How to bench bleed a brake master cylinder.
05-24-2004, 07:35 AM
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How to bench bleed a brake master cylinder.
The master cylinder on my '94 VX had 224K miles on it and the seals were beginning to leak. I decided to upgrade to the 15/16 size MC that is found in the '91 Civic EX 4-Door. The part number is 46100-SH4-A11. The mention of this upgrade is found in this thread -> https://honda-tech.com/zerothread?id=364783
First, pull your new master cylinder out of the packaging. If you bought a new one from Honda (I did) then it will come with two plastic plugs that plug up the brake line ports. I couldn't find a MC bench bleed kit that would work, so instead I rigged up my own kit using some clear plastic tubing and a cut up rubber jump rope.
I cut the end of the plastic port plugs off with a utility knife, creating a hollow plug. The plastic tubing fit inside the plugs tight. Then I inserted the plugs with tubes in them into the ports. You can see this below.
You need to run the tubing into the top of the reservoir. You need to secure it some how, so they stay put when you bleed the MC. I used a zip tie.
I just held the MC level in my hand and filled it about 3/4 full with brake fluid. Then I used the heel of my hand to pump the piston of the MC. Pump it slowy until you bleed all of the air out. It will take quite a few pumps. Don't compress the piston in all the way, just about 3/4 of the way in. I've been told you can damage the seals in the MC if you compress it all the way in while bleeding.
Some people put it in a vise and use a screwdriver handle to pump the piston. It's not really necessary, pumping the piston isn't that hard.
After the air is bled out, leave all the bleeding apparatus in place. Then install it in place of the old MC.
With the new MC in place of the old, remove the bleeding tubes, and connect the hard brake lines to the MC. Keep a rag underneath the MC to catch any brake fluid that drips out. It'll eat your paint alive. Yes, I know the engine bay is dirty. I don't really care, it's my beater.
Fill the MC up with brake fluid and put the cap on. Bleed the rest of the brake system if necessary. It wasn't necessary on my car. The pedal was rock hard.
Using this larger MC was an EXCELLENT upgrade. The brake feel is so solid and the it engages with less pedal travel. It makes me have much more confidence in my car's safety.
FYI: I am using stock sized Brembo rotors up front with some Axxis pads. The rears are stock drums.
Modified by boomslang at 9:10 AM 7/13/2005
First, pull your new master cylinder out of the packaging. If you bought a new one from Honda (I did) then it will come with two plastic plugs that plug up the brake line ports. I couldn't find a MC bench bleed kit that would work, so instead I rigged up my own kit using some clear plastic tubing and a cut up rubber jump rope.
I cut the end of the plastic port plugs off with a utility knife, creating a hollow plug. The plastic tubing fit inside the plugs tight. Then I inserted the plugs with tubes in them into the ports. You can see this below.
You need to run the tubing into the top of the reservoir. You need to secure it some how, so they stay put when you bleed the MC. I used a zip tie.
I just held the MC level in my hand and filled it about 3/4 full with brake fluid. Then I used the heel of my hand to pump the piston of the MC. Pump it slowy until you bleed all of the air out. It will take quite a few pumps. Don't compress the piston in all the way, just about 3/4 of the way in. I've been told you can damage the seals in the MC if you compress it all the way in while bleeding.
Some people put it in a vise and use a screwdriver handle to pump the piston. It's not really necessary, pumping the piston isn't that hard.
After the air is bled out, leave all the bleeding apparatus in place. Then install it in place of the old MC.
With the new MC in place of the old, remove the bleeding tubes, and connect the hard brake lines to the MC. Keep a rag underneath the MC to catch any brake fluid that drips out. It'll eat your paint alive. Yes, I know the engine bay is dirty. I don't really care, it's my beater.
Fill the MC up with brake fluid and put the cap on. Bleed the rest of the brake system if necessary. It wasn't necessary on my car. The pedal was rock hard.
Using this larger MC was an EXCELLENT upgrade. The brake feel is so solid and the it engages with less pedal travel. It makes me have much more confidence in my car's safety.
FYI: I am using stock sized Brembo rotors up front with some Axxis pads. The rears are stock drums.
Modified by boomslang at 9:10 AM 7/13/2005
05-24-2004, 07:53 AM
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Re: How to bench bleed a brake master cylinder. (boomslang)
Very good DIY. Lovin the jump rope 
Would I have to do this when installing 4 wheel GSR disc brakes & MC/BB? I thought I would just have to bleed the whole system normally.
Would I have to do this when installing 4 wheel GSR disc brakes & MC/BB? I thought I would just have to bleed the whole system normally.
05-24-2004, 08:31 AM
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Re: How to bench bleed a brake master cylinder. (Built2Spill)
informative write up....
just wonderin is that Master Cylinder used? or brand new?
and where did you get the master cylinder ?
just wonderin is that Master Cylinder used? or brand new?
and where did you get the master cylinder ?
05-24-2004, 09:06 AM
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Re: How to bench bleed a brake master cylinder. (EL-Driver)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by EL-Driver »</TD></TR><TR><TD CLASS="quote">informative write up....
just wonderin is that Master Cylinder used? or brand new?
and where did you get the master cylinder ?</TD></TR></TABLE>
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by boomslang »</TD></TR><TR><TD CLASS="quote">First, pull your new master cylinder out of the packaging. If you bought a new one from Honda (I did) then it will come with two plastic plugs that plug up the brake line ports. I couldn't find a MC bench bleed kit that would work, so instead I rigged up my own kit using some clear plastic tubing and a cut up rubber jump rope.</TD></TR></TABLE>
just wonderin is that Master Cylinder used? or brand new?
and where did you get the master cylinder ?</TD></TR></TABLE>
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by boomslang »</TD></TR><TR><TD CLASS="quote">First, pull your new master cylinder out of the packaging. If you bought a new one from Honda (I did) then it will come with two plastic plugs that plug up the brake line ports. I couldn't find a MC bench bleed kit that would work, so instead I rigged up my own kit using some clear plastic tubing and a cut up rubber jump rope.</TD></TR></TABLE>
05-24-2004, 09:44 AM
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Re: How to bench bleed a brake master cylinder. (boomslang)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by boomslang »</TD></TR><TR><TD CLASS="quote">Don't compress the piston in all the way, just about 3/4 of the way in. I've been told you can damage the seals in the MC if you compress it all the way in while bleeding. </TD></TR></TABLE>
I've heard of this as well, however it pertained to bleeding the brakes with the original MC installed. When normally applying pedal pressure, the piston does not go all the way in and the area that it does not touch can become rusted. So when you bleed the brakes normally and do the the 3-pump/hold/break the bleeder bolt loose, at this point you can push the piston farther into this rusted zone tearing the seals.
I've heard of this as well, however it pertained to bleeding the brakes with the original MC installed. When normally applying pedal pressure, the piston does not go all the way in and the area that it does not touch can become rusted. So when you bleed the brakes normally and do the the 3-pump/hold/break the bleeder bolt loose, at this point you can push the piston farther into this rusted zone tearing the seals.
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06-18-2004, 01:09 AM
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Re: How to bench bleed a brake master cylinder. (EE_Chris)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by EE_Chris »</TD></TR><TR><TD CLASS="quote">
I've heard of this as well, however it pertained to bleeding the brakes with the original MC installed. When normally applying pedal pressure, the piston does not go all the way in and the area that it does not touch can become rusted. So when you bleed the brakes normally and do the the 3-pump/hold/break the bleeder bolt loose, at this point you can push the piston farther into this rusted zone tearing the seals.</TD></TR></TABLE>
rust? i dont see how there should be any water for rust to form. dont you need oxygen for rust to form aswell? i jus cant see how rust will form when there is no air or water inside the mc. some one explain or elaborate so a dumbass like me can understand.
I've heard of this as well, however it pertained to bleeding the brakes with the original MC installed. When normally applying pedal pressure, the piston does not go all the way in and the area that it does not touch can become rusted. So when you bleed the brakes normally and do the the 3-pump/hold/break the bleeder bolt loose, at this point you can push the piston farther into this rusted zone tearing the seals.</TD></TR></TABLE>
rust? i dont see how there should be any water for rust to form. dont you need oxygen for rust to form aswell? i jus cant see how rust will form when there is no air or water inside the mc. some one explain or elaborate so a dumbass like me can understand.
06-18-2004, 06:51 AM
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Re: How to bench bleed a brake master cylinder. (carbine)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by carbine »</TD></TR><TR><TD CLASS="quote">Rust can occur without water and air.</TD></TR></TABLE>
Wrong....Rust can only occur in the presence of oxygen, more specifically water, because water is amphoteric (can act as an acid or a base) when it comes in contact with metal the oxygen in water removes electrons from the surface atoms of the metal and bonds with the metal to form oxides which is basically rust. That is why rust deteriorates metal, because the water is acting like an acid breaking it down.
Wrong....Rust can only occur in the presence of oxygen, more specifically water, because water is amphoteric (can act as an acid or a base) when it comes in contact with metal the oxygen in water removes electrons from the surface atoms of the metal and bonds with the metal to form oxides which is basically rust. That is why rust deteriorates metal, because the water is acting like an acid breaking it down.
06-18-2004, 10:51 AM
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Re: How to bench bleed a brake master cylinder. (hatchdrvr)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by hatchdrvr »</TD></TR><TR><TD CLASS="quote">
Wrong....Rust can only occur in the presence of oxygen, more specifically water, because water is amphoteric (can act as an acid or a base) when it comes in contact with metal the oxygen in water removes electrons from the surface atoms of the metal and bonds with the metal to form oxides which is basically rust. That is why rust deteriorates metal, because the water is acting like an acid breaking it down. </TD></TR></TABLE>
nicely said.
so then whats all this rust bullshit talk all about? precaution?
Wrong....Rust can only occur in the presence of oxygen, more specifically water, because water is amphoteric (can act as an acid or a base) when it comes in contact with metal the oxygen in water removes electrons from the surface atoms of the metal and bonds with the metal to form oxides which is basically rust. That is why rust deteriorates metal, because the water is acting like an acid breaking it down.
</TD></TR></TABLE>nicely said.
so then whats all this rust bullshit talk all about? precaution?
06-18-2004, 11:29 AM
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Re: How to bench bleed a brake master cylinder. (Mr. Choi)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Mr. Choi »</TD></TR><TR><TD CLASS="quote">nicely said.
so then whats all this rust bullshit talk all about? precaution?</TD></TR></TABLE>
I've read, not experienced, that this has happened on high mileage and poorly maintained vehicles (read: not changing the brake fluid regularly).
Brake fluid is hygroscopic - it absorbs water real easy.
so then whats all this rust bullshit talk all about? precaution?</TD></TR></TABLE>
I've read, not experienced, that this has happened on high mileage and poorly maintained vehicles (read: not changing the brake fluid regularly).
Brake fluid is hygroscopic - it absorbs water real easy.
06-18-2004, 01:14 PM
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Re: How to bench bleed a brake master cylinder. (boomslang)
Very nice write up! Cool pics also. Btw i was told not to upgrade my mc if your not swapping the rear drums for disks. They told me that my brakes would lock up is this true has this happened to u ever since u made the upgrade.
Btw i was told not to upgrade my mc if your not swapping the rear drums for disks. They told me that my brakes would lock up is this true has this happened to u ever since u made the upgrade.
06-18-2004, 03:45 PM
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Re: How to bench bleed a brake master cylinder. (civic_type_r)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by civic_type_r »</TD></TR><TR><TD CLASS="quote">Very nice write up! Cool pics also. Btw i was told not to upgrade my mc if your not swapping the rear drums for disks. They told me that my brakes would lock up is this true has this happened to u ever since u made the upgrade.</TD></TR></TABLE>
No, they work great! Never been better!
I paid $140 for the new MC at http://www.hondaautomotiveparts.com
Btw i was told not to upgrade my mc if your not swapping the rear drums for disks. They told me that my brakes would lock up is this true has this happened to u ever since u made the upgrade.</TD></TR></TABLE>No, they work great! Never been better!
I paid $140 for the new MC at http://www.hondaautomotiveparts.com
06-18-2004, 04:31 PM
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Re: How to bench bleed a brake master cylinder. (EE_Chris)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by EE_Chris »</TD></TR><TR><TD CLASS="quote">
I've read, not experienced, that this has happened on high mileage and poorly maintained vehicles (read: not changing the brake fluid regularly).</TD></TR></TABLE>
It is not so much rust, but build up.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by boomslang »</TD></TR><TR><TD CLASS="quote">Don't compress the piston in all the way, just about 3/4 of the way in. I've been told you can damage the seals in the MC if you compress it all the way in while bleeding</TD></TR></TABLE>
You have to make sure that you bleed both primary and secondary. If you do not push it in far enough, you will not bleed the secondary and you will have air in the system.
I've read, not experienced, that this has happened on high mileage and poorly maintained vehicles (read: not changing the brake fluid regularly).</TD></TR></TABLE>
It is not so much rust, but build up.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by boomslang »</TD></TR><TR><TD CLASS="quote">Don't compress the piston in all the way, just about 3/4 of the way in. I've been told you can damage the seals in the MC if you compress it all the way in while bleeding</TD></TR></TABLE>
You have to make sure that you bleed both primary and secondary. If you do not push it in far enough, you will not bleed the secondary and you will have air in the system.
06-18-2004, 07:40 PM
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Re: How to bench bleed a brake master cylinder. (EE_Chris)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by EE_Chris »</TD></TR><TR><TD CLASS="quote">
I've read, not experienced, that this has happened on high mileage and poorly maintained vehicles (read: not changing the brake fluid regularly).
Brake fluid is hygroscopic - it absorbs water real easy.
</TD></TR></TABLE>
exactly, actually it's hydroscopic, but we won't split hairs.
I've read, not experienced, that this has happened on high mileage and poorly maintained vehicles (read: not changing the brake fluid regularly).
Brake fluid is hygroscopic - it absorbs water real easy.
</TD></TR></TABLE>
exactly, actually it's hydroscopic, but we won't split hairs.
06-18-2004, 08:06 PM
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Re: (nsxmatt)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by nsxmatt »</TD></TR><TR><TD CLASS="quote">$187.20 is retail from the dealer.</TD></TR></TABLE>
i got a refurb. 15/16 m/c from pep boys for $58 lifetime warranty
i looked at that price and shat myself when i was looking for one(180.00)
i got a refurb. 15/16 m/c from pep boys for $58
lifetime warranty i looked at that price and shat myself when i was looking for one(180.00)
06-19-2004, 09:11 AM
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Re: How to bench bleed a brake master cylinder. (civic_type_r)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by civic_type_r »</TD></TR><TR><TD CLASS="quote">Hey i forgot to ask u what camera do u own those are some clean pics!</TD></TR></TABLE>
It's a Sony DSC-S85, 4.1 megapixel. They no longer manufacture it now though.
It's a Sony DSC-S85, 4.1 megapixel. They no longer manufacture it now though.
06-23-2004, 06:49 AM
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Re: How to bench bleed a brake master cylinder. (boomslang)
check it out guys i informed myself autozone has the 91 civic ex mc remanufactured for 51.00 w/ lifetime warranty. Not to shabby...huh!
06-23-2004, 06:58 AM
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Re: How to bench bleed a brake master cylinder. (civic_type_r)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by civic_type_r »</TD></TR><TR><TD CLASS="quote">check it out guys i informed myself autozone has the 91 civic ex mc remanufactured for 51.00 w/ lifetime warranty. Not to shabby...huh! </TD></TR></TABLE>
Over the years, I've had more than my fill of reman Autozone parts. Blah! Give me OEM Honda!
</TD></TR></TABLE>Over the years, I've had more than my fill of reman Autozone parts. Blah! Give me OEM Honda!
06-23-2004, 07:24 AM
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Re: How to bench bleed a brake master cylinder. (carbine)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by carbine »</TD></TR><TR><TD CLASS="quote">Rust can occur without water and air.</TD></TR></TABLE>
Chemical formula for rust is Fe2O3 (iron oxide). So as you can see, gotta have some oxygen in there from somewhere...
Chemical formula for rust is Fe2O3 (iron oxide). So as you can see, gotta have some oxygen in there from somewhere...