of that petroleum product in my braking system.
a year later; my brake pedal felt spongy and droopy and dropped to the floor. Since, I've experienced it before with my MC and petroleum contamination; I immediately knew it was the MC.
When i went to change it out the 2nd time; I noticed i did not take off the OLD ROD SEAL.
so, there were two rod seals against the rod and firewall, letting air in.
I know that MC's in older honda's like to go out.
but this is all i can offer you. hope it helps.
Edit* the 2nd time changing out the MC; I thought I was bleeding incorrectly. could not get a pedal feel that i liked.
had my friend come over and help me. we bled it like 5 times. it still felt spongy to me.
then we got the smart idea to see if his pedal felt the same.
he has the same car; and sure enough the pedal feel felt the same.
Could be mind trick thing, ya know?
a year later; my brake pedal felt spongy and droopy and dropped to the floor. Since, I've experienced it before with my MC and petroleum contamination; I immediately knew it was the MC.
When i went to change it out the 2nd time; I noticed i did not take off the OLD ROD SEAL.
so, there were two rod seals against the rod and firewall, letting air in.
I know that MC's in older honda's like to go out.
but this is all i can offer you. hope it helps.
Edit* the 2nd time changing out the MC; I thought I was bleeding incorrectly. could not get a pedal feel that i liked.
had my friend come over and help me. we bled it like 5 times. it still felt spongy to me.
then we got the smart idea to see if his pedal felt the same.
he has the same car; and sure enough the pedal feel felt the same.
Could be mind trick thing, ya know?
Last edited by justnspace; 02-13-2013 at 01:06 PM.
#5
There was a TSB for the ABS/VSA Modulator in the 03-07 Accord; the faulty modulators allow air into the system. The part numbers appear to be different between the V6 Accords and the TLs, but it could be the problem.
Supposedly, you can bleed the modulator using the two-person method by bleeding each of the six flare nuts on the modulator itself, one at a time.
Supposedly, you can bleed the modulator using the two-person method by bleeding each of the six flare nuts on the modulator itself, one at a time.
Last edited by gwiffer; 02-13-2013 at 01:41 PM.
The following 2 users liked this post by gwiffer:
justnspace (02-13-2013),
YeuEmMaiMai (09-19-2014)
#7
Team Owner
Thread Starter
That sounds like it could be the problem, especially since it seems like no matter what I keep getting air in the system and sometimes pulsing the ABS will temporarily help. I'll take a look today. Thanks.
Trending Topics
#8
The TSB calls for replacing the modulator, but I would just try to bleed it if you can. Mine are kind of rusty, so I would definitely spray some WD or PBlaster on them beforehand.
#9
Team Owner
Thread Starter
I have to wonder if this has anything to do with my ABS being ultra conservative. The car stops very quick but if you just stomp the pedal the ABS leaves a lot on the table.
#11
Instructor
My car has had this minor issue since it was brand new. My GF at the time had an '05 TL so when I bought my '06 in Dec of '05 I was used to the way the TL drives. I immediately noticed the brakes on mine had a different feel. The pedal was lower and with more slop. It seemed like once this slop was taken up it was relatively firm with little travel once the brakes were applied. It's slightly different than the traditional air in the lines spongy feel. I lived with it for all these years because its not too bad.
Thanks,
Jon
#12
Drifting
IHC...checking the service records from my 08 prior to me buying it a year ago I found the the modulator was changed about 2 years prior to my purchase. Looks like Acura did it under warranty. Also about that TSB...I have found that parts numbers are different for Hondas and Acuras, even for identical parts. Isn't that correct?
#14
Chapter Leader (Southern Region)
I had a 94 Camry with the same symptoms.. to the extreme.. I almost ended up skidding into the back of a flatbed. Was able to maneuver to the shoulder.. no brakes, pumped to shit and just held the pedal down until 10 feet from the intersection the brakes kicked in with a billow of pad and tire smoke 20-30 feet in front of me. ..still alive so it's all good. ![what](https://acurazine.com/forums/images/smilies/what.gif)
I replaced the MC and brake booster, both were toast. Booster was hanging not allowing vacuum to return and it would feel soft once stopped and at times go all the way to the floor board. I didn't know how bad it was until I replaced both. It was like I dropped a viagra pill in the MC and the booster had just discovered internet porn.
You sure it's not your aggressive driving that has caused the pads to be on the edge of replacement skimming your fluid level to an abysmally bleak level![Bite Lip](https://acurazine.com/forums/images/smilies/bitelip.gif)
Somewhat relevant, my buddy came over complaining that his brakes were screeching.. I took a look and said there's your problem, you don't have any pad left, nor rotor (half the outside rotor on the rears was eaten away, metal-on-metal). Poor brake bias (Ford Edge).. 85% original front pad left, -% rear pad life.
![what](https://acurazine.com/forums/images/smilies/what.gif)
I replaced the MC and brake booster, both were toast. Booster was hanging not allowing vacuum to return and it would feel soft once stopped and at times go all the way to the floor board. I didn't know how bad it was until I replaced both. It was like I dropped a viagra pill in the MC and the booster had just discovered internet porn.
You sure it's not your aggressive driving that has caused the pads to be on the edge of replacement skimming your fluid level to an abysmally bleak level
![Bite Lip](https://acurazine.com/forums/images/smilies/bitelip.gif)
Somewhat relevant, my buddy came over complaining that his brakes were screeching.. I took a look and said there's your problem, you don't have any pad left, nor rotor (half the outside rotor on the rears was eaten away, metal-on-metal). Poor brake bias (Ford Edge).. 85% original front pad left, -% rear pad life.
#15
Racer
You know, I have noticed this too and thought I was the only one. I drove an ILX at Mid-Ohio for Acura's racing event, I loved the brakes, they had immediate engagement and were firm as all hell. So I set about getting this feel for my car, I have added SS lines all around, kept stock fluid, Fastbrakes Wilwood 4-pot 2-piece rear BBK, brand new pads for the front. I just re-bleed the front left caliper and my pedal feel got dramatically better and had close to that immediate engagement for about a week. Then it get's slushy again but all i have to do is pump the brakes until i cannot anymore when it's off then start the car and it get's firm like before. I am completely stumped with mine as well.
#16
Chapter Leader (Southern Region)
Talking about brake bias.. you might want to reconsider that rear BBK.
![Bite Lip](https://acurazine.com/forums/images/smilies/bitelip.gif)
![RIP](https://acurazine.com/forums/images/smilies/smitty.gif)
#17
Team Owner
Thread Starter
You know, I have noticed this too and thought I was the only one. I drove an ILX at Mid-Ohio for Acura's racing event, I loved the brakes, they had immediate engagement and were firm as all hell. So I set about getting this feel for my car, I have added SS lines all around, kept stock fluid, Fastbrakes Wilwood 4-pot 2-piece rear BBK, brand new pads for the front. I just re-bleed the front left caliper and my pedal feel got dramatically better and had close to that immediate engagement for about a week. Then it get's slushy again but all i have to do is pump the brakes until i cannot anymore when it's off then start the car and it get's firm like before. I am completely stumped with mine as well.
#19
Chapter Leader (Southern Region)
Last guy I know who did a rear BBK on a 3G ended up in a wall.
![Whistle](https://acurazine.com/forums/images/smilies/whistle.gif)
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csmeance (10-02-2014)
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