Changing the Master Brake Cylinder

[Zexell]

My master cylinder seal is leaking and I need to change my master cylinder but the damn shops around here are charging me 300+. I tried to search for it but not many ppl seem to be writing up about it. Is it easy? Is it hard?? A friend says just replace the master cylinder and bleed it. Is that all to it? Thanks in advance.

 

[wishihadatalon]

My master cylinder seal is leaking and I need to change my master cylinder but the damn shops around here are charging me 300+. I tried to search for it but not many ppl seem to be writing up about it. Is it easy? Is it hard?? A friend says just replace the master cylinder and bleed it. Is that all to it? Thanks in advance.

It is pretty simple to do. First you are going to want to get enough fluid out of the res and the lines so that when you disconnect the lines, you don't want to get brake fluid on your paint. I would probably get the fluid out by bleeding the back brakes (Stock system has 2 lines going to the prop valve. Of those 2 lines the prop valve sends fluid from each one to opposite sides of the car.) After your fluid is low enough you can disconnect the lines from the res to the master cylinder and then the lines that go to the prop vavle. Use a 10mm line wrench, and use a rag to catch the extra fluid. (If it is starting to turn without the fitting, I would give up on the line wrench and use a pair of vice grips.) After that you will want to loosen the 12mm or the 14mm that hold the master cylinder to the brake booster. After that it should be ready to pull out. Follow the instructions that come with the new master. You will want to add fluid with it off of the car and prime the cylinder (there is a term for this but I forgot what it was). This prevents adding air to the lines when you put the new master in and add fluid. Install is the same as taking it out just reverse.

If you are doing this it might be a good time to do a full fluid flush and put a nice quality fluid in.

I hope this helped.

 

[Zexell]

It is pretty simple to do. First you are going to want to get enough fluid out of the res and the lines so that when you disconnect the lines, you don't want to get brake fluid on your paint. I would probably get the fluid out by bleeding the back brakes (Stock system has 2 lines going to the prop valve. Of those 2 lines the prop valve sends fluid from each one to opposite sides of the car.) After your fluid is low enough you can disconnect the lines from the res to the master cylinder and then the lines that go to the prop vavle. Use a 10mm line wrench, and use a rag to catch the extra fluid. (If it is starting to turn without the fitting, I would give up on the line wrench and use a pair of vice grips.) After that you will want to loosen the 12mm or the 14mm that hold the master cylinder to the brake booster. After that it should be ready to pull out. Follow the instructions that come with the new master. You will want to add fluid with it off of the car and prime the cylinder (there is a term for this but I forgot what it was). This prevents adding air to the lines when you put the new master in and add fluid. Install is the same as taking it out just reverse.

If you are doing this it might be a good time to do a full fluid flush and put a nice quality fluid in.

I hope this helped.

Just making sure, to sum it all up. I flush out my old brake fluid through the rear brake, and dry the res as much as I could, then disconnect the res from the master cylinder. Replace master cylinder.

I have a question, can I just put the new master cylinder on put the fluid and bleed it instead of priming the new cylinder?

Appreciate it. What would be some nice quality fluid????

 

[wishihadatalon]

Just making sure, to sum it all up. I flush out my old brake fluid through the rear brake, and dry the res as much as I could, then disconnect the res from the master cylinder. Replace master cylinder.

I have a question, can I just put the new master cylinder on put the fluid and bleed it instead of priming the new cylinder?

Appreciate it. What would be some nice quality fluid????

I don't see why you shouldn't be able to.

 

[laserspeeddemon]

Well you didn't look very well.

http://www.dsmtuners.com/forums/showpost.php?p=1831301&postcount=10

The master is a PITA. and I mean it. But I got it down to a sceince.

First you will need a friend to help
Secondly here is a walk through.,
Removal
-Drop the lower dash under the steering column. (4 screws)
-Left the hood release lever and there will be 2 brass screws there, remove them
-Take the wire out of the hood release lever
-Remove the lower dash trim.
-REMOVE THE DRIVER SEAT (trust me this will help ALOT) 2, 14mm bolts, and 2, 14mm nuts, + one 12mm bolt that holds the belt to the seat.

Some say these next several steps are not necessary, I felt it cut a few hours out of work
--------------------------------------------------------------------------------------------------
-Take the steering cover wheel/horn off (1 screw at the bottom)
-Remove all the Steering wheel trim (screws on the bottom, can't remember how many)
-Remove the steering wheel nut (17-19 mm, can't remember)
-Either use a puller to get the wheel off, or if you are buff like me use pure muscle.
-Disconnect ALL the harnesses along the top of steering column.
-Drop the Steering column ( 8 bolts, all 12mm, four up top, four near the bottom)
IT DOES NOT NEED TO BE REMOVED, just able to move around, so you can work around it.
--------------------------------------------------------------------------------------------------
-Remove any Heating/Cooling ducts your feel is in your way.

Now you have full access to the master clutch assembly inside the car. There is a U-shaped clip that has a bolt (it doesn't have threads) going through it and the clutch pedal assmebly. It is held in by a cotter pin remove the cotter pin and "finagle" the bolt out, it pushes right out, there is no need to use a ratchet. Catch the washer that falls out.

Under the hood.
-This part is EASY, as long as you follow my directions!!!!
-Take the clutch line out the master cyclinder. It is a 10mm eyebolt. User a flare wrench. USE A FLARE WRENCH, USE A FLARE WRENCH. If you use a regular wrench you will destroy the eyebolt and have to replace the upper hardline for the clutch.
-There are two 12mm nuts that hold the master cylinder to the wall. The master cyclinder is the Skinner one. remove the 2 12mm nuts. And it will come right out.
-------------------------------------------------------------------------------
Installation
I will refer the master cyclinder as CMC (for Clutch Master Cylinder)
--------------------------------------------------------------------------
-First prime the CMC, put new DOT3 Break Fluid in it and pump it.
-Second you want to adjust the U-Clip till the bolt is about halfway on the threads and tighten the nut against it.
-Have your friend hold the new CMC in the hood. Don't bolt it down yet. He will need to move it around and you will need to move the pedal around until you can get the bolt through the clutch pedal assembly.
-Once you get the bolt through, put the bolt washer on the bolt and insert a new cotter pin and bind it.

Once this is down the rest is a cake-walk. The bolt, washer, pin installation is the hardest part IMO.

-Put the 2, 12mm nuts back in (in the engine back)
-Finger tighten the eyebolt in, and then use a 10mm flare-nut wrench to tight in the rest of the way down.

-Putting the Steering wheel column back up is another 2 man job, you will have to have your friend hold it up while you put the 8, 12mm bolts back in.
-Connect the harness connectors.
-Reinstall the trim on the Steering Column
-Reinstall the hood release lever
-Reinstall the lower dash trim.
-Reinstall Seats

BLEED, BLEED, BLEED the clutch pedal.
-----------------------------------------------------------------------------------

Take it for a test drive, you may need to adjust the U-Clip, but other then that, your done.

**EDIT** Well I look like and ass now. I just noticed this was a brake MC and not a clutch MC.

 

[wishihadatalon]

Well you didn't look very well.

http://www.dsmtuners.com/forums/showpost.php?p=1831301&postcount=10



**EDIT** Well I look like and ass now. I just noticed this was a brake MC and not a clutch MC.

You should read the title. The brake master cylinder is easy to replace. The clutch master is also very easy if you have the right wrenches.

 

[Defiant]

The job is very similar to the clutch master:
http://www.plymouthlaser.com/masterc.htm
I don't agree with the idea of running air into the brake system. The fronts and rears are crossed- you won't drain just one system by opening the rears.

 

[Zexell]

Thx for all the input fellas. I'm happy to say that it was a success.

I used a syringe and a turkey baster to suck the master cylinder and res dry. Then disconnected everything carefully, replaced master cylinder, filled the brake fluid, bled everything starting with the farthest from the master cylinder.

The first wheel I bled had a ton of air in it. After about a good 10 min of bleeding just one wheel, I finally got almost all the air out. I bled the rest and drove around for a bit. It feels good to not pump my brakes anymore. Damn seal.

Cost was about 80 bux, and it took about 3 hours, but if I had to do it again, probably 2 hours tops.

 

[wishihadatalon]

The job is very similar to the clutch master:
http://www.plymouthlaser.com/masterc.htm
I don't agree with the idea of running air into the brake system. The fronts and rears are crossed- you won't drain just one system by opening the rears.

Wrong. The right front and the left rear are tied into one side of the proportioning valve that is fed from one line from the master cylinder and the left front and the right rear are on set. They do this so that you still have front braking if you drop one brake line. You will not get fluid out of the front lines but you will get fluid out of the lines that feed each front and each rear just by opening up the rear bleeders.

Putting air into the system is less than ideal but if you do a very thorough flush then you shouldn't have a problem.

also doing a brake master cylinder requires no under dash work. Everything is inside the engine bay (unless you are changing the brake booster) it is far easier than a clutch master cylinder (which isn't even hard despite having to reach under the dash).

 

[eclipsh]

also doing a brake master cylinder requires no under dash work. Everything is inside the engine bay (unless you are changing the brake booster) it is far easier than a clutch master cylinder (which isn't even hard despite having to reach under the dash).

Ummm.... what about disconnecting the push rod for the master cylinder under the dash?

 

[wishihadatalon]

Ummm.... what about disconnecting the push rod for the master cylinder under the dash?

ummmmmmmmmmmmmm................. its part of the booster. Have you ever had a brake master off?

Or better yet I will post some pic of it.
http://i168.photobucket.com/albums/u168/wishihadatalon/P1010121.jpg
http://i168.photobucket.com/albums/u168/wishihadatalon/P1010120.jpg

 

[squeak104]

The main reason for wanting to get the air out before putting it on the car (and the term is bench bleeding) is because on some cars the master cylinder sits at an angle bringing the front of it up, making it almost impossible to get all the air out. Also saves a lot of time, especially if you do it for money.

 

[wishihadatalon]

The main reason for wanting to get the air out before putting it on the car (and the term is bench bleeding) is because on some cars the master cylinder sits at an angle bringing the front of it up, making it almost impossible to get all the air out. Also saves a lot of time, especially if you do it for money.

Thanks for that. I couldn't for the life of me remember the term.

 

[eclipsh]

ummmmmmmmmmmmmm................. its part of the booster. Have you ever had a brake master off?

Or better yet I will post some pic of it.
http://i168.photobucket.com/albums/u168/wishihadatalon/P1010121.jpg
http://i168.photobucket.com/albums/u168/wishihadatalon/P1010120.jpg

Well I feel sheepish.... I just pulled mine out to fix the clutch pedal assembly and realized that too.... oops. <--- me.

 

[1LE]

The clutch master is also very easy if you have the right wrenches.

Yep, and assuming somebody didn't gorilla the lines to it... I had a horrible time breaking them loose, definitely WAY overtorqued. Other than that, the physical swap there is easy. The killer on the whole deal was trying to bleed the air out of that horrendously stupid big air trapping loop of a line that goes ABOVE the cyl and has no bleed point (at least on a 2g, haven't seen a 1g setup)... Factory procedure (pump pedal) didn't work (didn't expect it to). The hand-vac method didn't work either. Took a big air compressor setup to blast fluid through at a high rate to force the air out of there...

 

[laserspeeddemon]

The hardest part for me was getting my 6', 200lbs frame, fat ass arms up to the clutch master cylinder rod to put the dowel pin in, washer and cotter pin (and bending it).

Without moving the lower dash, seats, and steering columns there is no way I could get my hands in there to put those three parts in.

Well I feel sheepish.... I just pulled mine out to fix the clutch pedal assembly and realized that too.... oops. <--- me.

+1 for the rebuilding the pedal assembly, well worth it.

 

[1LE]

The hardest part for me was getting my 6', 200lbs frame, fat ass arms up to the clutch master cylinder rod to put the dowel pin in, washer and cotter pin (and bending it).

Without moving the lower dash, seats, and steering columns there is no way I could get my hands in there to put those three parts in.

That's weird. I'm 6'2", was 215lbs at the time, and have a rollcage I have to work around and I found it fairly easy. Had to tilt the wheel up as far as it would go (which is not as high as stock because I have gauges on it, and the wiring prevents it), but other than that, I just slid in under the dash on my back (which was across the seat and side rollbar) and it was real easy. Didn't move or remove anything else. Although, if I was claustrophobic it would have been bad. My gut was tight against the steering wheel, and I had to very cautiously move my arms due to limited space. Was also on the slightly upside down side of flat... Not anywhere near as bad as it sounds since it's about a 2 minute operation when you get right in there like that.

I don't understand you'r "bending" comment for the cotter pin... On my car it's a snap pin. No bending required.

*edit* Just saw that you have a 1g, perhaps they don't have as much room and have a different pin setup!

 

[wishihadatalon]

The hardest part for me was getting my 6', 200lbs frame, fat ass arms up to the clutch master cylinder rod to put the dowel pin in, washer and cotter pin (and bending it).

Without moving the lower dash, seats, and steering columns there is no way I could get my hands in there to put those three parts in.



+1 for the rebuilding the pedal assembly, well worth it.

6'1" and 235lbs and I have done it 3-4 times in the course of 30 minutes trying to get a friends car right. I will admit that it sucks that you have to twist like that, but it isn't that bad. If you want crappy under dash work, try the pedal assembly Worst 2hrs of my life

 

[D_Eclipse9916]

Thx for all the input fellas. I'm happy to say that it was a success.

I used a syringe and a turkey baster to suck the master cylinder and res dry. Then disconnected everything carefully, replaced master cylinder, filled the brake fluid, bled everything starting with the farthest from the master cylinder.

The first wheel I bled had a ton of air in it. After about a good 10 min of bleeding just one wheel, I finally got almost all the air out. I bled the rest and drove around for a bit. It feels good to not pump my brakes anymore. Damn seal.

Cost was about 80 bux, and it took about 3 hours, but if I had to do it again, probably 2 hours tops.

Just a question for ya, how did you end up proving your master cylinder seal was gone?

 

[ENICKB]

My master cylinder i just bought has a bleed valve on the side (phillips) and my stock doesnt. Whats the proper procedure to bleed this master cylibder with the bleed valve on the side? (92 tsi awd)

 

[bryanwheat]

That isn't a bleeder valve, that is to hold the piston from going to far back in the master. Just bench bleed it like you would any other master. Put fluid in the reservoir, than put your fingers over the holes and have someone slowly push the pedal. The fluid and air will push past your fingers but your finger will seal the hole up so it doesn't pull air back in. When you get fluid coming out screw in the lines and bleed the brakes starting with the one the furthest from the from working to the closest. Make sure to wash all the brake fluid from your engine bay because it will eat the paint.

 

[black97spyder]

Sorry to revive this thread but I just changed my brake master cylinder on my 2g AWD Talon and it has ABS. Is there any different bleeding procedures with ABS after changing the master cylinder??